fix(catalog): track promoted family partials required by 13-family baseline

app_sw_package_vs_solution.html + pre_construction_model_info_stacked.html were staged as new files but missing from prior commits. catalog frame_contracts.yaml already references both (family=table / family=list); this commit reconciles the on-disk partials with the registry so the 13-family baseline matches `git ls-tree` after a clean checkout. No marker work (data-region-id / data-content-unit-id) — that axis stays with the marker-injection issue. Disjoint from family/variant architecture refactor (별 tracking issue).
feat(#94 ): IMP-94 u1~u6 Layer A region/content marker injection (stamper + render_slide chain + 4 zones_data.append placement_markers + 35 parity tests)
2026-05-27 12:14:57 +09:00 · 2026-05-27 08:15:08 +09:00 · 2026-05-26 14:30:21 +09:00 · 2026-05-26 14:15:02 +09:00 · 2026-05-26 13:05:39 +09:00 · 2026-05-26 06:12:13 +09:00
108 changed files with 22576 additions and 1047 deletions
@@ -0,0 +1,71 @@
+name: Multi-MDX Regression (IMP-91)
+
+# IMP-#91 u13 — auto-gate the mdx 01-05 acceptance set on every push to main
+# and on PRs targeting main. Failure of any integration test blocks the
+# commit. JSON report is emitted via pytest-json-report (u12 dep) and
+# uploaded as an artifact for u14/u15 status-board updater consumption.
+#
+# [[feedback_validation_first_for_closed_issues]] — fresh subprocess per CI run.
+# [[feedback_auto_pipeline_first]] — no manual review queue; deterministic gate.
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  multi-mdx-regression:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python 3.11
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+          cache: pip
+
+      - name: Install Chrome and ChromeDriver
+        uses: browser-actions/setup-chrome@v1
+        with:
+          install-chromedriver: true
+
+      - name: Install project (dev extras + selenium)
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install -e ".[dev]"
+          python -m pip install "selenium>=4.20"
+
+      - name: Run multi-mdx regression tests
+        run: |
+          python -m pytest -q -m integration \
+            tests/integration/test_multi_mdx_regression.py \
+            --json-report \
+            --json-report-file=imp91-report.json \
+            --json-report-omit keywords streams
+
+      - name: Upload pytest JSON report
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: imp91-multi-mdx-report
+          path: imp91-report.json
+          if-no-files-found: warn
+
+      - name: Update status-board markers (IMP-91 u15)
+        if: always()
+        run: |
+          python scripts/update_status_board.py \
+            --report imp91-report.json \
+            --board docs/architecture/PHASE-Z-PIPELINE-STATUS-BOARD.md
+
+      - name: Upload updated status board
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: imp91-status-board
+          path: docs/architecture/PHASE-Z-PIPELINE-STATUS-BOARD.md
+          if-no-files-found: warn
@@ -1,99 +1,200 @@
 /**
- * BottomActions - 하단 액션 버튼 영역
+ * BottomActions — Step 22 footer wire-up (IMP-56 #90 u20).
 *
- * 생성하기, 다운로드, 연동하기 버튼 컴포넌트
+ * Two real endpoints replace the prior placeholder toasts:
+ *   • POST /api/connect  (u18 / Front/vite.config.ts) — copies
+ *     data/runs/<run_id>/phase_z2/final.html + assets/ into the cel mirror
+ *     (`<CEL_PROJECT_ROOT>/public/slides/<slug>.html`).
+ *   • POST /api/export   (u19 / Front/vite.config.ts) — returns a standalone
+ *     text/html body with every `url(assets/...)` ref inlined as base64
+ *     data URLs. Response is piped into a Blob → a[download] click chain so
+ *     the user receives `<run_id>.html` portable for file:// or any host.
+ *
+ * The prior `serializeSlidePlan` JSON-download path was a dead reference
+ * (the export never existed in slidePlanUtils) and is removed here — the
+ * "다운로드" button now means standalone HTML download via /api/export.
+ * Both buttons disable when no run is loaded (runMeta == null) so the
+ * UI cannot fire requests with an undefined run_id.
 */

+import { useState } from "react";
 import { Sparkles, Download, Link2, Loader2 } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { toast } from "sonner";
-import type { SlidePlan, UserSelection } from "../types/designAgent";
-import { serializeSlidePlan } from "../utils/slidePlanUtils";
+import type { SlidePlan } from "../types/designAgent";
+import type { RunMeta } from "../services/designAgentApi";
+import { deriveUserOverridesKey } from "../utils/slidePlanUtils";
+
+// ─── pure request builders (exported for vitest; jsdom-free) ─────────────
+// The component below uses these verbatim. Each returns a {url, body} pair
+// so the test surface is the *literal* HTTP payload sent to the u18 / u19
+// middlewares — any future shape drift fails here before the network call.
+
+export function buildConnectRequest(
+  run_id: string,
+  slug: string,
+): { url: string; body: string } {
+  return {
+    url: "/api/connect",
+    body: JSON.stringify({ run_id, slug }),
+  };
+}
+
+export function buildExportRequest(
+  run_id: string,
+): { url: string; body: string } {
+  return {
+    url: "/api/export",
+    body: JSON.stringify({ run_id }),
+  };
+}
+
+export function buildDownloadFilename(run_id: string): string {
+  return `${run_id}.html`;
+}

 interface BottomActionsProps {
  slidePlan: SlidePlan | null;
-  userSelection: UserSelection;
+  runMeta: RunMeta | null;
+  uploadedFile: File | null;
  isLoading: boolean;
  onGenerate: () => void;
 }

 export default function BottomActions({
  slidePlan,
-  userSelection,
+  runMeta,
+  uploadedFile,
  isLoading,
  onGenerate,
 }: BottomActionsProps) {
-  const handleDownload = () => {
-    if (!slidePlan) {
-      toast.error("슬라이드 플랜이 없습니다. 먼저 생성하기를 눌러주세요.");
+  const [isConnecting, setIsConnecting] = useState(false);
+  const [isExporting, setIsExporting] = useState(false);
+
+  const runReady = !!runMeta && !!slidePlan;
+
+  const handleExport = async () => {
+    if (!runMeta) {
+      toast.error("Run 산출물이 없습니다. 먼저 생성하기를 눌러주세요.");
      return;
    }
-
-    const json = serializeSlidePlan(slidePlan, userSelection);
-    console.log("[Download] SlidePlan JSON:", json);
-
-    // JSON 파일 다운로드
-    const blob = new Blob([json], { type: "application/json" });
-    const url = URL.createObjectURL(blob);
-    const a = document.createElement("a");
-    a.href = url;
-    a.download = `slide-plan-${Date.now()}.json`;
-    a.click();
-    URL.revokeObjectURL(url);
-
-    toast.success("SlidePlan JSON이 다운로드되었습니다.");
+    setIsExporting(true);
+    try {
+      const exportReq = buildExportRequest(runMeta.run_id);
+      const resp = await fetch(exportReq.url, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: exportReq.body,
+      });
+      if (!resp.ok) {
+        const text = await resp.text();
+        toast.error(`Export 실패 (${resp.status}): ${text.slice(0, 160)}`);
+        return;
+      }
+      const blob = await resp.blob();
+      const objectUrl = URL.createObjectURL(blob);
+      const a = document.createElement("a");
+      a.href = objectUrl;
+      a.download = buildDownloadFilename(runMeta.run_id);
+      document.body.appendChild(a);
+      a.click();
+      a.remove();
+      URL.revokeObjectURL(objectUrl);
+      toast.success(`standalone HTML 다운로드 — ${runMeta.run_id}.html`);
+    } catch (err) {
+      toast.error(`Export 네트워크 오류: ${(err as Error).message}`);
+    } finally {
+      setIsExporting(false);
+    }
  };

-  const handleConnect = () => {
-    toast.info("연동하기 기능은 파이프라인 연결 후 활성화됩니다.");
+  const handleConnect = async () => {
+    if (!runMeta) {
+      toast.error("Run 산출물이 없습니다. 먼저 생성하기를 눌러주세요.");
+      return;
+    }
+    if (!uploadedFile) {
+      toast.error("MDX 파일이 없습니다 — slug 도출 불가.");
+      return;
+    }
+    const slug = deriveUserOverridesKey(uploadedFile.name);
+    setIsConnecting(true);
+    try {
+      const connectReq = buildConnectRequest(runMeta.run_id, slug);
+      const resp = await fetch(connectReq.url, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: connectReq.body,
+      });
+      const payload = (await resp.json().catch(() => ({}))) as {
+        success?: boolean;
+        assets_copied?: number;
+        error?: string;
+      };
+      if (!resp.ok || !payload.success) {
+        toast.error(
+          `Connect 실패 (${resp.status}): ${payload.error ?? "unknown error"}`,
+        );
+        return;
+      }
+      toast.success(
+        `cel 미러 연동 완료 — ${slug}.html (assets ${payload.assets_copied ?? 0}개 복사)`,
+      );
+    } catch (err) {
+      toast.error(`Connect 네트워크 오류: ${(err as Error).message}`);
+    } finally {
+      setIsConnecting(false);
+    }
  };

  return (
-    <div className="flex items-center justify-center gap-3 px-6 py-3 bg-white border-t border-slate-200">
-      <div className="flex items-center gap-1.5 mr-2">
-        <span className="w-5 h-5 rounded-full bg-blue-600 text-white text-xs flex items-center justify-center font-bold">4</span>
-        <span className="text-xs text-slate-500 font-medium">액션</span>
-      </div>
-      {/* 생성하기 */}
+    <div className="flex items-center gap-3">
      <Button
        onClick={onGenerate}
        disabled={isLoading}
-        className="gap-2 min-w-[120px]"
+        className="gap-2 h-9 text-[11px] font-bold uppercase tracking-widest bg-slate-900 hover:bg-slate-800"
        size="default"
      >
        {isLoading ? (
          <>
-            <Loader2 className="w-4 h-4 animate-spin" />
+            <Loader2 className="w-3.5 h-3.5 animate-spin" />
            생성 중...
          </>
        ) : (
          <>
-            <Sparkles className="w-4 h-4" />
+            <Sparkles className="w-3.5 h-3.5" />
            생성하기
          </>
        )}
      </Button>

-      {/* 다운로드 */}
      <Button
        variant="outline"
-        onClick={handleDownload}
-        disabled={!slidePlan || isLoading}
-        className="gap-2 min-w-[120px]"
+        onClick={handleExport}
+        disabled={!runReady || isExporting || isLoading}
+        className="gap-2 h-9 text-[11px] font-bold uppercase tracking-widest border-slate-200"
        size="default"
      >
-        <Download className="w-4 h-4" />
+        {isExporting ? (
+          <Loader2 className="w-3.5 h-3.5 animate-spin" />
+        ) : (
+          <Download className="w-3.5 h-3.5" />
+        )}
        다운로드
      </Button>

-      {/* 연동하기 */}
      <Button
        variant="outline"
        onClick={handleConnect}
-        className="gap-2 min-w-[120px] text-slate-500"
+        disabled={!runReady || isConnecting || isLoading}
+        className="gap-2 h-9 text-[11px] font-bold uppercase tracking-widest border-slate-200"
        size="default"
      >
-        <Link2 className="w-4 h-4" />
+        {isConnecting ? (
+          <Loader2 className="w-3.5 h-3.5 animate-spin" />
+        ) : (
+          <Link2 className="w-3.5 h-3.5" />
+        )}
        연동하기
      </Button>
    </div>
@@ -20,6 +20,19 @@ interface FramePanelProps {
  onNoDesignToggle: () => void;
 }

+// IMP-#84 u1 — silent-automation contract: frame selection delegates directly
+// to onFrameSelect for every V4 label (use_as_is / light_edit / restructure /
+// reject). Prior IMP-47B u11 surfaced a window.confirm popup on reject; that
+// popup is informational UI noise per `feedback_auto_pipeline_first` and is
+// removed. Frame identity is preserved on reject (AI 재구성 = content-only,
+// per AI 격리 contract); the popup never gated that contract.
+export function applyFrameSelection(
+  candidate: FrameCandidate,
+  onFrameSelect: (frameId: string) => void,
+): void {
+  onFrameSelect(candidate.id);
+}
+
 export default function FramePanel({
  slidePlan,
  selectedZone,
@@ -49,17 +62,9 @@ export default function FramePanel({

  const handleFrameSelect = React.useCallback(
    (candidate: FrameCandidate) => {
-      const isReject = candidate.label === "reject";
-      const alreadyApplied = currentFrameId === candidate.id;
-      if (isReject && !alreadyApplied) {
-        const ok = window.confirm(
-          `"${candidate.name}" 은 V4 reject 라벨입니다.\n선택 시 frame 은 유지되고 AI 가 콘텐츠를 frame 구조에 맞게 재구성합니다.\n계속하시겠습니까?`,
-        );
-        if (!ok) return;
-      }
-      onFrameSelect(candidate.id);
+      applyFrameSelection(candidate, onFrameSelect);
    },
-    [currentFrameId, onFrameSelect],
+    [onFrameSelect],
  );

  if (!selectedZone) {
@@ -28,7 +28,12 @@ import {
  crossedDragThreshold,
  type ImageDragDirection,
 } from "./slideCanvasDragMath";
-import type { ImageOverridesOverride } from "../services/userOverridesApi";
+import type {
+  ImageOverridesOverride,
+  StructureOverridesOverride,
+  StructureOverridePerZone,
+} from "../services/userOverridesApi";
+import StructureEditOverlay from "./StructureEditOverlay";

 interface SlideCanvasProps {
  slidePlan: SlidePlan | null;
@@ -36,10 +41,6 @@ interface SlideCanvasProps {
  userSelection: UserSelection;
  /** Phase Z 가 만든 final.html URL (iframe 으로 표시). */
  finalHtmlUrl?: string;
-  /** 슬라이드 단위 inline CSS override (catalog/template 무변, iframe contentDocument 에
-   *  동적 inject). Home 이 mdx 별 default visual 보완 등을 지정. 빈 문자열/undefined =
-   *  inject 안 함. 사용자 lock 2026-05-14 — slide-level only. */
-  slideOverrideCss?: string;
  /** 파이프라인 실행 중 표시 (loading state). */
  isPipelineRunning?: boolean;
  /** Phase 2 : pending layout 모드 — final.html iframe 숨기고 빈 layout zone 만 표시. */
@@ -77,16 +78,116 @@ interface SlideCanvasProps {
    imageId: string,
    geometry: { x: number; y: number; w: number; h: number }
  ) => void;
+  /** IMP-90 (#90) u13 — focusout-emitted capture; u15 debounces + PUTs. */
+  onTextEdit?: (capture: TextEditCapture) => void;
+  /** IMP-90 (#90) u14 — persisted structure overrides per zone
+   *  (slot_order + hidden_slots). When `editMode === "structure"` the
+   *  StructureEditOverlay reads from this to render the current state. */
+  structureOverrides?: StructureOverridesOverride;
+  /** IMP-90 (#90) u14 — emitted whenever the user reorders or hides a
+   *  slot in structure-mode. u15 will debounce + PUT to /api/user-
+   *  overrides; u14 only exposes the capture. SCOPE LOCK: inner shape is
+   *  `{slot_order, hidden_slots}` only (frame swap stays on `frames` axis). */
+  onStructureEdit?: (zoneId: string, capture: StructureOverridePerZone) => void;
 }

 const SLIDE_W = 1280;
 const SLIDE_H = 720;

+// IMP-90 (#90) u11 — discriminated edit mode. Replaces the prior single
+// `isEditMode` boolean. u11 introduces the enum + the toolbar UI surface;
+// gesture gating (text contentEditable vs structure reorder vs image-zone
+// drag/resize) stays unified behind `isEditMode = editMode !== 'off'` so
+// existing behavior is preserved byte-identical. u12 will discriminate the
+// gestures per mode (mutually exclusive). The 'off' state is the no-edit
+// baseline; 'image-zone' bundles image edit (#79) + zone resize (#81)
+// because both are pointer-driven canvas gestures on slide geometry.
+export type EditMode = "off" | "text" | "structure" | "image-zone";
+export const EDIT_MODES: ReadonlyArray<EditMode> = ["text", "structure", "image-zone"];
+/** Pure helper — given the current edit mode and the user's requested mode,
+ *  return the next mode. Clicking the active mode toggles back to 'off';
+ *  clicking a different mode switches; explicit 'off' always exits. */
+export function nextEditMode(current: EditMode, requested: EditMode): EditMode {
+  if (requested === "off") return "off";
+  return current === requested ? "off" : requested;
+}
+
+// IMP-90 (#90) u12 — per-mode gesture gating. Pure helper deriving the
+// boolean gates that drive SlideCanvas's useEffect branches (designMode
+// + iframe-side image click listener) and JSX conditionals (iframe
+// pointer-events, zone resize/drag affordances, image overlay). The
+// mapping enforces the mutually-exclusive contract from the issue body:
+//   text       -> contentEditable + iframe pointer-events:auto only.
+//   structure  -> nothing here; u14 will plant the structure overlay.
+//   image-zone -> zone resize/drag + image overlay; iframe pe:auto so
+//                 in-iframe user-content images can be click-selected.
+//   off        -> every gate false (baseline).
+// pendingLayout fully suppresses every gate — mirrors the existing
+// useEffect (line ~248) that forces editMode='off' on pendingLayout
+// entry. The helper still defensively returns all-false so a stray
+// pendingLayout=true with a non-'off' editMode never leaks gestures.
+export interface EditModeGates {
+  textEditing: boolean;
+  imageSelection: boolean;
+  iframePointerAuto: boolean;
+  zoneGestures: boolean;
+  imageOverlay: boolean;
+}
+export function computeEditModeGates(
+  editMode: EditMode,
+  isPendingLayout: boolean
+): EditModeGates {
+  if (isPendingLayout) {
+    return {
+      textEditing: false,
+      imageSelection: false,
+      iframePointerAuto: false,
+      zoneGestures: false,
+      imageOverlay: false,
+    };
+  }
+  return {
+    textEditing: editMode === "text",
+    imageSelection: editMode === "image-zone",
+    iframePointerAuto: editMode === "text" || editMode === "image-zone",
+    zoneGestures: editMode === "image-zone",
+    imageOverlay: editMode === "image-zone",
+  };
+}
+
+// IMP-90 (#90) u13 — pure helper resolving a contentEditable focusout
+// target into (zoneId, textPath, value). data-text-path stamped by u8 at
+// Step 13; .zone[data-zone-position] from Phase Z slide-base. Non-stamped
+// targets return null so capture silently skips. u15 will debounce + PUT.
+export interface TextEditCaptureTarget {
+  closest(selector: string): TextEditCaptureTarget | null;
+  getAttribute(name: string): string | null;
+  textContent: string | null;
+}
+export interface TextEditCapture {
+  zoneId: string;
+  textPath: string;
+  value: string;
+}
+export function deriveTextEditCapture(
+  target: TextEditCaptureTarget | null
+): TextEditCapture | null {
+  if (!target) return null;
+  const lineEl = target.closest("[data-text-path]");
+  if (!lineEl) return null;
+  const textPath = lineEl.getAttribute("data-text-path");
+  if (!textPath) return null;
+  const zoneEl = lineEl.closest(".zone[data-zone-position]");
+  if (!zoneEl) return null;
+  const zoneId = zoneEl.getAttribute("data-zone-position");
+  if (!zoneId) return null;
+  return { zoneId, textPath, value: (lineEl.textContent ?? "").trim() };
+}
+
 export default function SlideCanvas({
  slidePlan,
  userSelection,
  finalHtmlUrl,
-  slideOverrideCss,
  isPipelineRunning,
  isPendingLayout,
  pendingLayoutId,
@@ -98,6 +199,9 @@ export default function SlideCanvas({
  onZoneResize,
  imageOverrides,
  onImageResize,
+  onTextEdit,
+  structureOverrides,
+  onStructureEdit,
 }: SlideCanvasProps) {
  const containerRef = useRef<HTMLDivElement>(null);
  const [scale, setScale] = useState(1);
@@ -140,7 +244,15 @@ export default function SlideCanvas({
  // HTML 편집 모드 — 글벗 패턴 (designMode + contentEditable + outline CSS) 차용.
  // 활성 시 iframe 안 텍스트 element 직접 클릭하여 수정 가능. backend 반영은 별 작업.
  // pendingLayout 과 배타적 (충돌 방지).
-  const [isEditMode, setIsEditMode] = useState(false);
+  // IMP-90 (#90) u11 — `editMode` enum replaces the prior boolean. The
+  // `isEditMode` shim is kept ONLY for the pendingLayout coupling +
+  // zone-wrapper visual cues (border / hover / selected styling) that
+  // fire whenever any edit mode is active. u12 routes gesture-activating
+  // gates through `editGates` so text / structure / image-zone gestures
+  // are mutually exclusive.
+  const [editMode, setEditMode] = useState<EditMode>("off");
+  const isEditMode = editMode !== "off";
+  const editGates = computeEditModeGates(editMode, !!isPendingLayout);
  const iframeRef = useRef<HTMLIFrameElement>(null);

  // 편집 모드 toggle 시 iframe contentDocument 에 글벗 패턴 적용 / 해제.
@@ -164,11 +276,22 @@ export default function SlideCanvas({

    const editableTags = ["DIV", "P", "H1", "H2", "H3", "H4", "SPAN", "LI", "TD", "TH", "FIGCAPTION"];
    let inputHandler: ((e: Event) => void) | null = null;
+    // IMP-90 (#90) u13 — focusout (= bubbling blur) emits one capture per
+    // finished line edit; u15 will debounce + PUT.
+    let textEditCaptureHandler: ((e: Event) => void) | null = null;
    // IMP-51 (#79) u8 — user-content image click listeners installed
    // inside the iframe contentDocument. Tracked here so the cleanup
    // callback can remove them when edit mode exits (or iframe reloads).
    const imageClickBindings: Array<{ el: HTMLImageElement; handler: (e: Event) => void; prevCursor: string; prevOutline: string }> = [];
-    if (isEditMode) {
+
+    // IMP-90 (#90) u12 — text-editing gate: only the 'text' editMode
+    // turns designMode on + makes the editable tags contentEditable.
+    // The else branch tears the prior state down so leaving text mode
+    // (to structure / image-zone / off) immediately disables in-place
+    // text editing — required for mutual exclusivity vs the image-zone
+    // overlay's drag/resize gestures (a contentEditable cursor would
+    // otherwise be placed by every image click).
+    if (editGates.textEditing) {
      doc.designMode = "on";
      doc.querySelectorAll(".slide *").forEach((el) => {
        if (editableTags.includes((el as HTMLElement).tagName)) {
@@ -181,11 +304,28 @@ export default function SlideCanvas({
      };
      doc.addEventListener("input", inputHandler);

-      // IMP-51 (#79) u8 — wire click → selectedImageId on every stamped
-      // user-content image. Selector mirrors USER_CONTENT_IMAGE_SELECTOR
-      // in src/image_id_stamper.py (+ requires data-image-id which the
-      // stamper always emits). Decorative / frame imgs lacking the role
-      // attribute are intentionally NOT clickable here.
+      textEditCaptureHandler = (ev: Event) => {
+        const cap = deriveTextEditCapture(
+          ev.target as unknown as TextEditCaptureTarget | null
+        );
+        if (cap) onTextEdit?.(cap);
+      };
+      doc.addEventListener("focusout", textEditCaptureHandler);
+    } else {
+      doc.designMode = "off";
+      doc.querySelectorAll("[contenteditable]").forEach((el) => {
+        (el as HTMLElement).removeAttribute("contenteditable");
+      });
+    }
+
+    // IMP-90 (#90) u12 — image-selection gate: only the 'image-zone'
+    // editMode wires the in-iframe user-content image click → selection.
+    // Selector mirrors USER_CONTENT_IMAGE_SELECTOR in image_id_stamper.py
+    // (requires data-image-id which the stamper always emits). Decorative
+    // / frame imgs lacking the role attribute are NOT clickable. The
+    // else branch clears `selectedImageId` so the React-side overlay
+    // never lingers on a non-image-zone edit mode.
+    if (editGates.imageSelection) {
      const imgEls = doc.querySelectorAll<HTMLImageElement>(
        '.slide img[data-image-role="user-content"][data-image-id]'
      );
@@ -205,12 +345,6 @@ export default function SlideCanvas({
        imageClickBindings.push({ el: imgEl, handler, prevCursor, prevOutline });
      });
    } else {
-      doc.designMode = "off";
-      doc.querySelectorAll("[contenteditable]").forEach((el) => {
-        (el as HTMLElement).removeAttribute("contenteditable");
-      });
-      // edit-mode exit also clears stale image selection so the handle
-      // overlay never lingers on a non-editable iframe.
      setSelectedImageId(null);
    }

@@ -218,19 +352,60 @@ export default function SlideCanvas({
      if (inputHandler && doc) {
        doc.removeEventListener("input", inputHandler);
      }
+      if (textEditCaptureHandler && doc) {
+        doc.removeEventListener("focusout", textEditCaptureHandler);
+      }
      imageClickBindings.forEach(({ el, handler, prevCursor, prevOutline }) => {
        el.removeEventListener("click", handler);
        el.style.cursor = prevCursor;
        el.style.outline = prevOutline;
      });
    };
-  }, [isEditMode, finalHtmlUrl, onContentEdit]);
+  }, [editGates.textEditing, editGates.imageSelection, finalHtmlUrl, onContentEdit, onTextEdit]);

  // pendingLayout 진입 시 편집 모드 자동 OFF (충돌 방지).
  useEffect(() => {
-    if (isPendingLayout && isEditMode) setIsEditMode(false);
+    if (isPendingLayout && isEditMode) setEditMode("off");
  }, [isPendingLayout, isEditMode]);

+  // IMP-90 (#90) u14 — discover slot keys per zone for the structure
+  // overlay. Source = iframe DOM `data-text-path="{slot_key}.{line_index}"`
+  // attributes stamped by u8 (`src/text_path_stamper.py`). Unique slot_key
+  // prefixes per `.zone[data-zone-position]` form the overlay's slot list.
+  // Discovery runs only when entering structure mode (and resets on exit
+  // or iframe reload) so off / text / image-zone modes never pay this
+  // traversal cost.
+  const [slotKeysByZone, setSlotKeysByZone] = useState<
+    Record<string, string[]>
+  >({});
+  useEffect(() => {
+    if (editMode !== "structure" || isPendingLayout) {
+      setSlotKeysByZone({});
+      return;
+    }
+    const doc = iframeRef.current?.contentDocument;
+    if (!doc) return;
+    const next: Record<string, string[]> = {};
+    doc.querySelectorAll(".zone[data-zone-position]").forEach((zEl) => {
+      const zoneId = (zEl as HTMLElement).getAttribute("data-zone-position");
+      if (!zoneId) return;
+      const seen = new Set<string>();
+      const keys: string[] = [];
+      zEl.querySelectorAll("[data-text-path]").forEach((lineEl) => {
+        const path = (lineEl as HTMLElement).getAttribute("data-text-path");
+        if (!path) return;
+        const lastDot = path.lastIndexOf(".");
+        const slotKey = lastDot > 0 ? path.slice(0, lastDot) : path;
+        if (slotKey && !seen.has(slotKey)) {
+          seen.add(slotKey);
+          keys.push(slotKey);
+        }
+      });
+      next[zoneId] = keys;
+    });
+    setSlotKeysByZone(next);
+  }, [editMode, isPendingLayout, finalHtmlUrl]);
+
  // finalHtmlUrl 이 바뀌면 (= 다른 run / 재실행) stale 측정값 reset.
  // 새 iframe 의 onLoad 가 발화하면서 measuredZones 다시 채움.
  useEffect(() => {
@@ -337,28 +512,50 @@ export default function SlideCanvas({
            </button>
          )}

-          {/* 편집 모드 toggle 버튼 — normal mode + final.html 있을 때만.
-              글벗 패턴 차용 — designMode + contentEditable. backend 반영은 별 작업. */}
+          {/* IMP-90 (#90) u11 — discriminated edit-mode toolbar.
+              Replaces the prior single ✏ toggle. Three modes (text /
+              structure / image-zone) are mutually exclusive; clicking the
+              active mode toggles back to 'off'. Gesture gating per mode is
+              u12 — u11 only plants the state + UI surface, so all three
+              modes currently share the same `isEditMode` shim behavior. */}
          {!isPendingLayout && finalHtmlUrl && (
-            <button
-              onClick={(e) => {
-                e.stopPropagation();
-                setIsEditMode((p) => !p);
-              }}
-              className={`absolute top-2 right-2 z-30 text-[10px] font-bold uppercase tracking-tighter px-2.5 py-1 rounded shadow transition ${
-                isEditMode
-                  ? "bg-emerald-500 text-white hover:bg-emerald-600 ring-2 ring-emerald-200"
-                  : "bg-white text-slate-700 hover:bg-slate-100 border border-slate-200"
-              }`}
+            <div
+              data-testid="edit-mode-toolbar"
+              className="absolute top-2 right-2 z-30 flex gap-1"
              style={{ pointerEvents: "auto" }}
-              title={
-                isEditMode
-                  ? "편집 모드 — 텍스트 클릭하여 수정. 다시 클릭하여 종료. (변경은 frontend 만, backend 반영 미구현)"
-                  : "텍스트 직접 편집 모드 진입"
-              }
            >
-              {isEditMode ? "✏ 편집 중 (클릭 종료)" : "✏ 편집"}
-            </button>
+              {EDIT_MODES.map((mode) => {
+                const active = editMode === mode;
+                const label =
+                  mode === "text" ? "✏ 텍스트" : mode === "structure" ? "▦ 구조" : "🖼 이미지/존";
+                const title =
+                  mode === "text"
+                    ? "텍스트 편집 — 텍스트 클릭하여 직접 수정"
+                    : mode === "structure"
+                    ? "구조 편집 — slot 순서 / 숨김 변경 (u14 펜딩)"
+                    : "이미지/존 편집 — 이미지 드래그·리사이즈 + 존 리사이즈";
+                return (
+                  <button
+                    key={mode}
+                    type="button"
+                    data-testid={`edit-mode-${mode}`}
+                    aria-pressed={active}
+                    onClick={(e) => {
+                      e.stopPropagation();
+                      setEditMode((prev) => nextEditMode(prev, mode));
+                    }}
+                    className={`text-[10px] font-bold uppercase tracking-tighter px-2.5 py-1 rounded shadow transition ${
+                      active
+                        ? "bg-emerald-500 text-white hover:bg-emerald-600 ring-2 ring-emerald-200"
+                        : "bg-white text-slate-700 hover:bg-slate-100 border border-slate-200"
+                    }`}
+                    title={title}
+                  >
+                    {label}
+                  </button>
+                );
+              })}
+            </div>
          )}

          <div
@@ -380,7 +577,13 @@ export default function SlideCanvas({
              className="w-full h-full border-0 block"
              scrolling="no"
              sandbox="allow-same-origin allow-scripts"
-              style={{ pointerEvents: isEditMode ? "auto" : "none" }}
+              // IMP-90 (#90) u12 — iframe pointer-events gate. 'text' needs
+              // pe:auto so the user can click into text fields; 'image-zone'
+              // needs pe:auto so user-content image clicks can reach the
+              // in-iframe click handler that drives `selectedImageId`.
+              // 'structure' and 'off' keep pe:none — structure has no
+              // in-iframe gesture (u14 will overlay React-side controls).
+              style={{ pointerEvents: editGates.iframePointerAuto ? "auto" : "none" }}
              onLoad={(e) => {
                // IMP-14 (Step 13 A-4) — embedded vs standalone CSS reset 은 backend
                // slide_base.html 가 `?embedded=1` query 로 소유. frontend 가 더 이상
@@ -391,15 +594,6 @@ export default function SlideCanvas({
                  const doc = (e.currentTarget as HTMLIFrameElement).contentDocument;
                  if (!doc) return;

-                  // 2026-05-14 — slide-level override CSS (catalog/template 무변).
-                  // Home 이 mdx 별 default visual 보완 (bullet 간격 / zone 비율 등) 지정.
-                  if (slideOverrideCss && slideOverrideCss.trim()) {
-                    const overrideStyle = doc.createElement("style");
-                    overrideStyle.setAttribute("data-purpose", "slide-level-override");
-                    overrideStyle.textContent = slideOverrideCss;
-                    doc.head.appendChild(overrideStyle);
-                  }
-
                  // ── Zone DOM 측정 ──
                  // backend final.html 의 .zone[data-zone-position="..."] 요소를
                  // 찾아서 boundingClientRect 측정 → 1280×720 기준 정규화.
@@ -578,9 +772,11 @@ export default function SlideCanvas({
            const makeResizeHandler = (
              direction: ResizeDir
            ) => (ev: React.MouseEvent<HTMLDivElement>) => {
-              // resize 는 pendingLayout OR 편집 모드 활성. 2026-05-22 demo hot-fix —
-              // frame partial 에 @container aspect-ratio 회전이 들어가서 fixed px 제약 사라짐.
-              if ((!isPendingLayout && !isEditMode) || !onZoneResize) return;
+              // resize 는 pendingLayout OR image-zone 편집 모드 활성. 2026-05-22
+              // demo hot-fix — frame partial 에 @container aspect-ratio 회전이
+              // 들어가서 fixed px 제약 사라짐. IMP-90 u12: text/structure 모드
+              // 에서는 zone resize 비활성 (mutually exclusive per editGates).
+              if ((!isPendingLayout && !editGates.zoneGestures) || !onZoneResize) return;
              if (!measuredSlideBody) return;
              ev.preventDefault();
              ev.stopPropagation();
@@ -651,7 +847,10 @@ export default function SlideCanvas({
              ev: React.MouseEvent<HTMLDivElement>
            ) => {
              ev.stopPropagation();
-              const canDrag = !!((isPendingLayout || isEditMode) && measuredSlideBody && onZoneResize);
+              // IMP-90 u12: zone drag is image-zone-mode-only (text /
+              // structure suppress canDrag; non-zoneGestures click still
+              // triggers onZoneClick via the !dragged branch on mouse-up).
+              const canDrag = !!((isPendingLayout || editGates.zoneGestures) && measuredSlideBody && onZoneResize);
              const startMouseX = ev.clientX;
              const startMouseY = ev.clientY;
              const startGeom = { ...localGeom };
@@ -870,12 +1069,14 @@ export default function SlideCanvas({
                  </div>
                )}

-                {/* Step C : zone resize handles — 8 방향. pendingLayout OR 편집 모드 활성.
-                    2026-05-22 demo hot-fix — frame partial 에 @container aspect-ratio 회전
-                    들어간 후 fixed px 제약 사라져 편집 모드 resize 도 의미 있음.
+                {/* Step C : zone resize handles — 8 방향. pendingLayout OR image-zone
+                    편집 모드 활성. 2026-05-22 demo hot-fix — frame partial 에 @container
+                    aspect-ratio 회전 들어간 후 fixed px 제약 사라져 image-zone 모드 resize
+                    도 의미 있음. IMP-90 u12: text / structure 모드에서는 zone resize
+                    affordance 미노출 (editGates.zoneGestures = image-zone only).
                    edge handle (top/bottom/left/right) : 한 boundary 이동
                    corner handle (nw/ne/sw/se) : 두 boundary 동시. */}
-                {(isPendingLayout || isEditMode) && onZoneResize && (
+                {(isPendingLayout || editGates.zoneGestures) && onZoneResize && (
                  <>
                    {/* top edge */}
                    <div
@@ -955,8 +1156,10 @@ export default function SlideCanvas({
                    strips intercept the perimeter while the un-covered iframe
                    interior keeps text-edit reachability intact.
                    pendingLayout mode already has wrapper pointerEvents:auto,
-                    so these surfaces are only needed in edit mode. */}
-                {isEditMode && !isPendingLayout && onZoneResize && (
+                    so these surfaces are only needed in edit mode.
+                    IMP-90 u12: image-zone-mode-only — text / structure 모드는
+                    zone drag 안 함 (editGates.zoneGestures = false 두 모드 모두). */}
+                {editGates.zoneGestures && !isPendingLayout && onZoneResize && (
                  <>
                    <div
                      onMouseDown={handleZoneMouseDown}
@@ -1001,6 +1204,39 @@ export default function SlideCanvas({
            );
          })}

+          {/* IMP-90 (#90) u14 — structure edit overlay (slot reorder +
+              hide). Renders only in `editMode === "structure"` over each
+              measured zone, positioned at the zone's top-right inside the
+              slide-absolute coord space. Slot keys come from u14 iframe
+              traversal (`slotKeysByZone`). Mutations emit through
+              onStructureEdit; u15 will debounce + PUT. */}
+          {!isPendingLayout && editMode === "structure" && finalHtmlUrl &&
+            slidePlan?.zones.map((zone) => {
+              const m = measuredZones[zone.zone_id];
+              if (!m) return null;
+              const slotKeys = slotKeysByZone[zone.zone_id] ?? [];
+              const current = structureOverrides?.[zone.zone_id];
+              return (
+                <div
+                  key={`struct-${zone.id}`}
+                  className="absolute z-30"
+                  style={{
+                    left: m.x * W_SCALED,
+                    top: m.y * H_SCALED,
+                    width: m.w * W_SCALED,
+                    pointerEvents: "none",
+                  }}
+                >
+                  <StructureEditOverlay
+                    zoneId={zone.zone_id}
+                    slotKeys={slotKeys}
+                    current={current}
+                    onChange={onStructureEdit}
+                  />
+                </div>
+              );
+            })}
+
          {/* ── IMP-51 (#79) u8 — user-content image edit overlay ──
            Activates only in edit mode when an image_id appears in either
            `imageOverrides` (u11-fed persisted axis) or `measuredImages`
@@ -1028,7 +1264,11 @@ export default function SlideCanvas({
            `slideCanvasDragMath.ts` so the boundary contract Codex #16
            verified is exercised directly by vitest (mirror of how IMP-54
            u3 split the zone math out of SlideCanvas). */}
-          {!isPendingLayout && isEditMode && finalHtmlUrl && onImageResize &&
+          {/* IMP-90 u12: image overlay is image-zone-mode-only. text /
+              structure 모드에서는 image drag/resize affordance 미노출
+              (editGates.imageOverlay = false). pendingLayout 도 동일하게
+              suppress (computeEditModeGates 가 모두 false 반환). */}
+          {!isPendingLayout && editGates.imageOverlay && finalHtmlUrl && onImageResize &&
            Object.entries({ ...measuredImages, ...(imageOverrides ?? {}) }).map(
              ([imageId]) => {
                const persisted = imageOverrides?.[imageId];
@@ -0,0 +1,165 @@
+/**
+ * IMP-90 (#90) u14 — Structure edit overlay.
+ *
+ * React component + pure helpers that present a per-zone slot list with
+ * reorder (↑ / ↓) and hide (👁 / 🚫) affordances. Mounted by SlideCanvas
+ * when `editMode === "structure"`. Emits a `StructureOverridePerZone`
+ * tuple `{slot_order, hidden_slots}` through `onChange`; u15 will debounce
+ * + PUT this to `/api/user-overrides` (NOT u14 scope), and u16 reads the
+ * persisted axis at the next CLI generate run.
+ *
+ * SCOPE LOCK (binding contract):
+ *   - inner shape = `{slot_order, hidden_slots}` ONLY.
+ *   - frame swap stays on the existing `frames` axis (u6 backend resolver
+ *     rejects frame-swap-shaped inner keys).
+ *   - per-slot text content NEVER mutated here — `text_overrides` axis
+ *     (u4/u5/u13) handles that exclusively.
+ *
+ * The exported pure helpers (`resolveEffectiveSlotOrder`, `moveItem`) are
+ * the unit's vitest surface; React rendering is NOT tested because the
+ * Front package devDependencies do not include jsdom / @testing-library
+ * (verified by u11/u12/u13 test pattern).
+ */
+import type {
+  StructureOverridePerZone,
+} from "../services/userOverridesApi";
+
+export interface StructureEditOverlayProps {
+  zoneId: string;
+  /** Discovered slot keys for this zone (e.g. from iframe DOM
+   *  `data-text-path` prefixes). Order = backend default. */
+  slotKeys: ReadonlyArray<string>;
+  /** Current persisted override (or undefined). `slot_order` reorders the
+   *  discovered keys; missing keys keep backend order at the tail. */
+  current?: StructureOverridePerZone;
+  /** Emitted on every user mutation. u15 wires this to autosave. */
+  onChange?: (zoneId: string, next: StructureOverridePerZone) => void;
+}
+
+/** Apply `slot_order` override to the discovered slot list. Unknown
+ *  override entries are dropped; missing discovered keys are appended in
+ *  backend order so the user never loses a slot by partial-override. */
+export function resolveEffectiveSlotOrder(
+  slotKeys: ReadonlyArray<string>,
+  slotOrder?: ReadonlyArray<string> | null,
+): string[] {
+  if (!slotOrder || slotOrder.length === 0) return [...slotKeys];
+  const allowed = new Set(slotKeys);
+  const seen = new Set<string>();
+  const ordered: string[] = [];
+  for (const k of slotOrder) {
+    if (typeof k === "string" && allowed.has(k) && !seen.has(k)) {
+      ordered.push(k);
+      seen.add(k);
+    }
+  }
+  for (const k of slotKeys) {
+    if (!seen.has(k)) ordered.push(k);
+  }
+  return ordered;
+}
+
+/** Move `arr[index]` by `delta` positions. Out-of-range returns a fresh
+ *  copy of the input (defensive: caller can always treat the result as a
+ *  new reference). */
+export function moveItem<T>(
+  arr: ReadonlyArray<T>,
+  index: number,
+  delta: number,
+): T[] {
+  const next = arr.slice();
+  const target = index + delta;
+  if (
+    index < 0 ||
+    index >= next.length ||
+    target < 0 ||
+    target >= next.length
+  ) {
+    return next;
+  }
+  const tmp = next[index];
+  next[index] = next[target];
+  next[target] = tmp;
+  return next;
+}
+
+export default function StructureEditOverlay({
+  zoneId,
+  slotKeys,
+  current,
+  onChange,
+}: StructureEditOverlayProps) {
+  const effective = resolveEffectiveSlotOrder(slotKeys, current?.slot_order);
+  const hidden = new Set(current?.hidden_slots ?? []);
+  const emit = (nextOrder: string[], nextHidden: Set<string>) => {
+    onChange?.(zoneId, {
+      slot_order: nextOrder,
+      hidden_slots: Array.from(nextHidden),
+    });
+  };
+  return (
+    <div
+      data-testid={`structure-overlay-${zoneId}`}
+      className="bg-white/95 border border-emerald-300 rounded shadow p-2 flex flex-col gap-1 text-[10px]"
+      style={{ pointerEvents: "auto" }}
+    >
+      <div className="font-bold uppercase tracking-wider text-emerald-700 mb-1">
+        ▦ {zoneId}
+      </div>
+      {effective.length === 0 ? (
+        <div className="text-slate-400 italic">slot 없음</div>
+      ) : (
+        effective.map((key, i) => (
+          <div
+            key={key}
+            data-testid={`slot-${zoneId}-${key}`}
+            className="flex items-center gap-1"
+          >
+            <span
+              className={`flex-1 truncate ${
+                hidden.has(key) ? "text-slate-400 line-through" : "text-slate-700"
+              }`}
+            >
+              {key}
+            </span>
+            <button
+              type="button"
+              data-testid={`slot-up-${zoneId}-${key}`}
+              disabled={i === 0}
+              onClick={() => emit(moveItem(effective, i, -1), hidden)}
+              className="px-1 rounded border border-slate-200 disabled:opacity-30 hover:bg-slate-100"
+              title="위로"
+            >
+              ↑
+            </button>
+            <button
+              type="button"
+              data-testid={`slot-down-${zoneId}-${key}`}
+              disabled={i === effective.length - 1}
+              onClick={() => emit(moveItem(effective, i, 1), hidden)}
+              className="px-1 rounded border border-slate-200 disabled:opacity-30 hover:bg-slate-100"
+              title="아래로"
+            >
+              ↓
+            </button>
+            <button
+              type="button"
+              data-testid={`slot-hide-${zoneId}-${key}`}
+              aria-pressed={hidden.has(key)}
+              onClick={() => {
+                const nh = new Set(hidden);
+                if (nh.has(key)) nh.delete(key);
+                else nh.add(key);
+                emit(effective, nh);
+              }}
+              className="px-1 rounded border border-slate-200 hover:bg-slate-100"
+              title={hidden.has(key) ? "표시" : "숨김"}
+            >
+              {hidden.has(key) ? "🚫" : "👁"}
+            </button>
+          </div>
+        ))
+      )}
+    </div>
+  );
+}
@@ -16,9 +16,12 @@ import {
  moveSectionToZone,
  saveZoneSizes,
  saveImageOverride,
+  saveTextOverride,
+  saveStructureOverride,
  deriveUserOverridesKey,
  applyPersistedNonFrameOverrides,
  remapPersistedFramesToZoneFrames,
+  validateZoneGeometriesAgainstLayout,
 } from "../utils/slidePlanUtils";
 import {
  parseMdxFile,
@@ -40,8 +43,9 @@ import LeftMdxPanel from "../components/LeftMdxPanel";
 import SlideCanvas from "../components/SlideCanvas";
 import LayoutPanel from "../components/LayoutPanel";
 import FramePanel from "../components/FramePanel";
+import BottomActions from "../components/BottomActions";
 import {
-  Sparkles, Download, Link2, Loader2,
+  Sparkles, Loader2,
  CheckCircle2, HelpCircle,
 } from "lucide-react";
 import { Button } from "@/components/ui/button";
@@ -154,6 +158,31 @@ export default function Home() {
        }
        carriedZoneSections[targetPos].push(...zone.section_ids);
      });
+      // IMP-44 (#73) u4 — clear in-memory zone_geometries on layout flip.
+      // The persisted keys were valid for the *prior* preset; carrying them
+      // forward into the new preset would either trip the u1/u2 backend
+      // [override-warning] guards (foreign keys dropped, override_applied
+      // forced back to None) or partially apply on shared keys. Drop them
+      // up-front so the new layout starts from a clean even-split baseline,
+      // and persist a clear sentinel (null) so a subsequent reopen does not
+      // resurrect the stale snapshot from user_overrides.json.
+      const priorGeoms = p.userSelection.overrides.zone_geometries;
+      const hadPriorGeoms =
+        priorGeoms && typeof priorGeoms === "object" && Object.keys(priorGeoms).length > 0;
+      if (p.uploadedFile && hadPriorGeoms) {
+        const key = deriveUserOverridesKey(p.uploadedFile.name);
+        void saveUserOverrides(key, { zone_geometries: null });
+      }
+      // IMP-55 (#93) u12 — persist the marker reset to disk so a stale
+      // `manual_section_assignment: true` from a prior drag (written via
+      // u6's co-PUT) cannot survive the layout apply. The in-memory reset
+      // on line 192 protects the current session, but a page reload would
+      // re-seed from disk via u3's restore branch and re-arm the u7 gate.
+      // Unconditional — apply always resets, independent of hadPriorGeoms.
+      if (p.uploadedFile) {
+        const key = deriveUserOverridesKey(p.uploadedFile.name);
+        void saveUserOverrides(key, { manual_section_assignment: false });
+      }
      return {
        ...p,
        userSelection: {
@@ -162,6 +191,18 @@ export default function Home() {
            ...p.userSelection.overrides,
            layout_preset: layoutId,
            zone_sections: carriedZoneSections,
+            zone_geometries: {},
+            // IMP-55 (#93) u5 — reset the bool intent marker to `false` on
+            // layout apply. `carriedZoneSections` above is auto-carry (old
+            // zone.section_ids → new layout positions), NOT user drag-drop
+            // intent. Without this explicit reset the spread of
+            // `...p.userSelection.overrides` would carry a prior-drag `true`
+            // into the new layout, causing handleGenerate (u7) to forward
+            // auto-carried assignments as user overrides and re-trigger the
+            // PARTIAL_COVERAGE regression. The marker flips back to `true`
+            // only when the user actually drag-drops a section in the new
+            // layout (u6 handleSectionDrop).
+            manual_section_assignment: false,
          },
          selectedZoneId: null,
          selectedRegionId: null,
@@ -176,10 +217,27 @@ export default function Home() {
  // pending 모드 취소 → 평소 (final.html iframe) 모드 복귀.
  const handleCancelPendingLayout = useCallback(() => {
    setPendingLayout(null);
-    setState((p) => ({
-      ...p,
-      userSelection: createInitialUserSelection(p.slidePlan),
-    }));
+    setState((p) => {
+      // IMP-55 (#93) u12 — persist marker=false to disk on cancel. In-memory
+      // the u3 seed via createInitialUserSelection already pins false (u5
+      // contract), but if a prior drag-drop wrote `true` to disk via u6's
+      // co-PUT, that value would survive a reopen and re-arm the u7
+      // forwarding gate on the next page load. Symmetric with the apply
+      // path's disk PUT above.
+      if (p.uploadedFile) {
+        const key = deriveUserOverridesKey(p.uploadedFile.name);
+        void saveUserOverrides(key, { manual_section_assignment: false });
+      }
+      return {
+        ...p,
+        // IMP-55 (#93) u5 — cancel discards all pending overrides via
+        // `createInitialUserSelection`, whose u3 seed pins
+        // `manual_section_assignment: false`. In-memory reset is implicit
+        // via the seed; u12 adds the disk-side PUT above to keep persisted
+        // state consistent so a reopen does not re-arm the marker.
+        userSelection: createInitialUserSelection(p.slidePlan),
+      };
+    });
    setHasPendingChanges(false);
  }, []);

@@ -225,22 +283,6 @@ export default function Home() {
  // 호출되는 단일 callback. handleFileUpload 가 자동 분석 trigger.
  const [selectedSample, setSelectedSample] = useState<"03" | "04" | "05" | null>(null);

-  // 2026-05-14 — mdx 별 slide-level CSS override (catalog/template 무변, frontend layer only).
-  // SlideCanvas 의 iframe onLoad 에서 동적 inject. 사용자 룰 : "보고용 슬라이드 결과물 단위"
-  // 변경. mdx04 의 default (rank 1 = process_product_two_way) 일 때만 적용 — 사용자 frame
-  // override 후 (rank 2 = bim_dx_comparison_table 등) 다른 frame 시 무적용.
-  const MDX04_DEFAULT_OVERRIDE_CSS = `
-    .slide-body {
-      grid-template-rows: 0.38fr 0.60fr !important;
-      gap: 1.5% !important;
-    }
-    .f29b__cell .text-line + .text-line { margin-top: 1px !important; }
-    .f29b__cell:nth-child(n+3) {
-      padding-top: 3px !important;
-      margin-top: 2px !important;
-    }
-  `.trim();
-
  const handleSelectSample = useCallback(async (which: "03" | "04" | "05") => {
    try {
      const res = await fetch(`/api/sample-mdx?mdx=${encodeURIComponent(which)}`);
@@ -329,34 +371,69 @@ export default function Home() {

      // zone-geometry override — backend 의 build_layout_css 에 전달 (horizontal-2 /
      // vertical-2 만 적용). zone_id (top/bottom/...) → slide-body 내부 0~1 비율.
+      // IMP-44 (#73) u4 — validate against the active layout *before* the
+      // round-trip so foreign-preset keys never reach the backend. Mirrors
+      // the u1/u2 WARN+DROP guards on the frontend side: dropped keys surface
+      // as a toast (so the user knows why their resize "vanished"), and only
+      // the `kept` subset is forwarded. The active layout = the layout the
+      // backend will use, which is `overrides.layout` when the user has set
+      // one, else the default slidePlan preset (mirrors backend resolution).
      const zoneGeometries = state.userSelection.overrides.zone_geometries;
      if (zoneGeometries && Object.keys(zoneGeometries).length > 0) {
-        overrides.zoneGeometries = zoneGeometries;
+        const activeLayout = overrides.layout ?? sourcePlan.layout_preset;
+        const validation = validateZoneGeometriesAgainstLayout(
+          zoneGeometries,
+          activeLayout,
+        );
+        if (Object.keys(validation.dropped).length > 0) {
+          toast.error(
+            `zone_geometries layout-mismatch: dropped ${Object.keys(validation.dropped).join(", ")} (expected ${validation.expectedPositions.join(", ") || "—"}; layout=${activeLayout}).`,
+          );
+        }
+        if (Object.keys(validation.kept).length > 0) {
+          overrides.zoneGeometries = validation.kept;
+        }
      }

-      // 2026-05-22 — IMP-08 B-3 원래 동작 (sameAsDefault with effectiveSlidePlan) 복귀.
-      // 시연 안정성 우선. section swap 은 별 path (수동 drag detection) 로 풀어야 함.
-      // 임시 over-aggressive fix 가 default flow 깨뜨려 PARTIAL_COVERAGE 발생했음.
-      const userZoneSections = state.userSelection.overrides.zone_sections;
-      if (userZoneSections) {
-        const defaultByZone = new Map<string, string[]>();
-        sourcePlan.zones.forEach((z) => {
-          defaultByZone.set(z.zone_id, z.section_ids);
-        });
-        const zoneSectionsDiff: Record<string, string[]> = {};
-        for (const [zoneId, sids] of Object.entries(userZoneSections)) {
-          if (!Array.isArray(sids)) continue;
-          const cleaned = sids.filter((s) => typeof s === "string" && s.trim());
-          const defaults = defaultByZone.get(zoneId) ?? [];
-          const sameAsDefault =
-            cleaned.length === defaults.length &&
-            cleaned.every((sid, i) => sid === defaults[i]);
-          if (!sameAsDefault) {
-            zoneSectionsDiff[zoneId] = cleaned;
+      // IMP-55 (#93) u7 — Replace the IMP-08 B-3 self-compare with the bool
+      // `manual_section_assignment` intent marker gate. The prior code built
+      // `defaultByZone` from `sourcePlan.zones` and compared against the
+      // user's `overrides.zone_sections`, but `sourcePlan === effectiveSlidePlan`
+      // (Home.tsx:305) and `effectiveSlidePlan.zones === pendingZones`
+      // (Home.tsx:649), which is itself derived from
+      // `state.userSelection.overrides.zone_sections` via slidePlanUtils.ts.
+      // The comparison was degenerate (user input vs itself), so real drag-drop
+      // swaps were classified `sameAsDefault` and silently dropped from
+      // `overrides.zoneSections` — the exact regression IMP-55 fixes.
+      //   - true  → forward `zone_sections` filtered to zone_ids that exist in
+      //     `sourcePlan.zones` (cross-layout safety so foreign zone keys from a
+      //     stale persisted layout never reach backend `--override-section-
+      //     assignment`). u6 is the SOLE setter of true (real drag-drop).
+      //   - false → skip. Backend determines assignment from its own default
+      //     policy. u3 seeds false on first load, u5 resets false on layout
+      //     apply auto-carry, u12 persists false so a stale disk `true` cannot
+      //     survive a reopen-after-apply window.
+      // No `sameAsDefault` heuristic — the marker is the source of intent.
+      const manualMarker =
+        state.userSelection.overrides.manual_section_assignment;
+      if (manualMarker === true) {
+        const userZoneSections = state.userSelection.overrides.zone_sections;
+        if (userZoneSections) {
+          const validZoneIds = new Set(
+            sourcePlan.zones.map((z) => z.zone_id),
+          );
+          const zoneSectionsForward: Record<string, string[]> = {};
+          for (const [zoneId, sids] of Object.entries(userZoneSections)) {
+            if (!validZoneIds.has(zoneId)) continue;
+            if (!Array.isArray(sids)) continue;
+            const cleaned = sids.filter(
+              (s) => typeof s === "string" && s.trim(),
+            );
+            zoneSectionsForward[zoneId] = cleaned;
+          }
+          if (Object.keys(zoneSectionsForward).length > 0) {
+            overrides.zoneSections = zoneSectionsForward;
          }
-        }
-        if (Object.keys(zoneSectionsDiff).length > 0) {
-          overrides.zoneSections = zoneSectionsDiff;
        }
      }
    }
@@ -384,6 +461,14 @@ export default function Home() {
      // clicks Generate would race the PUT against /api/run; the u2
      // fallback could then load a stale persisted document.
      await flushUserOverrides();
+      // IMP-42 u4 — unconditional DIAG console.log on the handleGenerate
+      // entry-to-backend boundary. Surfaces the override payload + uploaded
+      // file name so the user can see exactly what crossed the wire when
+      // the pipeline fails silently. No env gate (silence is the bug).
+      console.log("[DIAG raw overrides]", {
+        file: state.uploadedFile.name,
+        overrides,
+      });
      const result = await runPipeline(state.uploadedFile, overrides);

      if (!result.success || !result.final_html_exists) {
@@ -450,7 +535,21 @@ export default function Home() {
  const handleSectionDrop = useCallback((sectionId: string, zoneId: string) => {
    setState((p) => {
      const newSelection = moveSectionToZone(p.userSelection, sectionId, zoneId);
-      const finalSelection = selectZone(newSelection, zoneId); // 이동된 존 자동 선택
+      const zoneSelected = selectZone(newSelection, zoneId); // 이동된 존 자동 선택
+      // IMP-55 (#93) u6 — flip the bool intent marker to `true` on real
+      // user drag-drop. Inverse of the u5 reset (layout apply/cancel
+      // auto-carry → false). handleGenerate (u7) gates `overrides.zoneSections`
+      // forwarding on this marker, so an unflipped drop would never reach
+      // the backend (the IMP-55 self-compare regression). The marker is
+      // flipped BEFORE persistence so the in-memory selection and the
+      // co-PUT body stay in sync atomically.
+      const finalSelection = {
+        ...zoneSelected,
+        overrides: {
+          ...zoneSelected.overrides,
+          manual_section_assignment: true,
+        },
+      };
      // IMP-52 u7 — persist the post-drop zone_sections snapshot. The on-disk
      // schema axis (`zone_sections`) shares the in-memory shape (zone_id →
      // section_ids), so we forward the full mutated value; the u4 PUT path
@@ -458,10 +557,15 @@ export default function Home() {
      // p.uploadedFile gate skips persistence before any MDX is loaded —
      // the demo-mode initial render path would otherwise PUT to the empty
      // key. saveUserOverrides is debounced (300ms) and per-key coalesced.
+      // IMP-55 (#93) u6 — co-PUT `manual_section_assignment: true` in the
+      // SAME body so the disk file never has the post-drop zone_sections
+      // without the marker (would otherwise look like an unmotivated
+      // IMP-52 zone_sections write to the u9 backend fallback).
      if (p.uploadedFile) {
        const key = deriveUserOverridesKey(p.uploadedFile.name);
        void saveUserOverrides(key, {
          zone_sections: finalSelection.overrides.zone_sections,
+          manual_section_assignment: true,
        });
      }
      return { ...p, userSelection: finalSelection };
@@ -579,6 +683,51 @@ export default function Home() {
    setHasPendingChanges(true);
  }, []);

+  // IMP-56 (#90) u15 — wire SlideCanvas u13 focusout capture into the new
+  // `text_overrides` persist axis. Mirrors handleImageResize: merge the
+  // (zoneId, textPath, value) tick via `saveTextOverride` (u15 pure helper)
+  // and schedule the 300ms-debounced PUT under the `text_overrides` axis.
+  // Per-axis coalescing in `saveUserOverrides` collapses rapid edits in
+  // the same line into a single PUT; per-key buckets isolate cross-MDX.
+  const handleTextEdit = useCallback(
+    (capture: { zoneId: string; textPath: string; value: string }) => {
+      setState((p) => {
+        const nextSelection = saveTextOverride(
+          p.userSelection, capture.zoneId, capture.textPath, capture.value,
+        );
+        if (p.uploadedFile) {
+          const key = deriveUserOverridesKey(p.uploadedFile.name);
+          void saveUserOverrides(key, {
+            text_overrides: nextSelection.overrides.text_overrides,
+          });
+        }
+        return { ...p, userSelection: nextSelection };
+      });
+      setHasPendingChanges(true);
+    },
+    [],
+  );
+
+  // IMP-56 (#90) u15 — wire SlideCanvas u14 structure overlay capture into
+  // the `structure_overrides` axis. Scope-locked to {slot_order,
+  // hidden_slots} — frame swap stays on the existing `frames` axis.
+  const handleStructureEdit = useCallback(
+    (zoneId: string, perZone: { slot_order?: string[]; hidden_slots?: string[] }) => {
+      setState((p) => {
+        const nextSelection = saveStructureOverride(p.userSelection, zoneId, perZone);
+        if (p.uploadedFile) {
+          const key = deriveUserOverridesKey(p.uploadedFile.name);
+          void saveUserOverrides(key, {
+            structure_overrides: nextSelection.overrides.structure_overrides,
+          });
+        }
+        return { ...p, userSelection: nextSelection };
+      });
+      setHasPendingChanges(true);
+    },
+    [],
+  );
+
  // pending mode 일 때 effectiveSlidePlan = pendingZones 가 swap 된 plan.
  // 그 외 = state.slidePlan. 모든 zone / region lookup 이 일관되게 이걸 사용 →
  // pending mode 의 region.id ("pending-region-N") 가 zone_frames key 로 들어가
@@ -590,17 +739,6 @@ export default function Home() {
    return state.slidePlan;
  }, [pendingZones, state.slidePlan, pendingLayout]);

-  // 2026-05-14 — slide-level CSS override 계산. mdx04 default (rank 1 = process_product_two_way)
-  // 일 때만 적용 (catalog 무변, slide 결과물에만 inject). 사용자 frame override 후 다른
-  // frame 시 무적용 (rank 2 의 frame visual 유지).
-  const slideOverrideCss = useMemo<string | undefined>(() => {
-    if (selectedSample !== "04") return undefined;
-    const zone04_2 = state.slidePlan?.zones.find((z) => z.zone_id === "bottom");
-    const frameId = zone04_2?.internal_regions[0]?.frame_match_strategy.frame_id;
-    if (frameId !== "process_product_two_way") return undefined;
-    return MDX04_DEFAULT_OVERRIDE_CSS;
-  }, [selectedSample, state.slidePlan]);
-
  // ── Frame 선택 ──
  const handleFrameSelect = useCallback((frameId: string) => {
    const zone = getSelectedZone(effectiveSlidePlan, state.userSelection);
@@ -761,7 +899,6 @@ export default function Home() {
            normalizedContent={state.normalizedContent}
            userSelection={state.userSelection}
            finalHtmlUrl={runMeta?.final_html_url}
-            slideOverrideCss={slideOverrideCss}
            isPipelineRunning={state.isLoading}
            isPendingLayout={!!pendingLayout}
            pendingLayoutId={pendingLayout}
@@ -779,6 +916,9 @@ export default function Home() {
            onZoneResize={handleZoneResize}
            imageOverrides={state.userSelection.overrides.image_overrides}
            onImageResize={handleImageResize}
+            onTextEdit={handleTextEdit}
+            structureOverrides={state.userSelection.overrides.structure_overrides}
+            onStructureEdit={handleStructureEdit}
          />
        </main>

@@ -821,11 +961,13 @@ export default function Home() {
            <span className="text-[10px] font-bold text-slate-500 uppercase tracking-tighter">Phase Z Engine Active</span>
          </div>
        </div>
-        <div className="flex items-center gap-3">
-          <Button variant="outline" onClick={() => toast.info("연동하기 기능은 준비 중입니다.")} className="gap-2 h-9 text-[11px] font-bold uppercase tracking-widest border-slate-200"><Link2 className="w-3.5 h-3.5" />Connect</Button>
-          <Button variant="outline" onClick={() => toast.info("다운로드 기능은 준비 중입니다.")} disabled={!state.slidePlan} className="gap-2 h-9 text-[11px] font-bold uppercase tracking-widest border-slate-200"><Download className="w-3.5 h-3.5" />Download</Button>
-          <Button onClick={() => toast.success("슬라이드 설정이 확정되었습니다.")} disabled={!state.slidePlan || state.isLoading} className="gap-2 h-9 text-[11px] font-bold uppercase tracking-widest bg-slate-900 hover:bg-slate-800"><Sparkles className="w-3.5 h-3.5" />Finalize Slide</Button>
-        </div>
+        <BottomActions
+          slidePlan={state.slidePlan}
+          runMeta={runMeta}
+          uploadedFile={state.uploadedFile}
+          isLoading={state.isLoading}
+          onGenerate={handleGenerate}
+        />
      </footer>
    </div>
  );
@@ -345,13 +345,25 @@ export interface PipelineOverrides {

 export async function runPipeline(
  file: File,
-  overrides?: PipelineOverrides
+  overrides?: PipelineOverrides,
+  // IMP-43 (#72) u6 — optional prev RUN_ID for incremental rerun. When set,
+  // the vite plugin forwards `--reuse-from <PREV_RUN_ID>` to the backend
+  // and the pipeline resumes at Step 7 (Step 0/1/2/5/6 artifacts copied
+  // from the prior run). When omitted / empty, the POST body is
+  // byte-identical to pre-u6 (no reuseFromRunId key → no flag forwarded).
+  reuseFromRunId?: string,
 ): Promise<RunPipelineResult> {
  const content = await file.text();
+  const body: Record<string, unknown> = {
+    filename: file.name,
+    content,
+    overrides,
+  };
+  if (reuseFromRunId) body.reuseFromRunId = reuseFromRunId;
  const res = await fetch("/api/run", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ filename: file.name, content, overrides }),
+    body: JSON.stringify(body),
  });
  const data = (await res.json()) as RunPipelineResult;
  if (!res.ok && !data.run_id) {
@@ -565,6 +577,13 @@ export async function loadRun(runId: string): Promise<LoadRunResult> {
    // sort 우선순위 = label (use_as_is > light_edit > restructure > reject) + confidence desc.
    // 모두 reject 인 경우 confidence desc 만 적용 (사용자 명시).
    const TOP_N_FRAMES = 6;
+    // IMP-39 u4 (issue #68) — local LABEL_PRIORITY is now a documentation
+    // mirror of templates/phase_z2/catalog/ranking_sort_policy.yaml (u1).
+    // Primary ordering arrives pre-sorted from the backend selector
+    // (src/phase_z2_pipeline.py lookup_v4_match_with_fallback :1186-1196 +
+    // _build_application_plan_unit u3 payload fields). This constant is read
+    // ONLY on the warn-fallback path below (legacy fixtures pre-u3 / payload
+    // missing). Kept verbatim so the fallback ordering matches u1/u2 contract.
    const LABEL_PRIORITY: Record<string, number> = {
      use_as_is: 0,
      light_edit: 1,
@@ -576,9 +595,6 @@ export async function loadRun(runId: string): Promise<LoadRunResult> {
    //   2) unit.v4_all_judgments   (pre-IMP-05 audit array)
    //   3) unit.v4_candidates      (legacy minimal)
    // fallback_chain alias is intentionally NOT read (Stage 2 guardrail).
-    const candidateEvidence = Array.isArray(unit.candidate_evidence)
-      ? unit.candidate_evidence
-      : [];
    const candidateMap = new Map<string, any>();
    const pushCandidate = (c: any) => {
      if (!c) return;
@@ -586,15 +602,64 @@ export async function loadRun(runId: string): Promise<LoadRunResult> {
      if (!key) return;
      if (!candidateMap.has(key)) candidateMap.set(key, c);
    };
-    candidateEvidence.forEach(pushCandidate);
-    (unit.v4_all_judgments ?? []).forEach(pushCandidate);
-    (unit.v4_candidates ?? []).forEach(pushCandidate);
-    const rawSource = Array.from(candidateMap.values());
-    const v4Source = [...rawSource].sort((a: any, b: any) => {
-      const lp = (LABEL_PRIORITY[a.label] ?? 99) - (LABEL_PRIORITY[b.label] ?? 99);
-      if (lp !== 0) return lp;
-      return (b.confidence ?? 0) - (a.confidence ?? 0);
-    });
+
+    // IMP-39 u4 (issue #68) — primary path: consume the backend Step 9
+    // payload as the single source of ordering truth.
+    //   • ``unit.sorted_candidate_evidence`` = policy-sorted selector trace
+    //     (src/phase_z2_pipeline.py :4163, alias of selection_trace[
+    //     "candidates"] sorted by u2 at :1186-1196). Same IMP-05 L2 schema
+    //     consumed below (template_id, label, confidence, frame_number,
+    //     frame_id, rank, catalog_registered, capacity_fit, route_hint, ...).
+    //   • ``unit.ranking_sort_policy`` = full single-source policy dict
+    //     (policy_type / label_priority / unknown_label_priority /
+    //     tie_break_axes) forwarded for telemetry + fallback parity check.
+    // When both are present we feed sorted_candidate_evidence through the
+    // existing dedup map (first occurrence wins, mirrors backend
+    // ``seen_template_ids`` semantics at :1204-1236) and SKIP the local
+    // re-sort — backend "rank 1" then equals frontend frame_candidates[0]
+    // by construction (Stage 1 root-cause fix).
+    const sortedCandidateEvidence: any[] | null = Array.isArray(
+      unit.sorted_candidate_evidence,
+    )
+      ? unit.sorted_candidate_evidence
+      : null;
+    const rankingSortPolicy = unit.ranking_sort_policy ?? null;
+    const backendPolicyPayloadPresent =
+      sortedCandidateEvidence !== null &&
+      sortedCandidateEvidence.length > 0 &&
+      rankingSortPolicy !== null;
+
+    let v4Source: any[];
+    if (backendPolicyPayloadPresent) {
+      sortedCandidateEvidence!.forEach(pushCandidate);
+      v4Source = Array.from(candidateMap.values());
+    } else {
+      // IMP-39 u4 — warn-fallback path. Legacy fixtures predating u3 (or
+      // any code path that strips the payload) lack the backend-sorted
+      // evidence; ordering then derives from local LABEL_PRIORITY mirror.
+      // Warning surfaces drift in dev console without hard-failing the UI
+      // (graceful: production sample audit deck remains renderable).
+      if (typeof console !== "undefined" && typeof console.warn === "function") {
+        console.warn(
+          `[IMP-39 u4] unit ${unit.unit_id ?? "<unknown>"}: backend payload ` +
+            "missing ranking_sort_policy / sorted_candidate_evidence — " +
+            "falling back to local LABEL_PRIORITY (legacy fixture path).",
+        );
+      }
+      const candidateEvidence = Array.isArray(unit.candidate_evidence)
+        ? unit.candidate_evidence
+        : [];
+      candidateEvidence.forEach(pushCandidate);
+      (unit.v4_all_judgments ?? []).forEach(pushCandidate);
+      (unit.v4_candidates ?? []).forEach(pushCandidate);
+      const rawSource = Array.from(candidateMap.values());
+      v4Source = [...rawSource].sort((a: any, b: any) => {
+        const lp =
+          (LABEL_PRIORITY[a.label] ?? 99) - (LABEL_PRIORITY[b.label] ?? 99);
+        if (lp !== 0) return lp;
+        return (b.confidence ?? 0) - (a.confidence ?? 0);
+      });
+    }
    // ─── IMP-41 u4 — application_candidates enrichment (issue #70) ───────────
    // Backend Step 9 emits `unit.application_candidates[]` (src/phase_z2_pipeline.py
    // _application_candidates_for_unit, :3071-3092) one entry per v4 candidate with
@@ -65,6 +65,47 @@ export type ImageOverride = {
 };
 export type ImageOverridesOverride = Record<string, ImageOverride>;

+/**
+ * IMP-55 #93 u1 — bool intent marker that gates whether persisted
+ * `zone_sections` are consumed by the backend pipeline. Frontend sets
+ * `true` only on a real user drag-drop (Home.tsx handleSectionDrop, u6)
+ * and `false` on layout apply/cancel auto-carry (u5/u12). Mirrors the
+ * Python KNOWN_AXES (`manual_section_assignment`) added in u1 and the
+ * Vite KNOWN_USER_OVERRIDES_AXES allowlist entry added in u1.
+ */
+export type ManualSectionAssignmentOverride = boolean;
+
+/**
+ * IMP-56 #90 u10 — Step-22 text-edit persist axis. Keyed by `zone_id`; the
+ * inner mapping is `text_path` (= `{slot_key}.{line_index}`) → line value.
+ * The `text_path` stamp is emitted by `src/text_path_stamper.py` (u8) and
+ * applied at Step 13 (u9); the value is consumed by `text_override_resolver`
+ * (u4) and applied at Step 12 (u5). Stale paths (frame swap / layout
+ * regression between sessions) are tolerated by the backend resolver as
+ * `skipped`, NOT raised — so the on-disk axis is forward-compat with layout
+ * and frame churn. Mirrors Python `KNOWN_AXES` entry (u1) and Vite
+ * `KNOWN_USER_OVERRIDES_AXES` allowlist entry (u3).
+ */
+export type TextOverridesPerZone = Record<string, string>;
+export type TextOverridesOverride = Record<string, TextOverridesPerZone>;
+
+/**
+ * IMP-56 #90 u10 — Step-22 structure-edit persist axis. Keyed by `zone_id`;
+ * the inner mapping is SCOPE-LOCKED to `{slot_order, hidden_slots}` — slot
+ * reorder + slot hide only. Frame swap stays on the existing `frames` axis;
+ * the `structure_override_resolver` (u6) rejects frame-swap-shaped inner
+ * keys at the validate gate so Phase Z's no-AI-HTML-structure invariant
+ * holds across this persisted axis too. Per-slot `list[str]` line content
+ * is NEVER mutated by the u7 Step-12 apply — that is the `text_overrides`
+ * axis above. Mirrors Python `KNOWN_AXES` entry (u2) and Vite
+ * `KNOWN_USER_OVERRIDES_AXES` allowlist entry (u3).
+ */
+export type StructureOverridePerZone = {
+  slot_order?: string[];
+  hidden_slots?: string[];
+};
+export type StructureOverridesOverride = Record<string, StructureOverridePerZone>;
+
 /** Full on-disk schema. All axes optional — file may carry any subset. */
 export interface UserOverrides {
  layout: string;
@@ -72,6 +113,9 @@ export interface UserOverrides {
  zone_geometries: ZoneGeometriesOverride;
  zone_sections: ZoneSectionsOverride;
  image_overrides: ImageOverridesOverride;
+  manual_section_assignment: ManualSectionAssignmentOverride;
+  text_overrides: TextOverridesOverride;
+  structure_overrides: StructureOverridesOverride;
 }

 /** Partial-mutation payload. `null` is the explicit clear sentinel (mirrors u4). */
@@ -213,6 +213,29 @@ export interface UserSelection {
    // `image_overrides` axis (KNOWN_AXES, src/user_overrides_io.py u1) and
    // the typed-client `ImageOverridesOverride` (services/userOverridesApi.ts u3).
    image_overrides: Record<string, { x: number; y: number; w: number; h: number }>;
+    // IMP-55 (#93) u3 — bool intent marker gating whether the backend
+    // consumes persisted `zone_sections` as a user override. Set to `true`
+    // only by the real drag-drop path (Home.tsx handleSectionDrop, u6); set
+    // back to `false` by the layout apply/cancel auto-carry path (u5/u12).
+    // handleGenerate (u7) reads this flag to decide whether to forward
+    // `overrides.zoneSections` to the backend, replacing the pre-IMP-55
+    // self-compare against `effectiveSlidePlan`. Seeded `false` in
+    // `createInitialUserSelection` and only restored on reopen when the
+    // persisted value is a real boolean (slidePlanUtils.ts u3 layering).
+    // Mirrors the on-disk axis added in u1 — Python KNOWN_AXES
+    // (src/user_overrides_io.py), Vite KNOWN_USER_OVERRIDES_AXES
+    // (Front/vite.config.ts), and `ManualSectionAssignmentOverride`
+    // (services/userOverridesApi.ts).
+    manual_section_assignment: boolean;
+    // IMP-56 #90 u10/u15 — Step-22 text + structure persist axes. Mirrors
+    // services/userOverridesApi.ts (`TextOverridesOverride` /
+    // `StructureOverridesOverride`). `text_overrides[zoneId][textPath] = value`
+    // is fed by SlideCanvas u13 focusout capture + Home u15 autosave;
+    // `structure_overrides[zoneId] = {slot_order, hidden_slots}` is fed by
+    // u14 overlay + u15 autosave. Both seeded `{}` in createInitialUserSelection
+    // and restored on reopen via applyPersistedNonFrameOverrides.
+    text_overrides: Record<string, Record<string, string>>;
+    structure_overrides: Record<string, { slot_order?: string[]; hidden_slots?: string[] }>;
  };
 }

@@ -1,5 +1,12 @@
 import type { UserSelection, SlidePlan, Zone, InternalRegion, LayoutPresetId } from "../types/designAgent";
-import type { UserOverrides } from "../services/userOverridesApi";
+import type {
+  StructureOverridePerZone,
+  StructureOverridesOverride,
+  TextOverridesOverride,
+  TextOverridesPerZone,
+  UserOverrides,
+} from "../services/userOverridesApi";
+import { computeZonePositions } from "../services/designAgentApi";

 // ─── IMP-52 u6 — restore-on-reopen helpers (pure, exported for testing) ────
 // These helpers compose persisted `user_overrides.json` payloads (typed by
@@ -84,9 +91,88 @@ export function applyPersistedNonFrameOverrides(
  ) {
    next.image_overrides = { ...persisted.image_overrides };
  }
+  // IMP-55 (#93) u3 — restore the bool intent marker only when the persisted
+  // value is a real `boolean`. A missing axis, `null` (the u4 clear sentinel
+  // observed post-flush), or any non-boolean shape (string "true", 1, {})
+  // intentionally falls through to the `createInitialUserSelection` seed of
+  // `false`. This is the fail-closed half of the marker contract: the
+  // backend pipeline (u9) consumes persisted `zone_sections` only when
+  // `manual_section_assignment is True`, so anything other than a real
+  // `true` MUST end up as `false` in memory to avoid resurrecting stale
+  // auto-carry assignments as user intent. Both `true` and `false` are
+  // restored verbatim (the explicit `false` from u12's apply/cancel write
+  // is meaningful — it pins the marker off across reopens).
+  if (typeof persisted.manual_section_assignment === "boolean") {
+    next.manual_section_assignment = persisted.manual_section_assignment;
+  }
+  // IMP-56 (#90) u15 — layer the two Step-22 persist axes through the
+  // u10 extract helpers; their `_isPlainObject` + dedupe gates already
+  // sanitize foreign / hand-edited payloads, so reopen never poisons
+  // memory with non-string values or non-list slot_order entries.
+  next.text_overrides = extractPersistedTextOverrides(persisted);
+  next.structure_overrides = extractPersistedStructureOverrides(persisted);
  return { ...selection, overrides: next };
 }

+// ─── IMP-56 #90 u10 — typed extract helpers for the two new persist axes ───
+// Pure helpers that defensively sanitize Step-22 text_overrides and
+// structure_overrides payloads off a `Partial<UserOverrides>` (typed by u10's
+// userOverridesApi extension). They mirror the backend validation gates
+// (`text_override_resolver` u4 / `structure_override_resolver` u6) on the
+// frontend so a hand-edited or schema-drift payload cannot poison memory.
+// Layering onto `UserSelection.overrides` arrives in u14~u16; until then
+// capture / autosave / restore wiring units consume these as typed.
+
+function _isPlainObject(x: unknown): x is Record<string, unknown> {
+  return !!x && typeof x === "object" && !Array.isArray(x);
+}
+
+function _dedupeStringList(arr: unknown): string[] {
+  if (!Array.isArray(arr)) return [];
+  const seen = new Set<string>();
+  const out: string[] = [];
+  for (const k of arr) {
+    if (typeof k === "string" && k.length > 0 && !seen.has(k)) {
+      seen.add(k);
+      out.push(k);
+    }
+  }
+  return out;
+}
+
+export function extractPersistedTextOverrides(
+  persisted: Partial<UserOverrides> | null | undefined,
+): TextOverridesOverride {
+  const raw = persisted?.text_overrides;
+  if (!_isPlainObject(raw)) return {};
+  const out: TextOverridesOverride = {};
+  for (const [zoneId, perZone] of Object.entries(raw)) {
+    if (!zoneId || !_isPlainObject(perZone)) continue;
+    const safe: TextOverridesPerZone = {};
+    for (const [textPath, value] of Object.entries(perZone)) {
+      if (textPath && typeof value === "string") safe[textPath] = value;
+    }
+    out[zoneId] = safe;
+  }
+  return out;
+}
+
+export function extractPersistedStructureOverrides(
+  persisted: Partial<UserOverrides> | null | undefined,
+): StructureOverridesOverride {
+  const raw = persisted?.structure_overrides;
+  if (!_isPlainObject(raw)) return {};
+  const out: StructureOverridesOverride = {};
+  for (const [zoneId, perZone] of Object.entries(raw)) {
+    if (!zoneId || !_isPlainObject(perZone)) continue;
+    const safe: StructureOverridePerZone = {};
+    if (Array.isArray(perZone.slot_order)) safe.slot_order = _dedupeStringList(perZone.slot_order);
+    if (Array.isArray(perZone.hidden_slots)) safe.hidden_slots = _dedupeStringList(perZone.hidden_slots);
+    out[zoneId] = safe;
+  }
+  return out;
+}
+
 /**
 * Remap persisted frames (`unit_id` → template_id) to the in-memory
 * `zone_frames` (region.id → template_id) using the freshly built
@@ -159,6 +245,20 @@ export function createInitialUserSelection(slidePlan?: SlidePlan | null): UserSe
      // here via `saveImageOverride` (SlideCanvas drag/resize handler) and
      // are seeded on reopen via `applyPersistedNonFrameOverrides`.
      image_overrides: {},
+      // IMP-56 (#90) u15 — Step-22 axes seeded empty. Entries land here
+      // via `saveTextOverride` (u13 focusout capture) and
+      // `saveStructureOverride` (u14 overlay) and are restored on reopen
+      // via `applyPersistedNonFrameOverrides`.
+      text_overrides: {},
+      structure_overrides: {},
+      // IMP-55 (#93) u3 — bool intent marker seeded `false` so a fresh
+      // MDX open (no persisted file, or persisted file with axis absent)
+      // never forwards `overrides.zoneSections` to the backend. The marker
+      // flips to `true` only via the real drag-drop path (Home.tsx u6) and
+      // is reset to `false` by layout apply/cancel auto-carry (u5/u12).
+      // `applyPersistedNonFrameOverrides` may restore a persisted boolean
+      // verbatim on reopen — see the bool-only guard there.
+      manual_section_assignment: false,
    },
  };
 }
@@ -206,6 +306,60 @@ export function saveImageOverride(
  };
 }

+/**
+ * IMP-56 (#90) u15 — record a single text-line capture (zone_id, text_path,
+ * value) onto the in-memory selection's `text_overrides` axis. Mirrors
+ * `saveImageOverride` (pure / immutable). u13's focusout capture emits one
+ * entry per finished edit; Home u15's handler funnels each emit through this
+ * helper before scheduling the debounced PUT (`saveUserOverrides` 300ms).
+ */
+export function saveTextOverride(
+  selection: UserSelection,
+  zoneId: string,
+  textPath: string,
+  value: string,
+): UserSelection {
+  const prevZone = selection.overrides.text_overrides[zoneId] ?? {};
+  return {
+    ...selection,
+    overrides: {
+      ...selection.overrides,
+      text_overrides: {
+        ...selection.overrides.text_overrides,
+        [zoneId]: { ...prevZone, [textPath]: value },
+      },
+    },
+  };
+}
+
+/**
+ * IMP-56 (#90) u15 — record a single structure capture (zone_id ↦
+ * {slot_order, hidden_slots}) onto the in-memory selection's
+ * `structure_overrides` axis. Scope-locked to slot reorder + hide (frame
+ * swap stays on the `frames` axis). u14's overlay emits one entry per
+ * user mutation; Home u15's handler funnels each emit through this
+ * helper before scheduling the debounced PUT.
+ */
+export function saveStructureOverride(
+  selection: UserSelection,
+  zoneId: string,
+  perZone: StructureOverridePerZone,
+): UserSelection {
+  return {
+    ...selection,
+    overrides: {
+      ...selection.overrides,
+      structure_overrides: {
+        ...selection.overrides.structure_overrides,
+        [zoneId]: {
+          ...(perZone.slot_order !== undefined && { slot_order: [...perZone.slot_order] }),
+          ...(perZone.hidden_slots !== undefined && { hidden_slots: [...perZone.hidden_slots] }),
+        },
+      },
+    },
+  };
+}
+
 export function saveZoneSizes(selection: UserSelection, groupId: string, sizes: number[]): UserSelection {
  return {
    ...selection,
@@ -320,3 +474,77 @@ export function getEffectiveLayoutId(slidePlan: SlidePlan | null, selection: Use
  if (selection.overrides.layout_preset) return selection.overrides.layout_preset;
  return slidePlan?.layout_preset || 'single';
 }
+
+// ─── IMP-44 (#73) u3 — zone_geometries layout-mismatch validation ───────────
+// Pure helper paired with the backend [override-warning] guards added in u1
+// (1-D horizontal-2 / vertical-2 branches of `build_layout_css`) and u2 (2-D
+// `_override_to_grid_tracks` call site). Same WARN+DROP / KEEP-known contract,
+// but expressed on the frontend so handleGenerate (u4) can validate against
+// the active layout *before* forwarding and surface a toast on dropped keys.
+//
+// Source of truth for expected positions = `computeZonePositions(layoutPreset)`
+// (designAgentApi.ts), which mirrors backend `layouts.yaml` (positions field).
+// Unknown layout (null / undefined / not in LAYOUT_PRESET_IDS) ⇒ fail-safe
+// drop-all: caller has no contract for projecting geometries onto an unknown
+// preset, so we keep zero keys rather than passing them through verbatim.
+
+export interface ZoneGeometryValue {
+  x: number;
+  y: number;
+  w: number;
+  h: number;
+}
+
+export interface ZoneGeometriesValidationResult {
+  kept: Record<string, ZoneGeometryValue>;
+  dropped: Record<string, ZoneGeometryValue>;
+  expectedPositions: string[];
+  valid: boolean;
+}
+
+export function validateZoneGeometriesAgainstLayout(
+  geoms: Record<string, ZoneGeometryValue> | null | undefined,
+  layoutPreset: LayoutPresetId | string | null | undefined,
+): ZoneGeometriesValidationResult {
+  const kept: Record<string, ZoneGeometryValue> = {};
+  const dropped: Record<string, ZoneGeometryValue> = {};
+  const safeGeoms =
+    geoms && typeof geoms === "object" && !Array.isArray(geoms) ? geoms : null;
+
+  // Unknown-layout fail-safe — drop everything; no expected positions known.
+  if (typeof layoutPreset !== "string" || !LAYOUT_PRESET_IDS.has(layoutPreset)) {
+    if (safeGeoms) {
+      for (const [k, v] of Object.entries(safeGeoms)) {
+        dropped[k] = v;
+      }
+    }
+    return {
+      kept,
+      dropped,
+      expectedPositions: [],
+      valid: Object.keys(dropped).length === 0,
+    };
+  }
+
+  const expectedPositions = computeZonePositions(
+    layoutPreset as LayoutPresetId,
+  ).map((p) => p.name);
+  const expectedSet = new Set(expectedPositions);
+
+  if (safeGeoms) {
+    for (const [k, v] of Object.entries(safeGeoms)) {
+      if (expectedSet.has(k)) {
+        kept[k] = v;
+      } else {
+        dropped[k] = v;
+      }
+    }
+  }
+
+  return {
+    kept,
+    dropped,
+    expectedPositions,
+    valid: Object.keys(dropped).length === 0,
+  };
+}
@@ -0,0 +1,117 @@
+// IMP-42 u4 — Source-slice coverage for the unconditional handleGenerate
+// DIAG console.log on the frontend → backend boundary (issue #71).
+//
+// Scope (Stage 2 unit u4 contract):
+//   1) A single `console.log("[DIAG raw overrides]", ...)` call exists
+//      inside handleGenerate and precedes the runPipeline call site.
+//   2) The DIAG call is unconditional — not wrapped in `if (...)` / `?:` /
+//      env-var gate / `__DEV__`-style guard. "Silence is the bug" per
+//      Stage 1 scope-lock (Codex #3) and the Step 13 backend mirror
+//      already landed in u3.
+//   3) The DIAG payload carries shape-only metadata — uploaded file name
+//      and the override payload object — without referencing raw MDX
+//      content or any other sample-specific identifier (RULE 0).
+//
+// Why source-slice (per Stage 2 plan): Home.tsx handleGenerate is wired to
+// React state, toast, and a 700-line component tree; the cheapest way to
+// pin a single-line surface and prove placement relative to runPipeline is
+// to read the source and assert ordering. No React rendering, no fetch
+// mock, no DOM. Mirrors the existing pure-helper pattern in
+// tests/imp41_application_mode.test.ts.
+
+import { describe, it, expect } from "vitest";
+import { readFileSync } from "node:fs";
+import { resolve } from "node:path";
+
+const HOME_TSX_PATH = resolve(__dirname, "..", "src", "pages", "Home.tsx");
+const HOME_TSX_SOURCE = readFileSync(HOME_TSX_PATH, "utf-8");
+
+// Locate the handleGenerate callback body. The closing brace of
+// useCallback's `async () => { ... }` is the next line whose indent matches
+// the opening `useCallback(async () => {` exactly — but a simpler proxy is
+// "from the handleGenerate keyword to the next useCallback declaration or
+// the end-of-file." This is sufficient to scope every assertion below to
+// the right function body.
+function sliceHandleGenerateBody(source: string): string {
+  const startMarker = "const handleGenerate = useCallback(async () =>";
+  const startIdx = source.indexOf(startMarker);
+  if (startIdx === -1) {
+    throw new Error("handleGenerate declaration not found in Home.tsx");
+  }
+  // End at the next top-level `const ` that begins a new useCallback /
+  // useMemo / hook binding. handleGenerate is followed by additional
+  // hooks (handleFileUpload sibling pattern); slicing to the next
+  // declaration is more than enough to capture the full body.
+  const afterStart = source.slice(startIdx + startMarker.length);
+  const nextDeclIdx = afterStart.search(/\n {2}const [A-Za-z]/);
+  return nextDeclIdx === -1 ? afterStart : afterStart.slice(0, nextDeclIdx);
+}
+
+const HANDLE_GENERATE_BODY = sliceHandleGenerateBody(HOME_TSX_SOURCE);
+
+describe("handleGenerate [DIAG raw overrides] (IMP-42 u4)", () => {
+  it("emits exactly one console.log labelled '[DIAG raw overrides]' inside handleGenerate", () => {
+    const matches = HANDLE_GENERATE_BODY.match(
+      /console\.log\(\s*"\[DIAG raw overrides\]"/g,
+    );
+    expect(matches).not.toBeNull();
+    // Exactly one DIAG site per Stage 2 contract — multiple calls would
+    // either be a copy-paste regression or evidence that the helper
+    // moved without removing the old site.
+    expect(matches?.length).toBe(1);
+  });
+
+  it("places the DIAG console.log before the runPipeline call site", () => {
+    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
+    const runPipelineIdx = HANDLE_GENERATE_BODY.indexOf(
+      "runPipeline(state.uploadedFile, overrides)",
+    );
+    expect(diagIdx).toBeGreaterThan(-1);
+    expect(runPipelineIdx).toBeGreaterThan(-1);
+    expect(diagIdx).toBeLessThan(runPipelineIdx);
+  });
+
+  it("is unconditional — no env-var gate or if-guard wraps the DIAG call", () => {
+    // Slice the 80 chars immediately preceding the DIAG console.log and
+    // confirm none of the common gating patterns appear directly above.
+    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
+    const preface = HANDLE_GENERATE_BODY.slice(Math.max(0, diagIdx - 200), diagIdx);
+    // Stage 1 contract: silence is the bug. Any gate here is a regression.
+    expect(preface).not.toMatch(/if\s*\([^)]*\)\s*$/m);
+    expect(preface).not.toMatch(/process\.env/);
+    expect(preface).not.toMatch(/import\.meta\.env/);
+    expect(preface).not.toMatch(/__DEV__/);
+    expect(preface).not.toMatch(/DIAG_VERBOSE/i);
+    expect(preface).not.toMatch(/DEBUG/);
+  });
+
+  it("forwards the file name and overrides object as shape-only payload", () => {
+    // The DIAG payload must include the uploaded file name (so the user
+    // can correlate the log line with the MDX they uploaded) and the
+    // overrides object (so the user can see what crossed the wire).
+    // It must NOT spread MDX text content or any other large blob —
+    // sample-agnostic and reviewable in a single log line.
+    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
+    const window = HANDLE_GENERATE_BODY.slice(diagIdx, diagIdx + 300);
+    // Both fields appear in the payload object literal.
+    expect(window).toMatch(/file:\s*state\.uploadedFile\.name/);
+    expect(window).toMatch(/\boverrides\b/);
+    // Sanity: the payload does not pass MDX raw content / a File blob.
+    expect(window).not.toMatch(/mdxContent|rawMdx|normalizedContent/);
+  });
+
+  it("runs after flushUserOverrides() so the persisted PUT is already committed", () => {
+    // Ordering invariant from IMP-52 u10 (already in place):
+    //   flushUserOverrides() → DIAG → runPipeline
+    // Asserts the DIAG sits between the flush and the network call so the
+    // logged overrides match what backend reads from disk.
+    const flushIdx = HANDLE_GENERATE_BODY.indexOf("await flushUserOverrides()");
+    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
+    const runPipelineIdx = HANDLE_GENERATE_BODY.indexOf(
+      "runPipeline(state.uploadedFile, overrides)",
+    );
+    expect(flushIdx).toBeGreaterThan(-1);
+    expect(diagIdx).toBeGreaterThan(flushIdx);
+    expect(diagIdx).toBeLessThan(runPipelineIdx);
+  });
+});
@@ -0,0 +1,122 @@
+// IMP-#84 u1 — FramePanel reject silent-automation contract.
+//
+// Stage 2 unit u1 scope:
+//   1) `applyFrameSelection(candidate, onFrameSelect)` invokes onFrameSelect
+//      with candidate.id verbatim for EVERY V4 label
+//      (use_as_is / light_edit / restructure / reject) — no window.confirm
+//      gate, no label-conditional branch, no frame swap.
+//   2) Source-presence checks pin the FramePanel.tsx wiring so the runtime
+//      button → handler → helper chain stays intact even though we cannot
+//      mount React (no jsdom / RTL / happy-dom in Front devDependencies —
+//      verified against the IMP-56 u20 `imp90_bottom_actions.test.ts` and
+//      IMP-92 u5 `imp47b_human_review_toast.test.tsx` precedent that
+//      explicitly skip DOM mounting).
+//   3) No `window.confirm` substring remains in FramePanel.tsx after u1.
+//
+// Out of scope (Stage 2 exit-report contract):
+//   - Home.tsx:523-524 `toast.error(aiReviewMsg)` (#92 operational-only).
+//   - FramePanel reject badge/tooltip read-only labels at L102/L147/L156
+//     (no popup trigger; preserved as silent operator hint).
+//   - Backend `zone.provisional` emission (handled by u2 template-only).
+
+import { readFileSync } from "node:fs";
+import { resolve, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+import { describe, it, expect, vi } from "vitest";
+import { applyFrameSelection } from "../src/components/FramePanel";
+import type { FrameCandidate } from "../src/types/designAgent";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const FRAME_PANEL_SOURCE = readFileSync(
+  resolve(__dirname, "../src/components/FramePanel.tsx"),
+  "utf-8",
+);
+
+function makeCandidate(
+  label: FrameCandidate["label"],
+  id: string,
+): FrameCandidate {
+  return {
+    id,
+    name: `Frame ${id}`,
+    score: 0.5,
+    confidence: "medium",
+    label,
+  };
+}
+
+describe("applyFrameSelection (IMP-#84 u1 — silent-automation contract)", () => {
+  it("forwards candidate.id to onFrameSelect for use_as_is label", () => {
+    const onFrameSelect = vi.fn();
+    applyFrameSelection(makeCandidate("use_as_is", "frame_a"), onFrameSelect);
+    expect(onFrameSelect).toHaveBeenCalledTimes(1);
+    expect(onFrameSelect).toHaveBeenCalledWith("frame_a");
+  });
+
+  it("forwards candidate.id to onFrameSelect for light_edit label", () => {
+    const onFrameSelect = vi.fn();
+    applyFrameSelection(makeCandidate("light_edit", "frame_b"), onFrameSelect);
+    expect(onFrameSelect).toHaveBeenCalledTimes(1);
+    expect(onFrameSelect).toHaveBeenCalledWith("frame_b");
+  });
+
+  it("forwards candidate.id to onFrameSelect for restructure label", () => {
+    const onFrameSelect = vi.fn();
+    applyFrameSelection(makeCandidate("restructure", "frame_c"), onFrameSelect);
+    expect(onFrameSelect).toHaveBeenCalledTimes(1);
+    expect(onFrameSelect).toHaveBeenCalledWith("frame_c");
+  });
+
+  it("forwards candidate.id to onFrameSelect for reject label — no popup, no frame swap", () => {
+    // Reject is the silent-automation pivot case: prior IMP-47B u11 gated
+    // this path with window.confirm; post-IMP-#84 the helper invokes
+    // onFrameSelect with the reject frame.id directly. Backend / AI 격리
+    // contract handles AI 재구성 (content-only, frame preserved).
+    const onFrameSelect = vi.fn();
+    applyFrameSelection(makeCandidate("reject", "frame_d"), onFrameSelect);
+    expect(onFrameSelect).toHaveBeenCalledTimes(1);
+    expect(onFrameSelect).toHaveBeenCalledWith("frame_d");
+  });
+
+  it("does not call onFrameSelect more than once per invocation", () => {
+    const onFrameSelect = vi.fn();
+    applyFrameSelection(makeCandidate("reject", "frame_e"), onFrameSelect);
+    applyFrameSelection(makeCandidate("use_as_is", "frame_f"), onFrameSelect);
+    expect(onFrameSelect).toHaveBeenCalledTimes(2);
+    expect(onFrameSelect).toHaveBeenNthCalledWith(1, "frame_e");
+    expect(onFrameSelect).toHaveBeenNthCalledWith(2, "frame_f");
+  });
+});
+
+describe("FramePanel.tsx source — silent-automation wiring pins (IMP-#84 u1)", () => {
+  it("has no window.confirm(...) call (popup removed; narrative mentions in comments are allowed)", () => {
+    // Match the call form `window.confirm(` rather than the bare substring
+    // so that explanatory comments documenting the removed popup are not
+    // flagged. A re-introduced call would carry an opening paren.
+    expect(FRAME_PANEL_SOURCE).not.toMatch(/\bwindow\.confirm\s*\(/);
+  });
+
+  it("does not embed the legacy reject-confirm Korean prompt body", () => {
+    // Prior IMP-47B u11 string fragment; absence guards against re-introduction.
+    expect(FRAME_PANEL_SOURCE).not.toContain("V4 reject 라벨입니다");
+    expect(FRAME_PANEL_SOURCE).not.toContain("계속하시겠습니까?");
+  });
+
+  it("wires the button onClick to handleFrameSelect(candidate)", () => {
+    expect(FRAME_PANEL_SOURCE).toContain(
+      "onClick={() => handleFrameSelect(candidate)}",
+    );
+  });
+
+  it("delegates handleFrameSelect body to applyFrameSelection", () => {
+    expect(FRAME_PANEL_SOURCE).toContain(
+      "applyFrameSelection(candidate, onFrameSelect)",
+    );
+  });
+
+  it("exports applyFrameSelection as a named export for caller-independent reuse", () => {
+    expect(FRAME_PANEL_SOURCE).toMatch(
+      /export function applyFrameSelection\(/,
+    );
+  });
+});
@@ -0,0 +1,90 @@
+// IMP-56 (#90) u20 — vitest coverage for the pure request builders exported
+// by `BottomActions`. The React component itself is not rendered (jsdom /
+// @testing-library NOT in Front devDependencies — verified against the prior
+// u14 `imp90_structure_overlay.test.tsx` pattern); we test the deterministic
+// pieces that drive the network payload sent to the u18 / u19 middlewares.
+//
+// Upstream / downstream contracts (verified by prior units):
+//   - u18 /api/connect : body shape = { run_id, slug } (Front/vite.config.ts
+//          handleConnectMirror — `imp90_connect_endpoint.test.ts`).
+//   - u19 /api/export  : body shape = { run_id }; response = raw text/html
+//          with `Content-Disposition: attachment; filename="<run_id>.html"`
+//          (Front/vite.config.ts handleExportStandalone —
+//          `imp90_export_endpoint.test.ts`).
+//
+// u20 scope: builders only. Any drift in URL or JSON shape fails here before
+// the request leaves the client. Toast / fetch / blob plumbing is not tested
+// (it would require jsdom + a fetch mock; the existing server-side tests
+// already pin the wire contract).
+
+import { describe, it, expect } from "vitest";
+import {
+  buildConnectRequest,
+  buildExportRequest,
+  buildDownloadFilename,
+} from "../src/components/BottomActions";
+
+describe("buildConnectRequest", () => {
+  it("targets /api/connect", () => {
+    const { url } = buildConnectRequest("run_42", "mdx_03");
+    expect(url).toBe("/api/connect");
+  });
+
+  it("emits { run_id, slug } JSON body — matches u18 middleware shape", () => {
+    const { body } = buildConnectRequest("run_42", "mdx_03");
+    expect(JSON.parse(body)).toEqual({ run_id: "run_42", slug: "mdx_03" });
+  });
+
+  it("preserves zero-length and unicode run_id verbatim (server validates)", () => {
+    const { body } = buildConnectRequest("", "x");
+    expect(JSON.parse(body)).toEqual({ run_id: "", slug: "x" });
+    const { body: uni } = buildConnectRequest("런", "슬러그");
+    expect(JSON.parse(uni)).toEqual({ run_id: "런", slug: "슬러그" });
+  });
+
+  it("does not leak extra keys (frame swap / overrides etc.)", () => {
+    const { body } = buildConnectRequest("r", "s");
+    expect(Object.keys(JSON.parse(body)).sort()).toEqual(["run_id", "slug"]);
+  });
+});
+
+describe("buildExportRequest", () => {
+  it("targets /api/export", () => {
+    const { url } = buildExportRequest("run_42");
+    expect(url).toBe("/api/export");
+  });
+
+  it("emits { run_id } JSON body — matches u19 middleware shape", () => {
+    const { body } = buildExportRequest("run_42");
+    expect(JSON.parse(body)).toEqual({ run_id: "run_42" });
+  });
+
+  it("does not leak extra keys (slug / format etc.)", () => {
+    const { body } = buildExportRequest("r");
+    expect(Object.keys(JSON.parse(body))).toEqual(["run_id"]);
+  });
+
+  it("preserves zero-length and unicode run_id verbatim (server validates)", () => {
+    expect(JSON.parse(buildExportRequest("").body)).toEqual({ run_id: "" });
+    expect(JSON.parse(buildExportRequest("런").body)).toEqual({ run_id: "런" });
+  });
+});
+
+describe("buildDownloadFilename", () => {
+  it("returns <run_id>.html for the a[download] click chain", () => {
+    expect(buildDownloadFilename("run_42")).toBe("run_42.html");
+  });
+
+  it("appends exactly one .html suffix even when run_id already ends in .html", () => {
+    // The server-side `Content-Disposition` already carries the same
+    // filename; we mirror it verbatim so browser default behavior wins.
+    // We intentionally do NOT strip a trailing `.html` — run_id is the
+    // backend's `Path(args.mdx_path).stem`-style key, which never contains
+    // a dot suffix (validated by `isValidUserOverridesKey` at u18/u19).
+    expect(buildDownloadFilename("foo.html")).toBe("foo.html.html");
+  });
+
+  it("returns just .html for empty run_id (server rejects upstream)", () => {
+    expect(buildDownloadFilename("")).toBe(".html");
+  });
+});
@@ -0,0 +1,282 @@
+// IMP-56 (#90) u18 — vitest coverage for the vite POST /api/connect
+// middleware and its supporting mirrorDirRecursive helper.
+//
+// Scope:
+//   1) mirrorDirRecursive (pure helper):
+//      - absent src → returns 0 (no-throw, no dst creation).
+//      - file-only src → flat copy + count.
+//      - nested src → recursive copy + count.
+//      - overwrites pre-existing dst files (cel mirror semantics).
+//   2) handleConnectMirror (POST):
+//      - method != POST → false (chain continues; next middleware may handle).
+//      - invalid JSON / non-object body → 400.
+//      - missing run_id or slug → 400.
+//      - invalid run_id or slug (key gate / path traversal) → 400.
+//      - final.html missing → 404.
+//      - success without run-assets dir → 200, assets_copied: 0, html copy ok.
+//      - success with run-assets dir → 200, assets_copied = file count, dst dir
+//        populated.
+//      - dstSlidesDir auto-created when celRoot/public/slides missing.
+//
+// Tests exercise the pure handler with mock req/res — no real vite server.
+
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { EventEmitter } from "node:events";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import {
+  handleConnectMirror,
+  mirrorDirRecursive,
+} from "../../vite.config";
+
+function makeMockRes() {
+  const state = {
+    statusCode: 0,
+    headers: {} as Record<string, string>,
+    body: "",
+    ended: false,
+  };
+  return {
+    state,
+    res: {
+      writeHead(status: number, headers?: Record<string, string>) {
+        state.statusCode = status;
+        if (headers) state.headers = headers;
+      },
+      end(body?: string) {
+        state.body = body ?? "";
+        state.ended = true;
+      },
+    },
+  };
+}
+
+function makeMockReq(opts: {
+  method?: string;
+}): EventEmitter & { method?: string; send: (body: string) => void } {
+  const ee = new EventEmitter() as EventEmitter & {
+    method?: string;
+    send: (body: string) => void;
+  };
+  ee.method = opts.method;
+  ee.send = (body: string) => {
+    if (body.length > 0) ee.emit("data", Buffer.from(body, "utf-8"));
+    ee.emit("end");
+  };
+  return ee;
+}
+
+function seedRun(daRoot: string, runId: string, htmlBody: string): string {
+  const runDir = path.join(daRoot, "data", "runs", runId, "phase_z2");
+  fs.mkdirSync(runDir, { recursive: true });
+  const html = path.join(runDir, "final.html");
+  fs.writeFileSync(html, htmlBody, "utf-8");
+  return runDir;
+}
+
+describe("mirrorDirRecursive (IMP-56 #90 u18)", () => {
+  let tmp: string;
+
+  beforeEach(() => {
+    tmp = fs.mkdtempSync(path.join(os.tmpdir(), "imp90-u18-mirror-"));
+  });
+
+  afterEach(() => {
+    fs.rmSync(tmp, { recursive: true, force: true });
+  });
+
+  it("returns 0 and does not throw when src absent", () => {
+    const dst = path.join(tmp, "dst");
+    const n = mirrorDirRecursive(path.join(tmp, "missing"), dst);
+    expect(n).toBe(0);
+    expect(fs.existsSync(dst)).toBe(false);
+  });
+
+  it("returns 0 when src exists but is a file (not a directory)", () => {
+    const srcFile = path.join(tmp, "src.txt");
+    fs.writeFileSync(srcFile, "x", "utf-8");
+    const dst = path.join(tmp, "dst");
+    const n = mirrorDirRecursive(srcFile, dst);
+    expect(n).toBe(0);
+    expect(fs.existsSync(dst)).toBe(false);
+  });
+
+  it("flat-copies file entries and returns the file count", () => {
+    const src = path.join(tmp, "src");
+    fs.mkdirSync(src);
+    fs.writeFileSync(path.join(src, "a.css"), "/*a*/", "utf-8");
+    fs.writeFileSync(path.join(src, "b.png"), "PNG", "utf-8");
+    const dst = path.join(tmp, "dst");
+    const n = mirrorDirRecursive(src, dst);
+    expect(n).toBe(2);
+    expect(fs.readFileSync(path.join(dst, "a.css"), "utf-8")).toBe("/*a*/");
+    expect(fs.readFileSync(path.join(dst, "b.png"), "utf-8")).toBe("PNG");
+  });
+
+  it("recurses into nested directories and counts only files", () => {
+    const src = path.join(tmp, "src");
+    fs.mkdirSync(path.join(src, "nested", "deep"), { recursive: true });
+    fs.writeFileSync(path.join(src, "root.txt"), "r", "utf-8");
+    fs.writeFileSync(path.join(src, "nested", "n.txt"), "n", "utf-8");
+    fs.writeFileSync(path.join(src, "nested", "deep", "d.txt"), "d", "utf-8");
+    const dst = path.join(tmp, "dst");
+    const n = mirrorDirRecursive(src, dst);
+    expect(n).toBe(3);
+    expect(fs.readFileSync(path.join(dst, "nested", "deep", "d.txt"), "utf-8"))
+      .toBe("d");
+  });
+
+  it("overwrites pre-existing files in dst (cel mirror semantics)", () => {
+    const src = path.join(tmp, "src");
+    fs.mkdirSync(src);
+    fs.writeFileSync(path.join(src, "a.css"), "NEW", "utf-8");
+    const dst = path.join(tmp, "dst");
+    fs.mkdirSync(dst);
+    fs.writeFileSync(path.join(dst, "a.css"), "OLD", "utf-8");
+    mirrorDirRecursive(src, dst);
+    expect(fs.readFileSync(path.join(dst, "a.css"), "utf-8")).toBe("NEW");
+  });
+});
+
+describe("handleConnectMirror (IMP-56 #90 u18)", () => {
+  let daRoot: string;
+  let celRoot: string;
+
+  beforeEach(() => {
+    daRoot = fs.mkdtempSync(path.join(os.tmpdir(), "imp90-u18-da-"));
+    celRoot = fs.mkdtempSync(path.join(os.tmpdir(), "imp90-u18-cel-"));
+  });
+
+  afterEach(() => {
+    fs.rmSync(daRoot, { recursive: true, force: true });
+    fs.rmSync(celRoot, { recursive: true, force: true });
+  });
+
+  it("returns false (next chained) when method != POST", () => {
+    const req = makeMockReq({ method: "GET" });
+    const { res, state } = makeMockRes();
+    const handled = handleConnectMirror(req, res, daRoot, celRoot);
+    expect(handled).toBe(false);
+    expect(state.ended).toBe(false);
+  });
+
+  it("returns 400 on invalid JSON body", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    const handled = handleConnectMirror(req, res, daRoot, celRoot);
+    expect(handled).toBe(true);
+    req.send("{not-json}");
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("invalid JSON");
+  });
+
+  it("returns 400 when body is not a JSON object (array root)", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify(["not", "an", "object"]));
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("body must be a JSON object");
+  });
+
+  it("returns 400 when run_id or slug is missing", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "abc" })); // slug missing
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("missing run_id or slug");
+  });
+
+  it("returns 400 when run_id contains path traversal", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "../escape", slug: "03" }));
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("invalid run_id or slug");
+  });
+
+  it("returns 400 when slug contains a forward slash", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "valid_id", slug: "03/etc" }));
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("invalid run_id or slug");
+  });
+
+  it("returns 404 when final.html does not exist for run_id", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "ghost_run", slug: "03" }));
+    expect(state.statusCode).toBe(404);
+    expect(JSON.parse(state.body).error).toBe("final.html not found");
+  });
+
+  it("copies final.html to cel/public/slides/<slug>.html on success", () => {
+    seedRun(daRoot, "mdx03_run", "<html>03</html>");
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "mdx03_run", slug: "03" }));
+
+    expect(state.statusCode).toBe(200);
+    const dstHtml = path.join(celRoot, "public", "slides", "03.html");
+    expect(fs.existsSync(dstHtml)).toBe(true);
+    expect(fs.readFileSync(dstHtml, "utf-8")).toBe("<html>03</html>");
+    const body = JSON.parse(state.body);
+    expect(body.success).toBe(true);
+    expect(body.run_id).toBe("mdx03_run");
+    expect(body.slug).toBe("03");
+    expect(body.assets_copied).toBe(0);
+    expect(body.html_target).toBe(dstHtml);
+  });
+
+  it("auto-creates cel/public/slides when missing", () => {
+    seedRun(daRoot, "mdx04_run", "<html>04</html>");
+    expect(fs.existsSync(path.join(celRoot, "public", "slides"))).toBe(false);
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "mdx04_run", slug: "04" }));
+    expect(state.statusCode).toBe(200);
+    expect(fs.existsSync(path.join(celRoot, "public", "slides", "04.html"))).toBe(true);
+  });
+
+  it("mirrors assets/ recursively when present in the run dir", () => {
+    const runDir = seedRun(daRoot, "mdx05_run", "<html>05</html>");
+    fs.mkdirSync(path.join(runDir, "assets", "css"), { recursive: true });
+    fs.writeFileSync(path.join(runDir, "assets", "main.css"), "*{}", "utf-8");
+    fs.writeFileSync(path.join(runDir, "assets", "css", "extra.css"), "p{}", "utf-8");
+
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "mdx05_run", slug: "05" }));
+
+    expect(state.statusCode).toBe(200);
+    expect(JSON.parse(state.body).assets_copied).toBe(2);
+    expect(fs.readFileSync(path.join(celRoot, "public", "slides", "assets", "main.css"), "utf-8"))
+      .toBe("*{}");
+    expect(fs.readFileSync(path.join(celRoot, "public", "slides", "assets", "css", "extra.css"), "utf-8"))
+      .toBe("p{}");
+  });
+
+  it("overwrites pre-existing cel slide html (re-Connect semantics)", () => {
+    seedRun(daRoot, "mdx03_run", "NEW");
+    const dstSlidesDir = path.join(celRoot, "public", "slides");
+    fs.mkdirSync(dstSlidesDir, { recursive: true });
+    fs.writeFileSync(path.join(dstSlidesDir, "03.html"), "OLD", "utf-8");
+
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleConnectMirror(req, res, daRoot, celRoot);
+    req.send(JSON.stringify({ run_id: "mdx03_run", slug: "03" }));
+
+    expect(state.statusCode).toBe(200);
+    expect(fs.readFileSync(path.join(dstSlidesDir, "03.html"), "utf-8")).toBe("NEW");
+  });
+});
@@ -0,0 +1,219 @@
+// IMP-90 (#90) u12 — vitest coverage for `computeEditModeGates`, the pure
+// helper that drives SlideCanvas's mutually-exclusive gesture gating.
+// u11 introduced the `EditMode` enum + toolbar; u12 splits the prior
+// `isEditMode` shim (which fired ALL gates whenever any edit mode was
+// active) into 5 per-gate booleans:
+//   textEditing       — designMode + contentEditable (text mode only).
+//   imageSelection    — in-iframe user-content image click listener
+//                       (image-zone mode only).
+//   iframePointerAuto — iframe pointer-events:auto so in-iframe gestures
+//                       (text caret OR image click) can reach the doc.
+//                       text mode + image-zone mode; structure stays
+//                       pe:none because u14 will overlay React controls.
+//   zoneGestures      — zone resize 8-handle ring + drag perimeter strips
+//                       + canDrag in handleZoneMouseDown
+//                       (image-zone mode only).
+//   imageOverlay      — React-side image edit overlay (image-zone only).
+//
+// Mutually-exclusive contract (from the issue body's "discriminated edit
+// mode"): no editMode value enables both `textEditing` and either
+// `imageSelection` or `zoneGestures` simultaneously. structure mode is
+// the no-op placeholder — u14 will plant the structure overlay there.
+// pendingLayout fully suppresses every gate (mirrors the existing
+// useEffect that forces editMode='off' on pendingLayout entry).
+//
+// Scope guard: this test exercises the pure helper only — no React
+// rendering, no DOM. testing-library/react is NOT in devDependencies
+// (verified in Front/package.json); helper-level coverage is the
+// established u11 pattern.
+
+import { describe, it, expect } from "vitest";
+import {
+  computeEditModeGates,
+  type EditMode,
+  type EditModeGates,
+} from "../src/components/SlideCanvas";
+
+const ALL_MODES: EditMode[] = ["off", "text", "structure", "image-zone"];
+
+describe("computeEditModeGates (IMP-90 u12) — pendingLayout suppression", () => {
+  it.each<EditMode>(ALL_MODES)(
+    "pendingLayout=true forces every gate false (editMode=%s)",
+    (mode) => {
+      const g = computeEditModeGates(mode, true);
+      expect(g).toEqual<EditModeGates>({
+        textEditing: false,
+        imageSelection: false,
+        iframePointerAuto: false,
+        zoneGestures: false,
+        imageOverlay: false,
+      });
+    }
+  );
+});
+
+describe("computeEditModeGates (IMP-90 u12) — off baseline", () => {
+  it("editMode=off pendingLayout=false: every gate false", () => {
+    expect(computeEditModeGates("off", false)).toEqual<EditModeGates>({
+      textEditing: false,
+      imageSelection: false,
+      iframePointerAuto: false,
+      zoneGestures: false,
+      imageOverlay: false,
+    });
+  });
+});
+
+describe("computeEditModeGates (IMP-90 u12) — text mode", () => {
+  const g = computeEditModeGates("text", false);
+
+  it("textEditing = true (designMode + contentEditable activate)", () => {
+    expect(g.textEditing).toBe(true);
+  });
+  it("iframePointerAuto = true (caret needs to reach the doc)", () => {
+    expect(g.iframePointerAuto).toBe(true);
+  });
+  it("imageSelection = false (no in-iframe image click listener)", () => {
+    expect(g.imageSelection).toBe(false);
+  });
+  it("zoneGestures = false (no zone resize / drag affordances)", () => {
+    expect(g.zoneGestures).toBe(false);
+  });
+  it("imageOverlay = false (no React-side image overlay)", () => {
+    expect(g.imageOverlay).toBe(false);
+  });
+});
+
+describe("computeEditModeGates (IMP-90 u12) — structure mode", () => {
+  const g = computeEditModeGates("structure", false);
+
+  // structure mode is the u14 placeholder — no gestures here yet. All five
+  // gates stay false so the iframe and React overlays remain quiescent
+  // until u14 plants the structure overlay on the React layer.
+  it("every gate false (u14 will plant the structure overlay later)", () => {
+    expect(g).toEqual<EditModeGates>({
+      textEditing: false,
+      imageSelection: false,
+      iframePointerAuto: false,
+      zoneGestures: false,
+      imageOverlay: false,
+    });
+  });
+});
+
+describe("computeEditModeGates (IMP-90 u12) — image-zone mode", () => {
+  const g = computeEditModeGates("image-zone", false);
+
+  it("textEditing = false (contentEditable would steal image clicks)", () => {
+    expect(g.textEditing).toBe(false);
+  });
+  it("imageSelection = true (in-iframe img click → selectedImageId)", () => {
+    expect(g.imageSelection).toBe(true);
+  });
+  it("iframePointerAuto = true (so image clicks reach the doc)", () => {
+    expect(g.iframePointerAuto).toBe(true);
+  });
+  it("zoneGestures = true (zone resize + drag affordances visible)", () => {
+    expect(g.zoneGestures).toBe(true);
+  });
+  it("imageOverlay = true (React-side overlay renders the drag handles)", () => {
+    expect(g.imageOverlay).toBe(true);
+  });
+});
+
+describe("computeEditModeGates (IMP-90 u12) — mutually exclusive contract", () => {
+  it("text mode never co-activates image-zone gates (imageSelection / zoneGestures / imageOverlay)", () => {
+    const g = computeEditModeGates("text", false);
+    expect(g.textEditing).toBe(true);
+    expect(g.imageSelection).toBe(false);
+    expect(g.zoneGestures).toBe(false);
+    expect(g.imageOverlay).toBe(false);
+  });
+
+  it("image-zone mode never co-activates text gates (textEditing)", () => {
+    const g = computeEditModeGates("image-zone", false);
+    expect(g.imageSelection).toBe(true);
+    expect(g.textEditing).toBe(false);
+  });
+
+  it.each<EditMode>(ALL_MODES)(
+    "for every editMode (%s), textEditing AND zoneGestures are NEVER both true",
+    (mode) => {
+      const g = computeEditModeGates(mode, false);
+      expect(g.textEditing && g.zoneGestures).toBe(false);
+    }
+  );
+
+  it.each<EditMode>(ALL_MODES)(
+    "for every editMode (%s), textEditing AND imageOverlay are NEVER both true",
+    (mode) => {
+      const g = computeEditModeGates(mode, false);
+      expect(g.textEditing && g.imageOverlay).toBe(false);
+    }
+  );
+
+  it.each<EditMode>(ALL_MODES)(
+    "for every editMode (%s), textEditing AND imageSelection are NEVER both true",
+    (mode) => {
+      const g = computeEditModeGates(mode, false);
+      expect(g.textEditing && g.imageSelection).toBe(false);
+    }
+  );
+});
+
+describe("computeEditModeGates (IMP-90 u12) — iframePointerAuto coupling", () => {
+  // pe:auto is the iframe-side prerequisite for ANY in-iframe gesture
+  // (text caret OR image click). The helper must NOT advertise an
+  // in-iframe gate as active while pe is none, or those gestures would
+  // be silently swallowed by the wrapper.
+  it.each<EditMode>(ALL_MODES)(
+    "textEditing → iframePointerAuto (editMode=%s)",
+    (mode) => {
+      const g = computeEditModeGates(mode, false);
+      if (g.textEditing) expect(g.iframePointerAuto).toBe(true);
+    }
+  );
+  it.each<EditMode>(ALL_MODES)(
+    "imageSelection → iframePointerAuto (editMode=%s)",
+    (mode) => {
+      const g = computeEditModeGates(mode, false);
+      if (g.imageSelection) expect(g.iframePointerAuto).toBe(true);
+    }
+  );
+});
+
+describe("computeEditModeGates (IMP-90 u12) — referential transparency", () => {
+  it("multiple calls with the same inputs return equal output", () => {
+    const a = computeEditModeGates("image-zone", false);
+    const b = computeEditModeGates("image-zone", false);
+    const c = computeEditModeGates("image-zone", false);
+    expect(a).toEqual(b);
+    expect(b).toEqual(c);
+  });
+
+  it("does not mutate captured state across calls (independent invocations)", () => {
+    const a = computeEditModeGates("text", false);
+    const _b = computeEditModeGates("image-zone", false);
+    // a must still reflect text mode after b's call.
+    expect(a.textEditing).toBe(true);
+    expect(a.imageSelection).toBe(false);
+  });
+});
+
+describe("computeEditModeGates (IMP-90 u12) — gate truthtable snapshot", () => {
+  // Snapshot for human-readable inspection — the per-mode flag layout
+  // is the contract u13 (text capture) and u14 (structure overlay)
+  // will build against. Any change requires updating both this test
+  // AND the consuming gates in SlideCanvas.tsx.
+  it("non-pendingLayout truthtable matches the u12 contract", () => {
+    const rows = (["off", "text", "structure", "image-zone"] as EditMode[]).map(
+      (m) => ({ mode: m, ...computeEditModeGates(m, false) })
+    );
+    expect(rows).toEqual([
+      { mode: "off", textEditing: false, imageSelection: false, iframePointerAuto: false, zoneGestures: false, imageOverlay: false },
+      { mode: "text", textEditing: true, imageSelection: false, iframePointerAuto: true, zoneGestures: false, imageOverlay: false },
+      { mode: "structure", textEditing: false, imageSelection: false, iframePointerAuto: false, zoneGestures: false, imageOverlay: false },
+      { mode: "image-zone", textEditing: false, imageSelection: true, iframePointerAuto: true, zoneGestures: true, imageOverlay: true },
+    ]);
+  });
+});
@@ -0,0 +1,133 @@
+// IMP-90 (#90) u11 — vitest coverage for the discriminated EditMode enum
+// and its pure transition helper `nextEditMode`. Replaces the prior single
+// `isEditMode` boolean state. u11 introduces ONLY the state surface + the
+// toolbar UI; gesture gating per mode is u12 (mutually exclusive) and must
+// not regress this contract.
+//
+// Scope (Stage 2 unit u11 contract):
+//   1) EDIT_MODES is the canonical ['text','structure','image-zone'] list
+//      in toolbar render order. 'off' is intentionally excluded from the
+//      iterable because it is the implicit baseline (no button); the
+//      toolbar only renders the three active modes per the u11 design.
+//   2) nextEditMode is a pure (current, requested) -> EditMode mapping
+//      with three rules:
+//        - requested === 'off'              -> 'off'   (explicit exit)
+//        - requested === current            -> 'off'   (toggle exit)
+//        - requested !== current && != 'off'-> requested (mode switch)
+//   3) The helper is referentially transparent — no side effects, no
+//      React, no useState, no DOM. SlideCanvas wires it as the useState
+//      updater callback (`setEditMode((prev) => nextEditMode(prev, m))`),
+//      so covering the helper here covers every toolbar click outcome
+//      directly without DOM rendering. (@testing-library/react is NOT in
+//      devDependencies; this mirrors the imp47b_human_review_toast pattern.)
+//   4) The exported EditMode type union must contain exactly the four
+//      members 'off' | 'text' | 'structure' | 'image-zone'. The runtime
+//      EDIT_MODES list intentionally excludes 'off' (see (1) above).
+//
+// Forward-compat note: u12 will discriminate per-mode gating but MUST NOT
+// alter the (current, requested) -> next contract verified here. Any
+// change to the toggle/switch/exit semantics is a scope-violation against
+// the u11 binding contract.
+
+import { describe, it, expect } from "vitest";
+import {
+  EDIT_MODES,
+  nextEditMode,
+  type EditMode,
+} from "../src/components/SlideCanvas";
+
+describe("EDIT_MODES (IMP-90 u11 — toolbar render order)", () => {
+  it("contains exactly the three active modes in toolbar order", () => {
+    expect(EDIT_MODES).toEqual(["text", "structure", "image-zone"]);
+  });
+
+  it("excludes 'off' — baseline is implicit, no toolbar button", () => {
+    expect(EDIT_MODES).not.toContain("off" as EditMode);
+  });
+
+  it("has length 3", () => {
+    expect(EDIT_MODES.length).toBe(3);
+  });
+});
+
+describe("nextEditMode (IMP-90 u11 — pure transition helper)", () => {
+  describe("explicit 'off' request always exits", () => {
+    it.each<EditMode>(["off", "text", "structure", "image-zone"])(
+      "current=%s, requested=off -> off",
+      (current) => {
+        expect(nextEditMode(current, "off")).toBe("off");
+      }
+    );
+  });
+
+  describe("clicking the active mode toggles back to 'off'", () => {
+    it.each<EditMode>(["text", "structure", "image-zone"])(
+      "current=%s, requested=%s -> off",
+      (mode) => {
+        expect(nextEditMode(mode, mode)).toBe("off");
+      }
+    );
+  });
+
+  describe("clicking a different mode switches", () => {
+    const cases: Array<[EditMode, EditMode]> = [
+      ["off", "text"],
+      ["off", "structure"],
+      ["off", "image-zone"],
+      ["text", "structure"],
+      ["text", "image-zone"],
+      ["structure", "text"],
+      ["structure", "image-zone"],
+      ["image-zone", "text"],
+      ["image-zone", "structure"],
+    ];
+    it.each(cases)("current=%s, requested=%s -> requested", (current, requested) => {
+      expect(nextEditMode(current, requested)).toBe(requested);
+    });
+  });
+
+  it("is referentially transparent — multiple calls with same inputs return same output", () => {
+    const a = nextEditMode("text", "structure");
+    const b = nextEditMode("text", "structure");
+    const c = nextEditMode("text", "structure");
+    expect(a).toBe("structure");
+    expect(b).toBe("structure");
+    expect(c).toBe("structure");
+  });
+
+  it("never returns a value outside the EditMode union", () => {
+    const all: EditMode[] = ["off", "text", "structure", "image-zone"];
+    for (const current of all) {
+      for (const requested of all) {
+        const result = nextEditMode(current, requested);
+        expect(all).toContain(result);
+      }
+    }
+  });
+
+  it("preserves toggle semantics under repeated identical clicks", () => {
+    // off -> text -> off -> text -> off (toggle behavior)
+    let m: EditMode = "off";
+    m = nextEditMode(m, "text");
+    expect(m).toBe("text");
+    m = nextEditMode(m, "text");
+    expect(m).toBe("off");
+    m = nextEditMode(m, "text");
+    expect(m).toBe("text");
+    m = nextEditMode(m, "text");
+    expect(m).toBe("off");
+  });
+
+  it("preserves switch semantics across distinct mode clicks", () => {
+    // off -> text -> structure -> image-zone -> off (via toggle)
+    let m: EditMode = "off";
+    m = nextEditMode(m, "text");
+    expect(m).toBe("text");
+    m = nextEditMode(m, "structure");
+    expect(m).toBe("structure");
+    m = nextEditMode(m, "image-zone");
+    expect(m).toBe("image-zone");
+    m = nextEditMode(m, "image-zone");
+    expect(m).toBe("off");
+  });
+});
@@ -0,0 +1,255 @@
+// IMP-56 (#90) u19 — vitest coverage for the vite POST /api/export
+// middleware and its supporting inlineAssetsAsDataUrls helper.
+//
+// Scope:
+//   1) inlineAssetsAsDataUrls (pure helper):
+//      - no url(assets/...) refs → passthrough.
+//      - single PNG ref → inlined as base64 data: URL with image/png mime.
+//      - multiple refs → all inlined.
+//      - SVG ref → image/svg+xml mime.
+//      - missing asset file → left as-is (no throw, no rewrite).
+//      - data:/http:/ URLs (non-asset) → untouched.
+//   2) handleExportStandalone (POST):
+//      - method != POST → false (chain continues; next middleware may handle).
+//      - invalid JSON / non-object body → 400.
+//      - missing run_id → 400.
+//      - invalid run_id (key gate / path traversal) → 400.
+//      - final.html missing → 404.
+//      - success → 200 with Content-Disposition: attachment; filename=...,
+//        Content-Type: text/html; charset=utf-8, body = inlined HTML.
+//
+// Tests exercise the pure handler with mock req/res — no real vite server.
+
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { EventEmitter } from "node:events";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import {
+  handleExportStandalone,
+  inlineAssetsAsDataUrls,
+} from "../../vite.config";
+
+function makeMockRes() {
+  const state = {
+    statusCode: 0,
+    headers: {} as Record<string, string>,
+    body: "",
+    ended: false,
+  };
+  return {
+    state,
+    res: {
+      writeHead(status: number, headers?: Record<string, string>) {
+        state.statusCode = status;
+        if (headers) state.headers = headers;
+      },
+      end(body?: string) {
+        state.body = body ?? "";
+        state.ended = true;
+      },
+    },
+  };
+}
+
+function makeMockReq(opts: {
+  method?: string;
+}): EventEmitter & { method?: string; send: (body: string) => void } {
+  const ee = new EventEmitter() as EventEmitter & {
+    method?: string;
+    send: (body: string) => void;
+  };
+  ee.method = opts.method;
+  ee.send = (body: string) => {
+    if (body.length > 0) ee.emit("data", Buffer.from(body, "utf-8"));
+    ee.emit("end");
+  };
+  return ee;
+}
+
+function seedRun(
+  daRoot: string,
+  runId: string,
+  htmlBody: string,
+  assets?: Record<string, Buffer | string>,
+): string {
+  const runDir = path.join(daRoot, "data", "runs", runId, "phase_z2");
+  fs.mkdirSync(runDir, { recursive: true });
+  const html = path.join(runDir, "final.html");
+  fs.writeFileSync(html, htmlBody, "utf-8");
+  if (assets) {
+    for (const [rel, buf] of Object.entries(assets)) {
+      const dst = path.join(runDir, "assets", rel);
+      fs.mkdirSync(path.dirname(dst), { recursive: true });
+      fs.writeFileSync(dst, buf);
+    }
+  }
+  return runDir;
+}
+
+describe("inlineAssetsAsDataUrls (IMP-56 #90 u19)", () => {
+  let tmp: string;
+
+  beforeEach(() => {
+    tmp = fs.mkdtempSync(path.join(os.tmpdir(), "imp90-u19-inline-"));
+  });
+
+  afterEach(() => {
+    fs.rmSync(tmp, { recursive: true, force: true });
+  });
+
+  it("returns html unchanged when no url(assets/...) refs are present", () => {
+    const html = "<html><style>body{color:red;}</style><body>hi</body></html>";
+    expect(inlineAssetsAsDataUrls(html, tmp)).toBe(html);
+  });
+
+  it("inlines a single PNG asset as a base64 data: URL with image/png mime", () => {
+    fs.mkdirSync(path.join(tmp, "frame_x"), { recursive: true });
+    const pngBytes = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
+    fs.writeFileSync(path.join(tmp, "frame_x", "a.png"), pngBytes);
+    const html = "background: url(assets/frame_x/a.png);";
+    const out = inlineAssetsAsDataUrls(html, tmp);
+    expect(out).toContain(`url("data:image/png;base64,${pngBytes.toString("base64")}")`);
+    expect(out).not.toContain("url(assets/frame_x/a.png)");
+  });
+
+  it("inlines multiple refs across the same HTML body", () => {
+    fs.mkdirSync(path.join(tmp, "f"), { recursive: true });
+    fs.writeFileSync(path.join(tmp, "f", "one.png"), Buffer.from("ONE"));
+    fs.writeFileSync(path.join(tmp, "f", "two.png"), Buffer.from("TWO"));
+    const html = "a{background:url(assets/f/one.png)} b{background:url(assets/f/two.png)}";
+    const out = inlineAssetsAsDataUrls(html, tmp);
+    expect(out).toContain(`data:image/png;base64,${Buffer.from("ONE").toString("base64")}`);
+    expect(out).toContain(`data:image/png;base64,${Buffer.from("TWO").toString("base64")}`);
+  });
+
+  it("uses image/svg+xml mime for .svg refs", () => {
+    fs.mkdirSync(path.join(tmp, "f"), { recursive: true });
+    fs.writeFileSync(path.join(tmp, "f", "icon.svg"), "<svg/>", "utf-8");
+    const html = "url(assets/f/icon.svg)";
+    const out = inlineAssetsAsDataUrls(html, tmp);
+    expect(out).toContain("data:image/svg+xml;base64,");
+  });
+
+  it("leaves the ref untouched when the asset file is missing", () => {
+    const html = "url(assets/missing/file.png)";
+    const out = inlineAssetsAsDataUrls(html, tmp);
+    expect(out).toBe(html);
+  });
+
+  it("does not touch data: or http(s): url() values (only matches assets/...)", () => {
+    const html =
+      "x{background:url(data:image/png;base64,AAA)} " +
+      "y{background:url(https://cdn.x/a.png)}";
+    expect(inlineAssetsAsDataUrls(html, tmp)).toBe(html);
+  });
+
+  it("handles quoted url(...) refs (single and double quotes)", () => {
+    fs.mkdirSync(path.join(tmp, "q"), { recursive: true });
+    fs.writeFileSync(path.join(tmp, "q", "k.png"), Buffer.from("K"));
+    const html =
+      "a{background:url('assets/q/k.png')} b{background:url(\"assets/q/k.png\")}";
+    const out = inlineAssetsAsDataUrls(html, tmp);
+    const data = `data:image/png;base64,${Buffer.from("K").toString("base64")}`;
+    expect(out.split(data).length - 1).toBe(2);
+  });
+});
+
+describe("handleExportStandalone (IMP-56 #90 u19)", () => {
+  let daRoot: string;
+
+  beforeEach(() => {
+    daRoot = fs.mkdtempSync(path.join(os.tmpdir(), "imp90-u19-da-"));
+  });
+
+  afterEach(() => {
+    fs.rmSync(daRoot, { recursive: true, force: true });
+  });
+
+  it("returns false (next chained) when method != POST", () => {
+    const req = makeMockReq({ method: "GET" });
+    const { res, state } = makeMockRes();
+    const handled = handleExportStandalone(req, res, daRoot);
+    expect(handled).toBe(false);
+    expect(state.ended).toBe(false);
+  });
+
+  it("returns 400 on invalid JSON body", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    const handled = handleExportStandalone(req, res, daRoot);
+    expect(handled).toBe(true);
+    req.send("{nope");
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("invalid JSON");
+  });
+
+  it("returns 400 when body is not a JSON object (array root)", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleExportStandalone(req, res, daRoot);
+    req.send(JSON.stringify(["x"]));
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("body must be a JSON object");
+  });
+
+  it("returns 400 when run_id is missing", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleExportStandalone(req, res, daRoot);
+    req.send(JSON.stringify({}));
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("missing run_id");
+  });
+
+  it("returns 400 when run_id contains path traversal", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleExportStandalone(req, res, daRoot);
+    req.send(JSON.stringify({ run_id: "../escape" }));
+    expect(state.statusCode).toBe(400);
+    expect(JSON.parse(state.body).error).toBe("invalid run_id");
+  });
+
+  it("returns 404 when final.html does not exist for run_id", () => {
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleExportStandalone(req, res, daRoot);
+    req.send(JSON.stringify({ run_id: "ghost_run" }));
+    expect(state.statusCode).toBe(404);
+    expect(JSON.parse(state.body).error).toBe("final.html not found");
+  });
+
+  it("returns 200 with text/html body + Content-Disposition on success", () => {
+    seedRun(daRoot, "mdx03_run", "<html><body>03</body></html>");
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleExportStandalone(req, res, daRoot);
+    req.send(JSON.stringify({ run_id: "mdx03_run" }));
+    expect(state.statusCode).toBe(200);
+    expect(state.headers["Content-Type"]).toBe("text/html; charset=utf-8");
+    expect(state.headers["Content-Disposition"]).toBe(
+      'attachment; filename="mdx03_run.html"',
+    );
+    expect(state.body).toBe("<html><body>03</body></html>");
+  });
+
+  it("inlines assets in final.html when run dir has assets/", () => {
+    const pngBytes = Buffer.from("PNGDATA");
+    seedRun(
+      daRoot,
+      "mdx05_run",
+      "<html><body><div style=\"background: url(assets/f/x.png)\"></div></body></html>",
+      { "f/x.png": pngBytes },
+    );
+    const req = makeMockReq({ method: "POST" });
+    const { res, state } = makeMockRes();
+    handleExportStandalone(req, res, daRoot);
+    req.send(JSON.stringify({ run_id: "mdx05_run" }));
+    expect(state.statusCode).toBe(200);
+    expect(state.body).toContain(
+      `data:image/png;base64,${pngBytes.toString("base64")}`,
+    );
+    expect(state.body).not.toContain("url(assets/f/x.png)");
+  });
+});
@@ -0,0 +1,150 @@
+// IMP-90 (#90) u14 — vitest coverage for the pure helpers exported by
+// `StructureEditOverlay`. The React component itself is not rendered
+// (jsdom / @testing-library NOT in Front devDependencies — verified in
+// `Front/package.json`); we test the deterministic pieces that drive its
+// JSX: `resolveEffectiveSlotOrder` (effective-order resolution under
+// override) and `moveItem` (immutable reorder primitive).
+//
+// Upstream / downstream contracts (verified by prior units):
+//   - u2  KNOWN_AXES += structure_overrides (Python backend).
+//   - u3  vite allowlist += structure_overrides.
+//   - u6  structure_override_resolver — inner shape locked to
+//         {slot_order, hidden_slots}; frame swap REJECTED to existing
+//         frames axis.
+//   - u10 typed-client `StructureOverridePerZone` + extract helper.
+//   - u15 (next) will debounce + PUT the emitted capture.
+//
+// u14 scope: pure helpers only. React render path is verified by Codex
+// auditor via static read of the JSX (no runtime test possible without
+// jsdom). Tests below are intentionally side-effect-free.
+
+import { describe, it, expect } from "vitest";
+import {
+  resolveEffectiveSlotOrder,
+  moveItem,
+} from "../src/components/StructureEditOverlay";
+
+// ─────────────────────────────────────────────────────────────────────
+// resolveEffectiveSlotOrder
+// ─────────────────────────────────────────────────────────────────────
+
+describe("resolveEffectiveSlotOrder — no override", () => {
+  it("returns a fresh copy of the discovered keys when slotOrder is undefined", () => {
+    const discovered = ["a", "b", "c"];
+    const out = resolveEffectiveSlotOrder(discovered, undefined);
+    expect(out).toEqual(["a", "b", "c"]);
+    expect(out).not.toBe(discovered);
+  });
+  it("returns a fresh copy when slotOrder is null", () => {
+    const out = resolveEffectiveSlotOrder(["a", "b"], null);
+    expect(out).toEqual(["a", "b"]);
+  });
+  it("returns a fresh copy when slotOrder is empty []", () => {
+    const out = resolveEffectiveSlotOrder(["a", "b"], []);
+    expect(out).toEqual(["a", "b"]);
+  });
+  it("handles empty discovered list (no slots in zone)", () => {
+    expect(resolveEffectiveSlotOrder([], undefined)).toEqual([]);
+    expect(resolveEffectiveSlotOrder([], ["x"])).toEqual([]);
+  });
+});
+
+describe("resolveEffectiveSlotOrder — full override", () => {
+  it("reorders all discovered keys per slotOrder", () => {
+    expect(
+      resolveEffectiveSlotOrder(["a", "b", "c"], ["c", "a", "b"]),
+    ).toEqual(["c", "a", "b"]);
+  });
+  it("is idempotent when slotOrder matches discovered order", () => {
+    expect(
+      resolveEffectiveSlotOrder(["a", "b", "c"], ["a", "b", "c"]),
+    ).toEqual(["a", "b", "c"]);
+  });
+});
+
+describe("resolveEffectiveSlotOrder — partial / drift override", () => {
+  it("appends missing discovered keys in backend order at the tail", () => {
+    // user reordered b -> first, but c was added later by backend.
+    expect(
+      resolveEffectiveSlotOrder(["a", "b", "c"], ["b", "a"]),
+    ).toEqual(["b", "a", "c"]);
+  });
+  it("drops override entries that no longer exist in discovered keys", () => {
+    // user had slot 'x' before; backend dropped it.
+    expect(
+      resolveEffectiveSlotOrder(["a", "b"], ["x", "a", "b"]),
+    ).toEqual(["a", "b"]);
+  });
+  it("dedupes duplicate entries within slotOrder", () => {
+    expect(
+      resolveEffectiveSlotOrder(["a", "b", "c"], ["a", "a", "b"]),
+    ).toEqual(["a", "b", "c"]);
+  });
+  it("dedupe + drop + append all together (stress)", () => {
+    expect(
+      resolveEffectiveSlotOrder(
+        ["a", "b", "c", "d"],
+        ["d", "x", "d", "a", "ghost"],
+      ),
+    ).toEqual(["d", "a", "b", "c"]);
+  });
+  it("ignores non-string entries in slotOrder", () => {
+    const bogus = ["a", null as unknown as string, undefined as unknown as string, "b"];
+    expect(resolveEffectiveSlotOrder(["a", "b"], bogus)).toEqual(["a", "b"]);
+  });
+});
+
+// ─────────────────────────────────────────────────────────────────────
+// moveItem
+// ─────────────────────────────────────────────────────────────────────
+
+describe("moveItem — happy paths", () => {
+  it("moves index 0 down by 1 (swap with index 1)", () => {
+    expect(moveItem(["a", "b", "c"], 0, 1)).toEqual(["b", "a", "c"]);
+  });
+  it("moves index 2 up by 1 (swap with index 1)", () => {
+    expect(moveItem(["a", "b", "c"], 2, -1)).toEqual(["a", "c", "b"]);
+  });
+  it("moves across larger delta (swap with target)", () => {
+    expect(moveItem(["a", "b", "c", "d"], 0, 2)).toEqual(["c", "b", "a", "d"]);
+  });
+});
+
+describe("moveItem — bounds", () => {
+  it("no-op (fresh copy) when moving first up", () => {
+    const src = ["a", "b", "c"];
+    const out = moveItem(src, 0, -1);
+    expect(out).toEqual(["a", "b", "c"]);
+    expect(out).not.toBe(src);
+  });
+  it("no-op when moving last down", () => {
+    expect(moveItem(["a", "b", "c"], 2, 1)).toEqual(["a", "b", "c"]);
+  });
+  it("no-op when index negative", () => {
+    expect(moveItem(["a", "b"], -1, 1)).toEqual(["a", "b"]);
+  });
+  it("no-op when index past end", () => {
+    expect(moveItem(["a", "b"], 5, -1)).toEqual(["a", "b"]);
+  });
+  it("no-op when target falls out of range from large delta", () => {
+    expect(moveItem(["a", "b", "c"], 1, 99)).toEqual(["a", "b", "c"]);
+  });
+  it("no-op on empty array (any index)", () => {
+    expect(moveItem<string>([], 0, 1)).toEqual([]);
+  });
+});
+
+describe("moveItem — immutability", () => {
+  it("never mutates the input array", () => {
+    const src = ["a", "b", "c"];
+    moveItem(src, 0, 1);
+    expect(src).toEqual(["a", "b", "c"]);
+  });
+  it("returns a new reference even when no-op", () => {
+    const src = ["a", "b"];
+    expect(moveItem(src, 0, -1)).not.toBe(src);
+  });
+  it("preserves T-typed values (number array)", () => {
+    expect(moveItem([1, 2, 3], 0, 1)).toEqual([2, 1, 3]);
+  });
+});
@@ -0,0 +1,259 @@
+// IMP-90 (#90) u13 — vitest coverage for `deriveTextEditCapture`, the pure
+// helper that resolves a contentEditable focusout target into the
+// (zone_id, text_path, value) capture tuple emitted by SlideCanvas.
+//
+// Upstream contract (verified by prior units):
+//   - u8 `src/text_path_stamper.py` stamps `data-text-path="{slot_key}.{
+//     line_index}"` on every rendered text-line opening tag at Step 13.
+//   - u9 wires the stamper into `render_slide` so the final.html consumed
+//     by SlideCanvas's iframe carries those attributes.
+//   - Phase Z slide-base wraps every zone in `.zone[data-zone-position]`
+//     (verified at SlideCanvas.tsx onLoad measure block).
+//
+// u13 scope: derive the capture tuple from any descendant of a stamped
+// line, OR the stamped line itself. Non-stamped targets (slide-base
+// title/footer, decorative spans outside the zone tree) return null so
+// the focusout handler silently skips them — never crashes.
+//
+// Forward-compat note: u15 will debounce + PUT the capture; u15 MUST NOT
+// alter the (target) -> {zoneId, textPath, value} | null contract verified
+// here. Any change to the resolution semantics is a scope-violation
+// against the u13 binding contract.
+//
+// jsdom is NOT in devDependencies (verified in Front/package.json); this
+// test mocks `TextEditCaptureTarget` with structurally-typed objects per
+// the established u11/u12 pure-helper pattern.
+
+import { describe, it, expect } from "vitest";
+import {
+  deriveTextEditCapture,
+  type TextEditCapture,
+  type TextEditCaptureTarget,
+} from "../src/components/SlideCanvas";
+
+// --- minimal closest-aware mock builders -----------------------------
+// Each node only needs to know which selectors it matches and its
+// parent chain — `closest` is implemented by walking parent pointers.
+
+interface MockNodeSpec {
+  matches: string[];
+  attrs?: Record<string, string>;
+  text?: string | null;
+  parent?: MockNode | null;
+}
+interface MockNode extends TextEditCaptureTarget {
+  matches(sel: string): boolean;
+  parent: MockNode | null;
+}
+function makeNode(spec: MockNodeSpec): MockNode {
+  const node: MockNode = {
+    parent: spec.parent ?? null,
+    matches(sel: string) {
+      return spec.matches.includes(sel);
+    },
+    closest(sel: string): TextEditCaptureTarget | null {
+      let cur: MockNode | null = node;
+      while (cur) {
+        if (cur.matches(sel)) return cur;
+        cur = cur.parent;
+      }
+      return null;
+    },
+    getAttribute(name: string): string | null {
+      return spec.attrs?.[name] ?? null;
+    },
+    textContent: spec.text === undefined ? null : spec.text,
+  };
+  return node;
+}
+
+// Canonical zone + line scaffold used across happy-path tests.
+// `null` for any field is preserved verbatim so edge cases (missing attr /
+// null textContent) can exercise the helper's defensive branches.
+function makeZoneLineScaffold(opts: {
+  zoneId?: string | null;
+  textPath?: string | null;
+  lineText?: string | null;
+}) {
+  const zone = makeNode({
+    matches: [".zone[data-zone-position]"],
+    attrs: opts.zoneId === null ? {} : { "data-zone-position": opts.zoneId ?? "top" },
+  });
+  const line = makeNode({
+    matches: ["[data-text-path]"],
+    attrs:
+      opts.textPath === null
+        ? {}
+        : { "data-text-path": opts.textPath ?? "row_1_left_body.0" },
+    text: opts.lineText === undefined ? "hello world" : opts.lineText,
+    parent: zone,
+  });
+  return { zone, line };
+}
+
+describe("deriveTextEditCapture (IMP-90 u13) — null inputs / non-stamped", () => {
+  it("returns null when target is null", () => {
+    expect(deriveTextEditCapture(null)).toBeNull();
+  });
+
+  it("returns null when no ancestor has data-text-path (e.g., slide title)", () => {
+    const title = makeNode({
+      matches: [".slide-title"],
+      text: "Phase Z 슬라이드",
+    });
+    expect(deriveTextEditCapture(title)).toBeNull();
+  });
+
+  it("returns null when the stamped line has no enclosing zone", () => {
+    // Decorative line stamped by the future u8 but rendered outside a
+    // zone (e.g., footer pill). u13 silently skips — caller never sees
+    // a half-resolved capture.
+    const orphanLine = makeNode({
+      matches: ["[data-text-path]"],
+      attrs: { "data-text-path": "footer.0" },
+      text: "결론",
+    });
+    expect(deriveTextEditCapture(orphanLine)).toBeNull();
+  });
+});
+
+describe("deriveTextEditCapture (IMP-90 u13) — happy path", () => {
+  it("resolves (zoneId, textPath, value) when target IS the stamped line", () => {
+    const { line } = makeZoneLineScaffold({
+      zoneId: "top",
+      textPath: "row_1_left_body.0",
+      lineText: "분석 결과",
+    });
+    expect(deriveTextEditCapture(line)).toEqual<TextEditCapture>({
+      zoneId: "top",
+      textPath: "row_1_left_body.0",
+      value: "분석 결과",
+    });
+  });
+
+  it("walks up to the stamped line when target is a nested descendant", () => {
+    const { zone, line } = makeZoneLineScaffold({
+      zoneId: "bottom_l",
+      textPath: "left_body.2",
+      lineText: "wrapped",
+    });
+    // emulate a SPAN inside the stamped line (e.g., bold inline span)
+    const innerSpan = makeNode({
+      matches: ["span.highlight"],
+      text: "ignored — closest walks to the line",
+      parent: line,
+    });
+    void zone;
+    expect(deriveTextEditCapture(innerSpan)).toEqual<TextEditCapture>({
+      zoneId: "bottom_l",
+      textPath: "left_body.2",
+      value: "wrapped",
+    });
+  });
+
+  it("preserves the line's textContent without HTML normalization", () => {
+    const { line } = makeZoneLineScaffold({
+      zoneId: "primary",
+      textPath: "headline.0",
+      lineText: "  spaced   inner   words  ",
+    });
+    // u13 trims outer whitespace but does NOT collapse interior whitespace
+    // — value mirrors what user typed, modulo blur-edge trim.
+    expect(deriveTextEditCapture(line)?.value).toBe("spaced   inner   words");
+  });
+
+  it("returns empty string when textContent is null (edge: empty line)", () => {
+    const { line } = makeZoneLineScaffold({
+      zoneId: "top",
+      textPath: "row_1_left_body.0",
+      lineText: null,
+    });
+    expect(deriveTextEditCapture(line)?.value).toBe("");
+  });
+
+  it("returns empty string when textContent is whitespace-only", () => {
+    const { line } = makeZoneLineScaffold({
+      zoneId: "top",
+      textPath: "row_1_left_body.0",
+      lineText: "   \n  \t  ",
+    });
+    expect(deriveTextEditCapture(line)?.value).toBe("");
+  });
+});
+
+describe("deriveTextEditCapture (IMP-90 u13) — missing attribute defensiveness", () => {
+  it("returns null when data-text-path attribute is absent on the matched line", () => {
+    // Should not happen with the u8 stamper, but a downstream mutation
+    // (e.g., user pasting a fresh element) could create a stamped-class
+    // node without the actual attribute. u13 stays defensive.
+    const zone = makeNode({
+      matches: [".zone[data-zone-position]"],
+      attrs: { "data-zone-position": "top" },
+    });
+    const lineNoPath = makeNode({
+      matches: ["[data-text-path]"],
+      attrs: {},
+      text: "hello",
+      parent: zone,
+    });
+    expect(deriveTextEditCapture(lineNoPath)).toBeNull();
+  });
+
+  it("returns null when data-zone-position attribute is absent on the matched zone", () => {
+    const zoneNoId = makeNode({
+      matches: [".zone[data-zone-position]"],
+      attrs: {},
+    });
+    const line = makeNode({
+      matches: ["[data-text-path]"],
+      attrs: { "data-text-path": "row_1_left_body.0" },
+      text: "hello",
+      parent: zoneNoId,
+    });
+    expect(deriveTextEditCapture(line)).toBeNull();
+  });
+});
+
+describe("deriveTextEditCapture (IMP-90 u13) — referential transparency", () => {
+  it("multiple calls with the same target return equal captures", () => {
+    const { line } = makeZoneLineScaffold({
+      zoneId: "top",
+      textPath: "row_1_left_body.0",
+      lineText: "stable",
+    });
+    const a = deriveTextEditCapture(line);
+    const b = deriveTextEditCapture(line);
+    expect(a).toEqual(b);
+    expect(a).not.toBe(b); // fresh objects each call (caller-friendly)
+  });
+
+  it("does not mutate the target element (attrs / parent / textContent unchanged)", () => {
+    const { line, zone } = makeZoneLineScaffold({
+      zoneId: "top",
+      textPath: "row_1_left_body.0",
+      lineText: "immutable",
+    });
+    deriveTextEditCapture(line);
+    expect(line.getAttribute("data-text-path")).toBe("row_1_left_body.0");
+    expect(line.textContent).toBe("immutable");
+    expect(zone.getAttribute("data-zone-position")).toBe("top");
+  });
+});
+
+describe("deriveTextEditCapture (IMP-90 u13) — zone id pass-through", () => {
+  // u13 does not validate the zone id shape — Phase Z slide-base owns the
+  // canonical zone position vocabulary, and u15 / pipeline-side resolver
+  // (u4) re-validate downstream. u13 just forwards whatever the stamped
+  // DOM declared.
+  const ZONE_IDS = ["top", "bottom_l", "bottom_r", "primary", "secondary"];
+  it.each(ZONE_IDS)("preserves zone id '%s' verbatim", (zid) => {
+    const { line } = makeZoneLineScaffold({
+      zoneId: zid,
+      textPath: `${zid}.0`,
+      lineText: "x",
+    });
+    const cap = deriveTextEditCapture(line);
+    expect(cap?.zoneId).toBe(zid);
+    expect(cap?.textPath).toBe(`${zid}.0`);
+  });
+});
@@ -0,0 +1,250 @@
+// IMP-43 (#72) u6 — /api/run reuseFromRunId forwarding coverage.
+//
+// Stage 2 unit scope:
+//   1) Front/client/src/services/designAgentApi.ts `runPipeline`:
+//      • accepts an optional 3rd arg `reuseFromRunId: string`.
+//      • includes `reuseFromRunId` in the POST body when truthy.
+//      • OMITS `reuseFromRunId` from the body when absent / empty / undefined
+//        → byte-identical to the pre-u6 POST contract (absent flag = full
+//        pipeline; backend u1 guard never sees an empty PREV_RUN_ID).
+//      • leaves `filename`, `content`, and `overrides` untouched alongside
+//        the new field (no payload-shape regression).
+//   2) Front/vite.config.ts `/api/run` handler:
+//      • declares `reuseFromRunId?: string` in the payload type so a typed
+//        client cannot send a payload the server silently drops.
+//      • destructures `reuseFromRunId` from `payload` (sibling of
+//        `overrides`, NOT nested under it — the backend u1 post-merge
+//        guard treats reuse as a pipeline mode, not an override).
+//      • forwards `--reuse-from <PREV_RUN_ID>` to spawn cliArgs guarded by
+//        a truthy check (empty string / undefined ⇒ no flag, per Stage 2
+//        contract: invalid CLI args must never reach argparse).
+//      • places the forward block AFTER the `--override-section-assignment`
+//        loop so the spawn argv preserves backend argparse's no-positional-
+//        before-flag expectation and so `--override-frame` (still allowed
+//        by the u1 guard) is positioned ahead of `--reuse-from`.
+//
+// runPipeline is exercised with a duck-typed `File` plus a `vi.stubGlobal`
+// fetch mock — mirrors the user_overrides_service.test.ts pattern. The
+// vite handler is source-sliced (mirrors handle_generate_diag.test.ts)
+// because the handler spawns python and a real /api/run round-trip is
+// out of unit-test scope.
+
+import { afterEach, beforeEach, describe, expect, it, vi, type Mock } from "vitest";
+import { readFileSync } from "node:fs";
+import { resolve } from "node:path";
+import { runPipeline } from "../src/services/designAgentApi";
+
+// ---------------------------------------------------------------------------
+// vite.config.ts source — read once for the handler source-slice assertions.
+// Path: Front/client/tests/ → Front/vite.config.ts (two levels up).
+// ---------------------------------------------------------------------------
+const VITE_CONFIG_PATH = resolve(__dirname, "..", "..", "vite.config.ts");
+const VITE_CONFIG_SOURCE = readFileSync(VITE_CONFIG_PATH, "utf-8");
+
+// ---------------------------------------------------------------------------
+// fetch mock — minimal Response stub mirroring runPipeline's `.ok` + `.json()`
+// + `.status` surface. Same shape as the user_overrides_service.test.ts
+// helper so the two test files stay drift-free.
+// ---------------------------------------------------------------------------
+type MockResponse = {
+  ok: boolean;
+  status: number;
+  json: () => Promise<unknown>;
+};
+
+function mockResponse(body: unknown, ok = true, status = 200): MockResponse {
+  return { ok, status, json: async () => body };
+}
+
+const SUCCESS_BODY = {
+  success: true,
+  run_id: "test_run_id_20260524",
+  exit_code: 0,
+  final_html_exists: true,
+  preview_exists: true,
+  stdout: "",
+  stderr: "",
+};
+
+// Duck-typed File — runPipeline reads only `.name` and `.text()`. Avoids a
+// hard dependency on the global File constructor (varies across node /
+// jsdom / happy-dom test environments).
+function makeFakeFile(name: string, content: string): File {
+  return {
+    name,
+    text: async () => content,
+  } as unknown as File;
+}
+
+let fetchMock: Mock;
+
+beforeEach(() => {
+  fetchMock = vi.fn();
+  vi.stubGlobal("fetch", fetchMock);
+});
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+function lastPostBody(): Record<string, unknown> {
+  const lastCall = fetchMock.mock.calls.at(-1);
+  if (!lastCall) throw new Error("fetch was not called");
+  const init = lastCall[1] as RequestInit | undefined;
+  if (!init?.body) throw new Error("fetch was called without a body");
+  return JSON.parse(String(init.body));
+}
+
+// ============================================================================
+// runPipeline (designAgentApi.ts) — forwarding/omission coverage
+// ============================================================================
+
+describe("runPipeline reuseFromRunId forwarding (IMP-43 #72 u6)", () => {
+  it("posts to /api/run via POST with JSON content-type", async () => {
+    fetchMock.mockResolvedValueOnce(mockResponse(SUCCESS_BODY));
+    await runPipeline(makeFakeFile("03.mdx", "# title"));
+    expect(fetchMock).toHaveBeenCalledTimes(1);
+    const [url, init] = fetchMock.mock.calls[0];
+    expect(url).toBe("/api/run");
+    expect((init as RequestInit).method).toBe("POST");
+    expect((init as RequestInit).headers).toMatchObject({
+      "Content-Type": "application/json",
+    });
+  });
+
+  it("includes reuseFromRunId in the POST body when provided", async () => {
+    fetchMock.mockResolvedValueOnce(mockResponse(SUCCESS_BODY));
+    await runPipeline(
+      makeFakeFile("03.mdx", "# title"),
+      undefined,
+      "mdx03_20260524080000",
+    );
+    const body = lastPostBody();
+    expect(body.reuseFromRunId).toBe("mdx03_20260524080000");
+    expect(body.filename).toBe("03.mdx");
+    expect(body.content).toBe("# title");
+  });
+
+  it("omits reuseFromRunId when 3rd arg is undefined (pre-u6 byte-identical)", async () => {
+    fetchMock.mockResolvedValueOnce(mockResponse(SUCCESS_BODY));
+    await runPipeline(makeFakeFile("03.mdx", "# title"));
+    const body = lastPostBody();
+    expect("reuseFromRunId" in body).toBe(false);
+    // Pre-u6 contract: filename/content are the only keys when overrides
+    // is undefined (JSON.stringify drops undefined values; pre-u6 emitted
+    // `JSON.stringify({filename, content, overrides})` with the same
+    // drop-undefined behaviour, so the wire body is byte-identical).
+    expect(Object.keys(body).sort()).toEqual(["content", "filename"]);
+  });
+
+  it("omits reuseFromRunId but keeps overrides when only overrides provided", async () => {
+    fetchMock.mockResolvedValueOnce(mockResponse(SUCCESS_BODY));
+    await runPipeline(makeFakeFile("03.mdx", "# title"), {
+      frames: { "03-1": "frame_07" },
+    });
+    const body = lastPostBody();
+    expect("reuseFromRunId" in body).toBe(false);
+    expect(Object.keys(body).sort()).toEqual([
+      "content",
+      "filename",
+      "overrides",
+    ]);
+    expect(body.overrides).toEqual({ frames: { "03-1": "frame_07" } });
+  });
+
+  it("omits reuseFromRunId when passed an empty string (truthy guard)", async () => {
+    fetchMock.mockResolvedValueOnce(mockResponse(SUCCESS_BODY));
+    await runPipeline(makeFakeFile("03.mdx", "# title"), undefined, "");
+    const body = lastPostBody();
+    expect("reuseFromRunId" in body).toBe(false);
+  });
+
+  it("forwards reuseFromRunId alongside frame overrides (the only u1-permitted combo)", async () => {
+    fetchMock.mockResolvedValueOnce(mockResponse(SUCCESS_BODY));
+    await runPipeline(
+      makeFakeFile("03.mdx", "# title"),
+      { frames: { "03-1+03-2": "frame_07" } },
+      "mdx03_20260524080000",
+    );
+    const body = lastPostBody();
+    expect(body.overrides).toEqual({ frames: { "03-1+03-2": "frame_07" } });
+    expect(body.reuseFromRunId).toBe("mdx03_20260524080000");
+  });
+
+  it("returns the parsed RunPipelineResult on success", async () => {
+    fetchMock.mockResolvedValueOnce(mockResponse(SUCCESS_BODY));
+    const res = await runPipeline(
+      makeFakeFile("03.mdx", "# title"),
+      undefined,
+      "mdx03_20260524080000",
+    );
+    expect(res.success).toBe(true);
+    expect(res.run_id).toBe("test_run_id_20260524");
+  });
+});
+
+// ============================================================================
+// /api/run handler (vite.config.ts) — source-slice forwarding contract
+// ============================================================================
+
+describe("/api/run handler reuseFromRunId source-slice (IMP-43 #72 u6)", () => {
+  it("declares reuseFromRunId?: string on the /api/run payload type", () => {
+    // Payload type at the top of the /api/run handler body. The
+    // optional-string declaration is the single source-of-truth for what
+    // shape the handler accepts; a typed frontend client (u5 saveUserOverrides
+    // sibling pattern) cannot silently send a payload the server drops.
+    expect(VITE_CONFIG_SOURCE).toMatch(/reuseFromRunId\?:\s*string\s*;/);
+  });
+
+  it("destructures reuseFromRunId from payload alongside filename/content/overrides", () => {
+    expect(VITE_CONFIG_SOURCE).toMatch(
+      /const\s*\{\s*filename\s*,\s*content\s*,\s*overrides\s*,\s*reuseFromRunId\s*\}\s*=\s*payload\s*;/,
+    );
+  });
+
+  it("forwards --reuse-from <PREV_RUN_ID> after the override-section-assignment loop", () => {
+    // Stage 2 contract: reuse_from is a pipeline mode, not an override.
+    // The forward block must sit AFTER the last override loop so the spawn
+    // argv preserves the order documented in the u1 backend post-merge
+    // guard (overrides parsed first; reuse_from precondition runs against
+    // the merged overrides view).
+    const reuseFromIdx = VITE_CONFIG_SOURCE.indexOf('"--reuse-from"');
+    const zoneSectionsIdx = VITE_CONFIG_SOURCE.indexOf(
+      '"--override-section-assignment"',
+    );
+    expect(reuseFromIdx).toBeGreaterThan(-1);
+    expect(zoneSectionsIdx).toBeGreaterThan(-1);
+    expect(reuseFromIdx).toBeGreaterThan(zoneSectionsIdx);
+  });
+
+  it("guards the forward with a truthy check on reuseFromRunId", () => {
+    // Empty string / undefined ⇒ no flag pushed (Stage 2 contract: invalid
+    // CLI args must never reach argparse — the backend u1 guard would
+    // fail-closed with `reuse_artifact_missing` on the empty PREV_RUN_ID).
+    const reuseFromIdx = VITE_CONFIG_SOURCE.indexOf('"--reuse-from"');
+    expect(reuseFromIdx).toBeGreaterThan(-1);
+    const preface = VITE_CONFIG_SOURCE.slice(
+      Math.max(0, reuseFromIdx - 200),
+      reuseFromIdx,
+    );
+    expect(preface).toMatch(/if\s*\(\s*reuseFromRunId/);
+    expect(preface).toMatch(/typeof\s+reuseFromRunId\s*===\s*"string"/);
+  });
+
+  it("pushes reuseFromRunId as the --reuse-from argument value (no string interpolation)", () => {
+    // The CLI value must be the raw PREV_RUN_ID — no `=` join, no quoting
+    // (spawn is shell:false). Mirrors the `--override-layout` shape.
+    const reuseFromIdx = VITE_CONFIG_SOURCE.indexOf('"--reuse-from"');
+    expect(reuseFromIdx).toBeGreaterThan(-1);
+    // Window spans both before (`cliArgs.push(`) and after
+    // (`reuseFromRunId)`) the literal so the full push expression is
+    // captured.
+    const window = VITE_CONFIG_SOURCE.slice(
+      Math.max(0, reuseFromIdx - 100),
+      reuseFromIdx + 200,
+    );
+    expect(window).toMatch(
+      /cliArgs\.push\(\s*"--reuse-from"\s*,\s*reuseFromRunId\s*\)/,
+    );
+  });
+});
@@ -305,19 +305,61 @@ describe("handleGetUserOverrides (IMP-52 u3)", () => {
 // IMP-52 u4 — PUT endpoint coverage
 // ---------------------------------------------------------------------------

-describe("KNOWN_USER_OVERRIDES_AXES (IMP-52 u4)", () => {
+describe("KNOWN_USER_OVERRIDES_AXES (IMP-52 u4 + IMP-56 #90 u3 allowlist sync)", () => {
  it("matches the Python KNOWN_AXES tuple in src/user_overrides_io.py", () => {
    // The on-disk schema is shared with backend pipeline fallback (u2).
    // Any drift here means a PUT could write an axis that the Python
    // load() ignores, or vice-versa, silently losing user overrides.
+    // IMP-56 #90 u3 closes the prior `slide_css` gap (IMP-45 #74) and
+    // pre-wires `text_overrides` (IMP-56 #90 u1) +
+    // `structure_overrides` (IMP-56 #90 u2) — full 9-axis mirror of the
+    // Python tuple, same order.
    expect(KNOWN_USER_OVERRIDES_AXES).toEqual([
      "layout",
      "zone_geometries",
      "zone_sections",
      "frames",
      "image_overrides",
+      "slide_css",
+      "manual_section_assignment",
+      "text_overrides",
+      "structure_overrides",
    ]);
  });
+
+  it("includes the 3 axes added by IMP-56 #90 u3 (allowlist sync)", () => {
+    // Spot-check the diff in addition to the full-equality assertion so a
+    // future edit that drops one of the new axes fails with a localized
+    // error rather than a 9-vs-N tuple-diff that obscures intent.
+    expect(KNOWN_USER_OVERRIDES_AXES).toContain("slide_css");
+    expect(KNOWN_USER_OVERRIDES_AXES).toContain("text_overrides");
+    expect(KNOWN_USER_OVERRIDES_AXES).toContain("structure_overrides");
+    expect(KNOWN_USER_OVERRIDES_AXES.length).toBe(9);
+  });
+});
+
+describe("mergeUserOverrides (IMP-55 #93 u1) — manual_section_assignment bool axis", () => {
+  it("merges bool true / false literally and clears on null", () => {
+    // The PUT handler must treat the bool axis like any other allowlisted
+    // axis: replace on write, preserve when absent, delete on null. Tests
+    // both true→false flip and explicit null-clear so the backend (u9)
+    // sees the exact frontend intent.
+    let merged = mergeUserOverrides({}, { manual_section_assignment: true });
+    expect(merged.manual_section_assignment).toBe(true);
+
+    merged = mergeUserOverrides(merged, { manual_section_assignment: false });
+    expect(merged.manual_section_assignment).toBe(false);
+
+    merged = mergeUserOverrides(merged, { manual_section_assignment: null });
+    expect("manual_section_assignment" in merged).toBe(false);
+  });
+
+  it("preserves bool axis when partial touches only a sibling axis", () => {
+    const existing = { manual_section_assignment: true, layout: "old" };
+    const merged = mergeUserOverrides(existing, { layout: "new" });
+    expect(merged.manual_section_assignment).toBe(true);
+    expect(merged.layout).toBe("new");
+  });
 });

 describe("mergeUserOverrides (IMP-52 u4)", () => {
@@ -35,6 +35,8 @@ import {
  deriveUserOverridesKey,
  remapPersistedFramesToZoneFrames,
  saveImageOverride,
+  saveTextOverride,
+  saveStructureOverride,
 } from "../src/utils/slidePlanUtils";

 // ─── Fixtures ───────────────────────────────────────────────────────────────
@@ -54,6 +56,16 @@ function makeSelection(overrides?: Partial<UserSelection["overrides"]>): UserSel
      // axis declared on `UserSelection.overrides`. Empty by default so the
      // existing IMP-52 cases remain unchanged in shape.
      image_overrides: {},
+      // IMP-55 (#93) u3 — bool intent marker is REQUIRED on
+      // `UserSelection.overrides` (not optional). Default to `false` so every
+      // pre-existing fixture matches the `createInitialUserSelection` seed
+      // and stays compile-clean after u3 widened the type.
+      manual_section_assignment: false,
+      // IMP-56 (#90) u15 — keep the fixture in sync with the two Step-22
+      // persist axes declared on `UserSelection.overrides`. Empty by
+      // default so pre-existing cases retain their shape.
+      text_overrides: {},
+      structure_overrides: {},
      ...overrides,
    },
  };
@@ -460,3 +472,235 @@ describe("image_overrides axis — saveImageOverride (IMP-51 u11)", () => {
    expect(sel.overrides.image_overrides).toEqual(before);
  });
 });
+
+// ─── IMP-55 (#93) u3 — manual_section_assignment bool axis ──────────────────
+// Restore-on-reopen / seed coverage for the bool intent marker. Production
+// branch lives at `slidePlanUtils.ts` — `applyPersistedNonFrameOverrides`
+// guards with `typeof persisted.manual_section_assignment === "boolean"`,
+// and `createInitialUserSelection` seeds the axis to `false`. The marker
+// gates whether `handleGenerate` (u7) forwards `overrides.zoneSections`
+// to the backend; the pipeline (u9) consumes persisted `zone_sections`
+// only when the marker is exactly `true`, so any non-boolean payload MUST
+// end up `false` in memory (fail-closed).
+
+describe("manual_section_assignment axis — applyPersistedNonFrameOverrides (IMP-55 #93 u3)", () => {
+  it("restores literal true verbatim", () => {
+    const sel = makeSelection();
+    const next = applyPersistedNonFrameOverrides(sel, {
+      manual_section_assignment: true,
+    });
+    expect(next.overrides.manual_section_assignment).toBe(true);
+  });
+
+  it("restores literal false verbatim (u12 apply/cancel write must survive reopen)", () => {
+    // Seed `true` so the assertion proves `false` overwrites; a truthiness
+    // check instead of `typeof === \"boolean\"` would silently keep `true`
+    // and resurrect stale auto-carry assignments as user intent.
+    const sel = makeSelection({ manual_section_assignment: true });
+    const next = applyPersistedNonFrameOverrides(sel, {
+      manual_section_assignment: false,
+    });
+    expect(next.overrides.manual_section_assignment).toBe(false);
+  });
+
+  it("leaves the in-memory marker unchanged when the persisted axis is absent", () => {
+    const sel = makeSelection({ manual_section_assignment: true });
+    const next = applyPersistedNonFrameOverrides(sel, { layout: "horizontal-2" });
+    expect(next.overrides.manual_section_assignment).toBe(true);
+    expect(next.overrides.layout_preset).toBe("horizontal-2");
+  });
+
+  it.each([
+    ["null clear sentinel", null],
+    ['string "true"', "true"],
+    ['string "false"', "false"],
+    ["number 1", 1],
+    ["number 0", 0],
+    ["object {}", {}],
+    ["array []", []],
+  ])("ignores non-boolean payload (%s) — keeps prior in-memory value", (_label, payload) => {
+    const sel = makeSelection({ manual_section_assignment: true });
+    const next = applyPersistedNonFrameOverrides(sel, {
+      manual_section_assignment: payload as unknown as boolean,
+    });
+    expect(next.overrides.manual_section_assignment).toBe(true);
+  });
+
+  it("seeds an empty selection with manual_section_assignment=false (createInitialUserSelection)", () => {
+    const sel = createInitialUserSelection();
+    expect(sel.overrides.manual_section_assignment).toBe(false);
+  });
+
+  it("returns a NEW selection object (no input mutation) when restoring the marker", () => {
+    const sel = makeSelection({ manual_section_assignment: false });
+    const next = applyPersistedNonFrameOverrides(sel, {
+      manual_section_assignment: true,
+    });
+    expect(next).not.toBe(sel);
+    expect(next.overrides).not.toBe(sel.overrides);
+    // Input still pristine — proves the helper does not flip the fixture.
+    expect(sel.overrides.manual_section_assignment).toBe(false);
+  });
+
+  it("layers the bool axis alongside other persisted axes in a single call", () => {
+    const sel = makeSelection();
+    const next = applyPersistedNonFrameOverrides(sel, {
+      layout: "vertical-2",
+      zone_sections: { top: ["03-1"], bottom: ["03-2"] },
+      manual_section_assignment: true,
+    });
+    expect(next.overrides.layout_preset).toBe("vertical-2");
+    expect(next.overrides.zone_sections).toEqual({
+      top: ["03-1"],
+      bottom: ["03-2"],
+    });
+    expect(next.overrides.manual_section_assignment).toBe(true);
+  });
+});
+
+// ─── IMP-56 (#90) u15 — text_overrides + structure_overrides axes ───────────
+// Pure helpers wired by Home.tsx into the SlideCanvas u13 focusout capture
+// (text) and u14 structure overlay emit (structure). Tests cover:
+//   • saveTextOverride / saveStructureOverride immutability + merge semantics
+//   • createInitialUserSelection seeding the two new axes empty
+//   • applyPersistedNonFrameOverrides layering via the u10 extract helpers
+
+describe("text_overrides axis — saveTextOverride (IMP-56 u15)", () => {
+  it("records a fresh (zoneId, textPath, value) tuple", () => {
+    const sel = makeSelection();
+    const next = saveTextOverride(sel, "top", "row_1_left_body.0", "분석 결과");
+    expect(next.overrides.text_overrides).toEqual({
+      top: { "row_1_left_body.0": "분석 결과" },
+    });
+  });
+
+  it("merges within the same zone without erasing prior text_paths", () => {
+    const sel = makeSelection({
+      text_overrides: { top: { "row_1_left_body.0": "기존" } },
+    });
+    const next = saveTextOverride(sel, "top", "row_1_left_body.1", "신규");
+    expect(next.overrides.text_overrides.top).toEqual({
+      "row_1_left_body.0": "기존",
+      "row_1_left_body.1": "신규",
+    });
+  });
+
+  it("overwrites the same textPath value within a zone", () => {
+    const sel = makeSelection({
+      text_overrides: { top: { "headline.0": "v1" } },
+    });
+    const next = saveTextOverride(sel, "top", "headline.0", "v2");
+    expect(next.overrides.text_overrides.top).toEqual({ "headline.0": "v2" });
+  });
+
+  it("does not mutate the input selection (immutable contract)", () => {
+    const sel = makeSelection({
+      text_overrides: { top: { "headline.0": "before" } },
+    });
+    saveTextOverride(sel, "top", "headline.0", "after");
+    expect(sel.overrides.text_overrides).toEqual({
+      top: { "headline.0": "before" },
+    });
+  });
+
+  it("seeds an empty text_overrides on a fresh selection", () => {
+    const sel = createInitialUserSelection();
+    expect(sel.overrides.text_overrides).toEqual({});
+  });
+});
+
+describe("structure_overrides axis — saveStructureOverride (IMP-56 u15)", () => {
+  it("records a fresh (zoneId → {slot_order, hidden_slots}) tuple", () => {
+    const sel = makeSelection();
+    const next = saveStructureOverride(sel, "top", {
+      slot_order: ["b", "a"],
+      hidden_slots: ["c"],
+    });
+    expect(next.overrides.structure_overrides).toEqual({
+      top: { slot_order: ["b", "a"], hidden_slots: ["c"] },
+    });
+  });
+
+  it("replaces an existing zone entry verbatim (no merge within zone)", () => {
+    const sel = makeSelection({
+      structure_overrides: { top: { slot_order: ["a", "b"], hidden_slots: [] } },
+    });
+    const next = saveStructureOverride(sel, "top", {
+      slot_order: ["b", "a"],
+      hidden_slots: ["a"],
+    });
+    expect(next.overrides.structure_overrides.top).toEqual({
+      slot_order: ["b", "a"],
+      hidden_slots: ["a"],
+    });
+  });
+
+  it("keeps unrelated zones intact when updating one zone", () => {
+    const sel = makeSelection({
+      structure_overrides: {
+        top: { slot_order: ["x"], hidden_slots: [] },
+        bottom_l: { slot_order: ["y"], hidden_slots: ["z"] },
+      },
+    });
+    const next = saveStructureOverride(sel, "top", {
+      slot_order: ["x", "x2"],
+      hidden_slots: [],
+    });
+    expect(next.overrides.structure_overrides.bottom_l).toEqual({
+      slot_order: ["y"],
+      hidden_slots: ["z"],
+    });
+  });
+
+  it("does not mutate the input perZone object after save", () => {
+    const sel = makeSelection();
+    const perZone = { slot_order: ["a"], hidden_slots: ["b"] };
+    const next = saveStructureOverride(sel, "top", perZone);
+    perZone.slot_order.push("MUTATED");
+    expect(next.overrides.structure_overrides.top.slot_order).toEqual(["a"]);
+  });
+
+  it("seeds an empty structure_overrides on a fresh selection", () => {
+    const sel = createInitialUserSelection();
+    expect(sel.overrides.structure_overrides).toEqual({});
+  });
+});
+
+describe("Step-22 axes — applyPersistedNonFrameOverrides restore (IMP-56 u15)", () => {
+  it("layers persisted text_overrides through the u10 extract helper", () => {
+    const sel = makeSelection();
+    const next = applyPersistedNonFrameOverrides(sel, {
+      text_overrides: {
+        top: { "row_1_left_body.0": "복원" },
+      },
+    });
+    expect(next.overrides.text_overrides).toEqual({
+      top: { "row_1_left_body.0": "복원" },
+    });
+  });
+
+  it("layers persisted structure_overrides through the u10 extract helper", () => {
+    const sel = makeSelection();
+    const next = applyPersistedNonFrameOverrides(sel, {
+      structure_overrides: {
+        top: { slot_order: ["b", "a"], hidden_slots: ["c"] },
+      },
+    });
+    expect(next.overrides.structure_overrides).toEqual({
+      top: { slot_order: ["b", "a"], hidden_slots: ["c"] },
+    });
+  });
+
+  it("drops non-object payloads silently (no throw, axis stays empty)", () => {
+    const sel = makeSelection();
+    const next = applyPersistedNonFrameOverrides(sel, {
+      text_overrides: "garbage" as unknown as Record<string, Record<string, string>>,
+      structure_overrides: ["bad"] as unknown as Record<
+        string,
+        { slot_order?: string[]; hidden_slots?: string[] }
+      >,
+    });
+    expect(next.overrides.text_overrides).toEqual({});
+    expect(next.overrides.structure_overrides).toEqual({});
+  });
+});
@@ -559,3 +559,67 @@ describe("saveUserOverrides (IMP-51 #79 u3) — image_overrides axis", () => {
    });
  });
 });
+
+// ============================================================================
+// IMP-55 #93 u1 — manual_section_assignment axis (7th axis) parity coverage
+//
+// The bool intent marker rides on the same per-axis coalescing rails as the
+// 6 sibling axes. These tests lock the typed client behavior so a regression
+// in the boolean serialization (e.g., coercion to "true" string, dropped
+// `false` due to truthy filtering) fails here instead of in Home.tsx (u6/u7)
+// or the backend gate (u9~u11).
+// ============================================================================
+
+describe("saveUserOverrides (IMP-55 #93 u1) — manual_section_assignment axis", () => {
+  it("PUT body carries only manual_section_assignment when it is the sole mutated axis", async () => {
+    fetchMock.mockResolvedValue(mockResponse({}));
+    void saveUserOverrides("03", { manual_section_assignment: true });
+    vi.advanceTimersByTime(300);
+    await drainMicrotasks();
+
+    const body = lastPutBody() as Record<string, unknown>;
+    expect(Object.keys(body)).toEqual(["manual_section_assignment"]);
+    expect(body.manual_section_assignment).toBe(true);
+  });
+
+  it("later-wins coalesces true → false within a single debounce window", async () => {
+    // Drag-then-cancel inside 300 ms — server must see only the final
+    // `false`, not a transient `true` that would re-enable backend
+    // consumption of stale zone_sections.
+    fetchMock.mockResolvedValue(mockResponse({}));
+    void saveUserOverrides("03", { manual_section_assignment: true });
+    void saveUserOverrides("03", { manual_section_assignment: false });
+
+    vi.advanceTimersByTime(300);
+    await drainMicrotasks();
+    expect(putCallsCount()).toBe(1);
+    expect(lastPutBody()).toEqual({ manual_section_assignment: false });
+  });
+
+  it("forwards null sentinel verbatim (explicit clear)", async () => {
+    fetchMock.mockResolvedValue(mockResponse({}));
+    void saveUserOverrides("03", { manual_section_assignment: null });
+
+    vi.advanceTimersByTime(300);
+    await drainMicrotasks();
+    expect(lastPutBody()).toEqual({ manual_section_assignment: null });
+  });
+
+  it("coalesces with zone_sections sibling into a single PUT (drag-drop pair)", async () => {
+    // Real-world drag flow (u6): one save() sets the bool + zone_sections
+    // together. Asserts both axes survive coalescing as a single PUT body.
+    fetchMock.mockResolvedValue(mockResponse({}));
+    void saveUserOverrides("03", {
+      zone_sections: { left: ["03-2"], right: ["03-1"] },
+      manual_section_assignment: true,
+    });
+
+    vi.advanceTimersByTime(300);
+    await drainMicrotasks();
+    expect(putCallsCount()).toBe(1);
+    expect(lastPutBody()).toEqual({
+      zone_sections: { left: ["03-2"], right: ["03-1"] },
+      manual_section_assignment: true,
+    });
+  });
+});
@@ -85,6 +85,22 @@ function sliceHandler(source: string, name: string): string {
  return source.slice(start, end);
 }

+/**
+ * IMP-55 #93 u8 — strip JS/TS line + block comments so source-pattern
+ * regex checks assert against LIVE code only. The u5 / u7 docblocks in
+ * Home.tsx intentionally reference removed identifiers (e.g. `defaultByZone`,
+ * `sameAsDefault`, `zoneSectionsDiff`) and the marker axis name in prose to
+ * document the Stage 1 root cause for future readers — those references are
+ * documentation, not behavior, and must not trigger negative-match guards.
+ * Strips `// ...` to EOL and `/* ... */` (incl. multi-line) — keeps string
+ * literals intact because we only consume the result for regex-match tests.
+ */
+function stripComments(source: string): string {
+  return source
+    .replace(/\/\*[\s\S]*?\*\//g, "")
+    .replace(/\/\/.*$/gm, "");
+}
+
 describe("Home.tsx write-side wiring (IMP-52 u10) — source pattern", () => {
  it("handleSectionDrop persists zone_sections behind uploadedFile gate", () => {
    const block = sliceHandler(HOME_TSX, "handleSectionDrop");
@@ -567,3 +583,220 @@ describe("restore-on-reopen end-to-end (IMP-52 u10)", () => {
    expect(remapPersistedFramesToZoneFrames(plan, persisted.frames)).toEqual({});
  });
 });
+
+// ─── IMP-55 #93 u8 — manual_section_assignment intent marker contract ─────
+// Verifies four axes of the marker contract introduced in u3 (type) / u5
+// (apply reset) / u6 (drag flip + co-PUT) / u7 (generate gate):
+//   1) Drag dual-axis persistence — handleSectionDrop persists BOTH
+//      `zone_sections` AND `manual_section_assignment: true` in the SAME
+//      PUT body (co-PUT atomicity — disk never sees post-drop zone_sections
+//      without the marker).
+//   2) Apply / cancel reset — handleApplyPendingLayout writes explicit
+//      `manual_section_assignment: false` after the `...overrides` spread,
+//      and handleCancelPendingLayout relies on createInitialUserSelection
+//      (which u3 seeds to `false`) to drop a prior `true`.
+//   3) Marker-gated forwarding — handleGenerate gates `overrides.zoneSections`
+//      forwarding strictly on `manualMarker === true` (NOT truthiness, NOT
+//      `!= null`, NOT presence). u3-seeded `false` and absent values both
+//      skip forwarding.
+//   4) sameAsDefault NOT required — the Stage 1 anti-pattern (defaultByZone
+//      / sameAsDefault / zoneSectionsDiff self-compare loop) is gone from
+//      `handleGenerate` entirely; the marker is the source of intent.
+
+describe("IMP-55 #93 u8 — manual_section_assignment marker contract", () => {
+  it("handleSectionDrop sets marker true in-memory before persistence", () => {
+    const block = sliceHandler(HOME_TSX, "handleSectionDrop");
+    // finalSelection literal (built from zoneSelected, then marker = true)
+    // must occur BEFORE the saveUserOverrides call so the in-memory state
+    // and the PUT body source from the same overrides shape.
+    const markerIdx = block.search(/manual_section_assignment:\s*true/);
+    const saveIdx = block.search(/saveUserOverrides\(/);
+    expect(markerIdx).toBeGreaterThan(-1);
+    expect(saveIdx).toBeGreaterThan(-1);
+    expect(markerIdx).toBeLessThan(saveIdx);
+  });
+
+  it("handleSectionDrop co-PUTs zone_sections + manual_section_assignment:true (single body)", () => {
+    const block = sliceHandler(HOME_TSX, "handleSectionDrop");
+    // Single saveUserOverrides call carrying BOTH axes. The regex spans the
+    // call body to prove the two keys live in the same object literal — a
+    // future split into two PUTs would race the 300ms debounce and re-open
+    // the IMP-55 stale-disk window.
+    expect(block).toMatch(
+      /saveUserOverrides\([\s\S]*?zone_sections:[\s\S]*?manual_section_assignment:\s*true[\s\S]*?\)/,
+    );
+    // Exactly ONE saveUserOverrides call in the handler.
+    const calls = block.match(/saveUserOverrides\(/g) ?? [];
+    expect(calls.length).toBe(1);
+  });
+
+  it("handleApplyPendingLayout resets the marker to false in overrides literal", () => {
+    const block = sliceHandler(HOME_TSX, "handleApplyPendingLayout");
+    // After spreading `...p.userSelection.overrides`, the explicit
+    // `manual_section_assignment: false` overrides any prior-drag `true`.
+    // Without this the layout flip would carry the marker through, and u7
+    // would forward auto-carried assignments as user overrides → the
+    // PARTIAL_COVERAGE regression that motivated IMP-55.
+    expect(block).toMatch(/\.\.\.p\.userSelection\.overrides[\s\S]*?manual_section_assignment:\s*false/);
+  });
+
+  it("handleCancelPendingLayout uses createInitialUserSelection (u3 seeds false)", () => {
+    const block = sliceHandler(HOME_TSX, "handleCancelPendingLayout");
+    // Cancel discards all pending in-memory edits via the fresh-selection
+    // helper — the seed (u3) is the single source of truth for the
+    // in-memory marker on this path. u12 adds a separate disk-side
+    // saveUserOverrides PUT (covered by the u12 describe block below);
+    // the in-memory userSelection literal still has no explicit marker
+    // field — the seed handles it.
+    expect(block).toMatch(/createInitialUserSelection\(p\.slidePlan\)/);
+    // In-memory contract: no `manual_section_assignment` property appears
+    // inside the userSelection assignment. The only marker reference in
+    // live code lives inside the u12 saveUserOverrides(...) call body.
+    const codeOnly = stripComments(block);
+    expect(codeOnly).not.toMatch(
+      /userSelection:[\s\S]*?manual_section_assignment/,
+    );
+  });
+
+  it("handleGenerate gates overrides.zoneSections on manualMarker === true (strict bool)", () => {
+    const block = sliceHandler(HOME_TSX, "handleGenerate");
+    // Marker read AND strict-equality gate. `===` not `==`, not truthiness,
+    // not presence — so `false` / absent both skip forwarding (fail-closed).
+    expect(block).toMatch(/state\.userSelection\.overrides\.manual_section_assignment/);
+    expect(block).toMatch(/manualMarker\s*===\s*true/);
+    // The assignment to `overrides.zoneSections` must live INSIDE the
+    // marker-true branch.
+    const gateIdx = block.search(/if\s*\(\s*manualMarker\s*===\s*true\s*\)/);
+    const assignIdx = block.search(/overrides\.zoneSections\s*=/);
+    expect(gateIdx).toBeGreaterThan(-1);
+    expect(assignIdx).toBeGreaterThan(gateIdx);
+  });
+
+  it("handleGenerate filters forwarded zone_sections to valid zone_ids only (cross-layout safety)", () => {
+    const block = sliceHandler(HOME_TSX, "handleGenerate");
+    // A stale persisted layout could carry zone_ids that do not exist in
+    // the current sourcePlan (e.g. horizontal-2 `top`/`bottom` while the
+    // current layout is vertical-2 `left`/`right`). Those foreign keys
+    // must be dropped before reaching the backend `--override-section-
+    // assignment` so they cannot trigger PARTIAL_COVERAGE.
+    expect(block).toMatch(/validZoneIds\s*=\s*new Set\(\s*sourcePlan\.zones\.map\(\(z\)\s*=>\s*z\.zone_id\)/);
+    expect(block).toMatch(/if\s*\(!validZoneIds\.has\(zoneId\)\)\s*continue/);
+  });
+
+  it("handleGenerate no longer contains the IMP-08 B-3 self-compare anti-pattern", () => {
+    // Strip comments — the u7 docblock intentionally references the removed
+    // identifiers (`defaultByZone` / `sameAsDefault` / `zoneSectionsDiff`)
+    // in prose to explain the Stage 1 root cause for future readers; the
+    // regression we guard against is the LIVE code re-emerging.
+    const block = stripComments(sliceHandler(HOME_TSX, "handleGenerate"));
+    // The Stage 1 root cause: these identifiers compared user input against
+    // itself (sourcePlan === effectiveSlidePlan → zones === pendingZones,
+    // both derived from the same overrides.zone_sections). u7 deleted the
+    // entire block.
+    expect(block).not.toMatch(/\bdefaultByZone\b/);
+    expect(block).not.toMatch(/\bsameAsDefault\b/);
+    expect(block).not.toMatch(/\bzoneSectionsDiff\b/);
+  });
+
+  it("co-PUT payload contract: marker=true + zone_sections land in a single PUT body", async () => {
+    fetchMock.mockResolvedValue(mockResponse({}));
+    // Shape produced by handleSectionDrop after the u6 marker flip.
+    void saveUserOverrides("03_demo", {
+      zone_sections: { left: ["03-2"], right: ["03-1"] },
+      manual_section_assignment: true,
+    });
+    vi.advanceTimersByTime(300);
+    await drainMicrotasks();
+    expect(fetchMock).toHaveBeenCalledTimes(1);
+    const body = lastPutBody() as Record<string, unknown>;
+    // Both axes in the same PUT body — exact equality, not arrayContaining,
+    // because any extra axis would mean a foreign mutation leaked through.
+    expect(Object.keys(body).sort()).toEqual(
+      ["manual_section_assignment", "zone_sections"].sort(),
+    );
+    expect(body.manual_section_assignment).toBe(true);
+    expect(body.zone_sections).toEqual({ left: ["03-2"], right: ["03-1"] });
+  });
+
+  it("co-PUT payload contract: marker=false carries explicitly through saveUserOverrides", async () => {
+    // u12 will add the apply/cancel explicit `false` PUT; the typed client
+    // must already propagate the literal `false` through the debounce
+    // bucket. A truthiness-based coalesce in the bucket merge would drop
+    // the value and re-open the stale-disk window. This locks the wire
+    // contract independently of the u12 caller-site write.
+    fetchMock.mockResolvedValue(mockResponse({}));
+    void saveUserOverrides("03_demo", { manual_section_assignment: false });
+    vi.advanceTimersByTime(300);
+    await drainMicrotasks();
+    const body = lastPutBody() as Record<string, unknown>;
+    expect(Object.keys(body)).toEqual(["manual_section_assignment"]);
+    expect(body.manual_section_assignment).toBe(false);
+  });
+});
+
+// ─── IMP-55 #93 u12 — stale-disk marker reset on apply / cancel ───────────
+// u5 resets the in-memory marker on layout apply, and u3's seed via
+// `createInitialUserSelection` resets it on cancel. But the disk persists
+// independently — a prior drag wrote `true` via u6's co-PUT, so after a
+// page reload the u3 restore branch would re-seed `true` and the u7 gate
+// would forward auto-carried section assignments → PARTIAL_COVERAGE
+// regression. u12 closes that window by writing `manual_section_assignment:
+// false` to disk via saveUserOverrides on both apply and cancel paths.
+describe("IMP-55 #93 u12 — stale-disk marker reset on layout apply/cancel", () => {
+  it("handleApplyPendingLayout source contains a marker=false saveUserOverrides PUT", () => {
+    const block = sliceHandler(HOME_TSX, "handleApplyPendingLayout");
+    // Stripped-comment source so the u5 docblock prose doesn't satisfy the
+    // assertion — must be a real call expression.
+    const code = stripComments(block);
+    // Uploaded-file gate (mirrors the u6 / other handler pattern — the
+    // demo-mode initial render path must not PUT to an empty key).
+    expect(code).toMatch(
+      /if\s*\(\s*p\.uploadedFile\s*\)[\s\S]*?saveUserOverrides\([\s\S]*?manual_section_assignment:\s*false[\s\S]*?\)/,
+    );
+    expect(code).toMatch(/deriveUserOverridesKey\(p\.uploadedFile\.name\)/);
+  });
+
+  it("handleCancelPendingLayout source contains a marker=false saveUserOverrides PUT", () => {
+    const block = sliceHandler(HOME_TSX, "handleCancelPendingLayout");
+    const code = stripComments(block);
+    // Cancel handler converts from arrow-body to function-body for the
+    // disk PUT; the in-memory reset still comes from createInitialUserSelection.
+    expect(code).toMatch(
+      /if\s*\(\s*p\.uploadedFile\s*\)[\s\S]*?saveUserOverrides\([\s\S]*?manual_section_assignment:\s*false[\s\S]*?\)/,
+    );
+    expect(code).toMatch(/createInitialUserSelection\(p\.slidePlan\)/);
+  });
+
+  it("apply path PUT payload: marker=false carries alone (no auto-carry leakage)", async () => {
+    // The apply handler issues a dedicated PUT for the marker reset that is
+    // independent of the (conditional) zone_geometries PUT and of the
+    // in-memory zone_sections rewrite. The wire contract for this PUT must
+    // contain only the marker — if zone_sections leaked into the same body
+    // it would re-arm the u9 backend fallback gate against u12's intent.
+    fetchMock.mockResolvedValue(mockResponse({}));
+    void saveUserOverrides("03_demo", { manual_section_assignment: false });
+    vi.advanceTimersByTime(300);
+    await drainMicrotasks();
+    expect(fetchMock).toHaveBeenCalledTimes(1);
+    const body = lastPutBody() as Record<string, unknown>;
+    expect(Object.keys(body)).toEqual(["manual_section_assignment"]);
+    expect(body.manual_section_assignment).toBe(false);
+  });
+
+  it("apply path PUT is unconditional (does NOT gate on hadPriorGeoms)", () => {
+    // The u4 zone_geometries PUT inside handleApplyPendingLayout is
+    // conditional (`p.uploadedFile && hadPriorGeoms`). The u12 marker PUT
+    // must NOT inherit that gate — a stale disk `true` can exist without
+    // any prior zone_geometries, so the reset must always fire.
+    const code = stripComments(sliceHandler(HOME_TSX, "handleApplyPendingLayout"));
+    // Locate the marker PUT and verify its enclosing `if` clause is just
+    // `p.uploadedFile`, not the compound `... && hadPriorGeoms` guard.
+    const markerCallMatch = code.match(
+      /if\s*\(([^)]*)\)\s*\{[^}]*saveUserOverrides\([^)]*manual_section_assignment:\s*false[^)]*\)/,
+    );
+    expect(markerCallMatch).not.toBeNull();
+    if (markerCallMatch) {
+      expect(markerCallMatch[1].trim()).toBe("p.uploadedFile");
+    }
+  });
+});
@@ -0,0 +1,222 @@
+// IMP-44 (#73) u3 — vitest coverage for `validateZoneGeometriesAgainstLayout`.
+//
+// Pairs with the backend [override-warning] guards added in u1 (1-D
+// horizontal-2 / vertical-2 branches of `build_layout_css`) and u2 (2-D
+// `_override_to_grid_tracks` call site). Same WARN+DROP unknown / KEEP known
+// contract; this helper lets handleGenerate (u4) validate against the active
+// layout before forwarding so the user sees a toast on dropped keys rather
+// than the backend silently even-splitting non-overridden zones with a false
+// `computation=user_override_geometry` signal.
+//
+// Cases (Stage 2 scope-lock):
+//   1) horizontal-2 → vertical-2 mismatch (all keys dropped)
+//   2) passthrough (all keys recognized)
+//   3) partial mix (some kept, some dropped)
+//   4) empty input ({} on a known layout)
+//   5) unknown-layout fail-safe (preset null / undefined / unknown string)
+
+import { describe, it, expect } from "vitest";
+import { validateZoneGeometriesAgainstLayout } from "../src/utils/slidePlanUtils";
+
+const g = (x: number, y: number, w: number, h: number) => ({ x, y, w, h });
+
+describe("validateZoneGeometriesAgainstLayout (IMP-44 u3)", () => {
+  // ── 1. mismatch ──────────────────────────────────────────────────────────
+  it("drops horizontal-2 keys when the active layout is vertical-2", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      { top: g(0, 0, 1, 0.4), bottom: g(0, 0.4, 1, 0.6) },
+      "vertical-2",
+    );
+    expect(result.kept).toEqual({});
+    expect(result.dropped).toEqual({
+      top: g(0, 0, 1, 0.4),
+      bottom: g(0, 0.4, 1, 0.6),
+    });
+    expect(result.expectedPositions).toEqual(["left", "right"]);
+    expect(result.valid).toBe(false);
+  });
+
+  it("drops vertical-2 keys when the active layout is horizontal-2", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      { left: g(0, 0, 0.5, 1), right: g(0.5, 0, 0.5, 1) },
+      "horizontal-2",
+    );
+    expect(result.kept).toEqual({});
+    expect(Object.keys(result.dropped).sort()).toEqual(["left", "right"]);
+    expect(result.expectedPositions).toEqual(["top", "bottom"]);
+    expect(result.valid).toBe(false);
+  });
+
+  // ── 2. passthrough ───────────────────────────────────────────────────────
+  it("keeps all keys when every input key is in the active layout positions", () => {
+    const input = {
+      top: g(0, 0, 1, 0.4),
+      bottom: g(0, 0.4, 1, 0.6),
+    };
+    const result = validateZoneGeometriesAgainstLayout(input, "horizontal-2");
+    expect(result.kept).toEqual(input);
+    expect(result.dropped).toEqual({});
+    expect(result.expectedPositions).toEqual(["top", "bottom"]);
+    expect(result.valid).toBe(true);
+  });
+
+  it("passes a single 'primary' key through on the 'single' preset", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      { primary: g(0, 0, 1, 1) },
+      "single",
+    );
+    expect(result.kept).toEqual({ primary: g(0, 0, 1, 1) });
+    expect(result.dropped).toEqual({});
+    expect(result.expectedPositions).toEqual(["primary"]);
+    expect(result.valid).toBe(true);
+  });
+
+  it("recognizes the 2-D preset positions reported by computeZonePositions (top-1-bottom-2)", () => {
+    const input = {
+      top: g(0, 0, 1, 0.5),
+      "bottom-left": g(0, 0.5, 0.5, 0.5),
+      "bottom-right": g(0.5, 0.5, 0.5, 0.5),
+    };
+    const result = validateZoneGeometriesAgainstLayout(input, "top-1-bottom-2");
+    expect(result.kept).toEqual(input);
+    expect(result.dropped).toEqual({});
+    expect(result.expectedPositions).toEqual([
+      "top",
+      "bottom-left",
+      "bottom-right",
+    ]);
+    expect(result.valid).toBe(true);
+  });
+
+  // ── 3. partial mix ───────────────────────────────────────────────────────
+  it("keeps known keys and drops unknown keys on a partial-mix input", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      { top: g(0, 0, 1, 0.4), foo: g(0, 0, 1, 1) },
+      "horizontal-2",
+    );
+    expect(result.kept).toEqual({ top: g(0, 0, 1, 0.4) });
+    expect(result.dropped).toEqual({ foo: g(0, 0, 1, 1) });
+    expect(result.expectedPositions).toEqual(["top", "bottom"]);
+    expect(result.valid).toBe(false);
+  });
+
+  it("on a 2-D preset, keeps known 2-D track keys and drops legacy 1-D keys", () => {
+    // Simulates the user resizing under top-1-bottom-2, then flipping to
+    // grid-2x2 — legacy `bottom-left` stays valid; `top` (no longer a 2x2
+    // position) gets dropped.
+    const result = validateZoneGeometriesAgainstLayout(
+      {
+        top: g(0, 0, 1, 0.5),
+        "bottom-left": g(0, 0.5, 0.5, 0.5),
+        "top-left": g(0, 0, 0.5, 0.5),
+      },
+      "grid-2x2",
+    );
+    expect(result.kept).toEqual({
+      "bottom-left": g(0, 0.5, 0.5, 0.5),
+      "top-left": g(0, 0, 0.5, 0.5),
+    });
+    expect(result.dropped).toEqual({ top: g(0, 0, 1, 0.5) });
+    expect(result.expectedPositions).toEqual([
+      "top-left",
+      "top-right",
+      "bottom-left",
+      "bottom-right",
+    ]);
+    expect(result.valid).toBe(false);
+  });
+
+  // ── 4. empty input ───────────────────────────────────────────────────────
+  it("returns empty kept/dropped and valid=true on an empty {} input", () => {
+    const result = validateZoneGeometriesAgainstLayout({}, "horizontal-2");
+    expect(result.kept).toEqual({});
+    expect(result.dropped).toEqual({});
+    expect(result.expectedPositions).toEqual(["top", "bottom"]);
+    expect(result.valid).toBe(true);
+  });
+
+  it("treats null / undefined geoms as empty input (no throw, valid=true on a known layout)", () => {
+    const nullResult = validateZoneGeometriesAgainstLayout(null, "vertical-2");
+    expect(nullResult.kept).toEqual({});
+    expect(nullResult.dropped).toEqual({});
+    expect(nullResult.expectedPositions).toEqual(["left", "right"]);
+    expect(nullResult.valid).toBe(true);
+
+    const undefResult = validateZoneGeometriesAgainstLayout(
+      undefined,
+      "vertical-2",
+    );
+    expect(undefResult.kept).toEqual({});
+    expect(undefResult.dropped).toEqual({});
+    expect(undefResult.expectedPositions).toEqual(["left", "right"]);
+    expect(undefResult.valid).toBe(true);
+  });
+
+  it("ignores array payloads (defensive against hand-edited persisted files)", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      [] as unknown as Record<string, { x: number; y: number; w: number; h: number }>,
+      "horizontal-2",
+    );
+    expect(result.kept).toEqual({});
+    expect(result.dropped).toEqual({});
+    expect(result.expectedPositions).toEqual(["top", "bottom"]);
+    expect(result.valid).toBe(true);
+  });
+
+  // ── 5. unknown-layout fail-safe ──────────────────────────────────────────
+  it("drops every input key when layout is null (fail-safe)", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      { top: g(0, 0, 1, 0.4), bottom: g(0, 0.4, 1, 0.6) },
+      null,
+    );
+    expect(result.kept).toEqual({});
+    expect(result.dropped).toEqual({
+      top: g(0, 0, 1, 0.4),
+      bottom: g(0, 0.4, 1, 0.6),
+    });
+    expect(result.expectedPositions).toEqual([]);
+    expect(result.valid).toBe(false);
+  });
+
+  it("drops every input key when layout is undefined (fail-safe)", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      { primary: g(0, 0, 1, 1) },
+      undefined,
+    );
+    expect(result.kept).toEqual({});
+    expect(result.dropped).toEqual({ primary: g(0, 0, 1, 1) });
+    expect(result.expectedPositions).toEqual([]);
+    expect(result.valid).toBe(false);
+  });
+
+  it("drops every input key when layout is an unknown preset string (fail-safe)", () => {
+    const result = validateZoneGeometriesAgainstLayout(
+      { top: g(0, 0, 1, 0.4) },
+      "rogue-preset" as unknown as string,
+    );
+    expect(result.kept).toEqual({});
+    expect(result.dropped).toEqual({ top: g(0, 0, 1, 0.4) });
+    expect(result.expectedPositions).toEqual([]);
+    expect(result.valid).toBe(false);
+  });
+
+  it("returns empty kept/dropped/expectedPositions when layout is unknown AND geoms is empty", () => {
+    const result = validateZoneGeometriesAgainstLayout({}, null);
+    expect(result.kept).toEqual({});
+    expect(result.dropped).toEqual({});
+    expect(result.expectedPositions).toEqual([]);
+    // No keys to drop ⇒ vacuously valid; handleGenerate (u4) gates the toast
+    // on `Object.keys(dropped).length > 0`, not `valid`, so this is safe.
+    expect(result.valid).toBe(true);
+  });
+
+  // ── purity / mutation safety ─────────────────────────────────────────────
+  it("does not mutate the input geometries object", () => {
+    const input = { top: g(0, 0, 1, 0.4), foo: g(0, 0, 1, 1) };
+    const inputKeysBefore = Object.keys(input).sort();
+    validateZoneGeometriesAgainstLayout(input, "horizontal-2");
+    expect(Object.keys(input).sort()).toEqual(inputKeysBefore);
+    // Sample value still pristine.
+    expect(input.top).toEqual(g(0, 0, 1, 0.4));
+  });
+});
@@ -219,19 +219,36 @@ function vitePluginStorageProxy(): Plugin {

 export const USER_OVERRIDES_KEY_RE = /^[A-Za-z0-9_][A-Za-z0-9_.\-]*$/;

-// The five in-scope axes — exact mirror of KNOWN_AXES in
-// src/user_overrides_io.py. Any payload key outside this allowlist is
-// silently dropped by the PUT handler (u4) so the on-disk schema cannot
-// drift from the backend pipeline (u2) contract. Foreign top-level keys
-// already on disk are preserved verbatim (see mergeUserOverrides).
+// The nine in-scope axes — full mirror of KNOWN_AXES in
+// src/user_overrides_io.py. Order matches the Python tuple verbatim so
+// a side-by-side audit reads as a no-op. Any payload key outside this
+// allowlist is silently dropped by the PUT handler (u4) so the on-disk
+// schema cannot drift from the backend pipeline (u2) contract. Foreign
+// top-level keys already on disk are preserved verbatim (see
+// mergeUserOverrides).
 // IMP-51 (#79) u2: added `image_overrides` (image_id → {x,y,w,h}
 // percent-of-slide coordinates).
+// IMP-55 (#93) u1: added `manual_section_assignment` (bool intent marker
+// — drag-drop sets true, layout apply/cancel sets false).
+// IMP-56 (#90) u3: allowlist sync — closes the prior `slide_css` gap
+// (IMP-45 #74; the Step-22 slide CSS edit path will write it from the
+// frontend) and pre-wires `text_overrides` (IMP-56 #90 u1, keyed by
+// {zone_id: {text_path: value}}) + `structure_overrides` (IMP-56 #90 u2,
+// keyed by {zone_id: {slot_order, hidden_slots}} — scope LOCKED to slot
+// reorder + hide; frame swap stays on the existing `frames` axis to
+// preserve Phase Z's no-AI-HTML-structure invariant) so the Step-22
+// capture path (u10~u17) can PUT either axis without a follow-on
+// allowlist edit.
 export const KNOWN_USER_OVERRIDES_AXES = [
  "layout",
  "zone_geometries",
  "zone_sections",
  "frames",
  "image_overrides",
+  "slide_css",
+  "manual_section_assignment",
+  "text_overrides",
+  "structure_overrides",
 ] as const;
 export type KnownUserOverridesAxis = (typeof KNOWN_USER_OVERRIDES_AXES)[number];

@@ -500,6 +517,211 @@ export function handlePutUserOverrides(
  return true;
 }

+// =============================================================================
+// IMP-56 (#90) u18 — POST /api/connect : cel astro dev mirror copy.
+//
+// Body: {"run_id": "<id>", "slug": "<mdx-stem>"}.
+//   • Copies <DESIGN_AGENT_ROOT>/data/runs/<run_id>/phase_z2/final.html →
+//     <CEL_PROJECT_ROOT>/public/slides/<slug>.html (overwrite).
+//   • If <run_dir>/phase_z2/assets/ exists, mirrors its contents into
+//     <CEL_PROJECT_ROOT>/public/slides/assets/ (overwrite copy, recursive).
+//   • run_id and slug are validated through the existing
+//     isValidUserOverridesKey gate so path-traversal payloads are rejected.
+// =============================================================================
+
+export function mirrorDirRecursive(srcDir: string, dstDir: string): number {
+  if (!fs.existsSync(srcDir) || !fs.statSync(srcDir).isDirectory()) return 0;
+  if (!fs.existsSync(dstDir)) fs.mkdirSync(dstDir, { recursive: true });
+  let count = 0;
+  for (const entry of fs.readdirSync(srcDir, { withFileTypes: true })) {
+    const srcPath = path.join(srcDir, entry.name);
+    const dstPath = path.join(dstDir, entry.name);
+    if (entry.isDirectory()) {
+      count += mirrorDirRecursive(srcPath, dstPath);
+    } else if (entry.isFile()) {
+      fs.copyFileSync(srcPath, dstPath);
+      count += 1;
+    }
+  }
+  return count;
+}
+
+export function handleConnectMirror(
+  req: PutReqLike,
+  res: ResLike,
+  designAgentRoot: string,
+  celRoot: string,
+): boolean {
+  if (req.method !== "POST") return false;
+  let body = "";
+  req.on("data", (chunk: Buffer | string) => {
+    body += typeof chunk === "string" ? chunk : chunk.toString();
+  });
+  req.on("end", () => {
+    let parsed: unknown;
+    try {
+      parsed = body.length > 0 ? JSON.parse(body) : {};
+    } catch {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "invalid JSON" }));
+      return;
+    }
+    if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "body must be a JSON object" }));
+      return;
+    }
+    const { run_id, slug } = parsed as { run_id?: unknown; slug?: unknown };
+    if (typeof run_id !== "string" || typeof slug !== "string") {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "missing run_id or slug" }));
+      return;
+    }
+    if (!isValidUserOverridesKey(run_id) || !isValidUserOverridesKey(slug)) {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "invalid run_id or slug" }));
+      return;
+    }
+    const runDir = path.join(designAgentRoot, "data", "runs", run_id, "phase_z2");
+    const srcHtml = path.join(runDir, "final.html");
+    if (!fs.existsSync(srcHtml)) {
+      res.writeHead(404, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "final.html not found" }));
+      return;
+    }
+    const dstSlidesDir = path.join(celRoot, "public", "slides");
+    if (!fs.existsSync(dstSlidesDir)) fs.mkdirSync(dstSlidesDir, { recursive: true });
+    const dstHtml = path.join(dstSlidesDir, `${slug}.html`);
+    try {
+      fs.copyFileSync(srcHtml, dstHtml);
+    } catch (err) {
+      res.writeHead(500, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: `copy failed: ${String(err)}` }));
+      return;
+    }
+    const assetsCopied = mirrorDirRecursive(
+      path.join(runDir, "assets"),
+      path.join(dstSlidesDir, "assets"),
+    );
+    res.writeHead(200, { "Content-Type": "application/json; charset=utf-8" });
+    res.end(JSON.stringify({ success: true, run_id, slug, html_target: dstHtml, assets_copied: assetsCopied }));
+  });
+  req.on("error", () => {
+    res.writeHead(500, { "Content-Type": "application/json; charset=utf-8" });
+    res.end(JSON.stringify({ error: "request error" }));
+  });
+  return true;
+}
+
+// =============================================================================
+// IMP-56 (#90) u19 — POST /api/export : standalone HTML download.
+//
+// Body: {"run_id": "<id>"}.
+//   • Reads <DESIGN_AGENT_ROOT>/data/runs/<run_id>/phase_z2/final.html.
+//   • Inlines every `url(assets/<frame>/<file>)` reference (the only
+//     external dep emitted by the Phase Z2 render path — verified by grep
+//     against templates/phase_z2/slide_base.html and a representative run)
+//     as a base64 data URL so the emitted HTML is portable (file:// open
+//     or any external host, no co-located assets/ dir required). Mirrors
+//     u18 validation: isValidUserOverridesKey gate for path-traversal
+//     rejection; final.html missing → 404.
+//   • Response: 200 text/html with Content-Disposition: attachment so the
+//     browser triggers a download with `<run_id>.html` filename. Raw HTML
+//     body (NOT JSON-wrapped) — the BottomActions wiring (u20) will pipe
+//     the response body straight into a Blob → a[download] click chain
+//     mirroring the existing serializeSlidePlan JSON download flow.
+// =============================================================================
+
+export function inlineAssetsAsDataUrls(html: string, assetsRoot: string): string {
+  // Match `url(assets/<rel-path>)` (with optional single/double quotes,
+  // optional surrounding whitespace). The Phase Z2 render path emits
+  // `url(assets/<frame>/<file>.png)` verbatim into inline `style="..."`
+  // custom-property declarations (see slide_base.html `--card-frame-bg`
+  // etc.) — there is no `<link rel="stylesheet">` or `<img src>` external
+  // ref to handle. Keeping the matcher narrow avoids accidentally
+  // rewriting `data:` / `http(s):` / sibling-path URLs that the render
+  // path does not produce.
+  const URL_RE = /url\(\s*(['"]?)assets\/([^)'"]+)\1\s*\)/g;
+  return html.replace(URL_RE, (match, _quote: string, rel: string) => {
+    const filePath = path.join(assetsRoot, rel);
+    if (!fs.existsSync(filePath) || !fs.statSync(filePath).isFile()) return match;
+    const ext = path.extname(filePath).toLowerCase().slice(1);
+    const mime =
+      ext === "png" ? "image/png" :
+      ext === "jpg" || ext === "jpeg" ? "image/jpeg" :
+      ext === "svg" ? "image/svg+xml" :
+      ext === "webp" ? "image/webp" :
+      ext === "gif" ? "image/gif" :
+      "application/octet-stream";
+    const buf = fs.readFileSync(filePath);
+    return `url("data:${mime};base64,${buf.toString("base64")}")`;
+  });
+}
+
+export function handleExportStandalone(
+  req: PutReqLike,
+  res: ResLike,
+  designAgentRoot: string,
+): boolean {
+  if (req.method !== "POST") return false;
+  let body = "";
+  req.on("data", (chunk: Buffer | string) => {
+    body += typeof chunk === "string" ? chunk : chunk.toString();
+  });
+  req.on("end", () => {
+    let parsed: unknown;
+    try {
+      parsed = body.length > 0 ? JSON.parse(body) : {};
+    } catch {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "invalid JSON" }));
+      return;
+    }
+    if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "body must be a JSON object" }));
+      return;
+    }
+    const { run_id } = parsed as { run_id?: unknown };
+    if (typeof run_id !== "string") {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "missing run_id" }));
+      return;
+    }
+    if (!isValidUserOverridesKey(run_id)) {
+      res.writeHead(400, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "invalid run_id" }));
+      return;
+    }
+    const runDir = path.join(designAgentRoot, "data", "runs", run_id, "phase_z2");
+    const srcHtml = path.join(runDir, "final.html");
+    if (!fs.existsSync(srcHtml)) {
+      res.writeHead(404, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: "final.html not found" }));
+      return;
+    }
+    let html: string;
+    try {
+      html = fs.readFileSync(srcHtml, "utf-8");
+    } catch (err) {
+      res.writeHead(500, { "Content-Type": "application/json; charset=utf-8" });
+      res.end(JSON.stringify({ error: `read failed: ${String(err)}` }));
+      return;
+    }
+    const inlined = inlineAssetsAsDataUrls(html, path.join(runDir, "assets"));
+    res.writeHead(200, {
+      "Content-Type": "text/html; charset=utf-8",
+      "Content-Disposition": `attachment; filename="${run_id}.html"`,
+    });
+    res.end(inlined);
+  });
+  req.on("error", () => {
+    res.writeHead(500, { "Content-Type": "application/json; charset=utf-8" });
+    res.end(JSON.stringify({ error: "request error" }));
+  });
+  return true;
+}
+
 // =============================================================================
 // Phase Z API Plugin — MDX 업로드 → 파이프라인 실행 → 결과 노출
 //
@@ -508,14 +730,19 @@ export function handlePutUserOverrides(
 //   GET  /data/runs/{run_id}/{path}  →  {DESIGN_AGENT_ROOT}/data/runs/{run_id}/phase_z2/{path}
 //   GET  /api/user-overrides/{key}   →  data/user_overrides/{key}.json (IMP-52 u3)
 //   PUT  /api/user-overrides/{key}   →  partial-merge save (IMP-52 u4)
+//   POST /api/connect                →  cel mirror (IMP-56 #90 u18)
+//   POST /api/export                 →  standalone HTML download (IMP-56 #90 u19)
 //
 // 환경 변수 (선택) :
 //   DESIGN_AGENT_ROOT  python pipeline 실행 cwd. default = D:/ad-hoc/kei/design_agent
+//   CEL_PROJECT_ROOT   cel astro dev repo root. default = D:/ad-hoc/cel
 // =============================================================================

 function vitePluginPhaseZApi(): Plugin {
  const DESIGN_AGENT_ROOT =
    process.env.DESIGN_AGENT_ROOT || "D:\\ad-hoc\\kei\\design_agent";
+  const CEL_PROJECT_ROOT =
+    process.env.CEL_PROJECT_ROOT || "D:\\ad-hoc\\cel";
  const UPLOADS_DIR = path.join(DESIGN_AGENT_ROOT, "samples", "uploads");
  const RUNS_DIR = path.join(DESIGN_AGENT_ROOT, "data", "runs");

@@ -543,6 +770,13 @@ function vitePluginPhaseZApi(): Plugin {
              // (e.g., "top": ["03-1-sub-1"]). Forwarded as --override-section-assignment.
              zoneSections?: Record<string, string[]>;
            };
+            // IMP-43 (#72) u6 — optional PREV_RUN_ID to reuse Step 0/1/2/5/6
+            // artifacts from a prior run and resume execution at Step 7.
+            // Lives at the payload root (NOT under `overrides`) because the
+            // backend u1 post-merge guard rejects most override axes when
+            // --reuse-from is supplied. Absent / empty = full pipeline
+            // (byte-identical to pre-u6 spawn).
+            reuseFromRunId?: string;
          };
          try {
            payload = JSON.parse(body);
@@ -554,7 +788,7 @@ function vitePluginPhaseZApi(): Plugin {
            return;
          }

-          const { filename, content, overrides } = payload;
+          const { filename, content, overrides, reuseFromRunId } = payload;
          if (!filename || typeof content !== "string") {
            res.writeHead(400, { "Content-Type": "application/json" });
            res.end(
@@ -638,6 +872,19 @@ function vitePluginPhaseZApi(): Plugin {
              );
            }
          }
+          // IMP-43 (#72) u6 — --reuse-from <PREV_RUN_ID> forward. Backend
+          // (u1) parses this flag, validates the snapshot, copies Step
+          // 0/1/2/5/6 artifacts from data/runs/<PREV_RUN_ID>/phase_z2 into
+          // the new run_dir, and resumes execution at Step 7. The post-merge
+          // guard at the same site rejects --override-layout /
+          // --override-zone-geometry / --override-section-assignment /
+          // --override-image with axis-named fail-closed exit; only
+          // --override-frame (above) is preserved. Truthy check excludes
+          // empty string + undefined so an invalid argument never reaches
+          // argparse.
+          if (reuseFromRunId && typeof reuseFromRunId === "string") {
+            cliArgs.push("--reuse-from", reuseFromRunId);
+          }
          console.log(
            `[phase-z-api] spawn pipeline: run_id=${runId}, mdx=${mdxPath}, args=${JSON.stringify(cliArgs.slice(2))}`
          );
@@ -775,6 +1022,27 @@ function vitePluginPhaseZApi(): Plugin {
        next();
      });

+      // ── POST /api/connect → cel astro public/slides mirror ──
+      // IMP-56 (#90) u18 — see handleConnectMirror docblock for body shape +
+      // copy semantics. Logic lives in the pure helper so vitest can drive
+      // it without booting vite.
+      server.middlewares.use("/api/connect", (req, res, next) => {
+        if (handleConnectMirror(req, res, DESIGN_AGENT_ROOT, CEL_PROJECT_ROOT)) return;
+        next();
+      });
+
+      // ── POST /api/export → standalone HTML download ──
+      // IMP-56 (#90) u19 — see handleExportStandalone docblock for body
+      // shape + inline-asset semantics. Logic lives in the pure helper
+      // (handleExportStandalone + inlineAssetsAsDataUrls) so vitest can
+      // drive it without booting vite. The response is raw text/html
+      // (Content-Disposition: attachment); the u20 BottomActions wiring
+      // will turn the response body into a Blob → a[download] click.
+      server.middlewares.use("/api/export", (req, res, next) => {
+        if (handleExportStandalone(req, res, DESIGN_AGENT_ROOT)) return;
+        next();
+      });
+
      // ── GET /data/runs/{run_id}/{path} →  {RUNS_DIR}/{run_id}/phase_z2/{path} ──
      server.middlewares.use("/data/runs", (req, res, next) => {
        if (req.method !== "GET") return next();
@@ -167,6 +167,42 @@ Step 0 (사전 준비) 의 Figma → HTML 변환은 *precondition phase 의 작

 ---

+## 7. Multi-MDX regression markers (IMP-91)
+
+> CI workflow `.github/workflows/multi-mdx-regression.yml` rewrites these via `scripts/update_status_board.py` after each push / PR. Initial value `?` = not yet observed. `PASS` / `FAIL` / `ERR` / `SKIP` = last CI run outcome per axis × mdx. Untouched markers remain `?` so collection failures are loud, not silent.
+
+| axis | mdx 01 | mdx 02 | mdx 03 | mdx 04 | mdx 05 |
+|---|---|---|---|---|---|
+| F0 normalize           | <!-- IMP-91:F0:01 -->?<!-- /IMP-91 --> | <!-- IMP-91:F0:02 -->?<!-- /IMP-91 --> | <!-- IMP-91:F0:03 -->?<!-- /IMP-91 --> | <!-- IMP-91:F0:04 -->?<!-- /IMP-91 --> | <!-- IMP-91:F0:05 -->?<!-- /IMP-91 --> |
+| F1 V4 ranking          | <!-- IMP-91:F1:01 -->?<!-- /IMP-91 --> | <!-- IMP-91:F1:02 -->?<!-- /IMP-91 --> | <!-- IMP-91:F1:03 -->?<!-- /IMP-91 --> | <!-- IMP-91:F1:04 -->?<!-- /IMP-91 --> | <!-- IMP-91:F1:05 -->?<!-- /IMP-91 --> |
+| F2 slot_payload        | <!-- IMP-91:F2:01 -->?<!-- /IMP-91 --> | <!-- IMP-91:F2:02 -->?<!-- /IMP-91 --> | <!-- IMP-91:F2:03 -->?<!-- /IMP-91 --> | <!-- IMP-91:F2:04 -->?<!-- /IMP-91 --> | <!-- IMP-91:F2:05 -->?<!-- /IMP-91 --> |
+| F3 classifier-only AI  | <!-- IMP-91:F3:01 -->?<!-- /IMP-91 --> | <!-- IMP-91:F3:02 -->?<!-- /IMP-91 --> | <!-- IMP-91:F3:03 -->?<!-- /IMP-91 --> | <!-- IMP-91:F3:04 -->?<!-- /IMP-91 --> | <!-- IMP-91:F3:05 -->?<!-- /IMP-91 --> |
+| F4 layout              | <!-- IMP-91:F4:01 -->?<!-- /IMP-91 --> | <!-- IMP-91:F4:02 -->?<!-- /IMP-91 --> | <!-- IMP-91:F4:03 -->?<!-- /IMP-91 --> | <!-- IMP-91:F4:04 -->?<!-- /IMP-91 --> | <!-- IMP-91:F4:05 -->?<!-- /IMP-91 --> |
+| F5 final.html          | <!-- IMP-91:F5:01 -->?<!-- /IMP-91 --> | <!-- IMP-91:F5:02 -->?<!-- /IMP-91 --> | <!-- IMP-91:F5:03 -->?<!-- /IMP-91 --> | <!-- IMP-91:F5:04 -->?<!-- /IMP-91 --> | <!-- IMP-91:F5:05 -->?<!-- /IMP-91 --> |
+
+---
+
+## 8. IMP-43 (#72) `--reuse-from` measured savings
+
+> Stage 2 §u8 binding contract: the issue-body 50–70% / 10–20s → 3–8s claim is **unverified** and is **not** mirrored here. Numbers below come from `scripts/measure_reuse_savings.py` on the project reference host; until that script is run and the values committed, every cell stays `TBD`.
+
+| axis | value |
+|---|---|
+| measurement script | `scripts/measure_reuse_savings.py` |
+| reuse boundary (Stage 1 lock) | Step 0 / 1 / 2 / 5 / 6 only; Step 7+ re-executes |
+| full rerun seconds (p50) | TBD |
+| full rerun seconds (p95) | TBD |
+| reuse seconds (p50) | TBD |
+| reuse seconds (p95) | TBD |
+| reuse / full ratio (p50) | TBD |
+| last measured | TBD (date / host / mdx / iterations) |
+
+Run protocol (per iteration): `(A)` seed → `(B)` full rerun with one self-discovered `--override-frame` pin → `(C)` `--reuse-from <seed>` with the same pin. The `(A)` seed time is reported separately and **not** included in the B-vs-C comparison — the reuse path's whole point is that the seed already exists from a prior interactive run.
+
+Invocation: `python -m scripts.measure_reuse_savings samples/mdx_batch/02.mdx --iterations 5` (mdx is argv-driven; the script does not pin a sample internally).
+
+---
+
 ## 사용 방법

 - 새 작업 들어오면 → 본 board 의 *어느 step* 의 status 를 바꾸는 작업인지 식별
@@ -1009,6 +1009,9 @@ def build_context_pack(n, title, body, sid, agent, rnd, start_cnt, compact=None)
    # 검증 실패 보고서 (rewind 시 이전 실패 맥락 전달).
    # 2026-05-16 — issue state 의 failure_report_path 를 source-of-truth 로.
    # 모든 stage NO (test-verify/final-close 뿐 아니라 code-edit 등) 의 from_stage 캐치.
+    # P7 (2026-05-26) — banned approaches injection (Codex CLI helper consensus).
+    #   failure_report 본문에서 known anti-pattern keyword 추출 → BANNED_APPROACHES block 생성
+    #   → 다음 round prompt 에 strong-marker 로 inject. 동일 방식 재제안 방지 (#84 round loop).
    failure_ctx = ""
    ist_fc = get_issue_state(n)
    fr_path_str = ist_fc.get("failure_report_path")
@@ -1016,9 +1019,42 @@ def build_context_pack(n, title, body, sid, agent, rnd, start_cnt, compact=None)
        fail_path = Path(fr_path_str)
        if fail_path.exists():
            from_sid = ist_fc.get("failure_from_stage", "?")
+            fail_body = fail_path.read_text(encoding='utf-8')
+            # P7 — extract banned approach signals (deterministic keyword scan).
+            #   각 entry: (regex, label, why). escape_hatch 는 future patch 의 JSON 구조 에서 형식화.
+            #   현재 단계 = prompt-injection 만 (Codex 단계화 안의 "즉시 patch" layer).
+            banned_signals = [
+                (r"tests:\s*\[\s*\]",
+                 "tests: [] empty test list per implementation unit",
+                 "Orchestrator strict rule — 1 unit = impl + test inseparable. NOT allowed to defer tests to later units."),
+                (r"@testing-library|jsdom|render\s*\(|screen\.",
+                 "DOM mount-based vitest (render() / screen / @testing-library)",
+                 "Front/package.json devDependencies has no jsdom / @testing-library/react. Mount-based tests cannot run."),
+                (r"toast\.error\s*\(\s*formatAiRepairHumanReviewMessage",
+                 "Home.tsx formatAiRepairHumanReviewMessage toast.error removal",
+                 "Post-#92 commit 896f273 rewrote the formatter to operational-only channel. Removing toast call = operational alert regression."),
+                (r"git\s+add\s+(-A|--all|\.)\b",
+                 "git add -A / git add . / git add --all",
+                 "Untracked artifact pollution risk. Stage 5 must add only files in unit's declared `files:` list explicitly."),
+            ]
+            hits = []
+            for pat, label, why in banned_signals:
+                if re.search(pat, fail_body, re.IGNORECASE):
+                    hits.append((label, why))
+            banned_block = ""
+            if hits:
+                banned_block = "\n=== BANNED APPROACHES (previously rejected — DO NOT REUSE) ===\n"
+                for i, (label, why) in enumerate(hits, 1):
+                    banned_block += f"{i}. {label}\n   reason: {why}\n"
+                banned_block += (
+                    "BINDING: re-proposing any banned approach above = automatic FINAL_CONSENSUS: NO. "
+                    "If environment/preconditions changed (e.g., new package install), state the EVIDENCE "
+                    "of the change BEFORE re-proposal.\n"
+                )
            failure_ctx = (
                f"\n\n=== REWIND: FAILURE REPORT (from {from_sid}) ===\n"
-                f"{fail_path.read_text(encoding='utf-8')[:1500]}\n"
+                f"{fail_body[:1500]}\n"
+                f"{banned_block}"
                f"Fix the issues above before re-attempting.\n"
            )

@@ -1447,10 +1483,22 @@ def run_stage(n, title, body, sid):
                            return (False, "unit with `tests: []` (forbidden — implementation + tests = same unit)")
                        return (True, "")
                    ok, reason = _iu_valid(last)
-                    if not ok:
-                        # current stage 의 comments 만 검색 (start_cnt 이후)
+                    # P7 (2026-05-26) — fallback skip when last YES body itself is invalid.
+                    # 이전: last invalid → comments[start_cnt:] 에서 valid block 찾아 구제 →
+                    # orchestrator 자기 supplement comment 의 Example block 이 valid 로 통과 (#84 round 5 슬립).
+                    # 변경: last 가 진짜 invalid 면 fallback 자체 skip. 단 last 의 _iu_valid 실패가
+                    # "block missing" 인 경우만 (Codex 가 YAML block 을 안 echo 한 경우) 이전 round 의
+                    # Claude plan 으로 fallback — 단 orchestrator-authored supplement 는 제외.
+                    if not ok and reason == "block missing":
                        for c in comments[start_cnt:]:
-                            ok2, _ = _iu_valid(c.get("body", ""))
+                            body = c.get("body", "") or ""
+                            # exclude orchestrator-authored supplement comments (own example block trap)
+                            ls = body.lstrip()
+                            if ls.startswith("⚠️ **[Orchestrator]**") or \
+                               ls.startswith("📌 **[오케스트레이터]**") or \
+                               ls.startswith("ℹ️ **[Orchestrator]**"):
+                                continue
+                            ok2, _ = _iu_valid(body)
                            if ok2:
                                ok = True; break
                    if not ok:
@@ -1548,6 +1596,45 @@ def run_stage(n, title, body, sid):
                        except: pass
                    # Never `continue` — checker is informational only (Stage 1 guardrail).

+                # P7 (2026-05-26) — final-close YES casual self-contradiction inline guard.
+                # parse_consensus 는 건드리지 않음 (다른 caller 영향 차단). YES 처리 block 안에서
+                # sid == "final-close" 인 경우만 casual contradiction 검사.
+                #
+                # 설계 의도 분기 (Patch B 와 분담) :
+                #   - explicit `disposition: KEEP_OPEN_*` line 이 있으면 = 의도된 keep-open
+                #     → 이 guard 통과 → Patch B (close PATCH skip) 가 처리.
+                #   - explicit disposition line 없이 "NO close signal" 또는 "DO NOT CLOSE"
+                #     casual 표현 만 있으면 = self-contradiction → supplement + continue.
+                #
+                # cf. #83 IMP-83 case = YES + explicit `disposition: KEEP_OPEN_AS_UMBRELLA_ANCHOR`
+                #     → 통과 (Patch B 가 close skip).
+                if sid == "final-close":
+                    has_explicit_disposition = bool(re.search(
+                        r"^\s*disposition\s*:\s*KEEP_OPEN",
+                        last, re.IGNORECASE | re.MULTILINE))
+                    if not has_explicit_disposition:
+                        casual_contradiction_patterns = [
+                            (r"NO\s+close\s+signal", "NO close signal"),
+                            (r"DO\s*NOT\s*CLOSE", "DO NOT CLOSE"),
+                        ]
+                        hit = None
+                        for p, label in casual_contradiction_patterns:
+                            if re.search(p, last, re.IGNORECASE):
+                                hit = label; break
+                        if hit:
+                            log(f"⚠️ Stage 6 YES casual self-contradiction ({hit}) — supplement requested")
+                            try: gitea(f"issues/{n}/comments", "POST", {"body":
+                                f"⚠️ **[Orchestrator]** Stage 6 FINAL_CONSENSUS: YES rejected — casual self-contradiction.\n\n"
+                                f"YES marker 와 동시에 본문에 `{hit}` 등장 — 명시적 `disposition:` line 없음.\n\n"
+                                "Resolution:\n"
+                                "  (a) If close intended → remove `{hit}` and re-state YES with close evidence.\n"
+                                "  (b) If keep-open intended → add explicit line:\n"
+                                "      `disposition: KEEP_OPEN_AS_UMBRELLA_ANCHOR` (or similar)\n"
+                                "      then orchestrator will honor keep-open at close PATCH (Patch B).\n"
+                                "  (c) Or switch to `FINAL_CONSENSUS: NO` with appropriate rewind_target."})
+                            except: pass
+                            continue
+
                log(f"✅ {si['label']} — YES (evidence verified)")
                # stage 완료 = unit counter + remaining tracker 모두 reset
                update_issue_state(n, continue_same_count=0, last_remaining_units=None)
@@ -1765,8 +1852,49 @@ def run_issue(n, until=None):
                           continue_same_count=0, last_remaining_units=None)

        if s["id"] == "final-close":
-            try: gitea(f"issues/{n}", "PATCH", {"state": "closed"}); log("Closed")
-            except: pass
+            # P7 (2026-05-26) — KEEP_OPEN guard. Stage 6 exit body / last YES body 가 명시적
+            # keep-open / no-close 신호 내면 close PATCH skip. body-level lock 이 있는 umbrella
+            # anchor (#83 IMP-83 등) 보호 — Stage 6 성공 = "올바른 disposition 확정" 이며,
+            # 그 disposition 이 KEEP_OPEN 일 수 있음.
+            keep_open_patterns = [
+                r"KEEP_OPEN_AS_UMBRELLA_ANCHOR",
+                r"DO\s*NOT\s*CLOSE",
+                r"disposition\s*:\s*KEEP_OPEN",
+                r"^\s*action\s*:\s*NONE",
+                r"^\s*state_after\s*:\s*open",
+                r"NO\s+close\s+signal",
+            ]
+            keep_open = False
+            # P7a (2026-05-26) — fetch comments fresh; `comments` is loop-local in stage block
+            # and not in scope at run_issue post-stage update. NameError fix.
+            try:
+                _cs = get_comments(n)
+                last_body = _cs[-1].get("body", "") if _cs else ""
+            except: last_body = ""
+            for p in keep_open_patterns:
+                if re.search(p, last_body, re.IGNORECASE | re.MULTILINE):
+                    keep_open = True; break
+            if not keep_open:
+                exit_path = _erp(n, "final-close")
+                if exit_path.exists():
+                    try:
+                        exit_body = exit_path.read_text(encoding="utf-8", errors="ignore")
+                        for p in keep_open_patterns:
+                            if re.search(p, exit_body, re.IGNORECASE | re.MULTILINE):
+                                keep_open = True; break
+                    except: pass
+            if keep_open:
+                log(f"Stage 6 KEEP_OPEN signal — issue #{n} NOT closed (umbrella/governance anchor honored)")
+                try: gitea(f"issues/{n}/comments", "POST", {"body":
+                    "ℹ️ **[Orchestrator]** Stage 6 KEEP_OPEN signal honored — issue not closed.\n\n"
+                    "Detected one of: `KEEP_OPEN_AS_UMBRELLA_ANCHOR`, `DO NOT CLOSE`, "
+                    "`disposition: KEEP_OPEN`, `action: NONE`, `state_after: open`, `NO close signal`.\n\n"
+                    "Orchestrator abstains from `PATCH state=closed` per user-decision-first lock. "
+                    "Final-close stage marked done; issue state preserved as `open`."})
+                except: pass
+            else:
+                try: gitea(f"issues/{n}", "PATCH", {"state": "closed"}); log("Closed")
+                except: pass

        i += 1

@@ -22,6 +22,7 @@ dependencies = [
 dev = [
    "pytest>=8.0",
    "pytest-asyncio>=0.24",
+    "pytest-json-report>=1.5",
    "ruff>=0.8",
 ]

@@ -33,4 +34,5 @@ target-version = "py310"
 asyncio_mode = "auto"
 markers = [
    "integration: end-to-end pipeline integration tests (heavy; invoke Selenium)",
+    "sweep: opt-in heavyweight sweep tests (IMP-43 u7b: 3 layouts × 3 mdx × frame-pin coverage). Invoke explicitly via `pytest -m sweep`; default CI must use `-m 'not sweep'`.",
 ]
@@ -2,6 +2,17 @@
 title: DX 지연 요인
 sidebar:
  order: 03
+slide_overrides:
+  css: |
+    .slide-body {
+      grid-template-rows: 0.38fr 0.60fr !important;
+      gap: 1.5% !important;
+    }
+    .f29b__cell .text-line + .text-line { margin-top: 1px !important; }
+    .f29b__cell:nth-child(n+3) {
+      padding-top: 3px !important;
+      margin-top: 2px !important;
+    }
 ---

 ## 1. DX에 대한 인식
@@ -0,0 +1,178 @@
+"""IMP-43 (#72) u8 — measure ``--reuse-from`` wall-clock savings.
+
+Argv-driven measurement helper for the Stage 2 §u8 binding contract:
+re-derive a realistic savings target instead of mirroring the
+unverified issue-body 50–70% / 10–20s → 3–8s claim.
+
+Per-iteration measurement protocol (mirrors the u7a equivalence
+harness, ``tests/test_phase_z2_reuse_from_equivalence_unit.py``):
+
+  (A) baseline   full run, no overrides              — reuse seed
+  (B) full rerun full run + one --override-frame pin — control path
+  (C) reuse      --reuse-from <seed> + same pin      — reuse path
+
+Wall-clock = ``time.perf_counter()`` around the subprocess.run call.
+The (A) seed run time is reported separately and NOT included in the
+B-vs-C comparison (the reuse path's whole point is that the seed
+already exists from a prior interactive run).
+
+For each iteration the frame pin is self-discovered from the seed
+run's ``step06_composition_plan.json``: the first unit's
+``frame_template_id`` is re-pinned to itself, exercising the
+``--override-frame`` CLI surface end-to-end without changing the
+semantic frame assignment (same approach the u7a/u7b equivalence
+tests already lock).
+
+Output: a JSON document to stdout with per-iteration timings,
+B/C p50 + p95, and the ratio C/B. Stderr carries the subprocess
+stdout/stderr tails on non-zero exits.
+
+Guardrails (Stage 2):
+  * argv-driven, no hardcoded mdx — caller picks the sample
+  * no hardcoded savings target — TBD until measured
+  * value + path + upstream provenance lives in the printed JSON
+  * does NOT mutate prev_run_dir; new runs land under fresh run_ids
+"""
+from __future__ import annotations
+
+import argparse
+import json
+import statistics
+import subprocess
+import sys
+import time
+import uuid
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+RUNS_DIR = REPO_ROOT / "data" / "runs"
+
+
+def _unique_run_id(prefix: str) -> str:
+    return f"{prefix}_imp43_u8_{uuid.uuid4().hex[:8]}"
+
+
+def _spawn(extra_args: list[str], timeout: int) -> tuple[subprocess.CompletedProcess, float]:
+    start = time.perf_counter()
+    cp = subprocess.run(
+        [sys.executable, "-m", "src.phase_z2_pipeline", *extra_args],
+        capture_output=True,
+        text=True,
+        timeout=timeout,
+        cwd=str(REPO_ROOT),
+    )
+    return cp, time.perf_counter() - start
+
+
+def _assert_ok(label: str, cp: subprocess.CompletedProcess) -> None:
+    if cp.returncode != 0:
+        sys.stderr.write(
+            f"[measure_reuse_savings] {label} failed rc={cp.returncode}\n"
+            f"--- stderr tail ---\n{cp.stderr[-2000:]}\n"
+            f"--- stdout tail ---\n{cp.stdout[-2000:]}\n"
+        )
+        raise SystemExit(2)
+
+
+def _discover_first_frame_pin(seed_run_id: str) -> tuple[str, str]:
+    p = RUNS_DIR / seed_run_id / "phase_z2" / "steps" / "step06_composition_plan.json"
+    payload = json.loads(p.read_text(encoding="utf-8"))
+    for u in payload.get("data", {}).get("selected_units") or []:
+        sids = u.get("source_section_ids") or []
+        tpl = u.get("frame_template_id")
+        if isinstance(sids, list) and sids and isinstance(tpl, str) and tpl:
+            return ("+".join(str(s) for s in sids), tpl)
+    raise SystemExit(
+        f"[measure_reuse_savings] seed {seed_run_id} step06 has no pinnable "
+        f"(unit_id, frame_template_id); path={p}"
+    )
+
+
+def _percentile(values: list[float], pct: float) -> float:
+    if not values:
+        return float("nan")
+    if len(values) == 1:
+        return values[0]
+    s = sorted(values)
+    k = (len(s) - 1) * pct
+    lo = int(k)
+    hi = min(lo + 1, len(s) - 1)
+    return s[lo] + (s[hi] - s[lo]) * (k - lo)
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser(
+        prog="python -m scripts.measure_reuse_savings",
+        description="Measure IMP-43 --reuse-from wall-clock savings.",
+    )
+    ap.add_argument("mdx_path", type=Path, help="MDX sample to measure against")
+    ap.add_argument("--iterations", type=int, default=3, help="trials (default 3)")
+    ap.add_argument("--timeout", type=int, default=900, help="per-run timeout seconds")
+    args = ap.parse_args()
+
+    if not args.mdx_path.is_file():
+        sys.stderr.write(f"[measure_reuse_savings] mdx not found: {args.mdx_path}\n")
+        return 2
+
+    iterations: list[dict] = []
+    for i in range(args.iterations):
+        seed_id = _unique_run_id(f"seed{i}")
+        cp_a, t_a = _spawn([str(args.mdx_path), seed_id], args.timeout)
+        _assert_ok(f"(A) seed iter={i}", cp_a)
+
+        unit_id, tpl_id = _discover_first_frame_pin(seed_id)
+        override = ["--override-frame", f"{unit_id}={tpl_id}"]
+
+        full_id = _unique_run_id(f"full{i}")
+        cp_b, t_b = _spawn([str(args.mdx_path), full_id, *override], args.timeout)
+        _assert_ok(f"(B) full rerun iter={i}", cp_b)
+
+        reuse_id = _unique_run_id(f"reuse{i}")
+        cp_c, t_c = _spawn(
+            [str(args.mdx_path), reuse_id, "--reuse-from", seed_id, *override],
+            args.timeout,
+        )
+        _assert_ok(f"(C) reuse iter={i}", cp_c)
+
+        iterations.append({
+            "iter": i,
+            "seed_run_id": seed_id,
+            "full_run_id": full_id,
+            "reuse_run_id": reuse_id,
+            "override_frame": f"{unit_id}={tpl_id}",
+            "seed_seconds": t_a,
+            "full_rerun_seconds": t_b,
+            "reuse_seconds": t_c,
+        })
+
+    full_times = [it["full_rerun_seconds"] for it in iterations]
+    reuse_times = [it["reuse_seconds"] for it in iterations]
+
+    summary = {
+        "mdx_path": str(args.mdx_path),
+        "iterations_count": len(iterations),
+        "full_rerun_seconds_p50": _percentile(full_times, 0.50),
+        "full_rerun_seconds_p95": _percentile(full_times, 0.95),
+        "reuse_seconds_p50": _percentile(reuse_times, 0.50),
+        "reuse_seconds_p95": _percentile(reuse_times, 0.95),
+        "reuse_over_full_ratio_p50": (
+            _percentile(reuse_times, 0.50) / _percentile(full_times, 0.50)
+            if full_times and statistics.median(full_times) > 0
+            else float("nan")
+        ),
+        "iterations": iterations,
+        "note": (
+            "IMP-43 (#72) u8 measurement. Issue-body 50–70% / 10–20s → 3–8s "
+            "claim is NOT honored here — actual numbers depend on host, "
+            "Selenium cold-start, and AI cache state. Update "
+            "docs/architecture/PHASE-Z-PIPELINE-STATUS-BOARD.md §8 with the "
+            "p50/p95 reported here when run on the project's reference host."
+        ),
+    }
+    sys.stdout.write(json.dumps(summary, ensure_ascii=False, indent=2))
+    sys.stdout.write("\n")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
@@ -0,0 +1,75 @@
+"""IMP-#91 u14 — idempotent status-board marker updater.
+
+Reads a pytest-json-report artifact emitted by the IMP-91 CI workflow and
+rewrites paired ``<!-- IMP-91:<axis>:<mdx> -->...<!-- /IMP-91 -->`` markers
+inside the Phase Z status board with a single-character outcome symbol.
+
+Pure functions (``parse_outcomes`` / ``update_board_text``) are exposed so
+``tests/scripts/test_update_status_board.py`` can exercise the contract
+without invoking pytest. The CLI just wires file IO around them so the
+GitHub Actions step in u15 can call it deterministically. The updater is
+additive: untouched markers stay; missing outcomes render ``?`` so a
+collection failure is loud, not silent. [[feedback_auto_pipeline_first]]
+[[feedback_artifact_status_naming]]
+"""
+from __future__ import annotations
+
+import argparse
+import json
+import re
+from pathlib import Path
+from typing import Dict, Mapping, Tuple
+
+AXIS_FROM_TEST = {
+    "test_normalize_snapshot_matches": "F0",
+    "test_v4_ranking_snapshot_matches": "F1",
+    "test_slot_payload_snapshot_matches": "F2",
+    "test_ai_classifier_snapshot_matches": "F3",
+    "test_layout_snapshot_matches": "F4",
+    "test_final_html_snapshot_matches": "F5",
+}
+SYMBOL = {"passed": "PASS", "failed": "FAIL", "error": "ERR", "skipped": "SKIP"}
+NODEID_RE = re.compile(r"::(test_[a-z0-9_]+)\[(\d{2})\]$")
+MARKER_RE = re.compile(
+    r"(<!-- IMP-91:(F[0-5]):(\d{2}) -->)(.*?)(<!-- /IMP-91 -->)", re.DOTALL
+)
+
+
+def parse_outcomes(report: Mapping[str, object]) -> Dict[Tuple[str, str], str]:
+    out: Dict[Tuple[str, str], str] = {}
+    for test in report.get("tests", []) or []:
+        m = NODEID_RE.search(str(test.get("nodeid", "")))
+        if not m:
+            continue
+        axis = AXIS_FROM_TEST.get(m.group(1))
+        if not axis:
+            continue
+        out[(axis, m.group(2))] = SYMBOL.get(str(test.get("outcome")), "?")
+    return out
+
+
+def update_board_text(board: str, outcomes: Mapping[Tuple[str, str], str]) -> str:
+    def repl(match: "re.Match[str]") -> str:
+        key = (match.group(2), match.group(3))
+        symbol = outcomes.get(key, "?")
+        return f"{match.group(1)}{symbol}{match.group(5)}"
+
+    return MARKER_RE.sub(repl, board)
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description="IMP-91 status-board updater")
+    parser.add_argument("--report", required=True, type=Path)
+    parser.add_argument("--board", required=True, type=Path)
+    args = parser.parse_args()
+    report = json.loads(args.report.read_text(encoding="utf-8"))
+    outcomes = parse_outcomes(report)
+    args.board.write_text(
+        update_board_text(args.board.read_text(encoding="utf-8"), outcomes),
+        encoding="utf-8",
+    )
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
@@ -392,6 +392,32 @@ def _clean_text(text: str) -> str:
 # 메인 함수
 # ══════════════════════════════════════

+def _extract_slide_overrides(metadata: dict[str, Any]) -> dict[str, Any]:
+    """Surface the nested ``slide_overrides`` mapping from frontmatter.
+
+    IMP-45 (#74) u2 — slide-level CSS override axis intake. Returns a
+    plain ``dict`` so callers (Step 13 injector) can read
+    ``slide_overrides.get("css")`` without re-parsing frontmatter.
+
+    Rules:
+    - Absent or non-mapping → ``{}``.
+    - Inside the mapping, ``css`` is kept only when it is a ``str``
+      (non-string values dropped to fail-closed against typo'd YAML
+      shapes such as ``css: [".x{}"]``).
+    - Unknown sibling keys (e.g., future ``slide_overrides.js``) are
+      preserved verbatim — generalization deferred per Stage 2 scope.
+    """
+    raw = metadata.get("slide_overrides")
+    if not isinstance(raw, dict):
+        return {}
+    out: dict[str, Any] = {}
+    for k, v in raw.items():
+        if k == "css" and not isinstance(v, str):
+            continue
+        out[k] = v
+    return out
+
+
 def normalize_mdx_content(raw_mdx: str) -> dict[str, Any]:
    """MDX 원본을 4-Layer 파서로 정규화.

@@ -405,11 +431,13 @@ def normalize_mdx_content(raw_mdx: str) -> dict[str, Any]:
            "popups": [{"title": str, "content": str}],
            "tables": [{"headers": list, "rows": list}],
            "sections": [{"level": int, "title": str, "content": str}],
+            "slide_overrides": {"css": str, ...} | {},
        }
    """
    # ── Layer 1: frontmatter 분리 ──
    metadata, body = frontmatter.parse(raw_mdx)
    title = metadata.get("title", "")
+    slide_overrides = _extract_slide_overrides(metadata)
    logger.info(f"[Layer 1] title='{title}', metadata keys={list(metadata.keys())}")

    # ── Layer 2: 코드블록 보호 → MDX 패턴 처리 ──
@@ -437,6 +465,7 @@ def normalize_mdx_content(raw_mdx: str) -> dict[str, Any]:
        "popups": popups,
        "tables": tables,
        "sections": sections,
+        "slide_overrides": slide_overrides,
    }


@@ -27,7 +27,9 @@ glue_compression           (SPACING_GLUE envelope, frame-scoped)
  ↓ 그래도 안 되면
 font_step_compression      (FONT_SIZE_STEPS, zone-scoped)
  ↓ 그래도 안 되면
-layout_adjust              (zone topology 변경)
+layout_adjust              (zone topology 변경 — 8-preset switch)
+  ↓ 그래도 안 되면
+frame_internal_fit_candidate (frame contract envelope 안 internal fit 변형)
  ↓ 그래도 안 되면
 frame_reselect             (V4 top-k 의 다른 frame)
  ↓ 그래도 안 되면
@@ -40,6 +42,33 @@ IMP-35 (#64) u2 — cascade terminal landed. `frame_reselect_insufficient`
 MISSING here; the actual executor stub + MISSING→IMPLEMENTED flip lives in
 `src/phase_z2_router.py` (u3 surface), so this module advertises the cascade
 terminal without claiming an implementation it does not own.
+
+IMP-88 (#88) u2 — Step 17 retry chain extension. Three new failure_type
+producers + cascade rows wire the three issue-body axes onto the deterministic
+chain WITHOUT activating any AI path or shared-margin shrink:
+
+  | failure_type                                  | next_proposed_action          |
+  |---|---|
+  | layout_adjust_insufficient                    | frame_internal_fit_candidate  |
+  | frame_internal_fit_candidate_insufficient     | frame_reselect                |
+  | image_fit_insufficient                        | layout_adjust                 |
+
+`layout_adjust_insufficient` is the cascade extension between
+`font_step_insufficient → layout_adjust` (existing) and the legacy
+`rerender_still_fails → frame_reselect` rejoin point — closing the open
+cascade tail that previously terminated salvage at `layout_adjust` with no
+next-step record.  `frame_internal_fit_candidate_insufficient` rejoins the
+existing `frame_reselect` mid-cascade, so V4 top-k swap remains reachable
+after the in-envelope salvage exhausts.  `image_fit_insufficient` (Step 17
+single-pass entry per u7) escalates onto the main cascade at `layout_adjust`
+so an image-driven overflow that cannot be fit inside the frame envelope
+benefits from layout topology change instead of any margin shrink
+(feedback_phase_z_spacing_direction guardrail).
+
+The three new `next_action` destinations (`layout_adjust`,
+`frame_internal_fit_candidate`, `image_fit`) are advertised as MISSING here.
+The MISSING → IMPLEMENTED flip lives on the deterministic planner units
+(u3/u4/u5) in `src/phase_z2_retry.py`; this module owns mapping only.
 """

 from __future__ import annotations
@@ -85,6 +114,28 @@ FAILURE_TYPE_DESCRIPTIONS: dict[str, str] = {
        "'frame_reselect' AND passed=False AND post_salvage_overflow present. "
        "Routes to details_popup_escalation in u2 (cascade terminal)."
    ),
+    # IMP-88 (#88) u2 — three new salvage failure producers wired onto the
+    # deterministic cascade. Classifier reuses the salvage_steps[-1] path
+    # introduced in IMP-12 u2 (SALVAGE_FAILURE_TYPE_BY_ACTION).
+    "layout_adjust_insufficient": (
+        "layout_adjust salvage step failed — 8-preset layout switch executed "
+        "but overflow persists post-rerender. Cascade exits onto "
+        "frame_internal_fit_candidate (frame envelope internal fit variant) "
+        "before V4 top-k frame_reselect."
+    ),
+    "frame_internal_fit_candidate_insufficient": (
+        "frame_internal_fit_candidate salvage step failed — variant adjustments "
+        "inside the declared frame contract envelope could not absorb the "
+        "remaining overflow. Cascade exits onto frame_reselect (V4 top-k "
+        "alternate frame swap)."
+    ),
+    "image_fit_insufficient": (
+        "image_fit salvage step failed — Step 17 single-pass image fit "
+        "(object-fit + max-w/h scoped to the offending frame) did not resolve "
+        "image_aspect_mismatch. Escalates onto the main cascade at "
+        "layout_adjust so a different layout topology can host the image "
+        "natural ratio (no shared margin shrink — Phase Z spacing direction)."
+    ),
 }


@@ -103,6 +154,17 @@ SALVAGE_FAILURE_TYPE_BY_ACTION: dict[str, str] = {
    # frame's HTML. classifier reads that entry; u2 adds the NEXT_ACTION row
    # that routes this onto details_popup_escalation.
    "frame_reselect":          "frame_reselect_insufficient",
+    # IMP-88 (#88) u2: producers for the three Step 17 retry chain actions
+    # (layout_adjust / image_fit / frame_internal_fit_candidate). The u6
+    # dispatcher (src/phase_z2_pipeline.py) appends salvage_steps entries with
+    # these action names when their planner-driven executor (u3/u4/u5) emits
+    # passed=False. The classifier path below already inspects
+    # salvage_steps[-1].action so no classifier change is required; u3 just
+    # registers the producer rows so the cascade keeps flowing instead of
+    # falling through to the defensive "not_attempted" fallback.
+    "layout_adjust":                "layout_adjust_insufficient",
+    "image_fit":                    "image_fit_insufficient",
+    "frame_internal_fit_candidate": "frame_internal_fit_candidate_insufficient",
 }


@@ -124,6 +186,15 @@ NEXT_ACTION_BY_FAILURE: dict[str, str] = {
    # only.
    "frame_reselect_insufficient":          "details_popup_escalation",
    "not_attempted":                        "none",
+    # IMP-88 (#88) u2 — Step 17 retry chain cascade extension. Closes the
+    # previously open tail at layout_adjust + adds the frame_internal_fit
+    # mid-cascade rejoin onto frame_reselect. image_fit (single-pass entry,
+    # u7) escalates onto layout_adjust when its single-pass transform cannot
+    # resolve image_aspect_mismatch — Phase Z spacing direction guardrail
+    # routes through layout/frame instead of shrinking shared margins.
+    "layout_adjust_insufficient":              "frame_internal_fit_candidate",
+    "frame_internal_fit_candidate_insufficient": "frame_reselect",
+    "image_fit_insufficient":                  "layout_adjust",
 }

 NEXT_ACTION_RATIONALE: dict[str, str] = {
@@ -161,6 +232,22 @@ NEXT_ACTION_RATIONALE: dict[str, str] = {
    "not_attempted": (
        "retry 시도 자체가 없었음 (visual ok 등) — escalation 불필요"
    ),
+    # IMP-88 (#88) u2 — Step 17 retry chain cascade rationale entries
+    "layout_adjust_insufficient": (
+        "layout_adjust salvage (8-preset switch) 후에도 overflow 잔존 → "
+        "frame_internal_fit_candidate 로 frame contract envelope 안 internal "
+        "fit 변형 시도. frame_reselect (V4 top-k 다른 frame) 는 cascade 다음 단계."
+    ),
+    "frame_internal_fit_candidate_insufficient": (
+        "frame contract envelope 안 internal fit 변형 (density / line rhythm) "
+        "도 overflow 못 흡수 → frame_reselect (V4 top-k 다른 frame) 로 escalate. "
+        "popup 직행은 frame_reselect 까지 소진 후 (cascade terminal)."
+    ),
+    "image_fit_insufficient": (
+        "image_fit Step 17 single-pass (object-fit / max-w/h frame-scoped) 가 "
+        "image_aspect_mismatch 못 해결 → layout_adjust 로 main cascade 진입. "
+        "공통 image CSS / 공통 spacing 축소 X (Phase Z spacing direction)."
+    ),
 }

 # 본 매핑이 가리키는 next action 들의 *현재 코드* 구현 상태
@@ -174,7 +261,13 @@ NEXT_ACTION_IMPLEMENTATION_STATUS: dict[str, str] = {
    "cross_zone_redistribute": "IMPLEMENTED",  # u4 plan_cross_zone_redistribute + apply_cross_zone_redistribute_css
    "glue_compression":        "IMPLEMENTED",  # u5 plan_glue_compression + apply_glue_compression_css
    "font_step_compression":   "IMPLEMENTED",  # u6 plan_font_step_compression + apply_font_step_compression_css
-    "layout_adjust":           "MISSING",
+    # IMP-88 (#88) u1→u7 (2026-05-24): layout_adjust flips here on the
+    # failure-router surface alongside the primary router surface. The
+    # cascade entry chains font_step_insufficient → layout_adjust and
+    # image_fit_insufficient → layout_adjust both reach this destination,
+    # which is now wired end-to-end via u3 (plan_layout_adjust) + u6
+    # (salvage dispatcher branch) + u7 (cascade entry trigger).
+    "layout_adjust":           "IMPLEMENTED",
    "frame_reselect":          "MISSING",
    # IMP-35 (#64) u2 — cascade terminal advertised as MISSING here. The
    # router executor stub + MISSING→IMPLEMENTED flip lives in
@@ -182,6 +275,18 @@ NEXT_ACTION_IMPLEMENTATION_STATUS: dict[str, str] = {
    # lands prevents premature "popup ready" claims from the failure-router
    # surface.
    "details_popup_escalation": "MISSING",
+    # IMP-88 (#88) u1→u7 (2026-05-24): Step 17 retry chain destinations
+    # flipped to IMPLEMENTED. frame_internal_fit_candidate is a cascade
+    # destination (layout_adjust_insufficient → frame_internal_fit_candidate)
+    # wired via u5 planner + u6 dispatcher branch + u7 cascade entry.
+    # image_fit is a Step 17 single-pass entry wired via u4 planner +
+    # u7 _attempt_step17_image_fit_single_pass; it also surfaces here so
+    # route_retry_failure never returns 'unknown' when image_fit_insufficient
+    # cascades onto layout_adjust. (Same precedent as IMP-12 u7 cascade
+    # actions above — planner-surface availability + orchestrator wiring
+    # together constitute IMPLEMENTED on the deterministic surface.)
+    "frame_internal_fit_candidate": "IMPLEMENTED",
+    "image_fit":                    "IMPLEMENTED",
    "none":                    "n/a",
 }

@@ -579,12 +579,23 @@ def _build_compare_table_2col(section, units, contract) -> dict:

    builder_options :
      item_parser                  : ITEM_PARSERS key (예: `compare_row_2col_item`)
-      col_a_label_default          : col_a header (MDX 미명시 시 fallback. F1-a fix)
-      col_b_label_default          : col_b header (MDX 미명시 시 fallback)
+      col_a_label_default          : col_a header literal in catalog.
+                                     Semantics depend on col_a_label_default_role.
+      col_a_label_default_role     : "placeholder" | "fallback" (IMP-40 #69).
+                                     placeholder = Figma visual placeholder; suppressed
+                                       at runtime → col_a_label emitted as "".
+                                     fallback    = MDX 미명시 시 catalog literal 사용.
+                                     absent      = legacy contracts default to fallback.
+      col_b_label_default          : col_b header literal (same policy as col_a).
+      col_b_label_default_role     : same role discriminator for col_b (IMP-40 #69).
      strip_col_prefix_aliases     : list[str] — col_a/col_b 값의 prefix `<alias>:`
                                     를 strip (Codex round 43 §F1-b — narrow alias).
                                     예 : ["BIM", "DX"]. default [] (no stripping).
      max_rows                     : N (default 999 — practical 한계).
+
+    NOTE: MDX 측 col_a_label / col_b_label inflow 경로 없음
+    (compare_row_2col_item parser → {label,col_a,col_b}, _resolve_title → title only).
+    placeholder role 은 col_*_label 을 빈 문자열로 확정 — 정책 결정점은 catalog 한 곳뿐.
    """
    options = contract["payload"]["builder_options"]
    parser_name = options["item_parser"]
@@ -595,8 +606,21 @@ def _build_compare_table_2col(section, units, contract) -> dict:
            f"but ITEM_PARSERS has no such entry."
        )

-    col_a_label = options.get("col_a_label_default", "")
-    col_b_label = options.get("col_b_label_default", "")
+    def _resolve_label_default(col_key: str) -> str:
+        default_key = f"{col_key}_label_default"
+        role_key = f"{col_key}_label_default_role"
+        role = options.get(role_key, "fallback")
+        if role == "placeholder":
+            return ""
+        if role == "fallback":
+            return options.get(default_key, "")
+        raise ValueError(
+            f"Contract '{contract['template_id']}' builder_options.{role_key}='{role}' "
+            f"is invalid; expected 'placeholder' or 'fallback' (IMP-40 #69)."
+        )
+
+    col_a_label = _resolve_label_default("col_a")
+    col_b_label = _resolve_label_default("col_b")
    strip_aliases = options.get("strip_col_prefix_aliases", []) or []
    max_rows = options.get("max_rows", 999)

@@ -428,3 +428,377 @@ def apply_font_step_compression_css(plan: dict) -> str:
        return ""
    return (f'[data-zone-position="{zone_position}"] {{\n'
            f"  font-size: {float(target_font_px):.1f}px;\n}}")
+
+
+# ──────────────────────────────────────
+# IMP-88 u3 : layout_adjust — Step 17 retry chain (8-preset topology swap).
+# Honors feedback_phase_z_spacing_direction: no shared margin / gap / slide-body
+# shrink. Cascade entry per u2: image_fit_insufficient → layout_adjust;
+# downstream per u2: layout_adjust_insufficient → frame_internal_fit_candidate.
+# Plan-only — dispatcher (u6) consumes new_layout_preset + new_zones_data and
+# rebuilds layout_css via apply_layout_adjust_layout_css(plan, gap_px).
+# ──────────────────────────────────────
+
+
+def _layout_swap_priority(current_topology: str, candidate_topology: str) -> int:
+    """Lower = preferred swap target. Honors topology-axis mirroring first."""
+    pair = frozenset({current_topology, candidate_topology})
+    if pair == frozenset({"rows", "cols"}):
+        return 0
+    if pair == frozenset({"T", "inverted-T"}):
+        return 1
+    if pair == frozenset({"side-T-left", "side-T-right"}):
+        return 2
+    return 3
+
+
+def plan_layout_adjust(
+    *, current_layout_preset: str, zones_data: list[dict],
+) -> dict:
+    """Layout-preset switch plan (Step 17 retry chain — IMP-88 u3).
+
+    Finds a render-ready sibling preset (same candidate_when.unit_count) and
+    remaps zone positions in catalog order. No common spacing shrink —
+    feedback_phase_z_spacing_direction lock: escalate via layout topology only.
+    """
+    from src.phase_z2_composition import LAYOUT_PRESETS
+    base = {
+        "action": "layout_adjust",
+        "current_layout_preset": current_layout_preset,
+    }
+    current_spec = LAYOUT_PRESETS.get(current_layout_preset)
+    if current_spec is None:
+        return {
+            **base, "feasible": False, "new_layout_preset": None,
+            "candidates_considered": [],
+            "failure_reason": (
+                f"current_layout_preset '{current_layout_preset}' not in "
+                f"LAYOUT_PRESETS catalog — cannot enumerate same-unit-count siblings."
+            ),
+        }
+    current_positions = list(current_spec.get("positions") or [])
+    if len(zones_data) != len(current_positions):
+        return {
+            **base, "feasible": False, "new_layout_preset": None,
+            "candidates_considered": [],
+            "failure_reason": (
+                f"zones_data length {len(zones_data)} != current preset "
+                f"'{current_layout_preset}' positions {current_positions} — "
+                f"cannot remap to a sibling preset."
+            ),
+        }
+    unit_count = (current_spec.get("candidate_when") or {}).get("unit_count")
+    candidates = [
+        pid for pid, spec in LAYOUT_PRESETS.items()
+        if pid != current_layout_preset
+        and spec.get("render_ready", False)
+        and ((spec.get("candidate_when") or {}).get("unit_count") == unit_count)
+    ]
+    base = {**base, "unit_count": unit_count,
+            "candidates_considered": list(candidates)}
+    if not candidates:
+        return {
+            **base, "feasible": False, "new_layout_preset": None,
+            "failure_reason": (
+                f"no render-ready 8-preset sibling for unit_count {unit_count} "
+                f"(current='{current_layout_preset}'). single (1) and grid-2x2 (4) "
+                f"have no swap target by catalog design."
+            ),
+        }
+    catalog_order = list(LAYOUT_PRESETS.keys())
+    current_topo = current_spec.get("topology")
+    candidates.sort(key=lambda pid: (
+        _layout_swap_priority(current_topo, LAYOUT_PRESETS[pid].get("topology")),
+        catalog_order.index(pid),
+    ))
+    new_preset = candidates[0]
+    new_positions = list(LAYOUT_PRESETS[new_preset].get("positions") or [])
+    new_zones_data = [
+        {**zd, "position": new_positions[i]} for i, zd in enumerate(zones_data)
+    ]
+    return {
+        **base,
+        "feasible": True,
+        "new_layout_preset": new_preset,
+        "swap_topology_from": current_topo,
+        "swap_topology_to": LAYOUT_PRESETS[new_preset].get("topology"),
+        "position_remap": dict(zip(current_positions, new_positions)),
+        "new_zones_data": new_zones_data,
+    }
+
+
+def apply_layout_adjust_layout_css(plan: dict, gap_px: int) -> Optional[dict]:
+    """Build a fresh layout_css dict for the swapped preset.
+
+    Returns None when plan is infeasible. Dispatcher (u6) re-renders with
+    render_slide(zones_data=plan['new_zones_data'], layout_preset=plan
+    ['new_layout_preset'], layout_css=<this return>, gap_px=gap_px).
+    """
+    if not plan.get("feasible"):
+        return None
+    new_preset = plan.get("new_layout_preset")
+    new_zones_data = plan.get("new_zones_data") or []
+    if not new_preset or not new_zones_data:
+        return None
+    from src.phase_z2_pipeline import build_layout_css
+    new_layout_css = dict(build_layout_css(new_preset, new_zones_data, gap=gap_px))
+    raw = dict(new_layout_css.get("raw_zone_layout") or {})
+    raw["layout_adjust_applied"] = True
+    raw["layout_adjust_from"] = plan.get("current_layout_preset")
+    raw["layout_adjust_to"] = new_preset
+    new_layout_css["raw_zone_layout"] = raw
+    return new_layout_css
+
+
+# ──────────────────────────────────────
+# IMP-88 u4 : image_fit — Step 17 single-pass image-scoped CSS override.
+# Consumes overflow_metrics.image_events directly (natural_w/h, rendered_w/h,
+# natural_ratio, rendered_ratio, delta). Honors feedback_phase_z_spacing
+# _direction — image-scoped CSS only, no shared margin / frame envelope shrink.
+# Plan-only — Step 17 entry (u7) is the runtime caller.
+# Default delta_tol mirrors src.phase_z2_pipeline.IMAGE_ASPECT_DELTA_TOL = 0.05;
+# overridable arg keeps tests free of the pipeline import cycle.
+# ──────────────────────────────────────
+
+
+def plan_image_fit(
+    *, image_event: dict, delta_tol: float = 0.05,
+) -> dict:
+    """Image_fit planner (Step 17 retry chain — IMP-88 u4).
+
+    Emits frame-scoped object-fit + max-width/height from a single
+    image_event (overflow_metrics.image_events). Image-scoped only.
+    """
+    base = {
+        "action": "image_fit",
+        "src": image_event.get("src"),
+        "zone_position": image_event.get("zone_position"),
+        "zone_template_id": image_event.get("zone_template_id"),
+    }
+    delta = image_event.get("delta")
+    if delta is None:
+        return {
+            **base, "feasible": False, "css_overrides": None,
+            "failure_reason": (
+                "image_event delta is None — image not loaded; no aspect "
+                "mismatch can be measured."
+            ),
+        }
+    if abs(float(delta)) <= float(delta_tol):
+        return {
+            **base, "feasible": False, "css_overrides": None,
+            "delta": float(delta),
+            "failure_reason": (
+                f"|delta|={abs(float(delta)):.4f} <= delta_tol={delta_tol} — "
+                f"no image_aspect_mismatch to correct (planner no-op)."
+            ),
+        }
+    rendered_w = image_event.get("rendered_w")
+    rendered_h = image_event.get("rendered_h")
+    if not (isinstance(rendered_w, (int, float)) and rendered_w > 0
+            and isinstance(rendered_h, (int, float)) and rendered_h > 0):
+        return {
+            **base, "feasible": False, "css_overrides": None,
+            "delta": float(delta),
+            "failure_reason": (
+                "image_event missing positive rendered_w / rendered_h — "
+                "cannot bound max-width / max-height for image-scoped CSS."
+            ),
+        }
+    return {
+        **base,
+        "feasible": True,
+        "delta": float(delta),
+        "natural_ratio": image_event.get("natural_ratio"),
+        "rendered_ratio": image_event.get("rendered_ratio"),
+        "natural_w": image_event.get("natural_w"),
+        "natural_h": image_event.get("natural_h"),
+        "rendered_w": int(rendered_w),
+        "rendered_h": int(rendered_h),
+        # delta > 0 ⇒ rendered_ratio > natural_ratio ⇒ rendered too wide ⇒
+        # width axis correction; delta < 0 ⇒ height axis correction.
+        "correction_axis": "width" if float(delta) > 0 else "height",
+        "css_overrides": {
+            "object_fit": "contain",
+            "max_width_px": int(rendered_w),
+            "max_height_px": int(rendered_h),
+            "width": "auto",
+            "height": "auto",
+        },
+    }
+
+
+def apply_image_fit_css(plan: dict) -> Optional[str]:
+    """Build a frame-scoped CSS snippet from a feasible image_fit plan.
+
+    Returns None when plan is infeasible. u7 (Step 17 entry) injects the
+    snippet into the per-slide style override and re-renders.
+    """
+    if not plan.get("feasible"):
+        return None
+    overrides = plan.get("css_overrides") or {}
+    if not overrides:
+        return None
+    src = plan.get("src") or ""
+    zone_position = plan.get("zone_position") or ""
+    if src:
+        selector = (
+            f".zone[data-zone-position=\"{zone_position}\"] "
+            f"img[src=\"{src}\"]"
+        )
+    else:
+        selector = f".zone[data-zone-position=\"{zone_position}\"] img"
+    return (
+        f"{selector} {{\n"
+        f"  object-fit: {overrides.get('object_fit', 'contain')};\n"
+        f"  max-width: {int(overrides.get('max_width_px') or 0)}px;\n"
+        f"  max-height: {int(overrides.get('max_height_px') or 0)}px;\n"
+        f"  width: {overrides.get('width', 'auto')};\n"
+        f"  height: {overrides.get('height', 'auto')};\n"
+        f"}}"
+    )
+
+
+# ──────────────────────────────────────
+# IMP-88 u5 : frame_internal_fit_candidate — Step 17 retry chain.
+# Operates ONLY inside the frame contract's declared `internal_envelope`
+# (PHASE-Z-PIPELINE-OVERVIEW.md:333 lock). Sub-mechanism names allowed by
+# the OVERVIEW: density envelope / line rhythm / internal grid row / text
+# block allocation — all unified under the single action label
+# `frame_internal_fit_candidate` so common-CSS/padding shrink antipatterns
+# stay quarantined ([[feedback_phase_z_spacing_direction]]).
+#
+# Envelope shape (dormant — catalog adds when contracts declare it):
+#   frame_contract["internal_envelope"] = {
+#       "variants": [
+#           {"name": "<sub_mechanism_name>",
+#            "excess_budget_px": <int — px of vertical excess this variant can absorb>,
+#            "css_overrides": {<css-property>: <value>, ...}},
+#           ...
+#       ]
+#   }
+# Selection = walk variants in catalog order, pick first whose excess_budget_px
+# >= effective excess_y (greedy). Catalog order = catalog author's priority.
+#
+# No frame contract currently declares `internal_envelope`, so the planner
+# returns infeasible(envelope_present=False) for every live frame today.
+# Cascade hand-off: NEXT_ACTION_BY_FAILURE['frame_internal_fit_candidate_
+# insufficient'] = 'frame_reselect' (set in u2). Plan-only — u6 (salvage
+# dispatcher) and u7 (Step 17 entry) own the runtime call site.
+#
+# frame_contract is an overridable kwarg so tests don't pay the mapper
+# catalog cache cost / pipeline import cycle (mirrors u4's delta_tol).
+# ──────────────────────────────────────
+
+
+def plan_frame_internal_fit_candidate(
+    *, frame_template_id: str,
+    frame_contract: Optional[dict] = None,
+    overflow_zone: Optional[dict] = None,
+) -> dict:
+    """frame_internal_fit_candidate planner (Step 17 retry chain — IMP-88 u5).
+
+    Walks `frame_contract['internal_envelope']['variants']` in catalog order
+    and picks the first variant whose excess_budget_px covers `overflow_zone
+    ['excess_y']`. Returns infeasible when no contract / no envelope / no
+    variant fits. No common-margin shrink — sub-mechanism CSS is frame-scoped.
+    """
+    base = {
+        "action": "frame_internal_fit_candidate",
+        "frame_template_id": frame_template_id,
+    }
+    if frame_contract is None:
+        from src.phase_z2_mapper import get_contract
+        frame_contract = get_contract(frame_template_id)
+    if frame_contract is None:
+        return {
+            **base, "feasible": False, "envelope_present": False,
+            "candidates_considered": [], "selected_variant": None,
+            "css_overrides": None,
+            "failure_reason": (
+                f"no frame contract registered for template_id "
+                f"'{frame_template_id}' — cannot enumerate internal_envelope."
+            ),
+        }
+    envelope = frame_contract.get("internal_envelope")
+    if not isinstance(envelope, dict):
+        return {
+            **base, "feasible": False, "envelope_present": False,
+            "candidates_considered": [], "selected_variant": None,
+            "css_overrides": None,
+            "failure_reason": (
+                f"frame contract '{frame_template_id}' does not declare "
+                f"internal_envelope — cascade should escalate to frame_reselect."
+            ),
+        }
+    variants = list(envelope.get("variants") or [])
+    candidates_considered = [v.get("name") for v in variants if isinstance(v, dict)]
+    if not variants:
+        return {
+            **base, "feasible": False, "envelope_present": True,
+            "envelope_keys": sorted(envelope.keys()),
+            "candidates_considered": candidates_considered,
+            "selected_variant": None, "css_overrides": None,
+            "failure_reason": (
+                f"frame contract '{frame_template_id}' internal_envelope "
+                f"declares no variants — no sub-mechanism available."
+            ),
+        }
+    excess_y = 0
+    if isinstance(overflow_zone, dict):
+        ey = overflow_zone.get("excess_y")
+        if isinstance(ey, (int, float)) and ey > 0:
+            excess_y = int(math.ceil(float(ey)))
+    selected: Optional[dict] = None
+    for variant in variants:
+        if not isinstance(variant, dict):
+            continue
+        budget = variant.get("excess_budget_px")
+        if not isinstance(budget, (int, float)):
+            continue
+        if int(budget) >= excess_y:
+            selected = variant
+            break
+    if selected is None:
+        return {
+            **base, "feasible": False, "envelope_present": True,
+            "envelope_keys": sorted(envelope.keys()),
+            "candidates_considered": candidates_considered,
+            "selected_variant": None, "css_overrides": None,
+            "excess_y": excess_y,
+            "failure_reason": (
+                f"all {len(variants)} internal_envelope variant(s) for "
+                f"'{frame_template_id}' have excess_budget_px below excess_y="
+                f"{excess_y}px — internal fit cannot absorb overflow."
+            ),
+        }
+    overrides = selected.get("css_overrides") or {}
+    return {
+        **base, "feasible": True, "envelope_present": True,
+        "envelope_keys": sorted(envelope.keys()),
+        "candidates_considered": candidates_considered,
+        "selected_variant": selected.get("name"),
+        "selected_variant_budget_px": int(selected.get("excess_budget_px") or 0),
+        "excess_y": excess_y,
+        "css_overrides": dict(overrides),
+    }
+
+
+def apply_frame_internal_fit_candidate_css(plan: dict) -> Optional[str]:
+    """Build a frame-scoped CSS snippet from a feasible frame_internal_fit
+    plan. Returns None when plan is infeasible. u6 / u7 inject the snippet
+    into the per-slide style override and re-render.
+    """
+    if not plan.get("feasible"):
+        return None
+    overrides = plan.get("css_overrides") or {}
+    if not overrides:
+        return None
+    template_id = plan.get("frame_template_id") or ""
+    if not template_id:
+        return None
+    selector = f".zone[data-template-id=\"{template_id}\"]"
+    body_lines = [
+        f"  {prop}: {value};" for prop, value in overrides.items()
+    ]
+    return f"{selector} {{\n" + "\n".join(body_lines) + "\n}"
@@ -0,0 +1,301 @@
+"""IMP-43 (#72) u2 — Step 6 reuse snapshot schema (JSON-only).
+
+Stage 2 plan (locked) — ``--reuse-from PREV_RUN_ID`` reuses the
+Step 0 / 1 / 2 / 5 / 6 deterministic artifact subset plus the
+in-memory state that downstream steps need but that the existing
+``step02_normalized.json`` / ``step05_v4_evidence.json`` /
+``step06_composition_plan.json`` artifacts do not capture in a
+deserialize-ready form (e.g. ``CompositionUnit`` instances,
+``comp_debug``, ``v4_fallback_traces`` raw map, pre-override
+``layout_preset``). This module owns the schema for the additional
+``_reuse_snapshot.json`` sidecar written next to ``step06_composition_plan.json``.
+
+Scope (u2 only, Stage 2 unit split):
+    * Pure schema + serializers + validator. No file I/O.
+    * JSON-only — pickle is forbidden per Stage 2 guardrails.
+    * Provenance per top-level field: ``{value, source_path, upstream_step}``.
+    * ``mdx_sha256`` integrity key — ``--reuse-from`` must fail closed when
+      the prev run's MDX bytes don't match the current MDX bytes.
+    * ``schema_version`` — bumped on any non-additive shape change.
+
+Out of scope (deferred to later units):
+    * Writing the snapshot into the run_dir (u3).
+    * Copy / restore on ``--reuse-from`` (u4).
+    * Fail-closed snapshot/path errors at restore time (u4b).
+    * Threading ``reuse_from`` through ``run_phase_z2_mvp1`` (u5).
+"""
+from __future__ import annotations
+
+import json
+from typing import Any, Optional
+
+
+SNAPSHOT_VERSION = 1
+SNAPSHOT_FILENAME = "_reuse_snapshot.json"
+
+
+# Required top-level keys. Bare scalars (no provenance wrapper):
+#   - schema_version (contract key)
+#   - mdx_sha256 (integrity key)
+# All other keys are wrapped {value, source_path, upstream_step}.
+REQUIRED_TOP_LEVEL_KEYS: tuple[str, ...] = (
+    "schema_version",
+    "mdx_sha256",
+    "slide_title",
+    "slide_footer",
+    "sections",
+    "stage0_adapter_diagnostics",
+    "stage0_normalized_assets",
+    "v4_evidence",
+    "layout_preset_pre_override",
+    "units",
+    "comp_debug",
+    "v4_fallback_traces",
+    "ai_preflight",
+)
+
+_BARE_KEYS: frozenset[str] = frozenset({"schema_version", "mdx_sha256"})
+
+
+def _wrap(value: Any, *, source_path: str, upstream_step: str) -> dict[str, Any]:
+    return {
+        "value": value,
+        "source_path": source_path,
+        "upstream_step": upstream_step,
+    }
+
+
+def serialize_section(section: Any) -> dict[str, Any]:
+    """Serialize an ``MdxSection``-shaped object into a JSON-safe dict.
+
+    Duck-typed: accepts the production ``MdxSection`` dataclass or any
+    object exposing the same attribute names. Preserves the subset of
+    fields needed to reconstruct downstream pipeline behavior on the
+    reuse path.
+    """
+    return {
+        "section_id": section.section_id,
+        "section_num": section.section_num,
+        "title": section.title,
+        "raw_content": section.raw_content,
+        "heading_number": getattr(section, "heading_number", None),
+        "v4_alias_keys": list(getattr(section, "v4_alias_keys", []) or []),
+        "sub_sections": list(getattr(section, "sub_sections", []) or []),
+    }
+
+
+def serialize_unit(unit: Any) -> dict[str, Any]:
+    """Serialize a ``CompositionUnit``-shaped object into a JSON-safe dict.
+
+    ``v4_candidates`` entries are V4Match-duck-typed per the
+    CompositionUnit docstring; each is unwrapped to its 6 named
+    attributes so the snapshot file does not pin V4Match's dataclass
+    layout. ``v4_rank`` is included so the reuse path's Step 9
+    application-plan payload (``_build_application_plan_unit``)
+    remains byte-equivalent to the full-rerun path — full rerun stamps
+    each candidate's rank via ``_v4_match_from_judgment`` (e.g. 1, 2,
+    3, …) and Step 9 surfaces it under ``v4_candidates[i].v4_rank``.
+    Persisting it here lets the rehydrated ``_RehydratedV4Candidate``
+    expose the same attribute end-to-end and avoids None drift in the
+    Step 13 equivalence comparison (u7a).
+    """
+    return {
+        "source_section_ids": list(unit.source_section_ids),
+        "merge_type": unit.merge_type,
+        "frame_template_id": unit.frame_template_id,
+        "frame_id": unit.frame_id,
+        "frame_number": unit.frame_number,
+        "confidence": float(unit.confidence),
+        "label": unit.label,
+        "phase_z_status": unit.phase_z_status,
+        "raw_content": unit.raw_content,
+        "title": unit.title,
+        "v4_rank": unit.v4_rank,
+        "selection_path": unit.selection_path,
+        "fallback_reason": unit.fallback_reason,
+        "score": float(unit.score),
+        "rationale": dict(unit.rationale or {}),
+        "auto_selectable": bool(unit.auto_selectable),
+        "filter_reasons": list(unit.filter_reasons or []),
+        "notes": list(unit.notes or []),
+        "v4_candidates": [
+            {
+                "template_id": c.template_id,
+                "frame_id": c.frame_id,
+                "frame_number": c.frame_number,
+                "confidence": float(c.confidence),
+                "label": c.label,
+                "v4_rank": getattr(c, "v4_rank", None),
+            }
+            for c in (unit.v4_candidates or [])
+        ],
+        "provisional": bool(getattr(unit, "provisional", False)),
+    }
+
+
+def build_snapshot(
+    *,
+    mdx_sha256: str,
+    slide_title: Optional[str],
+    slide_footer: Optional[str],
+    sections: list,
+    stage0_adapter_diagnostics: Optional[dict],
+    stage0_normalized_assets: Optional[dict],
+    v4_evidence: list,
+    layout_preset_pre_override: Optional[str],
+    units: list,
+    comp_debug: Optional[dict],
+    v4_fallback_traces: Optional[dict],
+    ai_preflight: Optional[dict],
+) -> dict[str, Any]:
+    """Build a JSON-serializable Step 6 reuse snapshot with provenance.
+
+    Each top-level entry — except the two bare contract / integrity
+    keys (``schema_version``, ``mdx_sha256``) — is wrapped with
+    ``{value, source_path, upstream_step}``.
+
+    The function calls ``json.dumps(snapshot)`` at the end to enforce
+    JSON-safety at build time: any latent non-JSON value (set, Path,
+    dataclass instance, etc.) raises ``TypeError`` at the call site,
+    not later at restore.
+    """
+    snapshot: dict[str, Any] = {
+        "schema_version": SNAPSHOT_VERSION,
+        "mdx_sha256": mdx_sha256,
+        "slide_title": _wrap(
+            slide_title,
+            source_path="steps/step02_normalized.json#/slide_title",
+            upstream_step="step02",
+        ),
+        "slide_footer": _wrap(
+            slide_footer,
+            source_path="steps/step02_normalized.json#/slide_footer",
+            upstream_step="step02",
+        ),
+        "sections": _wrap(
+            [serialize_section(s) for s in sections],
+            source_path="steps/step02_normalized.json#/sections",
+            upstream_step="step02",
+        ),
+        "stage0_adapter_diagnostics": _wrap(
+            dict(stage0_adapter_diagnostics or {}),
+            source_path="steps/step02_normalized.json#/stage0_adapter_diagnostics",
+            upstream_step="step02",
+        ),
+        "stage0_normalized_assets": _wrap(
+            dict(stage0_normalized_assets or {}),
+            source_path="steps/step02_normalized.json#/stage0_normalized_assets",
+            upstream_step="step02",
+        ),
+        "v4_evidence": _wrap(
+            list(v4_evidence or []),
+            source_path="steps/step05_v4_evidence.json#/evidence_per_section",
+            upstream_step="step05",
+        ),
+        "layout_preset_pre_override": _wrap(
+            layout_preset_pre_override,
+            source_path="steps/step06_composition_plan.json#/layout_preset_decided",
+            upstream_step="step06",
+        ),
+        "units": _wrap(
+            [serialize_unit(u) for u in units],
+            source_path="steps/step06_composition_plan.json#/selected_units",
+            upstream_step="step06",
+        ),
+        "comp_debug": _wrap(
+            dict(comp_debug or {}),
+            source_path="steps/step06_composition_plan.json#/*",
+            upstream_step="step06",
+        ),
+        "v4_fallback_traces": _wrap(
+            dict(v4_fallback_traces or {}),
+            # v4_fallback_traces is assembled inside run_phase_z2_mvp1
+            # (see phase_z2_pipeline.py around the Step 5/6 boundary) and
+            # surfaces only partially into step06_composition_plan.json
+            # via the v4_fallback_summary / imp48_resplit fields. The
+            # canonical untruncated source is the in-memory dict at end
+            # of Step 6 — that's what the reuse path needs.
+            source_path="phase_z2_pipeline.run_phase_z2_mvp1::v4_fallback_traces",
+            upstream_step="step06",
+        ),
+        "ai_preflight": _wrap(
+            dict(ai_preflight or {}),
+            source_path="steps/step00_preconditions.json#/ai_preflight",
+            upstream_step="step00",
+        ),
+    }
+    json.dumps(snapshot)
+    return snapshot
+
+
+class SnapshotValidationError(ValueError):
+    """Raised by ``validate_snapshot`` when the snapshot is structurally
+    unusable or fails the ``mdx_sha256`` integrity check.
+
+    Subclass of ``ValueError`` so existing ``except ValueError`` callers
+    (u4b will add a tighter ``except SnapshotValidationError``) still
+    catch it without escaping to the outer CLI.
+    """
+
+
+def validate_snapshot(
+    snapshot: Any,
+    *,
+    expected_mdx_sha256: str,
+) -> None:
+    """Validate a loaded snapshot dict (fail-closed).
+
+    Raises ``SnapshotValidationError`` when:
+        * ``snapshot`` is not a dict
+        * ``schema_version`` is missing or != ``SNAPSHOT_VERSION``
+        * ``mdx_sha256`` is missing, non-string, or doesn't match
+          ``expected_mdx_sha256``
+        * any required top-level key is missing
+        * a wrapped entry doesn't expose ``{value, source_path, upstream_step}``
+
+    Returns ``None`` on success.
+
+    Callers (u4b) translate the raised error into an exit-code-2 abort
+    with the failing axis surfaced as `value + path + upstream`
+    (factual-verification guardrail).
+    """
+    if not isinstance(snapshot, dict):
+        raise SnapshotValidationError(
+            f"snapshot is not a dict (got {type(snapshot).__name__})"
+        )
+
+    version = snapshot.get("schema_version")
+    if version != SNAPSHOT_VERSION:
+        raise SnapshotValidationError(
+            f"schema_version mismatch: expected {SNAPSHOT_VERSION!r}, got {version!r}"
+        )
+
+    actual_sha = snapshot.get("mdx_sha256")
+    if not isinstance(actual_sha, str) or not actual_sha:
+        raise SnapshotValidationError(
+            f"mdx_sha256 missing or non-string: got {actual_sha!r}"
+        )
+    if actual_sha != expected_mdx_sha256:
+        raise SnapshotValidationError(
+            f"mdx_sha256 mismatch: snapshot={actual_sha!r} "
+            f"expected={expected_mdx_sha256!r}"
+        )
+
+    missing = [k for k in REQUIRED_TOP_LEVEL_KEYS if k not in snapshot]
+    if missing:
+        raise SnapshotValidationError(
+            f"missing required keys: {missing!r}"
+        )
+
+    for key, entry in snapshot.items():
+        if key in _BARE_KEYS:
+            continue
+        if not isinstance(entry, dict):
+            raise SnapshotValidationError(
+                f"key {key!r}: expected wrapper dict, got {type(entry).__name__}"
+            )
+        for field_name in ("value", "source_path", "upstream_step"):
+            if field_name not in entry:
+                raise SnapshotValidationError(
+                    f"key {key!r}: wrapper missing {field_name!r}"
+                )
@@ -25,13 +25,27 @@ from typing import Optional
 # ─── §4 mapping table (spec PHASE-Z-FIT-CLASSIFIER-ROUTER-SPEC §4) ──

 # category → proposed_action (primary)
+# IMP-88 (#88) u1 (2026-05-24): two ACTION_BY_CATEGORY edits to align the
+# primary router surface with PHASE-Z-PIPELINE-OVERVIEW.md Step 16 + Step 17
+# spec (anchor PHASE-Z-PIPELINE-OVERVIEW.md:321):
+#   1. NEW row `image_aspect_mismatch → image_fit` — closes the unmapped
+#      classifier emission (phase_z2_classifier.py:434-447) that previously
+#      returned proposed_action=None and stalled visual_check on overflow
+#      runs carrying image_event payloads.
+#   2. REMAP `frame_capacity_mismatch → frame_internal_fit_candidate`
+#      (previously frame_reselect) — OVERVIEW.md Step 17 locks
+#      frame_internal_fit_candidate as the per-zone first-pass salvage
+#      *inside* the declared frame envelope; frame_reselect (V4 top-k
+#      alternate frame swap) stays available downstream via the
+#      failure_router cascade (rerender_still_fails → frame_reselect).
 ACTION_BY_CATEGORY: dict[str, str] = {
    "minor_overflow":              "zone_ratio_retry",
    "moderate_overflow":           "layout_adjust",
    "structural_minor_overflow":   "zone_ratio_retry",
    "structural_major_overflow":   "details_popup_escalation",
    "tabular_overflow":            "details_popup_escalation",
-    "frame_capacity_mismatch":     "frame_reselect",
+    "image_aspect_mismatch":       "image_fit",
+    "frame_capacity_mismatch":     "frame_internal_fit_candidate",
    "layout_zone_mismatch":        "layout_adjust",
    "hard_visual_fail":            "abort",
 }
@@ -48,8 +62,13 @@ ACTION_RATIONALE: dict[str, str] = {
        "1+ structural unit 완전 잘림 → 의미 손실, popup 으로 escalate",
    "tabular_overflow":
        "표는 행 단위로 잘리면 의미 손실 → popup escalate (또는 table-friendly frame reselect)",
+    "image_aspect_mismatch":
+        "image 자연 비율과 렌더 비율 mismatch → frame 내부 image fit (object-fit / "
+        "max-w/h) 로 envelope 안에서 비율 회복. 공통 image CSS 변경 X (frame-scoped).",
    "frame_capacity_mismatch":
-        "composition capacity_fit 가 이미 mismatch 신호 → V4 top-k 의 다른 frame 평가",
+        "composition capacity_fit 가 이미 mismatch 신호 → frame contract envelope "
+        "안 internal fit 변형 (density / line rhythm / row 배치) 우선. "
+        "frame swap 은 cascade 다음 단계 (rerender_still_fails → frame_reselect).",
    "layout_zone_mismatch":
        "frame root 자체 overflow → layout preset 변경 또는 zone 키움",
    "hard_visual_fail":
@@ -61,7 +80,21 @@ ACTION_RATIONALE: dict[str, str] = {
 # A2 단계에서 이 매핑이 *어디까지 자동 처리되고 어디서 막히는지* trace 확보용
 ACTION_IMPLEMENTATION_STATUS: dict[str, str] = {
    "zone_ratio_retry":          "IMPLEMENTED",  # A3 (2026-04-29) phase_z2_retry.plan_zone_ratio_retry + pipeline orchestration
-    "layout_adjust":             "MISSING",
+    # IMP-88 (#88) u1→u7 (2026-05-24): three Step 17 retry actions registered
+    # here. u1 added the data-surface rows (initial state MISSING). u3/u4/u5
+    # landed the deterministic planners in src/phase_z2_retry.py. u6 wired the
+    # salvage dispatcher (_attempt_salvage_chain), and u7 wired the Step 17
+    # entry runtime (_attempt_step17_image_fit_single_pass + §11.7.1/§11.7.2).
+    # Status flips MISSING→IMPLEMENTED land here on u7 completion — once the
+    # end-to-end path (planner + apply + dispatcher + entry) is wired the
+    # action is IMPLEMENTED on the deterministic surface. (Same convention as
+    # IMP-12 u7 cascade rows below: planner-surface availability + orchestrator
+    # wiring together constitute IMPLEMENTED; route_action's
+    # implementation_status field reflects surface availability, not whether a
+    # given pipeline run has invoked the action.)
+    "layout_adjust":             "IMPLEMENTED",  # u3 plan_layout_adjust + u6 dispatcher branch + u7 cascade entry
+    "image_fit":                 "IMPLEMENTED",  # u4 plan_image_fit + u7 _attempt_step17_image_fit_single_pass entry
+    "frame_internal_fit_candidate": "IMPLEMENTED",  # u5 plan_frame_internal_fit_candidate + u6 dispatcher branch + u7 cascade entry
    # IMP-35 (#64) u3 — MISSING → IMPLEMENTED on the primary router surface.
    # `plan_details_popup_escalation` (below) provides the deterministic stub
    # that downstream units consume: u4 binds the AI split-decision contract
@@ -0,0 +1,137 @@
+"""IMP-94 (#94) u1 — region/content marker stamper for Phase Z final.html.
+
+Annotates each rendered family-partial root ``<div>`` with stable
+``data-region-id="..."`` and ``data-content-unit-id="..."`` attributes so
+downstream Layer A telemetry (placement_trace ↔ DOM parity, Step 21 self-
+report, fit_classifier read targets §6.4) can resolve a rendered zone
+back to its PlacementPlan ``slot_assignments[]`` entry.
+
+DOM contract (single point of truth — mirrored verbatim across the axis) ::
+
+    <div class="..." data-region-id="{region_id}" data-content-unit-id="{cuid}" ...
+         data-frame-id="..." data-template-id="...">
+
+The anchor is the uniform root-div emitted by every Phase Z family
+partial under ``templates/phase_z2/families/`` (13 partials, evidence
+confirmed via ``grep -l data-template-id`` = 13/13). All 13 partials
+carry the pattern::
+
+    <div class="<fNb>" data-frame-id="..." data-template-id="<family>">
+
+The stamper finds the FIRST such opening tag with a permissive regex
+and injects ``data-region-id`` + ``data-content-unit-id`` as new
+attributes. Existing attributes (class, data-frame-id, data-template-id,
+etc.) are preserved verbatim. The injection is idempotent — a zone that
+already carries ``data-region-id`` on its root div is left alone.
+
+Source of marker values : ``PlacementPlan.slot_assignments[].region_id``
+and ``.content_unit_id`` (see ``src/phase_z2_placement_planner.py``
+L253-258). u3 wires the live B4 path; u4 ensures non-live append paths
+default to ``placement_markers=[]`` so this stamper safely no-ops.
+
+Forward-compat / safety :
+- Empty / None ``markers`` → passthrough (returns ``zone_html`` unchanged).
+- Non-str / empty ``zone_html`` → passthrough.
+- Re-stamping (idempotent) preserves the first stamp.
+- Only the FIRST data-template-id root div is stamped (one per zone).
+- Markers with empty / missing ``region_id`` AND ``content_unit_id`` →
+  passthrough (no attribute injection).
+
+Guardrails (refs : Stage 1 binding contract, Stage 2 unit u1) :
+- AI-isolation : pure deterministic Python; no LLM calls.
+- Additive only : never edits / removes existing attributes.
+- Idempotent : ``data-region-id`` probe short-circuits before re-inject.
+- Disjoint from #96 (``data-frame-slot-id`` is a separate axis / attr).
+"""
+from __future__ import annotations
+
+import re
+from typing import Any, Iterable, Mapping
+
+REGION_ID_ATTR: str = "data-region-id"
+CONTENT_UNIT_ID_ATTR: str = "data-content-unit-id"
+
+# Matches the FIRST ``<div ... data-template-id="...">`` opening tag.
+# Group 1 captures the inner attribute string verbatim (incl. leading
+# whitespace) so the rewriter can re-emit it unchanged after injection.
+_ROOT_DIV_TAG_RE = re.compile(
+    r'<div\b((?=[^>]*\bdata-template-id\s*=\s*"[^"]+")[^>]*?)>',
+    flags=re.IGNORECASE | re.DOTALL,
+)
+# Probe for an existing ``data-region-id`` attribute (any value, any
+# quote) so re-stamping is idempotent.
+_HAS_REGION_ID_RE = re.compile(r"""\bdata-region-id\s*=""", flags=re.IGNORECASE)
+
+
+def _coerce_marker_value(value: Any) -> str:
+    """Return a safe attribute-value string for ``value``.
+
+    Non-str / None → ''. Strings are returned verbatim (caller responsible
+    for not embedding ``"`` since marker ids derive from
+    PlacementPlan.slot_assignments which are deterministic identifiers).
+    """
+    if value is None:
+        return ""
+    if not isinstance(value, str):
+        return ""
+    return value
+
+
+def stamp_zone_html(
+    zone_html: str,
+    markers: Iterable[Mapping[str, Any]] | None,
+) -> str:
+    """Stamp the root family-partial ``<div>`` with region / content-unit ids.
+
+    ``markers`` is an iterable of mapping objects shaped as ::
+
+        {
+          "region_id": "<region_id>",
+          "content_unit_id": "<content_unit_id>",
+          # optional, ignored here — reserved for #96 (89-d):
+          "frame_slot_id": "<frame_slot_id>",
+        }
+
+    Only ``markers[0]`` is consumed (one root div per zone). Excess
+    markers are reserved for a future per-slot stamper (#96) and are
+    silently ignored by this module.
+
+    Returns ``zone_html`` unchanged when:
+      - ``zone_html`` is not a non-empty string,
+      - ``markers`` is None / empty,
+      - no ``data-template-id`` root div is found,
+      - the root div already carries ``data-region-id`` (idempotent),
+      - the first marker carries neither ``region_id`` nor ``content_unit_id``.
+    """
+    if not isinstance(zone_html, str) or not zone_html:
+        return zone_html
+    if markers is None:
+        return zone_html
+    marker_list = list(markers)
+    if not marker_list:
+        return zone_html
+    first = marker_list[0]
+    if not isinstance(first, Mapping):
+        return zone_html
+    region_id = _coerce_marker_value(first.get("region_id"))
+    content_unit_id = _coerce_marker_value(first.get("content_unit_id"))
+    if not region_id and not content_unit_id:
+        return zone_html
+
+    stamped = {"done": False}
+
+    def _replace(match: re.Match[str]) -> str:
+        if stamped["done"]:
+            return match.group(0)
+        attrs = match.group(1) or ""
+        if _HAS_REGION_ID_RE.search(attrs):
+            stamped["done"] = True
+            return match.group(0)
+        stamped["done"] = True
+        injected = (
+            f' {REGION_ID_ATTR}="{region_id}"'
+            f' {CONTENT_UNIT_ID_ATTR}="{content_unit_id}"'
+        )
+        return f"<div{injected}{attrs}>"
+
+    return _ROOT_DIV_TAG_RE.sub(_replace, zone_html, count=1)
@@ -0,0 +1,87 @@
+"""IMP-45 (#74) u3 — slide-level CSS override injector for Phase Z final.html.
+
+Mirror of :func:`src.image_id_stamper.inject_image_overrides_style` contract
+(image_id_stamper.py:226-264) for the new ``slide_css`` override axis
+registered by u1 in :data:`src.user_overrides_io.KNOWN_AXES` and surfaced
+by u2 in :func:`src.mdx_normalizer.normalize_mdx_content` under the
+``slide_overrides.css`` frontmatter key.
+
+Single entry point :
+
+    :func:`inject_slide_css` (html, css) -> str
+
+Semantics (identical contract to image_overrides injector) :
+
+- Empty / falsy ``css`` -> ``html`` returned unchanged (no DOM mutation).
+- Marker-wrapped ``<style>`` block; re-injection replaces inner CSS in
+  place (idempotent on identical input; latest-wins on different input).
+- Injection precedence : (1) before first ``</head>`` (case-insensitive),
+  (2) immediately after the first ``<body ...>`` open tag, (3) at the
+  start of the document. Phase Z ``slide_base.html`` always emits
+  ``</head>`` so path 1 wins for production renders; paths 2/3 are
+  defensive fallbacks for fragment inputs.
+
+Marker sentinels (distinct from image_overrides markers so the two
+injectors can co-exist on the same document without collision; the
+literal form is pinned by the Stage 2 binding contract for IMP-45 /
+issue #74) :
+
+    <!--IMP45-SLIDE-CSS:OPEN-->
+    <!--IMP45-SLIDE-CSS:CLOSE-->
+
+Both injectors target ``</head>`` first, so call order determines DOM
+order. u4 calls ``inject_image_overrides_style`` first (existing Step 13
+behavior) and then ``inject_slide_css``, putting slide-level overrides
+after image overrides in cascade order so the editor-authored slide CSS
+wins ties at the same specificity (intended by IMP-45 scope).
+
+Guardrails :
+
+- No-hardcoding : ``css`` is caller-supplied verbatim. No sample-id or
+  frame-id branches.
+- AI-isolation : pure deterministic Python; no LLM calls.
+- Carve-out (IMP-46 #62) : brand-new module, does not touch the
+  #76 commit ``1186ad8`` cache region.
+"""
+from __future__ import annotations
+
+import re
+
+_IMP45_STYLE_MARKER_OPEN: str = "<!--IMP45-SLIDE-CSS:OPEN-->"
+_IMP45_STYLE_MARKER_CLOSE: str = "<!--IMP45-SLIDE-CSS:CLOSE-->"
+
+_IMP45_STYLE_BLOCK_RE = re.compile(
+    re.escape(_IMP45_STYLE_MARKER_OPEN) + r".*?" + re.escape(_IMP45_STYLE_MARKER_CLOSE),
+    flags=re.DOTALL,
+)
+_HEAD_CLOSE_RE = re.compile(r"</head\s*>", flags=re.IGNORECASE)
+_BODY_OPEN_RE = re.compile(r"<body\b[^>]*>", flags=re.IGNORECASE)
+
+
+def inject_slide_css(html: str, css: str | None) -> str:
+    """Inject a marker-wrapped ``<style>`` block carrying ``css`` into ``html``.
+
+    Empty or ``None`` ``css`` -> ``html`` returned unchanged. Re-injection
+    is idempotent : when a previously-injected marker block is present,
+    its inner CSS is replaced in place.
+
+    Injection precedence : ``</head>`` > ``<body ...>`` > document start.
+    """
+    if not css:
+        return html
+    block = (
+        f"{_IMP45_STYLE_MARKER_OPEN}\n"
+        f"<style>\n{css}\n</style>\n"
+        f"{_IMP45_STYLE_MARKER_CLOSE}"
+    )
+    if _IMP45_STYLE_MARKER_OPEN in html:
+        return _IMP45_STYLE_BLOCK_RE.sub(lambda _m: block, html, count=1)
+    head_close = _HEAD_CLOSE_RE.search(html)
+    if head_close is not None:
+        idx = head_close.start()
+        return html[:idx] + block + "\n" + html[idx:]
+    body_open = _BODY_OPEN_RE.search(html)
+    if body_open is not None:
+        idx = body_open.end()
+        return html[:idx] + "\n" + block + html[idx:]
+    return block + "\n" + html
@@ -0,0 +1,189 @@
+"""IMP-56 (#90) u6 — structure_override resolver (validator + apply).
+
+Step-22 user structure-edit persist axis. Consumed by Step 12 (u7 wiring)
+so a prior render's reorder / hide choices re-apply to the next render
+without re-clicking.
+
+Schema (defined verbatim in ``src/user_overrides_io.py:30`` u2) ::
+
+    structure_overrides = {
+        <zone_id>: {
+            "slot_order":   [<slot_key>, ...],   # optional, partial reorder
+            "hidden_slots": [<slot_key>, ...],   # optional, hide these slot_keys
+        },
+        ...
+    }
+
+SCOPE LOCK (Stage 2 u6 contract, IMP-56 #90 u2 docstring) :
+
+    The only allowed inner keys are ``slot_order`` and ``hidden_slots``.
+    Any other key (e.g., ``frame_id``, ``template_id``, ``unit_id``,
+    ``slot_payload``) is treated as a frame-swap / DOM-rebuild attempt and
+    is DROPPED at validate time. Frame swap stays on the existing
+    ``frames`` axis so the Phase Z no-AI-HTML-structure invariant remains
+    intact. There is intentionally NO escape hatch through this axis.
+
+API (deterministic, no AI) :
+
+- ``validate_structure_overrides(overrides)`` → sanitized copy. Per-entry
+  tolerant (drops malformed rows; never rejects the whole batch — mirrors
+  ``src.text_override_resolver.validate_text_overrides`` u4 contract).
+- ``apply_structure_override(zone, override)`` → ``True`` if the slot-payload
+  mapping was mutated (any hide or any reorder), ``False`` otherwise. The
+  ``zone`` argument is the slot-payload mapping at Step 12 (a mutable
+  mapping whose keys are slot_keys and whose values are typically
+  ``list[str]`` of lines). Identity-preserving: mutates in-place via
+  ``clear`` + ``update`` so caller references remain valid.
+
+Guardrails (refs : Stage 1 binding contract, Stage 2 unit u6) :
+
+- raw_content preservation is a wiring-layer (u7) responsibility — the
+  resolver only ever reorders / removes top-level slot_payload entries.
+  Per-slot ``list[str]`` line content is never inspected or mutated here.
+- AI-isolation : pure deterministic Python; no LLM calls.
+- Carve-out (IMP-46 #62) : brand-new module, does not touch the #76
+  commit ``1186ad8`` cache region.
+"""
+from __future__ import annotations
+
+from typing import Any, Mapping, MutableMapping
+
+
+class InvalidStructureOverride(ValueError):
+    """Reserved for future strict-mode parse errors.
+
+    Currently unused — the resolver follows the u4 per-entry-tolerant
+    contract and silently drops malformed rows at validate time rather
+    than raising. Kept as a public surface so u7 wiring (and future
+    strict-mode callers) can distinguish source-malformation from
+    stale-DOM misses without an API rev.
+    """
+
+
+_ALLOWED_INNER_KEYS: frozenset[str] = frozenset({"slot_order", "hidden_slots"})
+
+
+def _sanitize_slot_list(raw: Any) -> list[str]:
+    """Return a fresh list of non-empty string slot_keys (drop the rest)."""
+    if not isinstance(raw, list):
+        return []
+    out: list[str] = []
+    seen: set[str] = set()
+    for slot in raw:
+        if not isinstance(slot, str) or not slot:
+            continue
+        if slot in seen:
+            # De-dup defensively — a duplicate slot_key in slot_order would
+            # be meaningless (dicts can hold each key once); duplicate in
+            # hidden_slots is redundant. Drop subsequent occurrences.
+            continue
+        seen.add(slot)
+        out.append(slot)
+    return out
+
+
+def validate_structure_overrides(
+    overrides: Any,
+) -> dict[str, dict[str, list[str]]]:
+    """Return a sanitized copy of ``overrides`` (per-entry tolerant).
+
+    Drops:
+      - non-string or empty zone_ids,
+      - non-mapping per-zone payloads,
+      - per-zone inner keys other than ``slot_order`` / ``hidden_slots``
+        (frame-swap attempts are dropped at this gate — see SCOPE LOCK),
+      - non-list ``slot_order`` / ``hidden_slots`` values,
+      - non-string or empty slot_key entries within those lists,
+      - per-zone payloads that contain neither a non-empty ``slot_order``
+        nor a non-empty ``hidden_slots`` after sanitization (empty intent
+        carries no signal).
+
+    Returns a fresh ``dict`` AND fresh nested dicts / lists so callers can
+    use the result as a working buffer without aliasing the persisted
+    payload from ``user_overrides_io.load``.
+    """
+    if not isinstance(overrides, Mapping):
+        return {}
+    out: dict[str, dict[str, list[str]]] = {}
+    for zone_id, mapping in overrides.items():
+        if not isinstance(zone_id, str) or not zone_id:
+            continue
+        if not isinstance(mapping, Mapping):
+            continue
+        zone_out: dict[str, list[str]] = {}
+        for inner_key, inner_value in mapping.items():
+            if inner_key not in _ALLOWED_INNER_KEYS:
+                # Frame-swap attempt or unknown key — drop silently per
+                # SCOPE LOCK. No mechanism through this axis.
+                continue
+            sanitized = _sanitize_slot_list(inner_value)
+            if sanitized:
+                zone_out[inner_key] = sanitized
+        if zone_out:
+            out[zone_id] = zone_out
+    return out
+
+
+def apply_structure_override(
+    zone: MutableMapping[str, Any],
+    override: Mapping[str, Any],
+) -> bool:
+    """Apply ONE structure override to ``zone`` in-place.
+
+    ``zone`` is the slot-payload mapping at Step 12 — i.e. a mutable
+    mapping whose keys are slot_keys and whose values are the per-slot
+    line lists (or other content payload). Mutation is restricted to
+    top-level key membership + ordering; per-slot values are NEVER
+    inspected or modified here.
+
+    ``override`` is the per-zone payload after :func:`validate_structure_overrides`
+    sanitization — i.e. a mapping with only ``slot_order`` and / or
+    ``hidden_slots`` keys, each holding a list of non-empty str slot_keys.
+    This function is also defensive: if non-list values leak through, they
+    are treated as empty (no raise).
+
+    Semantics :
+      1. ``hidden_slots`` are popped first. Entries absent from ``zone``
+         are silently skipped (stale slot_keys from a prior frame).
+      2. ``slot_order`` partially reorders the surviving slot_keys:
+         listed keys (that are present in ``zone``) move to the front in
+         the given order; remaining keys keep their original relative
+         order at the tail. Unknown slot_keys are silently skipped.
+
+    Returns ``True`` if the zone's slot-payload mapping was mutated (any
+    hide that removed a key OR any reorder that changed key order),
+    ``False`` otherwise. Identity-preserving: rebuilds via
+    ``clear`` + ``update`` so the caller's reference to ``zone`` remains
+    valid.
+    """
+    mutated = False
+
+    raw_hidden = override.get("hidden_slots") if isinstance(override, Mapping) else None
+    hidden = _sanitize_slot_list(raw_hidden)
+    for slot in hidden:
+        if slot in zone:
+            del zone[slot]
+            mutated = True
+
+    raw_order = override.get("slot_order") if isinstance(override, Mapping) else None
+    desired_order_seed = _sanitize_slot_list(raw_order)
+
+    current_order = list(zone.keys())
+    desired_order: list[str] = []
+    seen: set[str] = set()
+    for slot in desired_order_seed:
+        if slot in zone and slot not in seen:
+            desired_order.append(slot)
+            seen.add(slot)
+    for slot in current_order:
+        if slot not in seen:
+            desired_order.append(slot)
+            seen.add(slot)
+
+    if desired_order != current_order:
+        snapshot = {k: zone[k] for k in desired_order}
+        zone.clear()
+        zone.update(snapshot)
+        mutated = True
+
+    return mutated
@@ -0,0 +1,143 @@
+"""IMP-56 (#90) u4 — text_override resolver (validator + apply).
+
+Step-22 user text-edit persist axis. Consumed by Step 12 (u5 wiring) so a
+prior render's text edits re-apply to the next render without re-clicking.
+
+Schema (defined verbatim in ``src/user_overrides_io.py:29`` u1) ::
+
+    text_overrides = {
+        <zone_id>: {<text_path>: <value: str>},
+        ...
+    }
+
+``text_path`` is the ``{slot_key}.{line_index}`` stamp emitted at Step 13
+by the u8 ``text_path_stamper`` (pending unit) and surfaced to the frontend
+SlideCanvas (u12) as ``data-text-path`` attributes on editable text nodes.
+The ``{slot_key}`` is a frame contract slot identifier (e.g.,
+``slot_title``); the ``{line_index}`` is the 0-based ordinal of the line
+within that slot's rendered text (typically one bullet / one paragraph).
+
+API (deterministic, no AI) :
+
+- ``parse_text_path(text_path)`` → ``(slot_key, line_index)`` or raises.
+- ``validate_text_overrides(overrides)`` → sanitized copy (drops malformed
+  per-entry; never rejects the whole batch — mirrors the per-entry
+  tolerance contract of ``src.image_id_stamper.build_image_overrides_style``
+  IMP-51 #79 u7).
+- ``apply_text_override(zone, text_path, value)`` → ``True`` on in-place
+  mutation; ``False`` if the path is absent / out-of-range. The ``zone``
+  argument is the slot-lines mapping at Step 12 — i.e. a mutable mapping
+  where ``zone[slot_key]`` is a ``list[str]`` of line strings. Wiring at
+  Step 12 (u5) is responsible for extracting that mapping from whatever
+  composition object holds it; this resolver is decoupled from the wrapper
+  shape so it can be re-targeted at Stage 5 (Step 12) layer-A or layer-B
+  composition data without an API rev.
+
+Guardrails (refs : Stage 1 binding contract, Stage 2 unit u4) :
+
+- raw_content preservation is a wiring-layer (u5) responsibility — the
+  resolver itself only ever mutates the lines mapping it was handed.
+- AI-isolation : pure deterministic Python; no LLM calls.
+- Carve-out (IMP-46 #62) : brand-new module, does not touch the #76
+  commit ``1186ad8`` cache region.
+"""
+from __future__ import annotations
+
+from typing import Any, Mapping, MutableMapping
+
+
+class InvalidTextOverride(ValueError):
+    """Raised when a ``text_path`` is malformed (parse-time)."""
+
+
+def parse_text_path(text_path: str) -> tuple[str, int]:
+    """Parse ``{slot_key}.{line_index}`` into ``(slot_key, line_index)``.
+
+    ``slot_key`` may itself contain ``.`` (e.g., compound keys), so the
+    parse splits on the LAST ``.`` only — ``rpartition`` semantics.
+    """
+    if not isinstance(text_path, str) or not text_path:
+        raise InvalidTextOverride(
+            f"text_path must be a non-empty string, got: {text_path!r}"
+        )
+    if "." not in text_path:
+        raise InvalidTextOverride(
+            f"text_path must contain '.' separator, got: {text_path!r}"
+        )
+    slot_key, _, idx_str = text_path.rpartition(".")
+    if not slot_key or not idx_str:
+        raise InvalidTextOverride(
+            f"text_path slot_key and line_index must both be non-empty, "
+            f"got: {text_path!r}"
+        )
+    try:
+        idx = int(idx_str)
+    except ValueError as exc:
+        raise InvalidTextOverride(
+            f"text_path line_index must be int, got: {text_path!r}"
+        ) from exc
+    if idx < 0:
+        raise InvalidTextOverride(
+            f"text_path line_index must be >= 0, got: {idx} in {text_path!r}"
+        )
+    return slot_key, idx
+
+
+def validate_text_overrides(overrides: Any) -> dict[str, dict[str, str]]:
+    """Return a sanitized copy of ``overrides`` (per-entry tolerant).
+
+    Drops:
+      - non-string or empty zone_ids,
+      - non-mapping per-zone payloads,
+      - non-string text_path keys, non-string values,
+      - text_paths that fail :func:`parse_text_path`.
+
+    Returns a fresh ``dict`` so callers can mutate without aliasing the
+    persisted payload from ``user_overrides_io.load``.
+    """
+    if not isinstance(overrides, Mapping):
+        return {}
+    out: dict[str, dict[str, str]] = {}
+    for zone_id, mapping in overrides.items():
+        if not isinstance(zone_id, str) or not zone_id:
+            continue
+        if not isinstance(mapping, Mapping):
+            continue
+        zone_out: dict[str, str] = {}
+        for text_path, value in mapping.items():
+            if not isinstance(text_path, str) or not isinstance(value, str):
+                continue
+            try:
+                parse_text_path(text_path)
+            except InvalidTextOverride:
+                continue
+            zone_out[text_path] = value
+        if zone_out:
+            out[zone_id] = zone_out
+    return out
+
+
+def apply_text_override(
+    zone: MutableMapping[str, Any],
+    text_path: str,
+    value: str,
+) -> bool:
+    """Apply ONE text override to ``zone`` in-place.
+
+    ``zone`` is the slot-lines mapping at Step 12 — i.e. a mutable mapping
+    where ``zone[slot_key]`` is a ``list[str]`` of line strings.
+
+    Returns ``True`` when the value was replaced. Returns ``False`` (no
+    mutation) when the ``slot_key`` is absent, the slot is not a list, or
+    ``line_index`` is out of range. Out-of-range / absent paths are NOT an
+    error — they happen naturally when a prior render's overrides target a
+    slot the new render no longer emits (frame swap, layout regression).
+    """
+    slot_key, idx = parse_text_path(text_path)
+    if slot_key not in zone:
+        return False
+    lines = zone[slot_key]
+    if not isinstance(lines, list) or idx >= len(lines):
+        return False
+    lines[idx] = value
+    return True
@@ -0,0 +1,155 @@
+"""IMP-56 (#90) u8 — text_path stamper for Phase Z final.html.
+
+Annotates rendered ``text-line`` DOM elements with a stable
+``data-text-path="{slot_key}.{line_index}"`` attribute so the frontend
+SlideCanvas (u10~u12) can attribute per-line edits back to the
+``text_overrides`` axis (u1 schema, u4 resolver, u5 Step-12 apply).
+
+DOM contract (single point of truth — mirrored verbatim across the axis) ::
+
+    .text-line[data-text-path="{slot_key}.{line_index}"]
+
+The ``{slot_key}.{line_index}`` grammar matches
+:func:`src.text_override_resolver.parse_text_path` verbatim (split on LAST
+``.`` — compound slot keys with embedded dots are supported).
+
+The text-line element format is emitted by every Phase Z family / frame
+template (e.g. ``templates/phase_z2/families/bim_current_problems_paired.html``
+line 143)::
+
+    <div class="text-line[ ...modifier classes...]">{{ line.text | safe }}</div>
+
+The stamper finds each ``text-line`` opening tag with a permissive regex
+and injects ``data-text-path="..."`` as the FIRST attribute. Existing
+attributes (class, etc.) are preserved verbatim. The injection is
+idempotent — a previously stamped element is left alone.
+
+Stamping order : the stamper iterates ``slot_payload`` in dict-iteration
+order and yields one stamp per ``list`` entry. The DOM walk consumes
+stamps in left-to-right order; templates currently emit slot lines in
+the same order they appear in ``slot_payload`` so the alignment holds.
+If a future template diverges, u9 wiring can pre-build the desired
+``(slot_key, line_index)`` sequence and pass it explicitly through the
+``stamps`` arg of :func:`stamp_zone_html`.
+
+Forward-compat / safety :
+- Scalar (non-list) slot values are silently skipped — they render
+  outside ``text-line`` divs (frame title, pill labels, etc.) and are
+  not addressable via the line-index grammar.
+- Excess ``text-line`` elements beyond ``sum(len(v) for v in
+  slot_payload.values() if isinstance(v, list))`` are left unstamped.
+- Re-stamping (idempotent) preserves the first stamp.
+
+Guardrails (refs : Stage 1 binding contract, Stage 2 unit u8) :
+- AI-isolation : pure deterministic Python; no LLM calls.
+- Carve-out (IMP-46 #62) : brand-new module; does not touch the #76
+  commit ``1186ad8`` cache region.
+- Idempotent : ``data-text-path`` probe short-circuits before re-inject.
+- u9 wiring (separate unit) is the only consumer; this module emits no
+  artifacts and reads no global state.
+"""
+from __future__ import annotations
+
+import re
+from typing import Any, Iterable, Iterator, Mapping
+
+TEXT_PATH_ATTR: str = "data-text-path"
+
+# Matches a ``<div ... class="... text-line ..." ...>`` opening tag.
+# Group 1 captures the inner attribute string verbatim (incl. leading
+# whitespace) so the rewriter can re-emit it unchanged after injection.
+_TEXT_LINE_TAG_RE = re.compile(
+    r'<div\b((?=[^>]*\bclass\s*=\s*"[^"]*\btext-line\b)[^>]*?)>',
+    flags=re.IGNORECASE | re.DOTALL,
+)
+# Probe for an existing ``data-text-path`` attribute (any value, any
+# quote) so re-stamping is idempotent.
+_HAS_TEXT_PATH_RE = re.compile(r"""\bdata-text-path\s*=""", flags=re.IGNORECASE)
+
+
+def build_text_path(slot_key: str, line_index: int) -> str:
+    """Return the canonical ``{slot_key}.{line_index}`` text_path string.
+
+    Mirrors the inverse of :func:`src.text_override_resolver.parse_text_path`
+    (last-dot split). ``slot_key`` may itself contain ``.`` (compound keys).
+    """
+    if not isinstance(slot_key, str) or not slot_key:
+        raise ValueError(
+            f"slot_key must be a non-empty string, got: {slot_key!r}"
+        )
+    if isinstance(line_index, bool) or not isinstance(line_index, int):
+        raise ValueError(
+            f"line_index must be a non-negative int, got: {line_index!r}"
+        )
+    if line_index < 0:
+        raise ValueError(
+            f"line_index must be a non-negative int, got: {line_index!r}"
+        )
+    return f"{slot_key}.{line_index}"
+
+
+def iter_zone_stamps(
+    slot_payload: Mapping[str, Any],
+) -> Iterator[tuple[str, int]]:
+    """Yield ``(slot_key, line_index)`` for every list-valued slot line.
+
+    Iteration order matches ``slot_payload`` dict iteration order. Non-
+    string / empty slot_keys are skipped. Non-list values are skipped
+    (scalar slots render outside ``text-line`` divs).
+    """
+    if not isinstance(slot_payload, Mapping):
+        return
+    for slot_key, value in slot_payload.items():
+        if not isinstance(slot_key, str) or not slot_key:
+            continue
+        if not isinstance(value, list):
+            continue
+        for line_index in range(len(value)):
+            yield slot_key, line_index
+
+
+def stamp_zone_html(
+    zone_html: str,
+    slot_payload_or_stamps: Mapping[str, Any] | Iterable[tuple[str, int]],
+) -> str:
+    """Stamp ``text-line`` opening tags in ``zone_html`` with ``data-text-path``.
+
+    The second arg accepts either:
+      - a ``slot_payload`` ``Mapping`` (uses :func:`iter_zone_stamps` order), or
+      - an iterable of pre-built ``(slot_key, line_index)`` tuples.
+
+    Stamps are consumed in left-to-right DOM order. A text-line already
+    carrying ``data-text-path`` is left unchanged (idempotent). Excess
+    text-line elements beyond the stamp sequence are also left unchanged.
+
+    Returns ``zone_html`` unchanged when there are no stamps to apply or
+    the input is not a non-empty string.
+    """
+    if not isinstance(zone_html, str) or not zone_html:
+        return zone_html
+    if isinstance(slot_payload_or_stamps, Mapping):
+        stamps = list(iter_zone_stamps(slot_payload_or_stamps))
+    else:
+        stamps = [
+            (sk, li)
+            for (sk, li) in slot_payload_or_stamps
+            if isinstance(sk, str) and sk and isinstance(li, int)
+            and not isinstance(li, bool) and li >= 0
+        ]
+    if not stamps:
+        return zone_html
+    counter = {"i": 0}
+
+    def _replace(match: re.Match[str]) -> str:
+        attrs = match.group(1) or ""
+        if _HAS_TEXT_PATH_RE.search(attrs):
+            return match.group(0)
+        i = counter["i"]
+        if i >= len(stamps):
+            return match.group(0)
+        counter["i"] = i + 1
+        slot_key, line_index = stamps[i]
+        path = build_text_path(slot_key, line_index)
+        return f'<div {TEXT_PATH_ATTR}="{path}"{attrs}>'
+
+    return _TEXT_LINE_TAG_RE.sub(_replace, zone_html)
@@ -5,14 +5,29 @@ auto-restores user choices without re-clicking. Source of truth = MDX-keyed
 file (stem of the MDX path), NOT ``data/runs/<run_id>/`` which mints a fresh
 run_id per ``/api/run`` invocation.

-Schema (5 axes; stable order; IMP-51 #79 u1 added ``image_overrides``):
+Schema (9 axes; stable order; IMP-51 #79 u1 added ``image_overrides``;
+IMP-45 #74 u1 added ``slide_css``; IMP-55 #93 u1 added
+``manual_section_assignment`` as a bool intent marker so the backend can
+distinguish a user drag-drop from frontend auto-carry zone_sections;
+IMP-56 #90 u1 added ``text_overrides`` as a Step-22 text-edit persist axis
+keyed by ``{zone_id: {text_path: value}}`` where ``text_path`` is the
+``{slot_key}.{line_index}`` stamp emitted by u8; IMP-56 #90 u2 added
+``structure_overrides`` as a Step-22 structure-edit persist axis keyed by
+``{zone_id: {"slot_order": [<slot_key>, ...], "hidden_slots": [<slot_key>, ...]}}``
+— scope is intentionally LOCKED to slot reorder + hide; frame swap stays
+on the existing ``frames`` axis to prevent the Phase Z regression of
+AI-driven HTML structure mutation):

    {
-      "layout":          <string|null>,
-      "zone_geometries": {<zone_id>: {"x": float, "y": float, "w": float, "h": float}},
-      "zone_sections":   {<zone_id>: [<section_id>, ...]},
-      "frames":          {<unit_id>: <template_id>},
-      "image_overrides": {<image_id>: {"x": float, "y": float, "w": float, "h": float}}
+      "layout":                    <string|null>,
+      "zone_geometries":           {<zone_id>: {"x": float, "y": float, "w": float, "h": float}},
+      "zone_sections":             {<zone_id>: [<section_id>, ...]},
+      "frames":                    {<unit_id>: <template_id>},
+      "image_overrides":           {<image_id>: {"x": float, "y": float, "w": float, "h": float}},
+      "slide_css":                 <string|null>,
+      "manual_section_assignment": <bool>,
+      "text_overrides":            {<zone_id>: {<text_path>: <string>}},
+      "structure_overrides":       {<zone_id>: {"slot_order": [<slot_key>, ...], "hidden_slots": [<slot_key>, ...]}}
    }

 ``image_id`` is the stable identifier emitted by the user-content image
@@ -53,16 +68,31 @@ from typing import Any, Optional
 _PKG_ROOT = Path(__file__).resolve().parent.parent
 DEFAULT_OVERRIDES_ROOT = _PKG_ROOT / "data" / "user_overrides"

-# The five in-scope axes (IMP-51 #79 u1 added ``image_overrides``). Any
-# other top-level key in the file is preserved but ignored by callers —
-# keeps the file forward-compatible with future axes (e.g., zone_sizes)
-# without a schema bump here.
+# The nine in-scope axes (IMP-51 #79 u1 added ``image_overrides``; IMP-45
+# #74 u1 added ``slide_css``; IMP-55 #93 u1 added
+# ``manual_section_assignment`` — bool intent marker that gates whether
+# persisted ``zone_sections`` are consumed by the backend pipeline; IMP-56
+# #90 u1 added ``text_overrides`` — Step-22 text-edit persist axis keyed by
+# ``{zone_id: {text_path: value}}`` where ``text_path`` is the
+# ``{slot_key}.{line_index}`` stamp emitted by u8 / consumed by u4+u5;
+# IMP-56 #90 u2 added ``structure_overrides`` — Step-22 structure-edit
+# persist axis keyed by ``{zone_id: {"slot_order": [...], "hidden_slots":
+# [...]}}``, scope LOCKED to slot reorder + hide so the resolver (u6) /
+# Step-12 apply (u7) cannot mutate frame identity — frame swap stays on
+# the existing ``frames`` axis to keep Phase Z's no-AI-HTML-structure
+# invariant intact). Any other top-level key in the file is preserved but
+# ignored by callers — keeps the file forward-compatible with future axes
+# (e.g., zone_sizes) without a schema bump here.
 KNOWN_AXES: tuple[str, ...] = (
    "layout",
    "zone_geometries",
    "zone_sections",
    "frames",
    "image_overrides",
+    "slide_css",
+    "manual_section_assignment",
+    "text_overrides",
+    "structure_overrides",
 )

 # Key validation — MDX stem must be safe for filesystem use. Allow
@@ -474,7 +474,9 @@ bim_dx_comparison_table:
    builder_options:
      item_parser: compare_row_2col_item    # NEW parser — top_bullet → {label, col_a, col_b}
      col_a_label_default: "BIM"            # F1-a (Codex round 43) — explicit default
+      col_a_label_default_role: placeholder # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      col_b_label_default: "DX"             # F1-a — explicit default
+      col_b_label_default_role: placeholder # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      strip_col_prefix_aliases:             # F1-b (Codex round 43) — narrow alias 만 strip
        - "BIM"
        - "DX"
@@ -1785,8 +1787,11 @@ industry_current_status_three_col:
    builder_options:
      item_parser: compare_row_3col_item       # NEW parser placeholder — top_bullet → {label, col_a, col_b, col_c}. Peer parity with compare_row_2col_item.
      col_a_label_default: "제조업"             # F30 source column 1 label (analysis.md three_industries anchor set).
+      col_a_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      col_b_label_default: "건축"               # F30 source column 2 label.
+      col_b_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      col_c_label_default: "토목"               # F30 source column 3 label (강조 테두리 빨간색 cue — visual styling).
+      col_c_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      max_rows: 12                              # typical 4-6, overflow 보호 (peer parity with compare_table_2col max_rows 12).


@@ -1847,6 +1852,9 @@ industry_characteristics_three_col:
    builder_options:
      item_parser: compare_row_3col_item       # Shared parser with industry_current_status_three_col (F30) — top_bullet → {label, col_a, col_b, col_c}. Peer parity with compare_row_2col_item.
      col_a_label_default: "제조업"             # F31 source column 1 label (analysis.md three_industries anchor set; shared with F30).
+      col_a_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      col_b_label_default: "건축"               # F31 source column 2 label (shared with F30).
+      col_b_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      col_c_label_default: "토목"               # F31 source column 3 label (강조 테두리 빨간색 cue — visual styling; shared with F30).
+      col_c_label_default_role: placeholder    # IMP-40 (#69) — Figma visual placeholder; suppressed at runtime, NOT a fallback
      max_rows: 12                              # typical 3-4 (F31 compressed view), overflow 보호 (peer parity with compare_table_2col + F30 compare_table_3col max_rows 12).
@@ -0,0 +1,50 @@
+# IMP-39 single-source ranking sort policy — backend ↔ frontend mirror.
+#
+# 도입 배경 (issue #68):
+#   Backend `lookup_v4_match_with_fallback` 는 V4 raw confidence-desc 순서로
+#   first-eligible 선택 (label_priority 무시). Frontend `designAgentApi.ts` 는
+#   동일 source 를 (label_priority asc, confidence desc) 로 재정렬 후 slice.
+#   결과: 낮은-confidence 높은-priority label 이 raw 상 뒤에 있을 때
+#   backend "rank 1 selected" ≠ frontend `frame_candidates[0]` divergence.
+#
+# 정책 결정 (Stage 1~2 LOCK, 4 round 합의):
+#   - 단일 source 위치 = 본 yaml (catalog hot-reload + frontend mirror 가능)
+#   - frame_contracts.yaml / v4_fallback_policy.yaml 오염 회피 (분리 파일)
+#   - 정렬 axes = (label_priority asc, confidence desc, v4_rank asc)
+#   - tie-break = 원본 v4_rank 보존 (frontend LABEL_PRIORITY 와 1:1)
+#
+# 적용 path:
+#   - backend: src/phase_z2_pipeline.py `apply_ranking_sort` (helper, u1)
+#       + `lookup_v4_match_with_fallback` selector loop (u2)
+#       + `_build_application_plan_unit` Step 9 payload (u3)
+#   - frontend: Front/client/src/services/designAgentApi.ts (u4)
+#       → unit.ranking_sort_policy + unit.sorted_candidate_evidence 우선 read
+#       → local LABEL_PRIORITY 는 warn-fallback only
+
+policy_type: deterministic_label_priority_then_confidence
+
+# label_priority:
+#   lower value = higher priority (use_as_is 가 첫 후보)
+#   sort key = (label_priority asc, confidence desc, v4_rank asc)
+label_priority:
+  use_as_is: 0
+  light_edit: 1
+  restructure: 2
+  reject: 3
+
+# unknown_label_priority:
+#   label 이 위 매트릭스에 없을 시 부여되는 우선순위 (최하위 push).
+#   frontend `LABEL_PRIORITY[label] ?? 99` 와 1:1.
+unknown_label_priority: 99
+
+# tie_break_axes:
+#   동일 label_priority 시 적용 순서 — frontend mirror 와 1:1.
+#   confidence_desc: 큰 confidence 가 앞
+#   v4_rank_asc: 동일 confidence 시 raw v4 rank (1, 2, 3 ...) 작은 게 앞
+tie_break_axes:
+  - confidence_desc
+  - v4_rank_asc
+
+# graceful fallback (yaml 없을 시):
+#   loader 가 default policy_type=deterministic_label_priority_then_confidence
+#   + 위 label_priority 매트릭스 로 fall through (backward compat / boot-safe).
@@ -0,0 +1,242 @@
+<!-- Phase Z-2 MVP-1.5b frame-derived adapted block. -->
+{#
+─────────────────────────────────────────────────────────────────────────────
+Visual Provenance — figma_to_html_agent/blocks/1171281203/ (frame 23)
+─────────────────────────────────────────────────────────────────────────────
+Frame 23 = "Application S/W 의 구분".
+구조 (figma 1:1) :
+  ① title gradient (Application S/W = orange→brown, 의 구분 = green→black)
+  ② CSS Grid table (label col + col_a + col_b)
+  ③ header row :
+     - col 1 (label) = teal #589e8d
+     - col 2 (Package) = teal #589e8d
+     - col 3 (Solution) = orange #ef7a26
+  ④ N data rows : zebra (odd 흰 0.85 / even peach rgba(253,198,158,0.2))
+     - 각 row : 좌측 label cell + 좌 data + 우 data
+     - cell border : 1.5px solid #888
+  ⑤ bullet (•) + accent (.hl orange #a14101, .big 50px 강조)
+
+slots (bim_dx_comparison_table 와 동일 — builder = process_product_pair) :
+  - title                              : section.title (zone 중목차)
+  - col_a_label / col_b_label          : h3 title (Package / Solution 또는 mdx h3 title)
+  - col_a_body.sections[].title         : subsection title (= row label)
+  - col_a_body.sections[].text_lines / transforms
+  - col_b_body                         : same
+
+Axis A+B fit — container query (cqh) + jinja line count 산식.
+─────────────────────────────────────────────────────────────────────────────
+#}
+
+<style>
+  .f23b {
+    width: 100%; height: 100%;
+    display: flex; flex-direction: column;
+    gap: 4px;
+    font-family: 'Noto Sans KR', 'Pretendard', sans-serif;
+    word-break: keep-all;
+    container-type: size;
+    container-name: f23b-root;
+  }
+  /* 중목차 (zone title) — gradient 보존, 사용자 룰 (미변경). */
+  .f23b__title {
+    font-size: var(--font-zone-title);
+    font-weight: 700;
+    line-height: var(--lh-zone-title);
+    background-image: linear-gradient(180deg, #000 0%, #883700 100%);
+    -webkit-background-clip: text; background-clip: text;
+    color: transparent;
+    flex-shrink: 0;
+    filter: drop-shadow(0 0 3px rgba(50,44,30,0.4));
+  }
+
+  /* CSS Grid table — 사용자 lock 2026-05-15 : 의미 없는 label col (구분/숫자)
+     제거, 2 col 로 전체 폭 활용. */
+  .f23b__tbl {
+    display: grid;
+    grid-template-columns: 1fr 1fr;
+    grid-auto-rows: minmax(0, auto);
+    flex: 1 1 auto;
+    min-height: 0;
+    overflow: hidden;
+    border-radius: clamp(4px, 1cqh, 8px);
+    border: 1px solid #888;
+  }
+  /* 회전 비활성 — 사용자 lock 2026-05-15 : 03-2 는 2 col table 유지. */
+
+  /* header row */
+  .f23b__th {
+    padding: clamp(4px, 1.5cqh, 10px) clamp(4px, 1cqw, 8px);
+    display: flex; align-items: center; justify-content: center;
+    font-weight: 700;
+    font-size: var(--font-sub-title);
+    line-height: 1.15;
+    color: #fff;
+    text-align: center;
+    letter-spacing: -0.03em;
+    border-right: 1px solid #888;
+  }
+  .f23b__th:last-child { border-right: none; }
+  .f23b__th--label,
+  .f23b__th--a { background: #589e8d; }                    /* figma teal */
+  .f23b__th--b { background: #ef7a26; }                    /* figma orange */
+
+  /* data row cells */
+  .f23b__td {
+    padding: clamp(4px, 1.2cqh, 10px) clamp(4px, 1cqw, 10px);
+    border-top: 1px solid #888;
+    border-right: 1px solid #888;
+    color: #000;
+    font-size: var(--font-body);
+    line-height: clamp(1.2em, calc(70cqh / var(--max-body-lines, 6)), 1.6em);
+    font-weight: 500;
+    overflow: hidden;
+    min-height: 0;
+  }
+  .f23b__td:last-child { border-right: none; }
+  .f23b__td--label {
+    font-weight: 700;
+    text-align: center;
+    display: flex; align-items: center; justify-content: center;
+    font-size: var(--font-sub-title);
+    line-height: 1.2;
+  }
+
+  /* zebra — 첫 번째 data row 가 row N, 두 번째 row 가 N+1 ... */
+  .f23b__row--odd  .f23b__td { background: rgba(255,255,255,0.85); }
+  .f23b__row--even .f23b__td { background: rgba(253,198,158,0.2); }
+
+  /* bullet + accent */
+  .f23b__td .text-line {
+    position: relative;
+    padding-left: clamp(12px, 2cqw, 18px);
+  }
+  .f23b__td .text-line::before {
+    content: "•";
+    position: absolute;
+    left: clamp(2px, 0.5cqw, 6px); top: 0;
+    color: #555;
+    font-weight: 700;
+    line-height: inherit;
+  }
+  .f23b__td .text-line strong { font-weight: 700; color: #a14101; }   /* figma .hl */
+  .f23b__td .accent           { font-weight: 700; color: #a14101; }
+  .f23b__td .text-line--sub   { padding-left: clamp(20px, 4cqw, 28px); color: #444; }
+  .f23b__td .text-line--sub::before {
+    content: "\25B8";                                       /* ▸ */
+    left: clamp(8px, 1.5cqw, 14px);
+    color: #888;
+    font-size: 0.85em;
+  }
+
+  /* AS-IS/TO-BE mini transforms (콘텐츠 무손실 + 내용 기반 폭). 사용자 lock
+     2026-05-15 : 표 안 내용이 좌측정렬 환경이라 mini table 도 좌측 정렬.
+     cell 안 텍스트는 그대로 center align. */
+  .f23b__transforms {
+    display: table;
+    margin-left: 0;
+    margin-right: auto;
+    border-collapse: separate;
+    border-spacing: 6px 1px;
+    font-size: 0.95em;
+  }
+  .f23b__transforms-head,
+  .f23b__transforms-row { display: table-row; }
+  .f23b__transforms-head > * {
+    display: table-cell;
+    text-align: center;
+    font-weight: 900;
+    font-size: 0.85em;
+    color: #6b4423;
+    padding: 0 4px 1px;
+    border-bottom: 1px solid rgba(107,68,35,0.3);
+  }
+  .f23b__transforms-cell,
+  .f23b__transforms-arrow {
+    display: table-cell;
+    text-align: center;
+    padding: 1px 6px;
+    vertical-align: middle;
+  }
+  .f23b__transforms-cell { color: #1a1a1a; font-weight: 500; }
+  .f23b__transforms-cell--to { color: #a14101; font-weight: 700; }
+  .f23b__transforms-arrow { font-weight: 700; color: #9c6f3f; }
+
+  /* row title (subsection label) — figma 의 좌측 td-label 같은 row-bound label */
+  .f23b__item-title {
+    font-weight: 900;
+    color: #6b4423;
+    margin-bottom: 2px;
+    font-size: 0.95em;
+  }
+</style>
+
+<div class="f23b" data-frame-id="1171281203" data-template-id="app_sw_package_vs_solution">
+
+  <div class="f23b__title">{{ slot_payload.title }}</div>
+
+  <div class="f23b__tbl">
+    {# header row — 2 col (label col 제거, 사용자 lock 2026-05-15) #}
+    <div class="f23b__th f23b__th--a">{{ slot_payload.col_a_label | safe }}</div>
+    <div class="f23b__th f23b__th--b">{{ slot_payload.col_b_label | safe }}</div>
+
+    {# data rows — col_a_body.sections 와 col_b_body.sections 를 row 별 페어 #}
+    {% set a_secs = slot_payload.col_a_body.sections or [] %}
+    {% set b_secs = slot_payload.col_b_body.sections or [] %}
+    {% set row_count = [a_secs | length, b_secs | length] | max %}
+    {% for i in range(row_count) %}
+      {% set a = a_secs[i] if i < (a_secs | length) else none %}
+      {% set b = b_secs[i] if i < (b_secs | length) else none %}
+      {% set row_class = 'f23b__row--' ~ ('odd' if loop.index0 % 2 == 0 else 'even') %}
+
+      {# col_a cell #}
+      <div class="f23b__td {{ row_class }}" style="--max-body-lines: {{ (a.text_lines | length if a and a.text_lines else 1) + (a.transforms | length if a and a.transforms else 0) }};">
+        {% if a %}
+          {% if a.title %}<div class="f23b__item-title">{{ a.title | safe }}</div>{% endif %}
+          {% if a.transforms %}
+          <div class="f23b__transforms">
+            <div class="f23b__transforms-head">
+              <span class="f23b__transforms-from">AS-IS</span>
+              <span></span>
+              <span class="f23b__transforms-to">TO-BE</span>
+            </div>
+            {% for t in a.transforms %}
+            <div class="f23b__transforms-row">
+              <div class="f23b__transforms-cell f23b__transforms-cell--from">{{ t.from | safe }}</div>
+              <div class="f23b__transforms-arrow">➜</div>
+              <div class="f23b__transforms-cell f23b__transforms-cell--to">{{ t.to | safe }}</div>
+            </div>
+            {% endfor %}
+          </div>
+          {% elif a.text_lines %}
+          {% for line in a.text_lines %}<div class="text-line{% if line.indent and line.indent > 0 %} text-line--sub{% endif %}">{{ line.text | safe }}</div>{% endfor %}
+          {% endif %}
+        {% endif %}
+      </div>
+
+      {# col_b cell #}
+      <div class="f23b__td {{ row_class }}" style="--max-body-lines: {{ (b.text_lines | length if b and b.text_lines else 1) + (b.transforms | length if b and b.transforms else 0) }};">
+        {% if b %}
+          {% if b.title %}<div class="f23b__item-title">{{ b.title | safe }}</div>{% endif %}
+          {% if b.transforms %}
+          <div class="f23b__transforms">
+            <div class="f23b__transforms-head">
+              <span class="f23b__transforms-from">AS-IS</span>
+              <span></span>
+              <span class="f23b__transforms-to">TO-BE</span>
+            </div>
+            {% for t in b.transforms %}
+            <div class="f23b__transforms-row">
+              <div class="f23b__transforms-cell f23b__transforms-cell--from">{{ t.from | safe }}</div>
+              <div class="f23b__transforms-arrow">➜</div>
+              <div class="f23b__transforms-cell f23b__transforms-cell--to">{{ t.to | safe }}</div>
+            </div>
+            {% endfor %}
+          </div>
+          {% elif b.text_lines %}
+          {% for line in b.text_lines %}<div class="text-line{% if line.indent and line.indent > 0 %} text-line--sub{% endif %}">{{ line.text | safe }}</div>{% endfor %}
+          {% endif %}
+        {% endif %}
+      </div>
+    {% endfor %}
+  </div>
+</div>
@@ -0,0 +1,194 @@
+<!-- Phase Z-2 신규 frame partial — Frame 9 (1171281180) pre_construction_model_info_stacked.
+     2026-05-14 — V4 04-1 top rank-1 매칭 (의미 conf=0.722) + structure cardinality 5 일치.
+     사용자 룰 부합 : Figma visual (계단 pill / 5 색상 / vertical label) 유지 + 콘텐츠 cardinality
+     에 맞춰 보완 (pill 안 1 라인 → multi-line: pill_N_label + pill_N_body). -->
+{#
+─────────────────────────────────────────────────────────────────────────────
+Visual Provenance — figma_to_html_agent/blocks/1171281180/index.html
+─────────────────────────────────────────────────────────────────────────────
+PROMOTED (Figma 1:1):
+  - title-bar background : #fbd5b9 (line 43) + box-shadow
+  - title text gradient   : #cc5200 (line 128) 강조부
+  - vertical label color  : #144838 (line 68) + text-shadow drop
+  - pill background       : rgba(255,255,255,0.5) (line 88)
+  - pill border-radius    : 30px (line 89)
+  - pill box-shadow       : 2px 4px 5px rgba(0,0,0,0.5) (line 90)
+  - 5 pill border-bottom 색상 (line 141, 147, 153, 159, 165):
+      1: #fb5915, 2: #e79000, 3: #e9a804, 4: #919f00, 5: #0d6361
+
+ADAPTED (zone flex 재구성):
+  - 1153×592 absolute → flex column layout
+  - pill height 70px hardcode → dynamic (콘텐츠 양에 따라 auto)
+  - 계단 배치 (width/margin-left hardcode) → 가운데 정렬 + width 100%
+    (계단은 1 라인 짧은 텍스트 전제, multi-line 콘텐츠엔 부적합)
+  - 1 pill 1 라인 → pill_N_label (title) + pill_N_body (text_lines)
+    (사용자 룰 = frame 구조를 콘텐츠에 맞춰 보완)
+
+NOT PROMOTED:
+  - 좌측 arc-deco SVG (장식 — 공간 절약 위해 단순화)
+  - arrow PNG (CSS triangle 대체 가능, 일단 ▶ 문자 사용)
+
+slots : title + pill_N_label / pill_N_body (N = 1.._slot_count) — dynamic.
+#}
+
+<style>
+  .f9b {
+    width: 100%; height: 100%;
+    display: flex; flex-direction: column;
+    gap: 6px;
+    font-family: 'Noto Sans KR', 'Pretendard', sans-serif;
+    word-break: keep-all;
+    position: relative;
+  }
+
+  /* 2026-05-14 — title 스타일 통일 (frame 29 process_product_two_way 와 동일 패턴) :
+     배경 box + box-shadow 제거, gradient 텍스트 만 유지. 사용자 룰 Q1. */
+  .f9b__title {
+    font-size: var(--font-zone-title);
+    font-weight: 700;
+    line-height: var(--lh-zone-title);
+    background-image: linear-gradient(180deg, #000 0%, #883700 100%);
+    -webkit-background-clip: text; background-clip: text;
+    color: transparent;
+    flex-shrink: 0;
+    padding-left: 4px;
+  }
+
+  .f9b__body {
+    flex: 1;
+    display: flex;
+    flex-direction: row;
+    gap: 8px;
+    min-height: 0;
+  }
+
+  /* 좌측 vertical label — 콘텐츠 있을 때만 표시 */
+  .f9b__vlabel {
+    flex: 0 0 auto;
+    width: 56px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    font-weight: 700;
+    font-size: var(--font-sub-title);
+    line-height: 1.2;
+    color: #144838;
+    text-align: center;
+    writing-mode: vertical-rl;
+    text-orientation: upright;
+    text-shadow: 0 2px 2px rgba(0,0,0,0.15);
+  }
+
+  /* 2026-05-14 — pill 배치 vertical → horizontal (grid). 5 pills 를 가로로 나열 →
+     우측 공란 활용 + 세로 공간 절약. auto-fit + minmax 으로 N 동적.
+     gap 넓찍 (사용자 lock 2026-05-14). */
+  .f9b__pill-rows {
+    flex: 1;
+    display: grid;
+    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
+    gap: 10px;
+    min-height: 0;
+  }
+
+  /* 2026-05-14 — bullet 줄간격 1/3 으로 압축 + 다른 간격 (padding, label↔body) 살짝 늘림. */
+  .f9b__pill {
+    min-height: 0;
+    background: rgba(255,255,255,0.7);
+    border-radius: 10px;
+    border-bottom: 3px solid;
+    box-shadow: 1px 2px 4px rgba(0,0,0,0.15);
+    padding: 8px 12px;
+    display: flex;
+    flex-direction: column;
+    gap: 5px;
+    overflow: hidden;
+    align-self: start;
+  }
+  /* Figma frame 9 의 5 색상 — nth-child cycle. N>5 면 default border-bottom 색 (회색). */
+  .f9b__pill:nth-child(5n+1) { border-bottom-color: #fb5915; }
+  .f9b__pill:nth-child(5n+2) { border-bottom-color: #e79000; }
+  .f9b__pill:nth-child(5n+3) { border-bottom-color: #e9a804; }
+  .f9b__pill:nth-child(5n+4) { border-bottom-color: #919f00; }
+  .f9b__pill:nth-child(5n)   { border-bottom-color: #0d6361; }
+
+  .f9b__pill-label {
+    font-size: var(--font-sub-title);
+    font-weight: 900;
+    line-height: 1.2;
+    color: #144838;
+    margin-bottom: 4px;
+    display: flex;
+    align-items: center;
+    gap: 6px;
+  }
+  /* arrow indicator — Figma frame 9 의 좌측 화살표 (▶) approximation */
+  .f9b__pill-label::before {
+    content: "▶";
+    flex-shrink: 0;
+    color: currentColor;
+    font-size: 0.85em;
+  }
+
+  /* 2026-05-14 — bullet 줄간격 1/3 으로 압축 : line-height 1.3 → 1.05 (약 1/3 감소).
+     bullet 간 gap 2 → 1 로 더 압축. 가독성 임계 (한 bullet 안 line wrap 시 라인 겹침 직전). */
+  .f9b__pill-body {
+    flex: 1 1 auto;
+    overflow: hidden;
+    min-height: 0;
+    color: #0c271e;
+    font-size: var(--font-body);
+    line-height: 1.05;
+    display: flex;
+    flex-direction: column;
+    gap: 1px;
+  }
+
+  /* 첫 line = 인용구 (italic + 무 마커) — 04-1 의 따옴표 인용구 패턴 */
+  .f9b__pill-body .text-line:first-child {
+    font-style: italic;
+    color: #5C3714;
+    padding-left: 0;
+  }
+  /* 이후 lines = 각 이슈 bullet (▪ 마커로 구분 강화) */
+  .f9b__pill-body .text-line:not(:first-child) {
+    position: relative;
+    padding-left: 12px;
+  }
+  .f9b__pill-body .text-line:not(:first-child)::before {
+    content: "▪";
+    position: absolute;
+    left: 0;
+    color: #919f00;
+    font-size: 0.9em;
+  }
+</style>
+
+<div class="f9b" data-frame-id="1171281180" data-template-id="pre_construction_model_info_stacked">
+  <div class="f9b__title">{{ slot_payload.title }}</div>
+  <div class="f9b__body">
+    {# vertical label — slot_payload.vlabel 있을 때만 표시 (현재 v0 미사용) #}
+    {% if slot_payload.vlabel %}
+    <div class="f9b__vlabel">{{ slot_payload.vlabel | safe }}</div>
+    {% endif %}
+
+    <div class="f9b__pill-rows">
+      {% set slot_count = slot_payload._slot_count or 5 %}
+      {% for n in range(1, slot_count + 1) %}
+        {% set label = slot_payload['pill_' ~ n ~ '_label'] %}
+        {% set body = slot_payload['pill_' ~ n ~ '_body'] %}
+        {% if label or body %}
+        <div class="f9b__pill" data-frame-slot-id="pill_dynamic" data-pill-n="{{ n }}">
+          {% if label %}
+          <div class="f9b__pill-label">{{ label | safe }}</div>
+          {% endif %}
+          {% if body %}
+          <div class="f9b__pill-body">
+            {% for line in body %}<div class="text-line{% if line.indent and line.indent > 0 %} text-line--indent-{{ line.indent }}{% endif %}">{{ line.text | safe }}</div>{% endfor %}
+          </div>
+          {% endif %}
+        </div>
+        {% endif %}
+      {% endfor %}
+    </div>
+  </div>
+</div>
@@ -114,42 +114,10 @@
      min-height: 0;
    }

-    /* ── IMP-30 u5 : provisional zone marker (first-render invariant) ──
-         When V4 rank-1 candidate falls outside MVP1_ALLOWED_STATUSES (chain_exhausted)
-         the pipeline still renders the rank-1 frame so the first-render invariant
-         holds, but the zone is tagged `provisional` so the user/AI can adapt later
-         (IMP-31). Visual contract:
-           - dashed amber border + striped wash → "needs adaptation" at a glance
-           - inline badge top-right → text label for non-color-perceiving readers
-         MDX content is preserved as-is; no shrink, no rewrite. */
-    .zone--provisional {
-      outline: 2px dashed #b8860b;
-      outline-offset: -2px;
-      background-image: repeating-linear-gradient(
-        45deg,
-        rgba(184, 134, 11, 0.04) 0,
-        rgba(184, 134, 11, 0.04) 8px,
-        transparent 8px,
-        transparent 16px
-      );
-    }
-    .zone--provisional .zone__needs-adaptation-badge {
-      position: absolute;
-      top: 4px;
-      right: 4px;
-      z-index: 10;
-      padding: 2px 6px;
-      background: #b8860b;
-      color: #fff;
-      font-size: 9px;
-      font-weight: 700;
-      line-height: 1.2;
-      letter-spacing: 0.04em;
-      border-radius: 2px;
-      text-transform: uppercase;
-      pointer-events: none;
-      box-shadow: 0 1px 2px rgba(0, 0, 0, 0.15);
-    }
+    /* IMP-84: provisional zone visual treatment removed (silent-automation
+       policy). `data-provisional="1"` attribute is still emitted on the
+       zone div as silent telemetry for downstream selectors / inspection;
+       no user-visible outline, wash, or badge. */

    /* ── Frame-family text layout contract (shared, reusable) ──
         feedback-1 (mvp1.5b_test7): visible improvement 강화.
@@ -355,6 +323,38 @@
      line-height: 1.5;
      color: #1e293b;
    }
+
+    /* ── IMP-90 u17 : print mode (Step 22 user-edit + Export).
+         Companion JS at body end opens popups so FULL raw_content prints. */
+    @media print {
+      @page { size: 1280px 720px; margin: 0; }
+      html, body {
+        background: #fff !important;
+        padding: 0 !important;
+        margin: 0 !important;
+        min-height: 0 !important;
+        display: block !important;
+      }
+      .slide {
+        box-shadow: none !important;
+        page-break-inside: avoid;
+        break-inside: avoid;
+      }
+      .zone__popup-summary { display: none !important; }
+      .zone__popup-details,
+      .zone__popup-details[open] { position: static !important; }
+      .zone__popup-body {
+        position: static !important;
+        top: auto !important;
+        right: auto !important;
+        max-height: none !important;
+        overflow: visible !important;
+        box-shadow: none !important;
+        border: none !important;
+        width: auto !important;
+        padding: 6px 0 0 0 !important;
+      }
+    }
  </style>
 </head>
 <body>
@@ -366,8 +366,7 @@
    <div class="slide-body">
      <div class="layout-{{ layout_preset }}">
        {% for zone in zones %}
-        <div class="zone{% if zone.provisional %} zone--provisional{% endif %}" data-zone-position="{{ zone.position }}" data-template-id="{{ zone.template_id }}"{% if zone.provisional %} data-provisional="1"{% endif %}{% if zone.has_popup %} data-has-popup="1"{% endif %} style="grid-area: {{ zone.position }};">
-          {% if zone.provisional %}<span class="zone__needs-adaptation-badge" aria-label="needs user or AI adaptation">needs adaptation</span>{% endif %}
+        <div class="zone" data-zone-position="{{ zone.position }}" data-template-id="{{ zone.template_id }}"{% if zone.provisional %} data-provisional="1"{% endif %}{% if zone.has_popup %} data-has-popup="1"{% endif %} style="grid-area: {{ zone.position }};">
          {{ zone.partial_html | safe }}
          {% if zone.has_popup %}
          {% set _popup_trigger = (zone.popup_binding.detail_trigger if zone.popup_binding else None) or {} %}
@@ -389,5 +388,22 @@
    </div>
    {% endif %}
  </div>
+  <script>
+  // IMP-90 u17 — beforeprint popup auto-expand (CLAUDE.md 자세히보기 contract).
+  // Body-level handler (outside any per-zone popup block) so the popup-render
+  // JS-free invariant (IMP-35 u8) is preserved on the per-zone path.
+  window.addEventListener('beforeprint', function () {
+    document.querySelectorAll('details').forEach(function (d) {
+      d.dataset.imp90PrintRestore = d.open ? '1' : '0';
+      d.open = true;
+    });
+  });
+  window.addEventListener('afterprint', function () {
+    document.querySelectorAll('details').forEach(function (d) {
+      if (d.dataset.imp90PrintRestore === '0') d.open = false;
+      delete d.dataset.imp90PrintRestore;
+    });
+  });
+  </script>
 </body>
 </html>
@@ -0,0 +1,73 @@
+{
+  "_doc": "IMP-91 u9 — F3 classifier-only AI axis. Pin observed step12 per-unit classifier label / route_hint / AI-isolation flags + coverage_invariant + step15 fit_classification + step16 router_active + step18 failure_type. Default-OFF AI invariant ([[feedback_ai_isolation_contract]]): ai_called MUST be False for every unit unless AI_FALLBACK_ENABLED is flipped via .env (not via pipeline default). If any unit flips ai_called=True silently, this snapshot fails loudly per [[feedback_demo_env_toggle_policy]].",
+  "01": {
+    "units": [
+      {"source_section_ids": ["01-2"], "label": "use_as_is", "route_hint": "direct_render", "provisional": false, "ai_called": false, "skip_reason": "not_provisional", "apply_status": "no_proposal"},
+      {"source_section_ids": ["01-1"], "label": "use_as_is", "route_hint": "direct_render", "provisional": false, "ai_called": false, "skip_reason": "not_provisional", "apply_status": "no_proposal"}
+    ],
+    "coverage_invariant_status": "ok",
+    "fit_visual_check_passed": true,
+    "fit_classifications_count": 0,
+    "fit_categories_seen": [],
+    "router_active": false,
+    "router_routed_count": 0,
+    "router_v4_fallback_used_count": 0,
+    "failure_type": "not_attempted"
+  },
+  "02": {
+    "units": [
+      {"source_section_ids": ["02-1"], "label": "use_as_is", "route_hint": "direct_render", "provisional": false, "ai_called": false, "skip_reason": "not_provisional", "apply_status": "no_proposal"},
+      {"source_section_ids": ["02-2-sub-1", "02-2-sub-2"], "label": "use_as_is", "route_hint": "direct_render", "provisional": true, "ai_called": false, "skip_reason": "route_not_ai_adaptation:direct_render", "apply_status": "no_proposal"}
+    ],
+    "coverage_invariant_status": "ok",
+    "fit_visual_check_passed": true,
+    "fit_classifications_count": 0,
+    "fit_categories_seen": [],
+    "router_active": false,
+    "router_routed_count": 0,
+    "router_v4_fallback_used_count": 0,
+    "failure_type": "not_attempted"
+  },
+  "03": {
+    "units": [
+      {"source_section_ids": ["03-1"], "label": "use_as_is", "route_hint": "direct_render", "provisional": false, "ai_called": false, "skip_reason": "not_provisional", "apply_status": "no_proposal"},
+      {"source_section_ids": ["03-2"], "label": "use_as_is", "route_hint": "direct_render", "provisional": false, "ai_called": false, "skip_reason": "not_provisional", "apply_status": "no_proposal"}
+    ],
+    "coverage_invariant_status": "ok",
+    "fit_visual_check_passed": true,
+    "fit_classifications_count": 0,
+    "fit_categories_seen": [],
+    "router_active": false,
+    "router_routed_count": 0,
+    "router_v4_fallback_used_count": 0,
+    "failure_type": "not_attempted"
+  },
+  "04": {
+    "units": [
+      {"source_section_ids": ["04-2-sub-2"], "label": "light_edit", "route_hint": "deterministic_minor_adjustment", "provisional": false, "ai_called": false, "skip_reason": "not_provisional", "apply_status": "no_proposal"},
+      {"source_section_ids": ["04-2-sub-1"], "label": "restructure", "route_hint": "ai_adaptation_required", "provisional": true, "ai_called": false, "skip_reason": "router_short_circuit", "apply_status": "no_proposal"},
+      {"source_section_ids": ["04-1"], "label": "reject", "route_hint": "ai_adaptation_required", "provisional": true, "ai_called": false, "skip_reason": "router_short_circuit", "apply_status": "no_proposal"}
+    ],
+    "coverage_invariant_status": "ok",
+    "fit_visual_check_passed": true,
+    "fit_classifications_count": 0,
+    "fit_categories_seen": [],
+    "router_active": false,
+    "router_routed_count": 0,
+    "router_v4_fallback_used_count": 0,
+    "failure_type": "not_attempted"
+  },
+  "05": {
+    "units": [
+      {"source_section_ids": ["05-1", "05-2-sub-1", "05-2-sub-2"], "label": "empty_shell", "route_hint": null, "provisional": true, "ai_called": false, "skip_reason": "route_not_ai_adaptation:None", "apply_status": "no_proposal"}
+    ],
+    "coverage_invariant_status": "ok",
+    "fit_visual_check_passed": true,
+    "fit_classifications_count": 0,
+    "fit_categories_seen": [],
+    "router_active": false,
+    "router_routed_count": 0,
+    "router_v4_fallback_used_count": 0,
+    "failure_type": "not_attempted"
+  }
+}
@@ -0,0 +1,43 @@
+{
+  "_doc": "IMP-#91 u5 — full_mdx_coverage / aligned_section_ids / covered_section_ids / filtered_section_ids snapshot pinned from observed step20_slide_status.json across MDX_SET (mdx 01-05). Drift = real change in coverage outcome; re-baseline only with conscious explanation in commit body.",
+  "01": {
+    "full_mdx_coverage": true,
+    "rendered": true,
+    "visual_check_passed": true,
+    "aligned_section_ids": ["01-1", "01-2"],
+    "covered_section_ids": ["01-1", "01-2"],
+    "filtered_section_ids": []
+  },
+  "02": {
+    "full_mdx_coverage": true,
+    "rendered": true,
+    "visual_check_passed": true,
+    "aligned_section_ids": ["02-1", "02-2-sub-1", "02-2-sub-2"],
+    "covered_section_ids": ["02-1", "02-2-sub-1", "02-2-sub-2"],
+    "filtered_section_ids": []
+  },
+  "03": {
+    "full_mdx_coverage": true,
+    "rendered": true,
+    "visual_check_passed": true,
+    "aligned_section_ids": ["03-1", "03-2"],
+    "covered_section_ids": ["03-1", "03-2"],
+    "filtered_section_ids": []
+  },
+  "04": {
+    "full_mdx_coverage": true,
+    "rendered": true,
+    "visual_check_passed": true,
+    "aligned_section_ids": ["04-1", "04-2-sub-1", "04-2-sub-2"],
+    "covered_section_ids": ["04-1", "04-2-sub-1", "04-2-sub-2"],
+    "filtered_section_ids": []
+  },
+  "05": {
+    "full_mdx_coverage": false,
+    "rendered": true,
+    "visual_check_passed": true,
+    "aligned_section_ids": ["05-1", "05-2-sub-1", "05-2-sub-2"],
+    "covered_section_ids": ["05-1", "05-2-sub-1", "05-2-sub-2"],
+    "filtered_section_ids": ["05-1", "05-2-sub-1", "05-2-sub-2"]
+  }
+}
@@ -0,0 +1,88 @@
+{
+  "_doc": "IMP-91 u11 — F5 final.html extraction axis. Pin step13_render.json metadata (step_status / pipeline_path_connected / render_inputs.zones_count / render_inputs.layout_preset / slide_title|footer non-empty / final_html_size_bytes) AND structural markers extracted from the on-disk final.html (HTML <title>, slide root count, slide-footer presence, data-zone-position/data-template-id topology). The HTML-extracted zone topology MUST match the step12 slot_payload (position, template_id) sequence already pinned in slot_payload.json (u8) — Jinja2 renders from step12, not step09, so step12 is the correct upstream parity source (step09 selection vs step12 __empty__ collapse is intentional per IMP-87 honesty gate and surfaces in u8). Drift between final.html and slot_payload = render pipeline disconnect. on-disk final.html size_bytes MUST equal step13's reported final_html_size_bytes (byte parity = no truncation / no double-write race).",
+  "01": {
+    "step13_status": "done",
+    "step13_pipeline_path_connected": true,
+    "render_inputs_zones_count": 2,
+    "render_inputs_layout_preset": "horizontal-2",
+    "render_inputs_slide_title_nonempty": true,
+    "render_inputs_slide_footer_nonempty": true,
+    "html_title_matches_render_input": true,
+    "html_slide_root_count": 1,
+    "html_slide_footer_present": true,
+    "html_zone_count": 2,
+    "html_zone_topology": [
+      {"position": "top", "template_id": "bim_dx_comparison_table"},
+      {"position": "bottom", "template_id": "construction_bim_three_usage"}
+    ],
+    "final_html_size_matches_step13_reported": true
+  },
+  "02": {
+    "step13_status": "done",
+    "step13_pipeline_path_connected": true,
+    "render_inputs_zones_count": 2,
+    "render_inputs_layout_preset": "horizontal-2",
+    "render_inputs_slide_title_nonempty": true,
+    "render_inputs_slide_footer_nonempty": true,
+    "html_title_matches_render_input": true,
+    "html_slide_root_count": 1,
+    "html_slide_footer_present": true,
+    "html_zone_count": 2,
+    "html_zone_topology": [
+      {"position": "top", "template_id": "construction_goals_three_circle_intersection"},
+      {"position": "bottom", "template_id": "__empty__"}
+    ],
+    "final_html_size_matches_step13_reported": true
+  },
+  "03": {
+    "step13_status": "done",
+    "step13_pipeline_path_connected": true,
+    "render_inputs_zones_count": 2,
+    "render_inputs_layout_preset": "vertical-2",
+    "render_inputs_slide_title_nonempty": true,
+    "render_inputs_slide_footer_nonempty": true,
+    "html_title_matches_render_input": true,
+    "html_slide_root_count": 1,
+    "html_slide_footer_present": true,
+    "html_zone_count": 2,
+    "html_zone_topology": [
+      {"position": "left", "template_id": "three_parallel_requirements"},
+      {"position": "right", "template_id": "process_product_two_way"}
+    ],
+    "final_html_size_matches_step13_reported": true
+  },
+  "04": {
+    "step13_status": "done",
+    "step13_pipeline_path_connected": true,
+    "render_inputs_zones_count": 3,
+    "render_inputs_layout_preset": "top-1-bottom-2",
+    "render_inputs_slide_title_nonempty": true,
+    "render_inputs_slide_footer_nonempty": true,
+    "html_title_matches_render_input": true,
+    "html_slide_root_count": 1,
+    "html_slide_footer_present": true,
+    "html_zone_count": 3,
+    "html_zone_topology": [
+      {"position": "top", "template_id": "bim_issues_quadrant_four"},
+      {"position": "bottom-left", "template_id": "__empty__"},
+      {"position": "bottom-right", "template_id": "__empty__"}
+    ],
+    "final_html_size_matches_step13_reported": true
+  },
+  "05": {
+    "step13_status": "done",
+    "step13_pipeline_path_connected": true,
+    "render_inputs_zones_count": 1,
+    "render_inputs_layout_preset": "single",
+    "render_inputs_slide_title_nonempty": true,
+    "render_inputs_slide_footer_nonempty": true,
+    "html_title_matches_render_input": true,
+    "html_slide_root_count": 1,
+    "html_slide_footer_present": true,
+    "html_zone_count": 1,
+    "html_zone_topology": [
+      {"position": "primary", "template_id": "__empty__"}
+    ],
+    "final_html_size_matches_step13_reported": true
+  }
+}
@@ -0,0 +1,133 @@
+{
+  "_doc": "IMP-91 u10 — F4 layout snapshot (step07 + step08). Pins observed layout decision axes (preset / candidates / override / computation / dynamic flags) + planning geometry (heights_px / widths_px / ratios / col_ratios) + per-zone planning shape (position / min_height_px / frame_cardinality_strict / sub_zones_count / region_layout_candidates). step_status='partial' = schema-lock marker per Step 7/8 note (region-level ratio + count-based v0 marker stays a marker, never silently flipped). layout_override_applied=True ONLY for mdx 03 (project_mdx03_frame_lock 2026-05-15 user lock — axis A vertical-2 override). Source: src/phase_z2_pipeline.py step07/step08 emit; auto_layout_preset=None for mdx 05 single-preset path. drift in heights_px/ratios = content_weight_distribution shift; drift in computation = decision-path swap (regression signal axis distinct from preset).",
+  "01": {
+    "step7_step_status": "partial",
+    "step7_pipeline_path_connected": true,
+    "layout_preset": "horizontal-2",
+    "auto_layout_preset": "horizontal-2",
+    "layout_override_applied": false,
+    "zones_count": 2,
+    "unit_count": 2,
+    "layout_candidates": ["horizontal-2", "vertical-2"],
+    "computation": "min_height_first + content_weight_distribution",
+    "dynamic_rows": true,
+    "dynamic_cols": false,
+    "heights_px": [299, 272],
+    "widths_px": [1180],
+    "ratios": [0.511, 0.465],
+    "width_ratios": [1.0],
+    "step8_step_status": "partial",
+    "step8_pipeline_path_connected": true,
+    "zone_heights_px_planned": [299, 272],
+    "zone_widths_px_planned": [1180],
+    "zone_col_ratios_planned": [1.0],
+    "per_zone_layout_shape": [
+      {"position": "top", "min_height_px": 350, "frame_cardinality_strict": 2, "sub_zones_count": 3, "region_layout_candidates": ["region-single"]},
+      {"position": "bottom", "min_height_px": 320, "frame_cardinality_strict": 3, "sub_zones_count": 3, "region_layout_candidates": ["region-single"]}
+    ]
+  },
+  "02": {
+    "step7_step_status": "partial",
+    "step7_pipeline_path_connected": true,
+    "layout_preset": "horizontal-2",
+    "auto_layout_preset": "horizontal-2",
+    "layout_override_applied": false,
+    "zones_count": 2,
+    "unit_count": 2,
+    "layout_candidates": ["horizontal-2", "vertical-2"],
+    "computation": "min_height_first + content_weight_distribution",
+    "dynamic_rows": true,
+    "dynamic_cols": false,
+    "heights_px": [273, 298],
+    "widths_px": [1180],
+    "ratios": [0.467, 0.509],
+    "width_ratios": [1.0],
+    "step8_step_status": "partial",
+    "step8_pipeline_path_connected": true,
+    "zone_heights_px_planned": [273, 298],
+    "zone_widths_px_planned": [1180],
+    "zone_col_ratios_planned": [1.0],
+    "per_zone_layout_shape": [
+      {"position": "top", "min_height_px": 320, "frame_cardinality_strict": 3, "sub_zones_count": 4, "region_layout_candidates": ["region-single"]},
+      {"position": "bottom", "min_height_px": 350, "frame_cardinality_strict": 3, "sub_zones_count": 3, "region_layout_candidates": ["region-single"]}
+    ]
+  },
+  "03": {
+    "step7_step_status": "partial",
+    "step7_pipeline_path_connected": true,
+    "layout_preset": "vertical-2",
+    "auto_layout_preset": "horizontal-2",
+    "layout_override_applied": true,
+    "zones_count": 2,
+    "unit_count": 2,
+    "layout_candidates": ["horizontal-2", "vertical-2"],
+    "computation": "user_override_geometry",
+    "dynamic_rows": false,
+    "dynamic_cols": true,
+    "heights_px": [585],
+    "widths_px": [408, 758],
+    "ratios": [1.0],
+    "width_ratios": [0.35, 0.65],
+    "step8_step_status": "partial",
+    "step8_pipeline_path_connected": true,
+    "zone_heights_px_planned": [585],
+    "zone_widths_px_planned": [408, 758],
+    "zone_col_ratios_planned": [0.35, 0.65],
+    "per_zone_layout_shape": [
+      {"position": "left", "min_height_px": 230, "frame_cardinality_strict": 3, "sub_zones_count": 3, "region_layout_candidates": ["region-single"]},
+      {"position": "right", "min_height_px": 345, "frame_cardinality_strict": 2, "sub_zones_count": 2, "region_layout_candidates": ["region-single"]}
+    ]
+  },
+  "04": {
+    "step7_step_status": "partial",
+    "step7_pipeline_path_connected": true,
+    "layout_preset": "top-1-bottom-2",
+    "auto_layout_preset": "top-1-bottom-2",
+    "layout_override_applied": false,
+    "zones_count": 3,
+    "unit_count": 3,
+    "layout_candidates": ["top-1-bottom-2", "top-2-bottom-1", "left-1-right-2", "left-2-right-1"],
+    "computation": "2d_dynamic_aggregated",
+    "dynamic_rows": true,
+    "dynamic_cols": true,
+    "heights_px": [221, 350],
+    "widths_px": [583, 583],
+    "ratios": [0.378, 0.598],
+    "width_ratios": [0.494, 0.494],
+    "step8_step_status": "partial",
+    "step8_pipeline_path_connected": true,
+    "zone_heights_px_planned": [221, 350],
+    "zone_widths_px_planned": [583, 583],
+    "zone_col_ratios_planned": [0.494, 0.494],
+    "per_zone_layout_shape": [
+      {"position": "top", "min_height_px": null, "frame_cardinality_strict": null, "sub_zones_count": 4, "region_layout_candidates": ["region-single"]},
+      {"position": "bottom-left", "min_height_px": 350, "frame_cardinality_strict": 4, "sub_zones_count": 5, "region_layout_candidates": ["region-single"]},
+      {"position": "bottom-right", "min_height_px": 350, "frame_cardinality_strict": null, "sub_zones_count": 1, "region_layout_candidates": ["region-single"]}
+    ]
+  },
+  "05": {
+    "step7_step_status": "partial",
+    "step7_pipeline_path_connected": true,
+    "layout_preset": "single",
+    "auto_layout_preset": null,
+    "layout_override_applied": false,
+    "zones_count": 1,
+    "unit_count": 1,
+    "layout_candidates": ["single"],
+    "computation": "fr_default_from_preset",
+    "dynamic_rows": false,
+    "dynamic_cols": false,
+    "heights_px": [585],
+    "widths_px": [1180],
+    "ratios": [1.0],
+    "width_ratios": [1.0],
+    "step8_step_status": "partial",
+    "step8_pipeline_path_connected": true,
+    "zone_heights_px_planned": [585],
+    "zone_widths_px_planned": [1180],
+    "zone_col_ratios_planned": [1.0],
+    "per_zone_layout_shape": [
+      {"position": "primary", "min_height_px": null, "frame_cardinality_strict": null, "sub_zones_count": 0, "region_layout_candidates": ["region-single"]}
+    ]
+  }
+}
@@ -0,0 +1,83 @@
+{
+  "_doc": "IMP-91 u6 — F0 normalize axis snapshot (step02_normalized.json). Pins observed current state per [[feedback_validation_first_for_closed_issues]] / Stage 1 'do not invent a new expectation'. step_status='partial' is the schema-lock marker for IMP-02/03 (orphans + details detection unimplemented). adapter_enabled/used=false reflects default-OFF canary (chained adapter trace OFF). asset counts are step02 collection state (popups/images/tables list aggregation in stage0_normalized_assets); they may grow when IMP-03 detection lands and the snapshot will drift loudly.",
+  "01": {
+    "step_num": 2,
+    "step_status": "partial",
+    "pipeline_path_connected": true,
+    "sections_count": 2,
+    "section_ids": ["01-1", "01-2"],
+    "orphans_count": 0,
+    "details_count": 0,
+    "adapter_enabled": false,
+    "adapter_used": false,
+    "assets_popups_count": 0,
+    "assets_images_count": 0,
+    "assets_tables_count": 0,
+    "slide_title_nonempty": true,
+    "slide_footer_nonempty": true
+  },
+  "02": {
+    "step_num": 2,
+    "step_status": "partial",
+    "pipeline_path_connected": true,
+    "sections_count": 2,
+    "section_ids": ["02-1", "02-2"],
+    "orphans_count": 0,
+    "details_count": 0,
+    "adapter_enabled": false,
+    "adapter_used": false,
+    "assets_popups_count": 0,
+    "assets_images_count": 0,
+    "assets_tables_count": 0,
+    "slide_title_nonempty": true,
+    "slide_footer_nonempty": true
+  },
+  "03": {
+    "step_num": 2,
+    "step_status": "partial",
+    "pipeline_path_connected": true,
+    "sections_count": 2,
+    "section_ids": ["03-1", "03-2"],
+    "orphans_count": 0,
+    "details_count": 0,
+    "adapter_enabled": false,
+    "adapter_used": false,
+    "assets_popups_count": 0,
+    "assets_images_count": 0,
+    "assets_tables_count": 0,
+    "slide_title_nonempty": true,
+    "slide_footer_nonempty": true
+  },
+  "04": {
+    "step_num": 2,
+    "step_status": "partial",
+    "pipeline_path_connected": true,
+    "sections_count": 2,
+    "section_ids": ["04-1", "04-2"],
+    "orphans_count": 0,
+    "details_count": 0,
+    "adapter_enabled": false,
+    "adapter_used": false,
+    "assets_popups_count": 0,
+    "assets_images_count": 0,
+    "assets_tables_count": 0,
+    "slide_title_nonempty": true,
+    "slide_footer_nonempty": true
+  },
+  "05": {
+    "step_num": 2,
+    "step_status": "partial",
+    "pipeline_path_connected": true,
+    "sections_count": 2,
+    "section_ids": ["05-1", "05-2"],
+    "orphans_count": 0,
+    "details_count": 0,
+    "adapter_enabled": false,
+    "adapter_used": false,
+    "assets_popups_count": 0,
+    "assets_images_count": 0,
+    "assets_tables_count": 0,
+    "slide_title_nonempty": true,
+    "slide_footer_nonempty": true
+  }
+}
@@ -0,0 +1,103 @@
+{
+  "_doc": "IMP-#91 u8 — F2 slot_payload axis. Pins step12_slot_payload.json per_zone structural shape (position / template_id / builder / slot_names / list_slot_counts / dict_slot_sub_counts / string_slot_nonempty) for mdx 01-05. Pins SHAPE not literal content — text edits in MDX won't drift this snapshot, but builder swap / slot rename / missing slot / list-cardinality drift will. __empty__ zones have builder=null and zero slots.",
+  "01": [
+    {
+      "position": "top",
+      "template_id": "bim_dx_comparison_table",
+      "builder": "compare_table_2col",
+      "slot_names": ["col_a_label", "col_b_label", "rows", "title"],
+      "list_slot_counts": {"rows": 2},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {"col_a_label": false, "col_b_label": false, "title": true}
+    },
+    {
+      "position": "bottom",
+      "template_id": "construction_bim_three_usage",
+      "builder": "quadrant_flat_slots",
+      "slot_names": ["category_1_body", "category_1_label", "category_2_body", "category_2_label", "category_3_body", "category_3_label", "title"],
+      "list_slot_counts": {"category_1_body": 2, "category_2_body": 2, "category_3_body": 2},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {"category_1_label": true, "category_2_label": true, "category_3_label": true, "title": true}
+    }
+  ],
+  "02": [
+    {
+      "position": "top",
+      "template_id": "construction_goals_three_circle_intersection",
+      "builder": "cycle_intersect_3",
+      "slot_names": ["circle_1_label", "circle_2_label", "circle_3_label", "intersection", "title"],
+      "list_slot_counts": {},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {"circle_1_label": true, "circle_2_label": true, "circle_3_label": true, "intersection": false, "title": true}
+    },
+    {
+      "position": "bottom",
+      "template_id": "__empty__",
+      "builder": null,
+      "slot_names": [],
+      "list_slot_counts": {},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {}
+    }
+  ],
+  "03": [
+    {
+      "position": "left",
+      "template_id": "three_parallel_requirements",
+      "builder": "items_with_role",
+      "slot_names": ["pillars", "title"],
+      "list_slot_counts": {"pillars": 3},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {"title": true}
+    },
+    {
+      "position": "right",
+      "template_id": "process_product_two_way",
+      "builder": "process_product_pair",
+      "slot_names": ["banner_left", "banner_right", "process", "product", "title"],
+      "list_slot_counts": {},
+      "dict_slot_sub_counts": {"process": {"sections": 3}, "product": {"sections": 3}},
+      "string_slot_nonempty": {"banner_left": true, "banner_right": true, "title": true}
+    }
+  ],
+  "04": [
+    {
+      "position": "top",
+      "template_id": "bim_issues_quadrant_four",
+      "builder": "quadrant_flat_slots",
+      "slot_names": ["quadrant_1_body", "quadrant_1_label", "quadrant_2_body", "quadrant_2_label", "quadrant_3_body", "quadrant_3_label", "quadrant_4_body", "quadrant_4_label", "title"],
+      "list_slot_counts": {"quadrant_1_body": 2, "quadrant_2_body": 2, "quadrant_3_body": 2, "quadrant_4_body": 2},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {"quadrant_1_label": true, "quadrant_2_label": true, "quadrant_3_label": true, "quadrant_4_label": true, "title": true}
+    },
+    {
+      "position": "bottom-left",
+      "template_id": "__empty__",
+      "builder": null,
+      "slot_names": [],
+      "list_slot_counts": {},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {}
+    },
+    {
+      "position": "bottom-right",
+      "template_id": "__empty__",
+      "builder": null,
+      "slot_names": [],
+      "list_slot_counts": {},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {}
+    }
+  ],
+  "05": [
+    {
+      "position": "primary",
+      "template_id": "__empty__",
+      "builder": null,
+      "slot_names": [],
+      "list_slot_counts": {},
+      "dict_slot_sub_counts": {},
+      "string_slot_nonempty": {}
+    }
+  ]
+}
@@ -0,0 +1,43 @@
+{
+  "_doc": "IMP-#91 u3 structural snapshot — pins observed step20 overall + step09 per-zone selected_template_id per mdx in the 01-05 acceptance set. Each entry is fresh-run evidence (not aspirational). Update only when an intentional pipeline change moves the observed value; treat unexplained drift as regression. [[feedback_validation_first_for_closed_issues]] [[feedback_artifact_status_naming]]",
+  "01": {
+    "overall": "PASS",
+    "zone_count": 2,
+    "zones": [
+      {"position": "top", "selected_template_id": "bim_dx_comparison_table"},
+      {"position": "bottom", "selected_template_id": "construction_bim_three_usage"}
+    ]
+  },
+  "02": {
+    "overall": "PASS",
+    "zone_count": 2,
+    "zones": [
+      {"position": "top", "selected_template_id": "construction_goals_three_circle_intersection"},
+      {"position": "bottom", "selected_template_id": "three_persona_benefits"}
+    ]
+  },
+  "03": {
+    "overall": "PASS",
+    "zone_count": 2,
+    "zones": [
+      {"position": "left", "selected_template_id": "three_parallel_requirements"},
+      {"position": "right", "selected_template_id": "process_product_two_way"}
+    ]
+  },
+  "04": {
+    "overall": "PASS",
+    "zone_count": 3,
+    "zones": [
+      {"position": "top", "selected_template_id": "bim_issues_quadrant_four"},
+      {"position": "bottom-left", "selected_template_id": "sw_dependency_four_problems"},
+      {"position": "bottom-right", "selected_template_id": "pre_construction_model_info_stacked"}
+    ]
+  },
+  "05": {
+    "overall": "EMPTY_SHELL_NO_CONTENT",
+    "zone_count": 1,
+    "zones": [
+      {"position": "primary", "selected_template_id": "__empty__"}
+    ]
+  }
+}
@@ -0,0 +1,112 @@
+{
+  "_doc": "IMP-91 u7 — F1 V4 ranking observed snapshot (step05_v4_evidence). Pins v4_source (POSIX-normalized), aligned_section_ids, and per-section {section_id, candidate_status, candidates: [{template_id, label, confidence}]}. confidence kept at current 4-decimal rounding. Sections appear in pipeline-emitted order.",
+  "01": {
+    "v4_source": "tests/matching/v4_full32_result.yaml",
+    "aligned_section_ids": ["01-1", "01-2"],
+    "sections": [
+      {
+        "section_id": "01-1",
+        "candidate_status": "ok",
+        "candidates": [
+          {"template_id": "construction_bim_three_usage", "label": "use_as_is", "confidence": 0.9101},
+          {"template_id": "construction_goals_three_circle_intersection", "label": "light_edit", "confidence": 0.8261},
+          {"template_id": "dx_sw_necessity_three_perspectives", "label": "light_edit", "confidence": 0.8168}
+        ]
+      },
+      {
+        "section_id": "01-2",
+        "candidate_status": "ok",
+        "candidates": [
+          {"template_id": "bim_dx_comparison_table", "label": "use_as_is", "confidence": 0.9459},
+          {"template_id": "app_sw_package_vs_solution", "label": "restructure", "confidence": 0.6813}
+        ]
+      }
+    ]
+  },
+  "02": {
+    "v4_source": "tests/matching/v4_full32_result.yaml",
+    "aligned_section_ids": ["02-1", "02-2-sub-1", "02-2-sub-2"],
+    "sections": [
+      {
+        "section_id": "02-1",
+        "candidate_status": "ok",
+        "candidates": [
+          {"template_id": "construction_goals_three_circle_intersection", "label": "use_as_is", "confidence": 0.914}
+        ]
+      },
+      {
+        "section_id": "02-2-sub-1",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      },
+      {
+        "section_id": "02-2-sub-2",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      }
+    ]
+  },
+  "03": {
+    "v4_source": "tests/matching/v4_full32_result.yaml",
+    "aligned_section_ids": ["03-1", "03-2"],
+    "sections": [
+      {
+        "section_id": "03-1",
+        "candidate_status": "ok",
+        "candidates": [
+          {"template_id": "three_parallel_requirements", "label": "use_as_is", "confidence": 0.9268},
+          {"template_id": "dx_sw_necessity_three_perspectives", "label": "light_edit", "confidence": 0.8413}
+        ]
+      },
+      {
+        "section_id": "03-2",
+        "candidate_status": "ok",
+        "candidates": [
+          {"template_id": "process_product_two_way", "label": "use_as_is", "confidence": 0.9198}
+        ]
+      }
+    ]
+  },
+  "04": {
+    "v4_source": "tests/matching/v4_full32_result.yaml",
+    "aligned_section_ids": ["04-1", "04-2-sub-1", "04-2-sub-2"],
+    "sections": [
+      {
+        "section_id": "04-1",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      },
+      {
+        "section_id": "04-2-sub-1",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      },
+      {
+        "section_id": "04-2-sub-2",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      }
+    ]
+  },
+  "05": {
+    "v4_source": "tests/matching/v4_full32_result.yaml",
+    "aligned_section_ids": ["05-1", "05-2-sub-1", "05-2-sub-2"],
+    "sections": [
+      {
+        "section_id": "05-1",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      },
+      {
+        "section_id": "05-2-sub-1",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      },
+      {
+        "section_id": "05-2-sub-2",
+        "candidate_status": "no_non_reject_v4_candidate",
+        "candidates": []
+      }
+    ]
+  }
+}
@@ -0,0 +1,48 @@
+{
+  "_doc": "u4 — pin observed step14_visual_check overflow/clip per mdx 01-05. Fresh subprocess observation per [[feedback_validation_first_for_closed_issues]]; drift surfaces visual regression (overflow / clip) loudly per [[feedback_artifact_status_naming]] 3-axis honesty. Snapshot pinned to current-state, not to invented expectation (Stage 1 scope-lock).",
+  "01": {
+    "slide_overflowed": false,
+    "slide_body_overflowed": false,
+    "passed": true,
+    "zones": [
+      {"position": "top", "template_id": "bim_dx_comparison_table", "overflowed": false, "clipped_inner_count": 0},
+      {"position": "bottom", "template_id": "construction_bim_three_usage", "overflowed": false, "clipped_inner_count": 0}
+    ]
+  },
+  "02": {
+    "slide_overflowed": false,
+    "slide_body_overflowed": false,
+    "passed": true,
+    "zones": [
+      {"position": "top", "template_id": "construction_goals_three_circle_intersection", "overflowed": false, "clipped_inner_count": 0},
+      {"position": "bottom", "template_id": "__empty__", "overflowed": false, "clipped_inner_count": 0}
+    ]
+  },
+  "03": {
+    "slide_overflowed": false,
+    "slide_body_overflowed": false,
+    "passed": true,
+    "zones": [
+      {"position": "left", "template_id": "three_parallel_requirements", "overflowed": false, "clipped_inner_count": 0},
+      {"position": "right", "template_id": "process_product_two_way", "overflowed": false, "clipped_inner_count": 0}
+    ]
+  },
+  "04": {
+    "slide_overflowed": false,
+    "slide_body_overflowed": false,
+    "passed": true,
+    "zones": [
+      {"position": "top", "template_id": "bim_issues_quadrant_four", "overflowed": false, "clipped_inner_count": 0},
+      {"position": "bottom-left", "template_id": "__empty__", "overflowed": false, "clipped_inner_count": 0},
+      {"position": "bottom-right", "template_id": "__empty__", "overflowed": false, "clipped_inner_count": 0}
+    ]
+  },
+  "05": {
+    "slide_overflowed": false,
+    "slide_body_overflowed": false,
+    "passed": true,
+    "zones": [
+      {"position": "primary", "template_id": "__empty__", "overflowed": false, "clipped_inner_count": 0}
+    ]
+  }
+}
@@ -0,0 +1,573 @@
+"""IMP-#91 u2 — multi-mdx regression CI scaffold (mdx 01-05 acceptance set).
+
+Session-scoped subprocess cache that runs each MDX acceptance fixture
+exactly once. u3-u11 extend this module with per-axis assertions
+(structural / visual / coverage / F0-F5). u2 alone pins the cache
+contract: each mdx in ``MDX_SET`` produces a run directory under
+``data/runs/<run_id>/phase_z2/`` containing the step JSONs and
+``final.html`` that downstream parametrized tests will read.
+
+[[feedback_validation_first_for_closed_issues]] — fresh subprocess per
+session, no frozen artifacts. [[feedback_artifact_status_naming]] — the
+overall status (PASS / RENDERED_WITH_VISUAL_REGRESSION /
+PARTIAL_COVERAGE / EMPTY_SHELL_NO_CONTENT) is asserted in u3-u5; u2
+only pins the artifact-production contract.
+"""
+from __future__ import annotations
+
+import json
+import re
+import subprocess
+import sys
+import uuid
+from pathlib import Path
+from typing import Dict, List, NamedTuple
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+SAMPLES_DIR = REPO_ROOT / "samples" / "mdx_batch"
+RUNS_DIR = REPO_ROOT / "data" / "runs"
+SNAPSHOTS_DIR = Path(__file__).resolve().parent / "__snapshots__"
+MDX_SET = ("01", "02", "03", "04", "05")
+
+
+class PipelineRun(NamedTuple):
+    mdx_id: str
+    run_id: str
+    returncode: int
+    stdout: str
+    stderr: str
+    run_dir: Path
+
+
+@pytest.fixture(scope="session")
+def multi_mdx_runs() -> Dict[str, PipelineRun]:
+    """Run the Phase Z pipeline once per mdx in ``MDX_SET`` (session-cached)."""
+    cache: Dict[str, PipelineRun] = {}
+    for mdx_id in MDX_SET:
+        run_id = f"imp91_{mdx_id}_{uuid.uuid4().hex[:8]}"
+        cp = subprocess.run(
+            [
+                sys.executable,
+                "-m",
+                "src.phase_z2_pipeline",
+                str(SAMPLES_DIR / f"{mdx_id}.mdx"),
+                run_id,
+            ],
+            capture_output=True,
+            text=True,
+            timeout=360,
+            cwd=str(REPO_ROOT),
+        )
+        cache[mdx_id] = PipelineRun(
+            mdx_id=mdx_id,
+            run_id=run_id,
+            returncode=cp.returncode,
+            stdout=cp.stdout,
+            stderr=cp.stderr,
+            run_dir=RUNS_DIR / run_id / "phase_z2",
+        )
+    return cache
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_pipeline_run_produces_step20_status(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """Cache contract: every mdx subprocess produces step20_slide_status.json."""
+    run = multi_mdx_runs[mdx_id]
+    status_path = run.run_dir / "steps" / "step20_slide_status.json"
+    assert status_path.is_file(), (
+        f"{mdx_id}.mdx run {run.run_id} did not produce {status_path} "
+        f"(returncode={run.returncode}); stderr tail: {run.stderr[-800:]}"
+    )
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_structural_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u3 — pin observed overall + per-zone selected_template_id against snapshot."""
+    snapshot = json.loads((SNAPSHOTS_DIR / "structural.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    status = json.loads(
+        (run.run_dir / "steps" / "step20_slide_status.json").read_text(encoding="utf-8")
+    )["data"]
+    frame_sel = json.loads(
+        (run.run_dir / "steps" / "step09_frame_selection.json").read_text(encoding="utf-8")
+    )["data"]
+    zones = frame_sel.get("per_zone", [])
+    actual_zones = [
+        {"position": z.get("position"), "selected_template_id": z.get("selected_template_id")}
+        for z in zones
+    ]
+    assert status.get("overall") == expected["overall"], (
+        f"{mdx_id}.mdx overall drift: expected {expected['overall']!r}, "
+        f"got {status.get('overall')!r}"
+    )
+    assert len(actual_zones) == expected["zone_count"], (
+        f"{mdx_id}.mdx zone_count drift: expected {expected['zone_count']}, "
+        f"got {len(actual_zones)} (zones={actual_zones})"
+    )
+    assert actual_zones == expected["zones"], (
+        f"{mdx_id}.mdx zone topology drift: expected {expected['zones']}, "
+        f"got {actual_zones}"
+    )
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_visual_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u4 — pin observed step14 visual_check overflow/clip against snapshot."""
+    snapshot = json.loads((SNAPSHOTS_DIR / "visual.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    visual = json.loads(
+        (run.run_dir / "steps" / "step14_visual_check.json").read_text(encoding="utf-8")
+    )["data"]
+    slide_overflowed = visual.get("slide", {}).get("overflowed")
+    slide_body_overflowed = visual.get("slide_body", {}).get("overflowed")
+    visual_passed = visual.get("passed")
+    actual_zones = [
+        {
+            "position": z.get("position"),
+            "template_id": z.get("template_id"),
+            "overflowed": z.get("overflowed"),
+            "clipped_inner_count": len(z.get("clipped_inner") or []),
+        }
+        for z in visual.get("zones", [])
+    ]
+    assert slide_overflowed == expected["slide_overflowed"], (
+        f"{mdx_id}.mdx slide.overflowed drift: expected {expected['slide_overflowed']}, "
+        f"got {slide_overflowed}"
+    )
+    assert slide_body_overflowed == expected["slide_body_overflowed"], (
+        f"{mdx_id}.mdx slide_body.overflowed drift: expected {expected['slide_body_overflowed']}, "
+        f"got {slide_body_overflowed}"
+    )
+    assert visual_passed == expected["passed"], (
+        f"{mdx_id}.mdx visual_check.passed drift: expected {expected['passed']}, "
+        f"got {visual_passed}"
+    )
+    assert actual_zones == expected["zones"], (
+        f"{mdx_id}.mdx zone visual drift: expected {expected['zones']}, "
+        f"got {actual_zones}"
+    )
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_coverage_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u5 — pin observed full_mdx_coverage + section_id parity against snapshot."""
+    snapshot = json.loads((SNAPSHOTS_DIR / "coverage.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    status = json.loads(
+        (run.run_dir / "steps" / "step20_slide_status.json").read_text(encoding="utf-8")
+    )["data"]
+    assert status.get("rendered") == expected["rendered"], (
+        f"{mdx_id}.mdx rendered drift: expected {expected['rendered']}, "
+        f"got {status.get('rendered')}"
+    )
+    assert status.get("visual_check_passed") == expected["visual_check_passed"], (
+        f"{mdx_id}.mdx visual_check_passed drift: expected {expected['visual_check_passed']}, "
+        f"got {status.get('visual_check_passed')}"
+    )
+    assert status.get("full_mdx_coverage") == expected["full_mdx_coverage"], (
+        f"{mdx_id}.mdx full_mdx_coverage drift: expected {expected['full_mdx_coverage']}, "
+        f"got {status.get('full_mdx_coverage')}"
+    )
+    assert sorted(status.get("aligned_section_ids") or []) == sorted(expected["aligned_section_ids"]), (
+        f"{mdx_id}.mdx aligned_section_ids drift: expected {expected['aligned_section_ids']}, "
+        f"got {status.get('aligned_section_ids')}"
+    )
+    assert sorted(status.get("covered_section_ids") or []) == sorted(expected["covered_section_ids"]), (
+        f"{mdx_id}.mdx covered_section_ids drift: expected {expected['covered_section_ids']}, "
+        f"got {status.get('covered_section_ids')}"
+    )
+    assert sorted(status.get("filtered_section_ids") or []) == sorted(expected["filtered_section_ids"]), (
+        f"{mdx_id}.mdx filtered_section_ids drift: expected {expected['filtered_section_ids']}, "
+        f"got {status.get('filtered_section_ids')}"
+    )
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_normalize_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u6 — F0 normalize: pin observed step02_normalized shape per mdx."""
+    snapshot = json.loads((SNAPSHOTS_DIR / "normalize.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    raw = json.loads(
+        (run.run_dir / "steps" / "step02_normalized.json").read_text(encoding="utf-8")
+    )
+    d = raw["data"]
+    diag = d.get("stage0_adapter_diagnostics", {}) or {}
+    assets = d.get("stage0_normalized_assets", {}) or {}
+    actual = {
+        "step_num": raw.get("step_num"),
+        "step_status": raw.get("step_status"),
+        "pipeline_path_connected": raw.get("pipeline_path_connected"),
+        "sections_count": d.get("sections_count"),
+        "section_ids": [s.get("section_id") for s in d.get("sections", [])],
+        "orphans_count": len(d.get("orphans") or []),
+        "details_count": len(d.get("details") or []),
+        "adapter_enabled": diag.get("enabled"),
+        "adapter_used": diag.get("used"),
+        "assets_popups_count": len(assets.get("popups") or []),
+        "assets_images_count": len(assets.get("images") or []),
+        "assets_tables_count": len(assets.get("tables") or []),
+        "slide_title_nonempty": bool(d.get("slide_title")),
+        "slide_footer_nonempty": bool(d.get("slide_footer")),
+    }
+    for key, want in expected.items():
+        got = actual[key]
+        assert got == want, (
+            f"{mdx_id}.mdx normalize.{key} drift: expected {want!r}, got {got!r}"
+        )
+    assert len(d.get("sections", [])) == expected["sections_count"], (
+        f"{mdx_id}.mdx sections list length mismatch with sections_count: "
+        f"sections_count={expected['sections_count']}, got len(sections)={len(d.get('sections', []))}"
+    )
+    for sect in d.get("sections", []):
+        assert (sect.get("raw_content_length") or 0) > 0, (
+            f"{mdx_id}.mdx section {sect.get('section_id')!r} has empty raw_content "
+            f"(length={sect.get('raw_content_length')!r}) — normalize lost content"
+        )
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_v4_ranking_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u7 — F1 V4 ranking: pin observed step05_v4_evidence per mdx.
+
+    Pins ``v4_source`` (POSIX-normalized for cross-platform stability),
+    ``aligned_section_ids``, and per-section
+    ``{section_id, candidate_status, candidates: [{template_id, label, confidence}]}``
+    in pipeline-emitted order. Confidence stays at the current 4-decimal
+    rounding emitted by the V4 yaml; drift any axis fails loudly so a
+    re-baseline is a conscious commit, not a silent shift.
+    """
+    snapshot = json.loads((SNAPSHOTS_DIR / "v4_ranking.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    raw = json.loads(
+        (run.run_dir / "steps" / "step05_v4_evidence.json").read_text(encoding="utf-8")
+    )
+    data = raw["data"]
+    actual_v4_source = str(data.get("v4_source") or "").replace("\\", "/")
+    actual_sections = [
+        {
+            "section_id": ev.get("section_id"),
+            "candidate_status": ev.get("candidate_status"),
+            "candidates": [
+                {
+                    "template_id": c.get("template_id"),
+                    "label": c.get("label"),
+                    "confidence": c.get("confidence"),
+                }
+                for c in (ev.get("v4_candidates") or [])
+            ],
+        }
+        for ev in (data.get("evidence_per_section") or [])
+    ]
+    assert actual_v4_source == expected["v4_source"], (
+        f"{mdx_id}.mdx v4_source drift: expected {expected['v4_source']!r}, "
+        f"got {actual_v4_source!r}"
+    )
+    assert data.get("aligned_section_ids") == expected["aligned_section_ids"], (
+        f"{mdx_id}.mdx aligned_section_ids drift: expected {expected['aligned_section_ids']}, "
+        f"got {data.get('aligned_section_ids')}"
+    )
+    assert actual_sections == expected["sections"], (
+        f"{mdx_id}.mdx V4 ranking drift: expected {expected['sections']}, "
+        f"got {actual_sections}"
+    )
+
+
+def _slot_payload_zone_shape(zone: dict) -> dict:
+    """Reduce a step12 per_zone entry to a content-agnostic structural shape.
+
+    Pins builder + slot names + per-slot list cardinality + dict sub-list
+    counts + string non-empty flags. MDX text edits don't drift this; a
+    builder swap, slot rename, missing slot, or list-cardinality change
+    does. Sub-dict shape pins ``sections`` length only — deeper field
+    pinning would require a fresh u8'-axis snapshot.
+    """
+    sp = zone.get("slot_payload") or {}
+    slot_names = sorted(sp.keys())
+    list_slot_counts: dict = {}
+    dict_slot_sub_counts: dict = {}
+    string_slot_nonempty: dict = {}
+    for name in slot_names:
+        value = sp[name]
+        if isinstance(value, list):
+            list_slot_counts[name] = len(value)
+        elif isinstance(value, dict):
+            sub: dict = {}
+            for sub_key, sub_val in value.items():
+                if isinstance(sub_val, list):
+                    sub[sub_key] = len(sub_val)
+            dict_slot_sub_counts[name] = sub
+        elif isinstance(value, str):
+            string_slot_nonempty[name] = bool(value.strip())
+    return {
+        "position": zone.get("position"),
+        "template_id": zone.get("template_id"),
+        "builder": zone.get("builder"),
+        "slot_names": slot_names,
+        "list_slot_counts": list_slot_counts,
+        "dict_slot_sub_counts": dict_slot_sub_counts,
+        "string_slot_nonempty": string_slot_nonempty,
+    }
+
+
+_AI_UNIT_KEYS = (
+    "source_section_ids", "label", "route_hint", "provisional",
+    "ai_called", "skip_reason", "apply_status",
+)
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_ai_classifier_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u9 — F3 classifier-only AI: pin step12/15/16/18 classifier signals.
+
+    [[feedback_ai_isolation_contract]] / [[feedback_demo_env_toggle_policy]]
+    central invariant: ``ai_called`` MUST stay False per unit by default;
+    activation requires explicit .env toggle, never pipeline default.
+    """
+    snapshot = json.loads((SNAPSHOTS_DIR / "ai_classifier.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    steps = multi_mdx_runs[mdx_id].run_dir / "steps"
+    ai = json.loads((steps / "step12_ai_repair.json").read_text(encoding="utf-8"))["data"]
+    fit = json.loads((steps / "step15_fit_classification.json").read_text(encoding="utf-8"))["data"]
+    router = json.loads((steps / "step16_router_decision.json").read_text(encoding="utf-8"))["data"]
+    failure = json.loads((steps / "step18_failure_classification.json").read_text(encoding="utf-8"))["data"]
+    units = [{k: u.get(k) for k in _AI_UNIT_KEYS} for u in (ai.get("per_unit") or [])]
+    actual = {
+        "units": units,
+        "coverage_invariant_status": (ai.get("coverage_invariant") or {}).get("status"),
+        "fit_visual_check_passed": fit.get("visual_check_passed"),
+        "fit_classifications_count": len(fit.get("classifications") or []),
+        "fit_categories_seen": fit.get("categories_seen") or [],
+        "router_active": router.get("router_active"),
+        "router_routed_count": router.get("routed_count"),
+        "router_v4_fallback_used_count": (router.get("v4_fallback_summary") or {}).get("fallback_used_count"),
+        "failure_type": failure.get("failure_type"),
+    }
+    for key, want in expected.items():
+        assert actual[key] == want, (
+            f"{mdx_id}.mdx ai_classifier.{key} drift: expected {want!r}, got {actual[key]!r}"
+        )
+    breaches = [u for u in units if u["ai_called"] is not False]
+    assert not breaches, (
+        f"{mdx_id}.mdx F3 AI-isolation breach (ai_called must be False by default): {breaches}"
+    )
+
+
+def _layout_zone_shape(zone: dict) -> dict:
+    """Reduce a step08 per_zone_plan entry to a content-agnostic F4 layout shape."""
+    sub_zones = zone.get("sub_zones_planned") or []
+    return {
+        "position": zone.get("position"),
+        "min_height_px": zone.get("min_height_px"),
+        "frame_cardinality_strict": zone.get("frame_cardinality_strict"),
+        "sub_zones_count": len(sub_zones),
+        "region_layout_candidates": zone.get("region_layout_candidates") or [],
+    }
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_layout_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u10 — F4 layout: pin step07_layout + step08_zone_region_ratios per mdx.
+
+    Pins the layout decision path (``layout_preset`` /
+    ``auto_layout_preset`` / ``layout_override_applied`` /
+    ``layout_candidates`` / ``computation``) + planning geometry
+    (``heights_px`` / ``widths_px`` / ``ratios`` / ``width_ratios``) +
+    per-zone planning shape (``position`` / ``min_height_px`` /
+    ``frame_cardinality_strict`` / ``sub_zones_count`` /
+    ``region_layout_candidates``). ``step_status='partial'`` is the
+    Step 7/8 schema-lock marker (region-level ratio + count-based v0).
+    mdx 03 is the only ``layout_override_applied=True`` case (vertical-2
+    user override per project_mdx03_frame_lock 2026-05-15 lock); drift
+    here flips F4 layer-A axis. mdx 04 ``top`` zone pins ``None`` for
+    min_height_px + frame_cardinality_strict (no frame cardinality on
+    the top zone — observed current state, not invented).
+    """
+    snapshot = json.loads((SNAPSHOTS_DIR / "layout.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    s7 = json.loads(
+        (run.run_dir / "steps" / "step07_layout.json").read_text(encoding="utf-8")
+    )
+    s8 = json.loads(
+        (run.run_dir / "steps" / "step08_zone_region_ratios.json").read_text(encoding="utf-8")
+    )
+    d7 = s7.get("data") or {}
+    d8 = s8.get("data") or {}
+    css = d7.get("layout_css") or {}
+    actual = {
+        "step7_step_status": s7.get("step_status"),
+        "step7_pipeline_path_connected": s7.get("pipeline_path_connected"),
+        "layout_preset": d7.get("layout_preset"),
+        "auto_layout_preset": d7.get("auto_layout_preset"),
+        "layout_override_applied": d7.get("layout_override_applied"),
+        "zones_count": d7.get("zones_count"),
+        "unit_count": d7.get("unit_count"),
+        "layout_candidates": d7.get("layout_candidates") or [],
+        "computation": css.get("computation"),
+        "dynamic_rows": css.get("dynamic_rows"),
+        "dynamic_cols": css.get("dynamic_cols"),
+        "heights_px": css.get("heights_px"),
+        "widths_px": css.get("widths_px"),
+        "ratios": css.get("ratios"),
+        "width_ratios": css.get("width_ratios"),
+        "step8_step_status": s8.get("step_status"),
+        "step8_pipeline_path_connected": s8.get("pipeline_path_connected"),
+        "zone_heights_px_planned": d8.get("zone_heights_px_planned"),
+        "zone_widths_px_planned": d8.get("zone_widths_px_planned"),
+        "zone_col_ratios_planned": d8.get("zone_col_ratios_planned"),
+        "per_zone_layout_shape": [
+            _layout_zone_shape(z) for z in (d8.get("per_zone_plan") or [])
+        ],
+    }
+    for key, want in expected.items():
+        got = actual[key]
+        assert got == want, (
+            f"{mdx_id}.mdx layout.{key} drift: expected {want!r}, got {got!r}"
+        )
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_slot_payload_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u8 — F2 slot_payload: pin observed step12_slot_payload per_zone shape per mdx.
+
+    Snapshot pins content-agnostic structural shape (builder + slot
+    names + list cardinality + dict sub-list counts + string non-empty
+    flags), not literal payload text. MDX wording tweaks won't drift
+    this; builder swap, slot rename, slot count drift, or __empty__
+    transitions will. Empty zones must have ``builder is None`` and no
+    slots — this is the IMP-87 empty_shell honesty contract surface for
+    F2.
+    """
+    snapshot = json.loads((SNAPSHOTS_DIR / "slot_payload.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    raw = json.loads(
+        (run.run_dir / "steps" / "step12_slot_payload.json").read_text(encoding="utf-8")
+    )
+    per_zone = raw["data"].get("per_zone") or []
+    actual = [_slot_payload_zone_shape(z) for z in per_zone]
+    assert len(actual) == len(expected), (
+        f"{mdx_id}.mdx step12 zone_count drift: expected {len(expected)}, "
+        f"got {len(actual)} (positions={[z.get('position') for z in actual]})"
+    )
+    for idx, (act, exp) in enumerate(zip(actual, expected)):
+        assert act == exp, (
+            f"{mdx_id}.mdx step12 zone[{idx}] ({exp.get('position')!r}) shape drift: "
+            f"expected {exp}, got {act}"
+        )
+
+
+_ZONE_TAG_RE = re.compile(
+    r'<div[^>]*\sdata-zone-position="([^"]+)"[^>]*\sdata-template-id="([^"]+)"',
+    re.IGNORECASE,
+)
+_SLIDE_ROOT_RE = re.compile(r'<div\s+class="slide"\s+data-page="1"')
+_TITLE_RE = re.compile(r'<title>([^<]*)</title>', re.IGNORECASE)
+
+
+def _extract_html_zone_topology(html: str) -> List[dict]:
+    """Extract (position, template_id) pairs in document order from final.html."""
+    return [
+        {"position": m.group(1), "template_id": m.group(2)}
+        for m in _ZONE_TAG_RE.finditer(html)
+    ]
+
+
+@pytest.mark.integration
+@pytest.mark.parametrize("mdx_id", MDX_SET)
+def test_final_html_snapshot_matches(
+    mdx_id: str, multi_mdx_runs: Dict[str, PipelineRun]
+) -> None:
+    """u11 — F5 final.html extraction: pin step13_render metadata + on-disk HTML structure.
+
+    Cross-snapshot parity gate: ``html_zone_topology`` (extracted from
+    final.html via ``data-zone-position`` / ``data-template-id`` markers)
+    MUST equal step12 slot_payload (u8) ``(position, template_id)``
+    sequence — Jinja2 renders from step12, not step09, so this is the
+    correct upstream parity (step09 selection vs step12 ``__empty__``
+    collapse is intentional per IMP-87 honesty gate and surfaces in u8).
+    Drift between final.html and slot_payload = render pipeline
+    disconnect. ``final.html`` on-disk size also MUST equal step13's
+    reported ``final_html_size_bytes`` — byte parity proves no
+    truncation / no double-write race.
+    """
+    snapshot = json.loads((SNAPSHOTS_DIR / "final_html.json").read_text(encoding="utf-8"))
+    expected = snapshot[mdx_id]
+    run = multi_mdx_runs[mdx_id]
+    raw13 = json.loads(
+        (run.run_dir / "steps" / "step13_render.json").read_text(encoding="utf-8")
+    )
+    d13 = raw13.get("data") or {}
+    ri = d13.get("render_inputs") or {}
+    final_path = run.run_dir / "final.html"
+    assert final_path.is_file(), f"{mdx_id}.mdx final.html missing at {final_path}"
+    html = final_path.read_text(encoding="utf-8")
+    title_match = _TITLE_RE.search(html)
+    html_title = title_match.group(1).strip() if title_match else ""
+    html_topology = _extract_html_zone_topology(html)
+    actual = {
+        "step13_status": raw13.get("step_status"),
+        "step13_pipeline_path_connected": raw13.get("pipeline_path_connected"),
+        "render_inputs_zones_count": ri.get("zones_count"),
+        "render_inputs_layout_preset": ri.get("layout_preset"),
+        "render_inputs_slide_title_nonempty": bool((ri.get("slide_title") or "").strip()),
+        "render_inputs_slide_footer_nonempty": bool((ri.get("slide_footer") or "").strip()),
+        "html_title_matches_render_input": html_title == (ri.get("slide_title") or "").strip(),
+        "html_slide_root_count": len(_SLIDE_ROOT_RE.findall(html)),
+        "html_slide_footer_present": '<div class="slide-footer">' in html,
+        "html_zone_count": len(html_topology),
+        "html_zone_topology": html_topology,
+        "final_html_size_matches_step13_reported": (
+            final_path.stat().st_size == d13.get("final_html_size_bytes")
+        ),
+    }
+    for key, want in expected.items():
+        assert actual[key] == want, (
+            f"{mdx_id}.mdx final_html.{key} drift: expected {want!r}, got {actual[key]!r}"
+        )
+    slot_payload = json.loads(
+        (SNAPSHOTS_DIR / "slot_payload.json").read_text(encoding="utf-8")
+    )[mdx_id]
+    slot_topology = [
+        {"position": z["position"], "template_id": z["template_id"]}
+        for z in slot_payload
+    ]
+    assert html_topology == slot_topology, (
+        f"{mdx_id}.mdx render pipeline disconnect: final.html zone topology "
+        f"{html_topology} does not match step12 slot_payload topology "
+        f"{slot_topology} (pinned in slot_payload.json u8)"
+    )
@@ -0,0 +1,56 @@
+fixture_id: synthetic_divergence
+purpose: |
+  Backend - frontend "rank 1" divergence regression - IMP-39 (#68).
+  Captures the Stage 1 root-cause scenario where the legacy backend
+  (raw V4 confidence-desc order) selects a high-confidence
+  lower-priority label, while the frontend (LABEL_PRIORITY asc +
+  confidence desc) selects the lower-confidence higher-priority
+  label. The single-source ranking policy
+  (templates/phase_z2/catalog/ranking_sort_policy.yaml, u1) resolves
+  the divergence so that both sides agree on "rank 1".
+
+source: synthetic
+sample_agnostic: true
+notes:
+  - No real frame_id / template_id / MDX section is referenced.
+  - Only the four sort keys matter: label, confidence, v4_full_rank.
+  - The `tag` field is a fixture-local identifier for assertions.
+  - Field name `v4_full_rank` mirrors v4_full32_result.yaml shape so
+    fixture and corpus audit (u8) share the same key contract.
+
+raw_judgments:
+  # confidence is strictly descending so v4_full_rank == raw V4
+  # confidence-desc rank (same axis as v4_full32_result.yaml).
+  - tag: synth_restructure_high
+    label: restructure
+    confidence: 0.92
+    v4_full_rank: 1
+  - tag: synth_light_edit_mid
+    label: light_edit
+    confidence: 0.70
+    v4_full_rank: 2
+  - tag: synth_use_as_is_low
+    label: use_as_is
+    confidence: 0.41
+    v4_full_rank: 3
+  - tag: synth_reject_low
+    label: reject
+    confidence: 0.30
+    v4_full_rank: 4
+
+expected_legacy_raw_order:
+  - synth_restructure_high
+  - synth_light_edit_mid
+  - synth_use_as_is_low
+  - synth_reject_low
+
+expected_policy_sorted_order:
+  - synth_use_as_is_low
+  - synth_light_edit_mid
+  - synth_restructure_high
+  - synth_reject_low
+
+divergence_axis:
+  pre_policy_rank_1_tag: synth_restructure_high
+  post_policy_rank_1_tag: synth_use_as_is_low
+  frontend_candidate_0_tag: synth_use_as_is_low
@@ -156,3 +156,109 @@ def test_top_1_bottom_2_dynamic_2d_populates_geometry():
    assert result["dynamic_cols"] is True
    assert len(result["heights_px"]) == 2   # R rows
    assert len(result["widths_px"]) == 2    # C cols
+
+
+# ────────────────────── IMP-44 u5 regression ──────────────────────
+# Regression coverage for the layout-override unknown-key guard
+# (Stage 1 root-cause #73). Asserts that foreign-preset keys are
+# dropped, structured [override-warning] is emitted, and
+# computation=user_override_geometry is NEVER reported when the
+# kept-key set is empty (no false override_applied=true).
+
+
+def test_imp44_h2_with_v2_keys_emits_warning_and_falls_through(capsys):
+    """horizontal-2 receiving vertical-2 keys (left/right) → all-unknown:
+    drop both, emit warning, fall through to dynamic dispatch.
+    computation must NOT be user_override_geometry."""
+    zones = [_zone("top", 0.6), _zone("bottom", 0.4)]
+    override = {
+        "left": {"x": 0, "y": 0, "w": 0.5, "h": 1.0},
+        "right": {"x": 0.5, "y": 0, "w": 0.5, "h": 1.0},
+    }
+    result = build_layout_css(
+        "horizontal-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "layout_preset=horizontal-2" in captured.err
+    assert "unknown_keys=['left', 'right']" in captured.err
+    assert "expected_positions=['top', 'bottom']" in captured.err
+    # All-unknown → no override applied (no silent fallback).
+    assert result["computation"] != "user_override_geometry"
+    raw = result.get("raw_zone_layout") or {}
+    if isinstance(raw, dict):
+        assert raw.get("override_applied") is not True
+
+
+def test_imp44_v2_with_h2_keys_emits_warning_and_falls_through(capsys):
+    """vertical-2 receiving horizontal-2 keys (top/bottom) → all-unknown:
+    drop both, emit warning, fall through to dynamic dispatch.
+    computation must NOT be user_override_geometry."""
+    zones = [_zone("left", 0.5), _zone("right", 0.5)]
+    override = {
+        "top": {"x": 0, "y": 0, "w": 1.0, "h": 0.3},
+        "bottom": {"x": 0, "y": 0.3, "w": 1.0, "h": 0.7},
+    }
+    result = build_layout_css(
+        "vertical-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "layout_preset=vertical-2" in captured.err
+    assert "unknown_keys=['bottom', 'top']" in captured.err
+    assert "expected_positions=['left', 'right']" in captured.err
+    assert result["computation"] != "user_override_geometry"
+    raw = result.get("raw_zone_layout") or {}
+    if isinstance(raw, dict):
+        assert raw.get("override_applied") is not True
+
+
+def test_imp44_partial_mix_keeps_known_drops_unknown(capsys):
+    """horizontal-2 receiving {top (known), left (unknown)}: keep top,
+    drop left, emit warning naming only 'left'. override_applied=True
+    must hold and the source must contain only the kept key."""
+    zones = [_zone("top", 0.6), _zone("bottom", 0.4)]
+    override = {
+        "top": {"x": 0, "y": 0, "w": 1.0, "h": 0.3},
+        "left": {"x": 0, "y": 0, "w": 0.5, "h": 1.0},
+    }
+    result = build_layout_css(
+        "horizontal-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "unknown_keys=['left']" in captured.err
+    # Known key applied → user_override_geometry computation.
+    assert result["computation"] == "user_override_geometry"
+    raw = result["raw_zone_layout"]
+    assert raw["override_applied"] is True
+    assert set(raw["source"].keys()) == {"top"}
+    # Sanity: top ratio (0.3) drives heights_px[0] < heights_px[1].
+    assert result["heights_px"][0] < result["heights_px"][1]
+
+
+def test_imp44_2d_preset_with_h2_keys_emits_warning_and_falls_through(capsys):
+    """2-D preset (top-1-bottom-2) receiving horizontal-2 keys
+    (top/bottom): all-unknown vs T positions
+    {top, bottom-left, bottom-right} → drop all, emit warning,
+    fall through to 2-D dynamic dispatch."""
+    zones = [
+        _zone("top", 0.5),
+        _zone("bottom-left", 0.25),
+        _zone("bottom-right", 0.25),
+    ]
+    override = {
+        "bottom": {"x": 0, "y": 0.3, "w": 1.0, "h": 0.7},
+    }
+    result = build_layout_css(
+        "top-1-bottom-2", zones, override_zone_geometries=override
+    )
+    captured = capsys.readouterr()
+    assert "[override-warning]" in captured.err
+    assert "layout_preset=top-1-bottom-2" in captured.err
+    assert "unknown_keys=['bottom']" in captured.err
+    # All-unknown → 2-D dynamic fallback (not user_override_geometry).
+    assert result["computation"] == "2d_dynamic_aggregated"
+    raw = result.get("raw_zone_layout") or {}
+    if isinstance(raw, dict):
+        assert raw.get("override_applied") is not True
@@ -0,0 +1,299 @@
+"""IMP-88 (#88) u2 — failure_router cascade extension tests.
+
+Stage 2 binding contract (unit u2): the failure_router data-surface is
+extended so the three Step 17 retry chain actions (layout_adjust, image_fit,
+frame_internal_fit_candidate) participate in the deterministic cascade
+WITHOUT activating any AI path or shrinking shared margins.
+
+Producer surface (`SALVAGE_FAILURE_TYPE_BY_ACTION`):
+  - layout_adjust                → layout_adjust_insufficient
+  - image_fit                    → image_fit_insufficient
+  - frame_internal_fit_candidate → frame_internal_fit_candidate_insufficient
+
+Cascade extension (`NEXT_ACTION_BY_FAILURE`):
+  - layout_adjust_insufficient                  → frame_internal_fit_candidate
+  - frame_internal_fit_candidate_insufficient   → frame_reselect
+  - image_fit_insufficient                      → layout_adjust
+
+Implementation status surface (`NEXT_ACTION_IMPLEMENTATION_STATUS`):
+  - layout_adjust                = IMPLEMENTED (u3 planner + u6 dispatcher + u7 entry)
+  - image_fit                    = IMPLEMENTED (u4 planner + u7 Step 17 single-pass entry)
+  - frame_internal_fit_candidate = IMPLEMENTED (u5 planner + u6 dispatcher + u7 entry)
+  - frame_reselect               = MISSING (separate axis, out of IMP-88 scope)
+  - details_popup_escalation     = MISSING here; flipped on the router surface
+    (src/phase_z2_router.py) by IMP-35 u3.
+
+Existing rows from IMP-12 / IMP-35 (#62 / #64) are guarded against regression.
+
+Post u7 completion (2026-05-24): status assertions in this file reflect the
+IMPLEMENTED end-state. The `_registered_as_missing` test name is renamed to
+`_registered_as_implemented_after_u7` so the surface contract is honest
+about the post-u7 state.
+"""
+from __future__ import annotations
+
+from src.phase_z2_failure_router import (
+    FAILURE_TYPE_DESCRIPTIONS,
+    NEXT_ACTION_BY_FAILURE,
+    NEXT_ACTION_IMPLEMENTATION_STATUS,
+    NEXT_ACTION_RATIONALE,
+    SALVAGE_FAILURE_TYPE_BY_ACTION,
+    classify_retry_failure,
+    enrich_retry_trace_with_failure_classification,
+    route_retry_failure,
+)
+
+
+# ─── FAILURE_TYPE_DESCRIPTIONS registry ──────────────────────────
+
+
+def test_imp88_three_new_failure_type_descriptions_registered():
+    """u2 registers three new failure_type descriptions for the Step 17
+    retry chain actions. Each entry is non-empty so trace consumers can
+    surface a human-readable failure reason."""
+    for ftype in (
+        "layout_adjust_insufficient",
+        "image_fit_insufficient",
+        "frame_internal_fit_candidate_insufficient",
+    ):
+        assert ftype in FAILURE_TYPE_DESCRIPTIONS, (
+            f"u2 must register {ftype} in FAILURE_TYPE_DESCRIPTIONS"
+        )
+        assert FAILURE_TYPE_DESCRIPTIONS[ftype].strip(), (
+            f"FAILURE_TYPE_DESCRIPTIONS[{ftype!r}] must be non-empty"
+        )
+
+
+# ─── SALVAGE_FAILURE_TYPE_BY_ACTION producers ─────────────────────
+
+
+def test_imp88_three_new_salvage_failure_producers_registered():
+    """u2 wires three new producers so when the u6 dispatcher emits a
+    salvage_steps[-1] entry whose action is one of the IMP-88 actions, the
+    classifier route lands on the correct failure_type instead of falling
+    through to the defensive not_attempted fallback."""
+    assert SALVAGE_FAILURE_TYPE_BY_ACTION["layout_adjust"] == (
+        "layout_adjust_insufficient"
+    )
+    assert SALVAGE_FAILURE_TYPE_BY_ACTION["image_fit"] == "image_fit_insufficient"
+    assert SALVAGE_FAILURE_TYPE_BY_ACTION["frame_internal_fit_candidate"] == (
+        "frame_internal_fit_candidate_insufficient"
+    )
+
+
+def test_imp88_existing_salvage_producers_preserved():
+    """Regression guard — IMP-12 / IMP-35 producers stay intact after u2."""
+    assert SALVAGE_FAILURE_TYPE_BY_ACTION["cross_zone_redistribute"] == (
+        "cross_zone_redistribute_insufficient"
+    )
+    assert SALVAGE_FAILURE_TYPE_BY_ACTION["glue_compression"] == (
+        "glue_absorption_insufficient"
+    )
+    assert SALVAGE_FAILURE_TYPE_BY_ACTION["font_step_compression"] == (
+        "font_step_insufficient"
+    )
+    assert SALVAGE_FAILURE_TYPE_BY_ACTION["frame_reselect"] == (
+        "frame_reselect_insufficient"
+    )
+
+
+# ─── NEXT_ACTION_BY_FAILURE cascade ───────────────────────────────
+
+
+def test_imp88_layout_adjust_insufficient_routes_to_frame_internal_fit():
+    """Cascade extension: layout_adjust_insufficient → frame_internal_fit_candidate.
+
+    Closes the previously open cascade tail at layout_adjust (font_step_insufficient
+    → layout_adjust was the last existing row that could land on layout_adjust;
+    after layout_adjust executed and failed there was no NEXT_ACTION row, so the
+    dispatcher would terminate). u2 adds the frame envelope internal-fit step
+    before frame_reselect.
+    """
+    assert NEXT_ACTION_BY_FAILURE["layout_adjust_insufficient"] == (
+        "frame_internal_fit_candidate"
+    )
+
+    nr = route_retry_failure("layout_adjust_insufficient")
+    assert nr["next_proposed_action"] == "frame_internal_fit_candidate"
+    # frame_internal_fit_candidate is IMPLEMENTED after u5 planner + u6
+    # dispatcher branch + u7 cascade entry.
+    assert nr["next_action_implementation_status"] == "IMPLEMENTED"
+    assert "frame_internal_fit_candidate" in (nr["next_action_rationale"] or "")
+
+
+def test_imp88_frame_internal_fit_insufficient_routes_to_frame_reselect():
+    """frame_internal_fit_candidate_insufficient → frame_reselect (V4 top-k swap).
+
+    Rejoins the existing rerender_still_fails → frame_reselect path mid-cascade.
+    """
+    assert NEXT_ACTION_BY_FAILURE["frame_internal_fit_candidate_insufficient"] == (
+        "frame_reselect"
+    )
+
+    nr = route_retry_failure("frame_internal_fit_candidate_insufficient")
+    assert nr["next_proposed_action"] == "frame_reselect"
+    # frame_reselect is OUT of IMP-88 scope and stays MISSING (separate axis).
+    assert nr["next_action_implementation_status"] == "MISSING"
+
+
+def test_imp88_image_fit_insufficient_routes_to_layout_adjust():
+    """image_fit (Step 17 single-pass entry per u7) escalates onto the main
+    cascade at layout_adjust when the single-pass image fit transform cannot
+    resolve image_aspect_mismatch. Phase Z spacing direction guardrail —
+    no shared margin shrink, escalate through layout topology change instead.
+    """
+    assert NEXT_ACTION_BY_FAILURE["image_fit_insufficient"] == "layout_adjust"
+
+    nr = route_retry_failure("image_fit_insufficient")
+    assert nr["next_proposed_action"] == "layout_adjust"
+    # layout_adjust is IMPLEMENTED after u3 planner + u6 dispatcher branch +
+    # u7 cascade entry. Cascade now flows end-to-end on the deterministic path.
+    assert nr["next_action_implementation_status"] == "IMPLEMENTED"
+    # Rationale must not claim a margin shrink (Phase Z spacing direction
+    # guardrail anchored at feedback_phase_z_spacing_direction).
+    rationale = (nr["next_action_rationale"] or "").lower()
+    assert "shrink" not in rationale
+    assert "축소 x" in rationale or "축소x" in rationale or "spacing direction" in rationale
+
+
+def test_imp88_existing_cascade_rows_preserved():
+    """Regression guard — the IMP-12 / IMP-35 cascade rows stay intact after u2."""
+    assert NEXT_ACTION_BY_FAILURE["donor_slack_insufficient"] == "cross_zone_redistribute"
+    assert NEXT_ACTION_BY_FAILURE["no_donor_candidates"] == "cross_zone_redistribute"
+    assert NEXT_ACTION_BY_FAILURE["cross_zone_redistribute_insufficient"] == "glue_compression"
+    assert NEXT_ACTION_BY_FAILURE["glue_absorption_insufficient"] == "font_step_compression"
+    assert NEXT_ACTION_BY_FAILURE["font_step_insufficient"] == "layout_adjust"
+    assert NEXT_ACTION_BY_FAILURE["rerender_still_fails"] == "frame_reselect"
+    assert NEXT_ACTION_BY_FAILURE["frame_reselect_insufficient"] == "details_popup_escalation"
+    assert NEXT_ACTION_BY_FAILURE["not_attempted"] == "none"
+
+
+# ─── NEXT_ACTION_IMPLEMENTATION_STATUS surface ────────────────────
+
+
+def test_imp88_new_next_action_destinations_registered_as_implemented_after_u7():
+    """u2 registered the two new cascade destinations (initial MISSING). After
+    u7 completion the rows flip to IMPLEMENTED on the failure-router surface:
+    frame_internal_fit_candidate via u5 planner + u6 dispatcher + u7 cascade
+    entry; image_fit via u4 planner + u7 Step 17 single-pass entry. (Same
+    precedent as IMP-12 u7 cascade actions — planner-surface + orchestrator
+    wiring together constitute IMPLEMENTED on the deterministic surface.)"""
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["frame_internal_fit_candidate"] == "IMPLEMENTED"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["image_fit"] == "IMPLEMENTED"
+
+
+def test_imp88_existing_implementation_status_preserved():
+    """Regression guard — IMP-12 u7 + IMP-35 u3 status rows stay intact.
+    Post u7 completion, layout_adjust on the failure-router surface flips
+    to IMPLEMENTED alongside the primary router surface (u3 planner + u6
+    dispatcher + u7 cascade entry)."""
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["cross_zone_redistribute"] == "IMPLEMENTED"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["glue_compression"] == "IMPLEMENTED"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["font_step_compression"] == "IMPLEMENTED"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["layout_adjust"] == "IMPLEMENTED"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["frame_reselect"] == "MISSING"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["details_popup_escalation"] == "MISSING"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["none"] == "n/a"
+
+
+# ─── End-to-end classifier + router path ──────────────────────────
+
+
+def test_imp88_three_new_salvage_failures_classifier_path_end_to_end():
+    """End-to-end: a salvage_steps[-1] entry with one of the three IMP-88
+    actions (layout_adjust / image_fit / frame_internal_fit_candidate) and
+    passed=False routes through classifier → router and lands on the
+    expected cascade next action. Confirms u2 producer + cascade rows are
+    wired through `classify_retry_failure` + `route_retry_failure` together.
+    """
+    cases = [
+        (
+            "layout_adjust",
+            "layout_adjust_insufficient",
+            "frame_internal_fit_candidate",
+        ),
+        (
+            "frame_internal_fit_candidate",
+            "frame_internal_fit_candidate_insufficient",
+            "frame_reselect",
+        ),
+        (
+            "image_fit",
+            "image_fit_insufficient",
+            "layout_adjust",
+        ),
+    ]
+    for action, expected_ftype, expected_next in cases:
+        trace = {
+            "retry_attempted": True,
+            "retry_passed": False,
+            "salvage_passed": False,
+            "salvage_steps": [
+                {
+                    "action": action,
+                    "passed": False,
+                    "failure_reason": f"{action} salvage failed (test)",
+                }
+            ],
+        }
+        fc = classify_retry_failure(trace)
+        assert fc is not None, f"classifier returned None for action={action}"
+        assert fc["failure_type"] == expected_ftype, (
+            f"classifier emitted {fc['failure_type']!r} for action={action}, "
+            f"expected {expected_ftype!r}"
+        )
+        nr = route_retry_failure(fc["failure_type"])
+        assert nr["next_proposed_action"] == expected_next, (
+            f"router routed {fc['failure_type']!r} → {nr['next_proposed_action']!r}, "
+            f"expected {expected_next!r}"
+        )
+
+
+def test_imp88_enrichment_composes_layout_adjust_insufficient_proposal():
+    """End-to-end via enrich_retry_trace_with_failure_classification — the
+    deterministic Step 17 dispatcher will read these fields off the trace,
+    so verify the public wrapper attaches both failure_classification and
+    next_action_proposal correctly for the layout_adjust salvage path."""
+    trace = {
+        "retry_attempted": True,
+        "retry_passed": False,
+        "salvage_passed": False,
+        "salvage_steps": [
+            {
+                "action": "layout_adjust",
+                "passed": False,
+                "failure_reason": "layout_adjust preset switch did not fit",
+            }
+        ],
+    }
+    enrich_retry_trace_with_failure_classification(trace)
+    assert trace["failure_classification"]["failure_type"] == (
+        "layout_adjust_insufficient"
+    )
+    assert trace["next_action_proposal"]["next_proposed_action"] == (
+        "frame_internal_fit_candidate"
+    )
+    # frame_internal_fit_candidate is IMPLEMENTED after u5 planner + u6
+    # dispatcher branch + u7 cascade entry.
+    assert trace["next_action_proposal"]["next_action_implementation_status"] == (
+        "IMPLEMENTED"
+    )
+
+
+# ─── Rationale registry coverage ──────────────────────────────────
+
+
+def test_imp88_three_new_failure_rationales_registered():
+    """u2 registers a rationale entry for each new failure_type so the
+    enrichment wrapper emits a non-empty rationale (debug-trace usability)."""
+    for ftype in (
+        "layout_adjust_insufficient",
+        "image_fit_insufficient",
+        "frame_internal_fit_candidate_insufficient",
+    ):
+        assert ftype in NEXT_ACTION_RATIONALE, (
+            f"u2 must register {ftype} in NEXT_ACTION_RATIONALE"
+        )
+        assert NEXT_ACTION_RATIONALE[ftype].strip(), (
+            f"NEXT_ACTION_RATIONALE[{ftype!r}] must be non-empty"
+        )
@@ -0,0 +1,437 @@
+"""IMP-39 u8 (issue #68) - corpus audit over tests/matching/v4_full32_result.yaml.
+
+Mirror-invariance regression on the REAL V4 full-32 judgments corpus
+(``tests/matching/v4_full32_result.yaml``). For every MDX section in the
+corpus, asserts that:
+
+  1. The backend ranking helper ``apply_ranking_sort`` (single-source
+     policy via ``templates/phase_z2/catalog/ranking_sort_policy.yaml``)
+     yields the same ordering as a Python mirror of the frontend
+     candidate sort (``Front/client/src/services/designAgentApi.ts``
+     warn-fallback path, lines 644-649). i.e. backend selector "rank 1"
+     == frontend ``frame_candidates[0]`` by construction across the
+     full corpus, with NO sample-specific carve-out.
+  2. The tie-break contract (label_priority asc, confidence desc,
+     v4_rank asc) holds when (label, confidence) ties occur in real
+     data (e.g. multi-restructure sections like 01-1 where rank=8
+     restructure rises above rank=5 reject under policy).
+  3. Real-data DIVERGENCE between raw V4 confidence-desc order and
+     policy-sorted order EXISTS in the corpus (audit honesty: proves
+     the policy is non-trivial on real samples, not just synthetic
+     u6 fixture).
+
+Sample-agnostic axis (RULE 0 / RULE 7):
+  - The test iterates ``data['mdx_sections']`` keys dynamically; no
+    section ID (``01-2``, ``03-1``, ``04-2.1``, ...) is hardcoded as
+    an assertion target. The corpus inventory is treated as a
+    parametrize source, not a contract.
+  - The test does NOT assert any specific ``frame_id`` /
+    ``template_id`` / ``frame_number``. Only the ordering contract
+    is asserted.
+  - The test does NOT depend on MDX 03/04/05 outcome / answer_map
+    correctness; it only validates that the policy is applied
+    uniformly across whatever sections the corpus happens to have.
+
+Scope (u8, Stage 2 plan):
+  - Real-data sweep of ``tests/matching/v4_full32_result.yaml``
+    confirming backend / frontend mirror invariance under
+    ``apply_ranking_sort`` + ``LABEL_PRIORITY`` mirror.
+  - Corpus uses ``v4_full_rank`` as the tie-break key, so calls pass
+    ``v4_rank_key="v4_full_rank"`` (matching u2 selector wiring).
+
+Out of scope (other units):
+  - u1 policy yaml shape: covered by ``test_ranking_sort_policy.py``.
+  - u2 selector wiring: integration covered indirectly via u7.
+  - u3 Step 9 payload forwarding: covered by u7.
+  - u4 frontend mirror: covered by u7.
+  - u5 pure permutation tests.
+  - u6 SYNTHETIC divergence fixture
+    (``tests/phase_z2/test_label_priority_synthetic.py``).
+  - u7 mdx04 env-toggle e2e
+    (``tests/phase_z2/test_imp39_mdx04_env_toggle_e2e.py``).
+  - V4 matching algorithm correctness (out of #68 scope, owner #5).
+  - ``MVP1_ALLOWED_STATUSES`` gate semantics (IMP-47B locked area).
+  - capacity-fit / catalog contract validation (orthogonal to policy).
+"""
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Any, Dict, List
+
+import pytest
+import yaml
+
+
+_REPO_ROOT = Path(__file__).resolve().parents[2]
+_CORPUS_PATH = _REPO_ROOT / "tests" / "matching" / "v4_full32_result.yaml"
+
+
+# Frontend LABEL_PRIORITY verbatim mirror — Front/client/src/services/
+# designAgentApi.ts:575-580 + warn-fallback sort :644-649. Kept inline (not
+# imported from python policy) so this audit catches drift if the frontend
+# TS constant ever diverges from the yaml policy. The yaml-shape equality
+# is exercised separately in test_ranking_sort_policy.py (u5).
+_FRONTEND_LABEL_PRIORITY: Dict[str, int] = {
+    "use_as_is": 0,
+    "light_edit": 1,
+    "restructure": 2,
+    "reject": 3,
+}
+_FRONTEND_UNKNOWN_PRIORITY = 99
+
+
+@pytest.fixture(autouse=True)
+def _reset_policy_cache():
+    """Mirror peer-test isolation - clear the cached single-source policy."""
+    import src.phase_z2_pipeline as pipeline
+
+    pipeline._RANKING_SORT_POLICY_CACHE = None
+    yield
+    pipeline._RANKING_SORT_POLICY_CACHE = None
+
+
+@pytest.fixture(scope="module")
+def corpus() -> Dict[str, Any]:
+    """Load v4_full32_result.yaml exactly once per test module run."""
+    assert _CORPUS_PATH.exists(), (
+        f"Corpus audit source missing: {_CORPUS_PATH}. u8 requires "
+        f"tests/matching/v4_full32_result.yaml present in repo."
+    )
+    with _CORPUS_PATH.open(encoding="utf-8") as f:
+        return yaml.safe_load(f)
+
+
+@pytest.fixture(scope="module")
+def section_ids(corpus) -> List[str]:
+    """Dynamic section inventory — NOT hardcoded.
+
+    Source = ``corpus['mdx_sections'].keys()``. The test asserts the
+    set is non-empty and each entry has a populated ``judgments_full32``
+    list. Section IDs themselves are treated as parametrize values, not
+    assertion targets.
+    """
+    return list(corpus["mdx_sections"].keys())
+
+
+def _frontend_mirror_sort(
+    judgments: List[Dict[str, Any]],
+) -> List[Dict[str, Any]]:
+    """Pure-Python mirror of frontend warn-fallback ordering.
+
+    Mirrors ``Front/client/src/services/designAgentApi.ts:644-649``:
+        v4Source.sort((a, b) => {
+          const lp = (LABEL_PRIORITY[a.label] ?? 99) - (LABEL_PRIORITY[b.label] ?? 99);
+          if (lp !== 0) return lp;
+          return (b.confidence ?? 0) - (a.confidence ?? 0);
+        });
+
+    NOTE on tie-break: the frontend warn-fallback path lacks the
+    explicit v4_rank tie-break the backend policy carries (yaml
+    ``tie_break_axes: [confidence_desc, v4_rank_asc]``). When (label,
+    confidence) are both equal, the frontend ``Array.prototype.sort``
+    is now stable (ES2019), so original order is preserved. Backend
+    ``apply_ranking_sort`` also uses Python's stable Timsort and adds
+    ``v4_rank asc`` only as a positive tie-break which agrees with raw
+    V4 order (v4_rank=1 first, raw V4 ordering is confidence-desc =
+    same as input). Net effect: identical ordering across both paths
+    on the real corpus. The audit below verifies this empirically.
+    """
+    return sorted(
+        judgments,
+        key=lambda j: (
+            _FRONTEND_LABEL_PRIORITY.get(j.get("label"), _FRONTEND_UNKNOWN_PRIORITY),
+            -float(j.get("confidence", 0.0)),
+        ),
+    )
+
+
+def _identity_key(judgment: Dict[str, Any]) -> tuple:
+    """Stable identity for a corpus judgment row.
+
+    ``v4_full_rank`` is unique per section (1..32), so it serves as the
+    section-local identity. Wrapped in a tuple with ``frame_number`` /
+    ``template_id`` for diagnostic richness in assert messages (these
+    extras are NOT used to derive ordering; only for failure diagnosis).
+    """
+    return (
+        judgment.get("v4_full_rank"),
+        judgment.get("frame_number"),
+        judgment.get("template_id"),
+    )
+
+
+# ─── corpus shape sanity ───────────────────────────────────────────────
+
+
+def test_corpus_file_is_present_and_non_empty(corpus, section_ids):
+    """RULE 5 factual: corpus path + section inventory both surface up."""
+    assert isinstance(corpus, dict)
+    assert "mdx_sections" in corpus
+    assert len(section_ids) > 0, (
+        f"v4_full32_result.yaml has zero mdx_sections — corpus audit "
+        f"cannot run. Path: {_CORPUS_PATH}"
+    )
+    for sec_id in section_ids:
+        section = corpus["mdx_sections"][sec_id]
+        judgments = section.get("judgments_full32")
+        assert isinstance(judgments, list) and len(judgments) > 0, (
+            f"Section {sec_id}: judgments_full32 missing or empty."
+        )
+        # Every judgment must carry the four sort-relevant fields.
+        for j in judgments:
+            assert "label" in j, f"{sec_id}: judgment missing 'label'."
+            assert "confidence" in j, f"{sec_id}: judgment missing 'confidence'."
+            assert "v4_full_rank" in j, (
+                f"{sec_id}: judgment missing 'v4_full_rank' (tie-break key)."
+            )
+
+
+# ─── backend ↔ frontend mirror invariance ───────────────────────────────
+
+
+def test_backend_policy_sort_matches_frontend_mirror_per_section(
+    corpus, section_ids,
+):
+    """Per-section: backend ``apply_ranking_sort`` == frontend mirror order."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    divergences: List[str] = []
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+
+        backend_sorted = apply_ranking_sort(
+            judgments,
+            v4_rank_key="v4_full_rank",
+        )
+        frontend_sorted = _frontend_mirror_sort(judgments)
+
+        backend_keys = [_identity_key(j) for j in backend_sorted]
+        frontend_keys = [_identity_key(j) for j in frontend_sorted]
+        if backend_keys != frontend_keys:
+            divergences.append(
+                f"section={sec_id} backend_head={backend_keys[0]} "
+                f"frontend_head={frontend_keys[0]} "
+                f"first_divergence_index="
+                f"{next((i for i, (a, b) in enumerate(zip(backend_keys, frontend_keys)) if a != b), 'tail')}"
+            )
+
+    assert not divergences, (
+        "backend ↔ frontend mirror divergence on real corpus:\n  "
+        + "\n  ".join(divergences)
+    )
+
+
+def test_backend_rank_1_equals_frontend_candidate_0_per_section(
+    corpus, section_ids,
+):
+    """Stage 1 root-cause head-of-list invariant on every corpus section."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    head_mismatches: List[str] = []
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+
+        backend_rank_1 = apply_ranking_sort(
+            judgments,
+            v4_rank_key="v4_full_rank",
+        )[0]
+        frontend_candidate_0 = _frontend_mirror_sort(judgments)[0]
+
+        if _identity_key(backend_rank_1) != _identity_key(frontend_candidate_0):
+            head_mismatches.append(
+                f"section={sec_id} "
+                f"backend_rank_1={_identity_key(backend_rank_1)} "
+                f"frontend_candidate_0={_identity_key(frontend_candidate_0)}"
+            )
+
+    assert not head_mismatches, (
+        "backend selector 'rank 1' diverges from frontend frame_candidates[0]:\n  "
+        + "\n  ".join(head_mismatches)
+    )
+
+
+# ─── tie-break + label-priority contract on real data ──────────────────
+
+
+def test_policy_ordering_respects_label_priority_per_section(
+    corpus, section_ids,
+):
+    """``label_priority`` weakly monotone across the policy-sorted list."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    violations: List[str] = []
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+        sorted_judgments = apply_ranking_sort(
+            judgments,
+            v4_rank_key="v4_full_rank",
+        )
+        priorities = [
+            _FRONTEND_LABEL_PRIORITY.get(j["label"], _FRONTEND_UNKNOWN_PRIORITY)
+            for j in sorted_judgments
+        ]
+        for i in range(len(priorities) - 1):
+            if priorities[i] > priorities[i + 1]:
+                violations.append(
+                    f"section={sec_id} idx={i} prio={priorities[i]} > "
+                    f"idx={i + 1} prio={priorities[i + 1]}"
+                )
+                break
+
+    assert not violations, (
+        "label_priority must be weakly monotone post-sort:\n  "
+        + "\n  ".join(violations)
+    )
+
+
+def test_policy_confidence_desc_within_label_group_per_section(
+    corpus, section_ids,
+):
+    """Within same label, confidence must be weakly descending."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    violations: List[str] = []
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+        sorted_judgments = apply_ranking_sort(
+            judgments,
+            v4_rank_key="v4_full_rank",
+        )
+        for i in range(len(sorted_judgments) - 1):
+            a, b = sorted_judgments[i], sorted_judgments[i + 1]
+            if a["label"] != b["label"]:
+                continue
+            if float(a["confidence"]) < float(b["confidence"]):
+                violations.append(
+                    f"section={sec_id} idx={i} label={a['label']} "
+                    f"conf={a['confidence']} < idx={i + 1} conf={b['confidence']}"
+                )
+                break
+
+    assert not violations, (
+        "confidence must be weakly desc within same-label runs:\n  "
+        + "\n  ".join(violations)
+    )
+
+
+def test_policy_v4_full_rank_asc_within_label_confidence_ties(
+    corpus, section_ids,
+):
+    """When (label, confidence) tie, smaller v4_full_rank first.
+
+    Real-data tie-break check. If no section in the corpus exhibits a
+    (label, confidence) tie, the test passes vacuously — this is the
+    correct contract: we only assert the tie-break behaviour where
+    it can actually be observed in the real data. Pure-permutation
+    tie-break coverage is owned by u5
+    (``test_v4_rank_asc_tie_break_on_equal_confidence``).
+    """
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    tie_break_violations: List[str] = []
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+        sorted_judgments = apply_ranking_sort(
+            judgments,
+            v4_rank_key="v4_full_rank",
+        )
+        for i in range(len(sorted_judgments) - 1):
+            a, b = sorted_judgments[i], sorted_judgments[i + 1]
+            if a["label"] != b["label"]:
+                continue
+            if float(a["confidence"]) != float(b["confidence"]):
+                continue
+            if int(a["v4_full_rank"]) > int(b["v4_full_rank"]):
+                tie_break_violations.append(
+                    f"section={sec_id} idx={i} v4_full_rank={a['v4_full_rank']} "
+                    f"> idx={i + 1} v4_full_rank={b['v4_full_rank']} "
+                    f"(label={a['label']} conf={a['confidence']})"
+                )
+
+    assert not tie_break_violations, (
+        "v4_full_rank must be weakly asc within (label, conf) ties:\n  "
+        + "\n  ".join(tie_break_violations)
+    )
+
+
+# ─── audit honesty: real divergence exists ─────────────────────────────
+
+
+def test_corpus_exhibits_real_policy_divergence(corpus, section_ids):
+    """At least one section MUST show raw-V4-order != policy-order.
+
+    Honesty check (RULE 5): the corpus audit is meaningful only if the
+    policy actually changes some real section's ordering. If every
+    section already sorts the same way under raw V4 confidence-desc
+    AND under the policy, then the policy is a no-op on this corpus
+    and we should know about it — either the corpus needs richer
+    samples or the divergence axis has shifted.
+
+    Currently observed (2026-05-24) raw-vs-policy mid-list divergence:
+    sections with multi-label diversity where a lower-confidence
+    higher-priority candidate sits behind a higher-confidence
+    lower-priority one (e.g. section 01-1 has rank=8 restructure
+    rising above rank=5/6/7 rejects under policy).
+    """
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    any_divergence = False
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+        # Raw V4 order: rows are stored in v4_full_rank asc (= confidence desc).
+        raw_keys = [_identity_key(j) for j in judgments]
+        policy_keys = [
+            _identity_key(j)
+            for j in apply_ranking_sort(judgments, v4_rank_key="v4_full_rank")
+        ]
+        if raw_keys != policy_keys:
+            any_divergence = True
+            break
+
+    assert any_divergence, (
+        "No corpus section shows raw-V4 vs policy ordering divergence. "
+        "The policy is a no-op on this corpus — either re-curate the "
+        "corpus or re-validate the divergence axis."
+    )
+
+
+# ─── determinism + non-mutation on real corpus ─────────────────────────
+
+
+def test_policy_sort_is_deterministic_across_calls_per_section(
+    corpus, section_ids,
+):
+    """Two consecutive calls on the same section yield identical ordering."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+        first = [
+            _identity_key(j)
+            for j in apply_ranking_sort(judgments, v4_rank_key="v4_full_rank")
+        ]
+        second = [
+            _identity_key(j)
+            for j in apply_ranking_sort(judgments, v4_rank_key="v4_full_rank")
+        ]
+        assert first == second, (
+            f"section={sec_id}: apply_ranking_sort is non-deterministic "
+            f"across calls."
+        )
+
+
+def test_corpus_input_lists_are_not_mutated(corpus, section_ids):
+    """Corpus rows survive ``apply_ranking_sort`` unchanged in place."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    for sec_id in section_ids:
+        judgments = corpus["mdx_sections"][sec_id]["judgments_full32"]
+        snapshot = [_identity_key(j) for j in judgments]
+
+        apply_ranking_sort(judgments, v4_rank_key="v4_full_rank")
+
+        post = [_identity_key(j) for j in judgments]
+        assert snapshot == post, (
+            f"section={sec_id}: apply_ranking_sort mutated source list "
+            f"in place (forbidden — see u5 non-mutation contract)."
+        )
@@ -0,0 +1,332 @@
+"""IMP-39 u7 (issue #68) — mdx04 env-toggle e2e (AI_FALLBACK_ENABLED=off).
+
+Stage 2 u7 axis G:
+    Run ``python -m src.phase_z2_pipeline samples/mdx_batch/04.mdx <run_id>``
+    with ``AI_FALLBACK_ENABLED=off`` and assert that the backend selector's
+    "rank 1" view agrees with the frontend ``frame_candidates[0]`` view —
+    i.e., the Stage 1 root-cause divergence (Backend src/phase_z2_pipeline.py
+    raw-confidence-desc iteration vs Frontend Front/client/src/services/
+    designAgentApi.ts label-priority resort) cannot recur once both sides
+    consume the single-source ranking_sort_policy.yaml contract (u1) via the
+    Step 9 payload (u3) and the frontend primary-path mirror (u4).
+
+Out of scope (per Stage 2 lock):
+    * The IMP-85 mdx04 BuilderMissingError downstream surface — covered by
+      ``tests/test_pipeline_smoke_imp85.py``. This e2e does NOT pin the
+      subprocess returncode; mdx04 may exit non-zero post-IMP-85 routing
+      while still emitting ``step09_application_plan.json`` whose unit
+      payload is what u3/u4 contract on.
+    * MVP1_ALLOWED_STATUSES gate / v4_fallback_policy max-rank /
+      capacity-fit / AI restructure / cache carve-out (IMP-46) / Phase Z
+      spacing semantics — all unchanged by IMP-39.
+    * Pure-permutation helper coverage (tests/test_ranking_sort_policy.py
+      u5) and the SYNTHETIC divergence regression
+      (tests/phase_z2/test_label_priority_synthetic.py u6).
+    * Corpus audit over v4_full32_result.yaml — u8.
+
+Demo env toggle policy (feedback_demo_env_toggle_policy 2026-05-08):
+    The subprocess is spawned with an EXPLICIT
+    ``env={..., "AI_FALLBACK_ENABLED": "false"}`` override even though
+    tests/conftest.py already sets the parent-process default to false.
+    This keeps the toggle expectation visible at the test level and
+    matches the .env-only activation policy (the .env file ships with
+    ``AI_FALLBACK_ENABLED=true``; the test isolates the off path).
+"""
+from __future__ import annotations
+
+import json
+import os
+import subprocess
+import sys
+import uuid
+from pathlib import Path
+from typing import Any
+
+import pytest
+import yaml
+
+from src.phase_z2_pipeline import apply_ranking_sort, load_ranking_sort_policy
+
+_REPO_ROOT = Path(__file__).resolve().parents[2]
+_SAMPLE_MDX = _REPO_ROOT / "samples" / "mdx_batch" / "04.mdx"
+_RUNS_DIR = _REPO_ROOT / "data" / "runs"
+_POLICY_YAML = (
+    _REPO_ROOT
+    / "templates"
+    / "phase_z2"
+    / "catalog"
+    / "ranking_sort_policy.yaml"
+)
+
+# Mirrors Front/client/src/services/designAgentApi.ts :567 — frontend slices
+# the dedup'd v4Source to this many candidates. The test asserts that the
+# frontend frame_candidates[0] mirror still equals sorted_candidate_evidence[0]
+# for any TOP_N_FRAMES >= 1, but we honor the precise frontend constant so
+# the dedup-then-slice path is exercised verbatim (not paraphrased).
+_FRONTEND_TOP_N_FRAMES = 6
+
+
+def _frontend_frame_candidates(sorted_evidence: list[dict]) -> list[dict]:
+    """Pure-Python mirror of Front/client/src/services/designAgentApi.ts
+    :586-650 primary path:
+
+      const candidateMap = new Map<string, any>();
+      const pushCandidate = (c: any) => {
+        if (!c) return;
+        const key = c.template_id ?? c.id ?? c.frame_id;
+        if (!key) return;
+        if (!candidateMap.has(key)) candidateMap.set(key, c);
+      };
+      sortedCandidateEvidence!.forEach(pushCandidate);
+      v4Source = Array.from(candidateMap.values());
+      frameCandidates = v4Source.slice(0, TOP_N_FRAMES);
+
+    Same first-occurrence-wins dedup ordering, same slice cap, same key
+    fallback chain. Kept inline (no shared util) so a TS-side refactor that
+    diverges the contract is forced to update this mirror explicitly.
+    """
+    seen: dict[Any, dict] = {}
+    for c in sorted_evidence:
+        if not isinstance(c, dict):
+            continue
+        key = c.get("template_id") or c.get("id") or c.get("frame_id")
+        if key is None or key == "":
+            continue
+        if key not in seen:
+            seen[key] = c
+    return list(seen.values())[:_FRONTEND_TOP_N_FRAMES]
+
+
+@pytest.fixture(scope="module")
+def mdx04_env_toggle_run() -> dict:
+    """Single subprocess run shared across u7 assertions.
+
+    Returns ``{"run_id": ..., "completed_process": ..., "plan_payload": ...}``.
+    The IMP-85 downstream surface may push returncode != 0 for mdx04 (out of
+    scope here) — we still expect ``step09_application_plan.json`` to be
+    emitted, because u3 forwards the payload before any IMP-85 builder-fit
+    path. The fixture xfails if mdx04 does not even reach step09.
+    """
+    assert _SAMPLE_MDX.exists(), f"sample missing: {_SAMPLE_MDX}"
+    run_id = f"imp39_u7_mdx04_{uuid.uuid4().hex[:8]}"
+    env = dict(os.environ)
+    env["AI_FALLBACK_ENABLED"] = "false"
+    env["AI_FALLBACK_AUTO_CACHE"] = "false"
+    cp = subprocess.run(
+        [
+            sys.executable,
+            "-m",
+            "src.phase_z2_pipeline",
+            str(_SAMPLE_MDX),
+            run_id,
+        ],
+        capture_output=True,
+        text=True,
+        timeout=240,
+        cwd=str(_REPO_ROOT),
+        env=env,
+    )
+    plan_path = (
+        _RUNS_DIR
+        / run_id
+        / "phase_z2"
+        / "steps"
+        / "step09_application_plan.json"
+    )
+    if not plan_path.is_file():
+        pytest.xfail(
+            "mdx04 subprocess did not emit step09_application_plan.json "
+            f"(IMP-85 area, out of scope for u7). returncode={cp.returncode}\n"
+            f"--- stderr tail ---\n{cp.stderr[-1500:]}\n"
+            f"--- stdout tail ---\n{cp.stdout[-1500:]}"
+        )
+    plan_payload = json.loads(plan_path.read_text(encoding="utf-8"))
+    return {
+        "run_id": run_id,
+        "completed_process": cp,
+        "plan_payload": plan_payload,
+    }
+
+
+def _units_with_v4(plan_payload: dict) -> list[dict]:
+    units = (plan_payload.get("data") or {}).get("units") or []
+    return [
+        u
+        for u in units
+        if isinstance(u.get("sorted_candidate_evidence"), list)
+        and u["sorted_candidate_evidence"]
+    ]
+
+
+def test_mdx04_env_toggle_step9_emits_u3_payload_fields(mdx04_env_toggle_run):
+    """Every Step 9 unit in the mdx04 e2e run carries the u3 additive fields
+    (``ranking_sort_policy`` + ``sorted_candidate_evidence``).
+
+    Locks: u3 payload forwarding (src/phase_z2_pipeline.py :4163-4164) is
+    exercised by the real subprocess path on mdx04, not just an in-process
+    helper smoke. Without this gate the u4 frontend primary path silently
+    degrades to the LABEL_PRIORITY warn-fallback and the Stage 1 divergence
+    can re-surface on legacy data.
+    """
+    plan = mdx04_env_toggle_run["plan_payload"]
+    units = (plan.get("data") or {}).get("units") or []
+    assert units, "mdx04 application_plan emitted zero units"
+    yaml_policy = yaml.safe_load(_POLICY_YAML.read_text(encoding="utf-8"))
+    expected_policy_type = yaml_policy["policy_type"]
+    expected_label_priority = yaml_policy["label_priority"]
+    expected_unknown = yaml_policy["unknown_label_priority"]
+    expected_tie_break = yaml_policy["tie_break_axes"]
+    for u in units:
+        assert "ranking_sort_policy" in u, (
+            f"unit {u.get('unit_id')!r} missing ranking_sort_policy "
+            "(u3 payload forwarding regressed)"
+        )
+        assert "sorted_candidate_evidence" in u, (
+            f"unit {u.get('unit_id')!r} missing sorted_candidate_evidence "
+            "(u3 payload forwarding regressed)"
+        )
+        pol = u["ranking_sort_policy"]
+        assert pol.get("policy_type") == expected_policy_type
+        assert pol.get("label_priority") == expected_label_priority
+        assert pol.get("unknown_label_priority") == expected_unknown
+        assert pol.get("tie_break_axes") == expected_tie_break
+
+
+def test_mdx04_sorted_candidate_evidence_is_policy_sorted(mdx04_env_toggle_run):
+    """``unit.sorted_candidate_evidence`` is already in policy order — i.e.,
+    ``apply_ranking_sort(evidence)`` is a no-op (idempotent).
+
+    This pins the u2 selector ordering invariant
+    (src/phase_z2_pipeline.py :1186-1196 sorts ``judgments`` BEFORE the
+    selector loop appends candidate_trace entries) against the real mdx04
+    pipeline path. Any future change that re-sorts the trace post-iteration
+    or appends out-of-order would fail this assertion.
+    """
+    plan = mdx04_env_toggle_run["plan_payload"]
+    units_with_v4 = _units_with_v4(plan)
+    assert units_with_v4, (
+        "mdx04 application_plan units have no V4 evidence; cannot evaluate "
+        "the sort-idempotency invariant"
+    )
+    policy = load_ranking_sort_policy()
+    for u in units_with_v4:
+        evidence = u["sorted_candidate_evidence"]
+        resorted = apply_ranking_sort(
+            evidence,
+            policy=policy,
+            label_key="label",
+            confidence_key="confidence",
+            v4_rank_key="v4_full_rank",
+        )
+        order_in = [
+            (c.get("label"), c.get("confidence"), c.get("template_id"))
+            for c in evidence
+        ]
+        order_out = [
+            (c.get("label"), c.get("confidence"), c.get("template_id"))
+            for c in resorted
+        ]
+        assert order_in == order_out, (
+            f"unit {u.get('unit_id')!r} sorted_candidate_evidence is not in "
+            f"policy order (u2 selector-loop ordering regressed):\n"
+            f"  observed: {order_in[:6]}\n"
+            f"  expected: {order_out[:6]}"
+        )
+
+
+def test_mdx04_backend_frontend_rank_one_mirror(mdx04_env_toggle_run):
+    """Stage 1 root-cause regression guard: backend "rank 1" view ≡
+    frontend ``frame_candidates[0]`` view on real mdx04 data.
+
+    Backend view = ``sorted_candidate_evidence[0]`` (policy-sorted selector
+    trace head — what the selector saw at iteration 1 of u2's sorted loop).
+    Frontend view = first entry of the dedup-then-slice mirror computed by
+    ``_frontend_frame_candidates`` (Front/client/src/services/designAgentApi.ts
+    :586-661 primary path verbatim).
+
+    These two MUST refer to the same V4 candidate (matched on
+    ``(template_id, label, confidence)``) for every unit emitted by the mdx04
+    pipeline run under ``AI_FALLBACK_ENABLED=off``. A mismatch here is the
+    exact post-fix surface of the Stage 1 root-cause divergence; the test is
+    sample-agnostic in its assertion (the divergence is structurally
+    impossible once both sides share the same source, not because mdx04
+    specifically lacks the divergence shape).
+    """
+    plan = mdx04_env_toggle_run["plan_payload"]
+    units_with_v4 = _units_with_v4(plan)
+    assert units_with_v4, "no V4-bearing units in mdx04 application_plan"
+    for u in units_with_v4:
+        evidence = u["sorted_candidate_evidence"]
+        backend_head = evidence[0]
+        frontend_candidates = _frontend_frame_candidates(evidence)
+        assert frontend_candidates, (
+            f"unit {u.get('unit_id')!r}: frontend dedup mirror produced "
+            "an empty frame_candidates list (key fallback chain regressed)"
+        )
+        frontend_head = frontend_candidates[0]
+        backend_key = (
+            backend_head.get("template_id"),
+            backend_head.get("label"),
+            backend_head.get("confidence"),
+        )
+        frontend_key = (
+            frontend_head.get("template_id"),
+            frontend_head.get("label"),
+            frontend_head.get("confidence"),
+        )
+        assert backend_key == frontend_key, (
+            f"unit {u.get('unit_id')!r} backend rank-1 ≠ frontend "
+            f"frame_candidates[0]:\n"
+            f"  backend  : {backend_key}\n"
+            f"  frontend : {frontend_key}\n"
+            "  → Stage 1 root-cause divergence has re-surfaced; check u2/u3/u4 wiring."
+        )
+
+
+def test_mdx04_application_status_ok_unit_selects_sorted_head(
+    mdx04_env_toggle_run,
+):
+    """When a unit's selector actually chose a real (non-provisional)
+    candidate (``application_status == "ok"`` and
+    ``selection_path == "rank_1"``), the chosen frame must be
+    ``sorted_candidate_evidence[0]``.
+
+    The candidate_evidence entry with ``decision == "selected"`` is the
+    selector's resolved choice; under u2 the loop iterates policy-sorted
+    order, so the head of ``sorted_candidate_evidence`` is the first
+    iteration. If the head is "selected" the invariant holds; the test
+    silently passes when no unit in this mdx04 run hits ok+rank_1 (the
+    scenario is sample-shape dependent and not contractually guaranteed
+    on every mdx04 emission).
+    """
+    plan = mdx04_env_toggle_run["plan_payload"]
+    units_with_v4 = _units_with_v4(plan)
+    checked = 0
+    for u in units_with_v4:
+        if u.get("application_status") != "ok":
+            continue
+        if u.get("selection_path") != "rank_1":
+            continue
+        evidence = u["sorted_candidate_evidence"]
+        head = evidence[0]
+        selected_entries = [
+            c for c in evidence if c.get("decision") == "selected"
+        ]
+        assert selected_entries, (
+            f"unit {u.get('unit_id')!r} has application_status=ok + "
+            "selection_path=rank_1 but no candidate_trace entry is marked "
+            "decision=selected (selector trace shape regressed)"
+        )
+        selected = selected_entries[0]
+        assert selected.get("template_id") == head.get("template_id"), (
+            f"unit {u.get('unit_id')!r}: backend selected template_id "
+            f"{selected.get('template_id')!r} ≠ sorted_candidate_evidence[0]"
+            f".template_id {head.get('template_id')!r}; u2 selector-loop "
+            "order must place the selected candidate at index 0"
+        )
+        checked += 1
+    # No hard floor — mdx04's V4 mix at the time of this test may yield zero
+    # ok+rank_1 units (sample-shape contingent). The mirror invariance above
+    # is the binding contract; this test is the stricter sub-invariant that
+    # only fires when a unit hits the ok+rank_1 path.
+    assert checked >= 0
@@ -0,0 +1,323 @@
+"""IMP-40 u4 (issue #69) — synthetic role-policy matrix for
+``_build_compare_table_2col`` label-default discriminator.
+
+Stage 2 u4 contract (verbatim)::
+
+    Add synthetic role-policy tests for placeholder, fallback, absent role,
+    and unknown role using minimal Section plus contract inputs.
+
+Why this is load-bearing
+========================
+
+u1 (frame_contracts.yaml F18) and u2 (F30/F31) opt the catalog into the
+new ``{col_key}_label_default_role`` discriminator. u3 (mapper) implements
+the runtime branch::
+
+    role == "placeholder" → col_{a,b}_label = ""        (Figma visual
+                                                         placeholder
+                                                         suppressed)
+    role == "fallback"    → col_{a,b}_label = catalog literal
+                                                         (legacy behavior)
+    role absent           → defaults to "fallback"        (backward compat
+                                                         for legacy
+                                                         contracts)
+    role unknown          → ValueError                    (no silent
+                                                         miscategorization)
+
+This file exercises that 4-row policy matrix at the
+``_build_compare_table_2col`` boundary with **synthetic** Section + contract
+inputs. No reliance on the YAML catalog, no sample-specific frame ids,
+no MDX 03 / 04 / 05 literals. Catalog-vs-mapper drift detection is the
+job of the integration snapshot path (u6), not this unit.
+
+Scope (u4, Stage 2 plan)
+========================
+
+* 4 policy rows: placeholder / fallback / absent / unknown.
+* ``SimpleNamespace`` Section stub (mirrors the pattern in
+  ``tests/test_phase_z2_mapper_builder_missing.py``).
+* Inline contract dicts — no catalog import.
+* ``title`` slot omitted (``_resolve_title`` returns ``{}`` when
+  ``payload.title.source`` is absent — verified at
+  ``src/phase_z2_mapper.py:371-382``); keeps the assertion surface focused
+  on ``col_a_label`` / ``col_b_label`` resolution.
+* Synthetic catalog literals (``LITERAL_COL_A`` / ``LITERAL_COL_B``) keep
+  the assertion sample-agnostic — the policy mechanism is the invariant,
+  not any specific Figma placeholder string.
+
+Out of scope (other units)
+==========================
+
+* u1 catalog F18 role keys: covered by the integration snapshot drift in
+  u6 + the catalog-shape check via grep.
+* u2 catalog F30 / F31 role keys: catalog-only, no runtime builder yet
+  (``compare_table_3col`` builder activation is a downstream follow-up
+  recorded in Stage 2 ``follow_up_candidates``).
+* u5 F18-reuse regression with non-BIM/DX top_bullets content: separate
+  unit in the same file.
+* u6 mdx 01 F18 ``slot_payload`` snapshot refresh.
+"""
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import pytest
+
+from src.phase_z2_mapper import _build_compare_table_2col
+
+
+# ─── Synthetic helpers ─────────────────────────────────────────────
+
+_LITERAL_COL_A = "LITERAL_COL_A"
+_LITERAL_COL_B = "LITERAL_COL_B"
+
+
+def _make_section(raw_content: str = ""):
+    """Minimal Section stub — only the attributes the builder reads.
+
+    ``_build_compare_table_2col`` only touches ``section`` indirectly via
+    ``_resolve_title``, which is a no-op when ``payload.title.source`` is
+    absent. We still pass an empty ``raw_content`` so future regressions
+    that start reading from it would surface immediately rather than
+    silently passing on a placeholder.
+    """
+    return SimpleNamespace(
+        section_id="synthetic-imp40-u4",
+        raw_content=raw_content,
+        title="SYNTHETIC_TITLE",
+        order=1,
+    )
+
+
+def _make_contract(
+    *,
+    template_id: str,
+    col_a_role: str | None,
+    col_b_role: str | None,
+) -> dict:
+    """Inline contract dict — synthetic, sample-agnostic.
+
+    role=None → key omitted entirely (legacy / absent-role axis).
+    """
+    builder_options: dict = {
+        "item_parser": "compare_row_2col_item",
+        "col_a_label_default": _LITERAL_COL_A,
+        "col_b_label_default": _LITERAL_COL_B,
+    }
+    if col_a_role is not None:
+        builder_options["col_a_label_default_role"] = col_a_role
+    if col_b_role is not None:
+        builder_options["col_b_label_default_role"] = col_b_role
+
+    return {
+        "template_id": template_id,
+        "source_shape": "top_bullets",
+        "cardinality": {},
+        "payload": {
+            "builder": "compare_table_2col",
+            "builder_options": builder_options,
+        },
+    }
+
+
+# ─── Policy row 1: placeholder → "" (Figma placeholder suppressed) ─
+
+def test_placeholder_role_emits_empty_label_for_both_columns():
+    """role=placeholder MUST suppress the catalog literal at runtime.
+
+    This is the IMP-40 leak-fix invariant: even though the catalog still
+    carries a Figma placeholder string (preserved for design preview),
+    the builder MUST NOT inject it into the runtime payload.
+    """
+    contract = _make_contract(
+        template_id="synthetic_placeholder_both",
+        col_a_role="placeholder",
+        col_b_role="placeholder",
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == ""
+    assert payload["col_b_label"] == ""
+    assert _LITERAL_COL_A not in payload["col_a_label"]
+    assert _LITERAL_COL_B not in payload["col_b_label"]
+
+
+# ─── Policy row 2: fallback → catalog literal (legacy behavior) ────
+
+def test_fallback_role_emits_catalog_literal_for_both_columns():
+    """role=fallback MUST preserve the pre-IMP-40 behavior byte-for-byte.
+
+    Legacy contracts that explicitly opt into ``fallback`` (or migrate
+    forward from absent-role) must keep emitting the catalog literal so
+    that frames where MDX genuinely omits a header still render a
+    meaningful default.
+    """
+    contract = _make_contract(
+        template_id="synthetic_fallback_both",
+        col_a_role="fallback",
+        col_b_role="fallback",
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == _LITERAL_COL_A
+    assert payload["col_b_label"] == _LITERAL_COL_B
+
+
+# ─── Policy row 3: absent role → fallback (backward compatibility) ─
+
+def test_absent_role_defaults_to_fallback_for_both_columns():
+    """Contracts without the new ``_role`` discriminator MUST be inert.
+
+    Backward compatibility guard: u1/u2 only add ``_role`` keys to the
+    targeted F18 / F30 / F31 frames. Every other ``compare_table_2col``
+    consumer in the catalog (current or future) that omits the key MUST
+    continue to receive the catalog literal — same as pre-IMP-40.
+    """
+    contract = _make_contract(
+        template_id="synthetic_absent_role",
+        col_a_role=None,
+        col_b_role=None,
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == _LITERAL_COL_A
+    assert payload["col_b_label"] == _LITERAL_COL_B
+
+
+def test_partial_role_mix_is_resolved_per_column():
+    """Role discriminator MUST be resolved independently per column.
+
+    Synthetic edge case: col_a=placeholder, col_b absent. The placeholder
+    column emits "", the absent column falls back to its catalog literal.
+    Guards against any future refactor that accidentally couples the two
+    columns through a shared resolution path.
+    """
+    contract = _make_contract(
+        template_id="synthetic_partial_mix",
+        col_a_role="placeholder",
+        col_b_role=None,
+    )
+
+    payload = _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    assert payload["col_a_label"] == ""
+    assert payload["col_b_label"] == _LITERAL_COL_B
+
+
+# ─── Policy row 4: unknown role → ValueError (fail-fast) ───────────
+
+def test_unknown_role_raises_value_error_with_contract_context():
+    """role=<garbage> MUST raise ValueError, not silently fall back.
+
+    A typo or stale role value in a hand-edited catalog must surface
+    immediately at build time rather than being miscategorized as
+    "fallback" or "placeholder". Error message MUST cite the contract
+    template_id, the role key, and the invalid value to make catalog
+    repair tractable.
+    """
+    contract = _make_contract(
+        template_id="synthetic_unknown_role",
+        col_a_role="not_a_real_role",
+        col_b_role="placeholder",
+    )
+
+    with pytest.raises(ValueError) as exc:
+        _build_compare_table_2col(_make_section(), units=[], contract=contract)
+
+    msg = str(exc.value)
+    assert "synthetic_unknown_role" in msg
+    assert "col_a_label_default_role" in msg
+    assert "not_a_real_role" in msg
+    assert "placeholder" in msg
+    assert "fallback" in msg
+
+
+# ─── u5 : F18-reuse regression — non-BIM/DX rows + placeholder role ─
+
+_F18_CATALOG_LITERAL_COL_A = "BIM"   # Verbatim F18 col_a_label_default (frame_contracts.yaml:476)
+_F18_CATALOG_LITERAL_COL_B = "DX"    # Verbatim F18 col_b_label_default (frame_contracts.yaml:477)
+_F18_LEAK_TOKENS = (_F18_CATALOG_LITERAL_COL_A, _F18_CATALOG_LITERAL_COL_B)
+
+
+def _make_f18_clone_contract() -> dict:
+    """F18-shaped contract — verbatim BIM/DX literals + placeholder role.
+
+    Mirrors the catalog state after u1: BIM/DX kept as Figma visual
+    placeholders, but the role discriminator tells the builder to
+    suppress them at runtime. The ``template_id`` is namespaced
+    (``synthetic_f18_reuse_non_bim_dx``) so the test is not coupled to
+    the real F18 frame id; the leak invariant is independent of the
+    template_id string.
+    """
+    return {
+        "template_id": "synthetic_f18_reuse_non_bim_dx",
+        "source_shape": "top_bullets",
+        "cardinality": {},
+        "payload": {
+            "builder": "compare_table_2col",
+            "builder_options": {
+                "item_parser": "compare_row_2col_item",
+                "col_a_label_default": _F18_CATALOG_LITERAL_COL_A,
+                "col_a_label_default_role": "placeholder",
+                "col_b_label_default": _F18_CATALOG_LITERAL_COL_B,
+                "col_b_label_default_role": "placeholder",
+            },
+        },
+    }
+
+
+def test_f18_reuse_with_non_bim_dx_rows_suppresses_catalog_placeholder():
+    """F18-reuse axis (mdx 04-2 scenario, synthetic): BIM/DX MUST NOT leak.
+
+    Models the downstream MDX that maps F18's anchor set to non-BIM/DX
+    content (the issue body cites 정책/조직 as a representative reuse).
+    With ``col_*_label_default_role="placeholder"``, the builder MUST
+    suppress the Figma literals at runtime. Because the synthetic rows
+    themselves carry no BIM / DX tokens, any appearance of those strings
+    anywhere in the payload would prove a catalog literal leaked through
+    — that is precisely the regression IMP-40 #69 must prevent.
+    """
+    contract = _make_f18_clone_contract()
+    units = [
+        (
+            "- **정책 도입 단계**",
+            ["  - 단기 우선순위 수립", "  - 부서별 협업 강화"],
+        ),
+        (
+            "- **조직 운영 구조**",
+            ["  - 의사결정 책임자 명시", "  - 정기 리뷰 사이클 운영"],
+        ),
+    ]
+
+    payload = _build_compare_table_2col(
+        _make_section(), units=units, contract=contract
+    )
+
+    # Placeholder role suppression at the header axis.
+    assert payload["col_a_label"] == ""
+    assert payload["col_b_label"] == ""
+
+    # Row content is derived from MDX-style synthetic units, not catalog.
+    assert len(payload["rows"]) == 2
+    assert payload["rows"][0]["label"] == "정책 도입 단계"
+    assert payload["rows"][0]["col_a"] == "단기 우선순위 수립"
+    assert payload["rows"][0]["col_b"] == "부서별 협업 강화"
+    assert payload["rows"][1]["label"] == "조직 운영 구조"
+    assert payload["rows"][1]["col_a"] == "의사결정 책임자 명시"
+    assert payload["rows"][1]["col_b"] == "정기 리뷰 사이클 운영"
+
+    # F18-leak invariant: BIM / DX tokens MUST NOT appear anywhere in payload.
+    for leak in _F18_LEAK_TOKENS:
+        assert leak not in payload["col_a_label"], (
+            f"placeholder role failed to suppress catalog literal '{leak}' in col_a_label"
+        )
+        assert leak not in payload["col_b_label"], (
+            f"placeholder role failed to suppress catalog literal '{leak}' in col_b_label"
+        )
+        for row in payload["rows"]:
+            assert leak not in row["label"]
+            assert leak not in row["col_a"]
+            assert leak not in row["col_b"]
@@ -0,0 +1,249 @@
+"""IMP-84 u2 — provisional zone silent-render contract.
+
+Pins that `templates/phase_z2/slide_base.html` no longer surfaces the
+provisional visual treatment (dashed outline, striped wash, badge span)
+while keeping `data-provisional="1"` as silent telemetry on the zone div.
+
+Stage 2 binding contract (IMP-84):
+  - Remove .zone--provisional class emission on the zone div.
+  - Remove .zone__needs-adaptation-badge <span> render.
+  - Remove the .zone--provisional CSS block and the
+    .zone__needs-adaptation-badge CSS block from the <style> section.
+  - Preserve data-provisional="1" attribute emission for provisional zones
+    (downstream telemetry / debug selectors). Out-of-scope: backend
+    `zone.provisional` flag emission itself.
+
+Helpers below intentionally mirror the IMP-30 first-render test helpers
+(_render_slide_base / _all_zone_div_openings / _all_badge_spans /
+_zone_div_for_position) so the silent-render contract is enforced by an
+independent rendering surface, not by the IMP-30 file (which u3 will
+invert separately).
+"""
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+from jinja2 import Environment, FileSystemLoader, select_autoescape
+
+
+# ─── helpers (mirrored from IMP-30 u5 to keep this test self-contained) ───
+
+def _render_slide_base(
+    zones: list[dict],
+    *,
+    layout_preset: str = "single",
+    layout_css: dict | None = None,
+) -> str:
+    """Render templates/phase_z2/slide_base.html via Jinja2 with a minimal
+    zones list. Bypasses render_slide() so the template-only silent-render
+    contract is exercised without the pipeline (no mapper, no contracts,
+    no token CSS loader). slot_payload / partial_html are stubbed so the
+    assertions focus on zone div / CSS surface only."""
+    template_dir = (
+        Path(__file__).resolve().parents[2] / "templates" / "phase_z2"
+    )
+    env = Environment(
+        loader=FileSystemLoader(str(template_dir)),
+        autoescape=select_autoescape(["html"]),
+    )
+    if layout_css is None:
+        layout_css = {
+            "cols": "1fr",
+            "rows": "1fr",
+            "areas": '"single"',
+        }
+    for z in zones:
+        z.setdefault("partial_html", "<div class=\"_stub_partial\">stub</div>")
+    base = env.get_template("slide_base.html")
+    return base.render(
+        slide_title="IMP-84 u2 silent-render test",
+        slide_footer=None,
+        zones=zones,
+        layout_preset=layout_preset,
+        layout_css=layout_css,
+        gap_px=12,
+        token_css="",
+        embedded_mode="standalone",
+    )
+
+
+def _zone_div_for_position(html: str, position: str) -> str:
+    """Return the opening `<div class="zone..." data-zone-position="X" ...>`
+    tag for the zone at the given `data-zone-position`. Anchors assertions
+    on zone-div-level attributes / classes only."""
+    pattern = re.compile(
+        r'<div class="zone[^"]*"\s+data-zone-position="'
+        + re.escape(position)
+        + r'"[^>]*>',
+        re.DOTALL,
+    )
+    match = pattern.search(html)
+    return match.group(0) if match else ""
+
+
+def _all_zone_div_openings(html: str) -> list[str]:
+    """Every zone-div opening tag in the layout body. Scopes class /
+    attribute checks away from the <style> block (which may still contain
+    selector strings if a future change re-introduces them)."""
+    return re.findall(
+        r'<div class="zone[^"]*"[^>]*data-zone-position="[^"]*"[^>]*>',
+        html,
+    )
+
+
+def _all_badge_spans(html: str) -> list[str]:
+    """Every `.zone__needs-adaptation-badge` <span> element in the rendered
+    body. Must be empty under the IMP-84 silent-render contract regardless
+    of zones[i].provisional value."""
+    return re.findall(
+        r'<span class="zone__needs-adaptation-badge"[^>]*>[^<]*</span>',
+        html,
+    )
+
+
+# ─── case 1 : non-provisional zone unchanged (regression boundary) ───
+
+def test_imp84_non_provisional_zone_unchanged():
+    """zones[i].provisional=False must render the zone div with no
+    provisional class, no data-provisional attr, no badge — byte-equivalent
+    to pre-IMP-84 baseline for the non-provisional path."""
+    zones = [
+        {
+            "position": "single",
+            "template_id": "MOCK_template_direct_a",
+            "slot_payload": {},
+            "content_weight": {"score": 1},
+            "min_height_px": 100,
+            "provisional": False,
+        }
+    ]
+    html = _render_slide_base(zones)
+    zone_open = _zone_div_for_position(html, "single")
+    assert zone_open != ""
+    assert "zone--provisional" not in zone_open
+    assert "data-provisional" not in zone_open
+    assert _all_badge_spans(html) == []
+
+
+# ─── case 2 : provisional zone silent — class / badge / wash removed ───
+
+def test_imp84_provisional_zone_emits_data_attr_only_no_visual():
+    """The core IMP-84 silent-render contract.
+
+    With zones[i].provisional=True, the rendered HTML MUST:
+      - NOT contain the `zone--provisional` class on any zone div
+      - NOT render a `.zone__needs-adaptation-badge` <span>
+      - NOT contain the human-visible "needs adaptation" label text
+      - STILL emit `data-provisional="1"` on the provisional zone div
+        (silent telemetry preserved for downstream selectors)
+    """
+    zones = [
+        {
+            "position": "single",
+            "template_id": "MOCK_template_restructure_a",
+            "slot_payload": {},
+            "content_weight": {"score": 1},
+            "min_height_px": 100,
+            "provisional": True,
+        }
+    ]
+    html = _render_slide_base(zones)
+    zone_open = _zone_div_for_position(html, "single")
+    assert zone_open != ""
+    assert "zone--provisional" not in zone_open
+    assert 'data-provisional="1"' in zone_open
+    assert _all_badge_spans(html) == []
+    assert "needs adaptation" not in html
+
+
+# ─── case 3 : mixed zones — telemetry isolation preserved ───
+
+def test_imp84_mixed_zones_data_provisional_only_on_provisional_zone():
+    """In a mixed-zone slide (one provisional + one normal), the silent
+    telemetry attribute must appear ONLY on the provisional zone div, and
+    no visual artifact may surface on either zone."""
+    zones = [
+        {
+            "position": "top",
+            "template_id": "MOCK_template_direct_a",
+            "slot_payload": {},
+            "content_weight": {"score": 1},
+            "min_height_px": 100,
+            "provisional": False,
+        },
+        {
+            "position": "bottom",
+            "template_id": "MOCK_template_restructure_a",
+            "slot_payload": {},
+            "content_weight": {"score": 1},
+            "min_height_px": 100,
+            "provisional": True,
+        },
+    ]
+    layout_css = {
+        "cols": "1fr",
+        "rows": "1fr 1fr",
+        "areas": '"top" "bottom"',
+    }
+    html = _render_slide_base(
+        zones, layout_preset="vertical-2", layout_css=layout_css
+    )
+    zone_divs = _all_zone_div_openings(html)
+    assert len(zone_divs) == 2
+
+    top_zone_open = _zone_div_for_position(html, "top")
+    bottom_zone_open = _zone_div_for_position(html, "bottom")
+    assert "data-provisional" not in top_zone_open
+    assert 'data-provisional="1"' in bottom_zone_open
+
+    for tag in zone_divs:
+        assert "zone--provisional" not in tag
+    assert _all_badge_spans(html) == []
+    assert "needs adaptation" not in html
+
+
+# ─── case 4 : <style> block free of provisional visual selectors ───
+
+def test_imp84_style_block_has_no_provisional_visual_selectors():
+    """The provisional visual CSS classes are deleted at source. A future
+    refactor that re-introduces `.zone--provisional` or
+    `.zone__needs-adaptation-badge` selectors into slide_base.html breaks
+    this test rather than silently restoring the visual badge."""
+    zones = [
+        {
+            "position": "single",
+            "template_id": "MOCK_template_restructure_a",
+            "slot_payload": {},
+            "content_weight": {"score": 1},
+            "min_height_px": 100,
+            "provisional": True,
+        }
+    ]
+    html = _render_slide_base(zones)
+    assert ".zone--provisional" not in html
+    assert ".zone__needs-adaptation-badge" not in html
+    assert "zone__needs-adaptation-badge" not in html
+
+
+# ─── case 5 : provisional defaults to false (template fallback) ───
+
+def test_imp84_provisional_none_falls_back_to_silent_non_provisional():
+    """When zones[i].provisional is explicitly None (falsy but not False),
+    the template's truthy check must NOT emit `data-provisional`. Pins the
+    template fallback so a refactor cannot silently invert the default."""
+    zones = [
+        {
+            "position": "single",
+            "template_id": "MOCK_template_direct_a",
+            "slot_payload": {},
+            "content_weight": {"score": 1},
+            "min_height_px": 100,
+            "provisional": None,
+        }
+    ]
+    html = _render_slide_base(zones)
+    zone_open = _zone_div_for_position(html, "single")
+    assert zone_open != ""
+    assert "data-provisional" not in zone_open
+    assert _all_badge_spans(html) == []
@@ -0,0 +1,200 @@
+"""IMP-39 u6 (issue #68) - synthetic divergence regression.
+
+Loads the SYNTHETIC fixture under
+``tests/phase_z2/fixtures/ranking_sort_policy/`` and asserts that the
+single-source ranking policy
+(``templates/phase_z2/catalog/ranking_sort_policy.yaml``, u1) resolves
+the backend - frontend "rank 1" divergence captured in Stage 1
+root-cause analysis.
+
+Divergence scenario (Stage 1 root cause):
+  - Pre-policy backend iterates ``judgments_full32`` in raw V4
+    confidence-desc order (``src/phase_z2_pipeline.py`` selector loop
+    behavior before u2). High-confidence ``restructure`` at
+    ``v4_full_rank=1`` wins; lower-confidence ``use_as_is`` further
+    down the list is shadowed.
+  - Frontend (``Front/client/src/services/designAgentApi.ts``)
+    re-sorts the same source by ``LABEL_PRIORITY asc + confidence
+    desc`` and surfaces ``use_as_is`` as ``frame_candidates[0]``.
+  - Backend "selected rank 1" and frontend ``frame_candidates[0]``
+    diverge.
+
+Post-policy (u2 wires ``apply_ranking_sort`` into the selector after
+the IMP-38 raw-window slice), backend selection order matches the
+frontend ordering: ``use_as_is`` is rank 1 on both sides.
+
+Scope (u6, Stage 2 plan):
+  - SYNTHETIC fixture only - sample-agnostic, no MDX 03/04/05
+    references, no real ``frame_id`` / ``template_id`` literals.
+  - Helper-level exercise of ``apply_ranking_sort`` (mirrors the
+    selector's policy step at
+    ``src/phase_z2_pipeline.py:1186-1196``).
+
+Out of scope (other units):
+  - u1 policy yaml shape: covered by ``test_ranking_sort_policy.py``.
+  - u2 selector wiring: integration covered elsewhere.
+  - u3 Step 9 payload forwarding.
+  - u4 frontend mirror.
+  - u7 mdx04 env-toggle e2e.
+  - u8 corpus audit over ``tests/matching/v4_full32_result.yaml``.
+"""
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+import yaml
+
+
+FIXTURE_PATH = (
+    Path(__file__).parent
+    / "fixtures"
+    / "ranking_sort_policy"
+    / "synthetic_divergence.yaml"
+)
+
+
+@pytest.fixture(autouse=True)
+def _reset_policy_cache():
+    """Mirror test_ranking_sort_policy.py isolation - clear the cached policy."""
+    import src.phase_z2_pipeline as pipeline
+
+    pipeline._RANKING_SORT_POLICY_CACHE = None
+    yield
+    pipeline._RANKING_SORT_POLICY_CACHE = None
+
+
+def _load_fixture() -> dict:
+    with FIXTURE_PATH.open(encoding="utf-8") as f:
+        return yaml.safe_load(f)
+
+
+def test_synthetic_fixture_shape_is_intact():
+    fixture = _load_fixture()
+
+    assert fixture["fixture_id"] == "synthetic_divergence"
+    assert fixture["sample_agnostic"] is True
+    raw = fixture["raw_judgments"]
+    assert len(raw) == 4
+    assert {j["label"] for j in raw} == {
+        "use_as_is",
+        "light_edit",
+        "restructure",
+        "reject",
+    }
+    assert len(fixture["expected_legacy_raw_order"]) == len(raw)
+    assert len(fixture["expected_policy_sorted_order"]) == len(raw)
+    div = fixture["divergence_axis"]
+    assert div["pre_policy_rank_1_tag"] != div["post_policy_rank_1_tag"]
+    assert div["post_policy_rank_1_tag"] == div["frontend_candidate_0_tag"]
+
+
+def test_legacy_raw_order_demonstrates_divergence():
+    """Pre-policy raw V4 confidence-desc order is the divergence source."""
+    fixture = _load_fixture()
+    raw = fixture["raw_judgments"]
+
+    assert [j["tag"] for j in raw] == fixture["expected_legacy_raw_order"]
+
+    pre_rank_1 = raw[0]
+    assert pre_rank_1["tag"] == fixture["divergence_axis"]["pre_policy_rank_1_tag"]
+    assert pre_rank_1["label"] == "restructure"
+
+    higher_priority_shadowed = next(
+        j for j in raw[1:] if j["label"] == "use_as_is"
+    )
+    assert higher_priority_shadowed["confidence"] < pre_rank_1["confidence"]
+
+
+def test_apply_ranking_sort_resolves_divergence():
+    """Post-policy order puts the higher-priority label first."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    fixture = _load_fixture()
+
+    sorted_judgments = apply_ranking_sort(
+        fixture["raw_judgments"],
+        label_key="label",
+        confidence_key="confidence",
+        v4_rank_key="v4_full_rank",
+    )
+
+    assert [j["tag"] for j in sorted_judgments] == fixture[
+        "expected_policy_sorted_order"
+    ]
+    assert sorted_judgments[0]["label"] == "use_as_is"
+    assert (
+        sorted_judgments[0]["tag"]
+        == fixture["divergence_axis"]["post_policy_rank_1_tag"]
+    )
+
+
+def test_backend_rank_1_aligns_with_frontend_candidate_zero():
+    """Backend selector policy step and frontend candidate ordering agree.
+
+    Mirrors the selector policy step at
+    ``src/phase_z2_pipeline.py:1186-1196`` (u2 wiring) and the frontend
+    ``frame_candidates[0]`` derivation from ``sorted_candidate_evidence``
+    (``Front/client/src/services/designAgentApi.ts`` u4 wiring). The
+    selector's MVP1 status gate / contract / capacity checks are
+    out of scope - u8 corpus audit exercises the real
+    catalog-registered flow.
+    """
+    from src.phase_z2_pipeline import (
+        apply_ranking_sort,
+        load_ranking_sort_policy,
+    )
+
+    fixture = _load_fixture()
+    policy = load_ranking_sort_policy()
+
+    sorted_window = apply_ranking_sort(
+        fixture["raw_judgments"],
+        policy=policy,
+        label_key="label",
+        confidence_key="confidence",
+        v4_rank_key="v4_full_rank",
+    )
+
+    backend_rank_1 = sorted_window[0]
+    frontend_candidate_0 = sorted_window[0]
+
+    expected_tag = fixture["divergence_axis"]["frontend_candidate_0_tag"]
+    assert backend_rank_1["tag"] == expected_tag
+    assert frontend_candidate_0["tag"] == expected_tag
+    assert backend_rank_1 is frontend_candidate_0
+
+
+def test_input_list_is_not_mutated():
+    """Fixture list reference and order survive ``apply_ranking_sort``."""
+    from src.phase_z2_pipeline import apply_ranking_sort
+
+    fixture = _load_fixture()
+    raw = fixture["raw_judgments"]
+    snapshot_tags = [j["tag"] for j in raw]
+
+    apply_ranking_sort(
+        raw,
+        label_key="label",
+        confidence_key="confidence",
+        v4_rank_key="v4_full_rank",
+    )
+
+    assert [j["tag"] for j in raw] == snapshot_tags
+
+
+def test_pre_policy_legacy_order_can_be_reproduced():
+    """Synthetic fixture's legacy order matches raw V4 confidence-desc.
+
+    Sanity check that ``expected_legacy_raw_order`` is consistent with
+    a confidence-desc sort of ``raw_judgments`` ignoring the policy.
+    This keeps the divergence axis honest if the fixture is edited.
+    """
+    fixture = _load_fixture()
+    raw = fixture["raw_judgments"]
+
+    confidence_desc = sorted(raw, key=lambda j: -j["confidence"])
+
+    assert [j["tag"] for j in confidence_desc] == fixture[
+        "expected_legacy_raw_order"
+    ]
@@ -0,0 +1,135 @@
+"""IMP-42 u2 (#71) — post-render HTML invalid path char detector diag tests.
+
+Stage 1/2 scope-lock §B: rendered partial / base HTML output must fail loud
+with a typed error when src / href / url(...) attribute values contain
+invalid path characters that would silently surface downstream as 404 /
+asset-load failures.
+
+Three production vectors are covered:
+  - Windows backslash from ``str(Path)`` (e.g. ``assets\\img.png``).
+  - Autoescape entity ``&amp;`` (raw ``&`` in raw path string).
+  - Autoescape entity ``&#39;`` (raw ``'`` in raw path string).
+
+Assertions cover RULE 0 generality:
+  - error type is ValueError (typed, not bare exception)
+  - error message cites context label + attr type + value snippet
+  - clean rendered HTML (forward slashes only) does not raise
+  - non-attribute backslash (body text) does not raise
+"""
+from __future__ import annotations
+
+import pytest
+
+from src.phase_z2_pipeline import _scan_rendered_html_for_invalid_path_chars
+
+
+# ─── backslash vector ────────────────────────────────────────────
+
+def test_backslash_in_src_raises_with_context_and_attr_label():
+    html = '<img src="assets\\img.png">'
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(html, "zone[0] template_id='foo'")
+    msg = str(exc_info.value)
+    assert "zone[0] template_id='foo'" in msg
+    assert "src" in msg
+    assert "assets\\img.png" in msg
+
+
+def test_backslash_in_href_raises():
+    html = '<link href="styles\\app.css" rel="stylesheet">'
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+    msg = str(exc_info.value)
+    assert "href" in msg
+    assert "styles\\app.css" in msg
+
+
+def test_backslash_in_url_raises():
+    html = "<style>body { background: url(images\\bg.png); }</style>"
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+    msg = str(exc_info.value)
+    assert "url(...)" in msg
+    assert "images\\bg.png" in msg
+
+
+def test_backslash_in_url_with_quotes_raises():
+    html = "<style>div { background: url('images\\bg.png'); }</style>"
+    with pytest.raises(ValueError):
+        _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+
+
+# ─── autoescape entity vectors ───────────────────────────────────
+
+def test_escaped_ampersand_in_src_raises():
+    html = '<img src="assets/img&amp;v=1.png">'
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+    msg = str(exc_info.value)
+    assert "&amp;" in msg
+    assert "src" in msg
+
+
+def test_escaped_apostrophe_in_href_raises():
+    html = '<a href="docs/it&#39;s-here.pdf">x</a>'
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+    msg = str(exc_info.value)
+    assert "&#39;" in msg
+    assert "href" in msg
+
+
+def test_escaped_ampersand_in_url_raises():
+    html = "<style>div { background: url('img&amp;.png'); }</style>"
+    with pytest.raises(ValueError):
+        _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+
+
+# ─── negative cases (must NOT raise) ─────────────────────────────
+
+def test_clean_forward_slash_src_does_not_raise():
+    html = '<img src="assets/img.png"><link href="styles/app.css" rel="stylesheet">'
+    _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+
+
+def test_clean_url_does_not_raise():
+    html = "<style>div { background: url('images/bg.png'); }</style>"
+    _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+
+
+def test_backslash_in_body_text_does_not_raise():
+    # Backslash outside src/href/url is not a path-attr signal.
+    html = "<p>Windows path example: C:\\Users\\foo</p>"
+    _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+
+
+def test_escaped_entities_in_body_text_do_not_raise():
+    # Body-text autoescape (e.g. legitimate &amp; in copy) is not a path signal.
+    html = "<p>AT&amp;T &#39;quoted&#39; text</p>"
+    _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+
+
+def test_empty_html_does_not_raise():
+    _scan_rendered_html_for_invalid_path_chars("", "ctx")
+
+
+# ─── error message contract ──────────────────────────────────────
+
+def test_error_message_truncates_long_value_to_snippet():
+    long_path = "a" * 200 + "\\img.png"
+    html = f'<img src="{long_path}">'
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(html, "ctx")
+    msg = str(exc_info.value)
+    assert "..." in msg  # truncation marker present
+
+
+def test_error_message_cites_context_label_verbatim():
+    html = '<img src="x\\y.png">'
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(
+            html, "zones_data[7] template_id='dx_sw_necessity_three_perspectives'"
+        )
+    msg = str(exc_info.value)
+    assert "zones_data[7]" in msg
+    assert "dx_sw_necessity_three_perspectives" in msg
@@ -0,0 +1,116 @@
+"""IMP-42 u1 (#71) — render_slide precondition assertion diag tests.
+
+Stage 1/2 scope-lock §A: Step 13 `render_slide()` partial render loop must
+fail loud with a typed error when a zone dict is missing `template_id` or
+`slot_payload`, instead of silently surfacing as Jinja `TemplateNotFound`
+or `KeyError` far from the Step 12 emit site.
+
+Assertions cover RULE 0 generality:
+  - error type is TypeError (typed, not bare AssertionError / KeyError)
+  - error message cites zone index + missing key
+  - empty-zone short-circuit (`__empty__`) still bypasses the precondition,
+    preserving the existing grid-identity behaviour from Codex #10 Catch N.
+"""
+from __future__ import annotations
+
+import pytest
+
+from src.phase_z2_pipeline import render_slide
+
+
+def _layout_css() -> dict:
+    return {"areas": '"primary"', "cols": "1fr", "rows": "1fr"}
+
+
+def _ok_zone() -> dict:
+    return {"position": "primary", "template_id": "__empty__", "slot_payload": {}}
+
+
+def _render(zones_data: list[dict]) -> str:
+    return render_slide(
+        slide_title="t",
+        slide_footer=None,
+        zones_data=zones_data,
+        layout_preset="single",
+        layout_css=_layout_css(),
+        gap_px=14,
+        embedded_mode="embedded",
+    )
+
+
+def test_template_id_missing_raises_typed_error_with_index_and_key():
+    zone = {"position": "primary", "slot_payload": {}}
+    with pytest.raises(TypeError) as exc_info:
+        _render([zone])
+    msg = str(exc_info.value)
+    assert "zones_data[0]" in msg
+    assert "template_id" in msg
+
+
+def test_template_id_empty_string_raises_typed_error():
+    zone = {"position": "primary", "template_id": "", "slot_payload": {}}
+    with pytest.raises(TypeError) as exc_info:
+        _render([zone])
+    msg = str(exc_info.value)
+    assert "zones_data[0]" in msg
+    assert "template_id" in msg
+    assert "non-empty" in msg
+
+
+def test_template_id_none_raises_typed_error():
+    zone = {"position": "primary", "template_id": None, "slot_payload": {}}
+    with pytest.raises(TypeError) as exc_info:
+        _render([zone])
+    msg = str(exc_info.value)
+    assert "zones_data[0]" in msg
+    assert "template_id" in msg
+
+
+def test_template_id_non_string_raises_typed_error():
+    zone = {"position": "primary", "template_id": 42, "slot_payload": {}}
+    with pytest.raises(TypeError) as exc_info:
+        _render([zone])
+    msg = str(exc_info.value)
+    assert "zones_data[0]" in msg
+    assert "template_id" in msg
+
+
+def test_slot_payload_missing_raises_typed_error_with_index_and_key():
+    zone = {"position": "primary", "template_id": "__placeholder__"}
+    with pytest.raises(TypeError) as exc_info:
+        _render([zone])
+    msg = str(exc_info.value)
+    assert "zones_data[0]" in msg
+    assert "slot_payload" in msg
+
+
+def test_slot_payload_non_dict_raises_typed_error():
+    zone = {
+        "position": "primary",
+        "template_id": "__placeholder__",
+        "slot_payload": ["not", "a", "dict"],
+    }
+    with pytest.raises(TypeError) as exc_info:
+        _render([zone])
+    msg = str(exc_info.value)
+    assert "zones_data[0]" in msg
+    assert "slot_payload" in msg
+    assert "dict" in msg
+
+
+def test_second_zone_failure_reports_correct_index():
+    zones = [_ok_zone(), {"position": "secondary", "slot_payload": {}}]
+    with pytest.raises(TypeError) as exc_info:
+        _render(zones)
+    msg = str(exc_info.value)
+    assert "zones_data[1]" in msg
+    assert "template_id" in msg
+
+
+def test_empty_zone_short_circuit_bypasses_precondition():
+    # __empty__ short-circuit must run before precondition checks so that
+    # legitimate empty zones (no slot_payload required) still render.
+    zones = [{"position": "primary", "template_id": "__empty__"}]
+    html = _render(zones)
+    assert isinstance(html, str)
+    assert len(html) > 0
@@ -0,0 +1,92 @@
+"""IMP-42 u5 (#71) — general 32-frame smoke for diag tools (registry-driven).
+
+Stage 1/2 RULE 0 lock: u1 (precondition assert), u2 (invalid-path detector),
+and u3 (backend DIAG) must work GENERALLY across every frame declared in
+``templates/phase_z2/catalog/frame_contracts.yaml`` — not only the MDX
+03/04/05 samples that motivated #71.
+
+The smoke enumerates every top-level frame contract and parametrizes the
+three diag behaviors against each ``template_id``. AI = 0, no visual_check,
+no real partial render — payloads are synthetic so the coverage stays
+sample-agnostic and never depends on frame-specific slot shapes.
+
+Each parametrized case covers one silent-fail vector from #71 root cause:
+  - u1 precondition: Step 13 partial render must fail loud on missing
+    ``slot_payload`` regardless of which frame contract is in play.
+  - u2 invalid path: post-render asset-ref scan must fire on a synthetic
+    backslash ``src`` value when the context cites any frame's id.
+  - u3 DIAG: ``_emit_diag_zones_shape`` must include the frame's
+    ``template_id`` in the JSON payload for every contract.
+"""
+from __future__ import annotations
+
+import json
+
+import pytest
+
+from src.phase_z2_mapper import load_frame_contracts
+from src.phase_z2_pipeline import (
+    _emit_diag_zones_shape,
+    _scan_rendered_html_for_invalid_path_chars,
+    render_slide,
+)
+
+
+_FRAME_IDS = sorted(load_frame_contracts().keys())
+
+
+def test_registry_has_expected_frame_count():
+    # Pin the 32-frame floor — additions are auto-covered by parametrize,
+    # while a regression that drops below 32 surfaces here loud.
+    assert len(_FRAME_IDS) >= 32, (
+        f"frame_contracts.yaml expected ≥ 32 entries, got {len(_FRAME_IDS)}: "
+        f"{_FRAME_IDS}"
+    )
+
+
+def _layout_css() -> dict:
+    return {"areas": '"primary"', "cols": "1fr", "rows": "1fr"}
+
+
+@pytest.mark.parametrize("template_id", _FRAME_IDS)
+def test_u1_precondition_fires_for_every_frame(template_id):
+    zone = {"position": "primary", "template_id": template_id}
+    with pytest.raises(TypeError) as exc_info:
+        render_slide(
+            slide_title="t",
+            slide_footer=None,
+            zones_data=[zone],
+            layout_preset="single",
+            layout_css=_layout_css(),
+            gap_px=14,
+            embedded_mode="embedded",
+        )
+    msg = str(exc_info.value)
+    assert "zones_data[0]" in msg
+    assert "slot_payload" in msg
+
+
+@pytest.mark.parametrize("template_id", _FRAME_IDS)
+def test_u2_invalid_char_detector_fires_for_every_frame_context(template_id):
+    html = '<img src="assets\\img.png">'
+    ctx = f"zones_data[0] template_id={template_id!r}"
+    with pytest.raises(ValueError) as exc_info:
+        _scan_rendered_html_for_invalid_path_chars(html, ctx)
+    msg = str(exc_info.value)
+    assert template_id in msg
+    assert "src" in msg
+
+
+@pytest.mark.parametrize("template_id", _FRAME_IDS)
+def test_u3_diag_emits_template_id_for_every_frame(template_id, capsys):
+    zones = [
+        {"position": "primary", "template_id": template_id, "slot_payload": {}}
+    ]
+    _emit_diag_zones_shape("Step 12 slot_payload emit", zones)
+    line = capsys.readouterr().out.strip()
+    prefix = "[DIAG] phase_z2 Step 12 slot_payload emit "
+    assert line.startswith(prefix), f"missing DIAG prefix on line={line!r}"
+    payload = json.loads(line[len(prefix):])
+    assert payload["zones_count"] == 1
+    assert payload["zones"][0]["template_id"] == template_id
+    assert payload["zones"][0]["slot_keys"] == []
@@ -0,0 +1,223 @@
+"""IMP-42 u3 (#71) — unconditional Step 12 / Step 13 backend DIAG terminal logs.
+
+Stage 1/2 scope-lock §C-backend: Step 12 slot_payload emit + Step 13
+render_slide entry must each emit a shape-only `[DIAG]` line to stdout
+on every slide loop, with no env gate. The line carries enough zone
+shape (position / template_id / slot_payload key list) to debug the
+silent 3-hop handoff documented in #71, without leaking raw slot
+content (RULE 0 sample-agnostic).
+
+Coverage:
+  - helper emits `[DIAG] phase_z2 <stage_label>` prefix
+  - helper payload is structured JSON with zones_count + per-zone shape
+  - per-zone shape includes i / position / template_id / slot_keys
+  - slot_keys is a sorted key list (never raw values)
+  - slot_keys is null when slot_payload is missing or non-dict
+  - extra_fields are merged into the payload at top level
+  - render_slide() entry call site fires the helper on every invocation
+  - source-slice confirms Step 12 emit site invokes the helper after
+    the slot_payload `_write_step_artifact(...)` call.
+
+Diag is unconditional — no env-var gate; silence is the bug per Stage 1.
+"""
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+
+from src import phase_z2_pipeline
+from src.phase_z2_pipeline import (
+    _emit_diag_zones_shape,
+    render_slide,
+)
+
+
+# ─── helper unit tests ───────────────────────────────────────────
+
+
+def _parse_diag_line(line: str, expected_label: str) -> dict:
+    prefix = f"[DIAG] phase_z2 {expected_label} "
+    assert line.startswith(prefix), (
+        f"expected DIAG prefix {prefix!r}, got line={line!r}"
+    )
+    return json.loads(line[len(prefix):])
+
+
+def test_helper_emits_diag_prefix_and_json(capsys):
+    zones = [{"position": "primary", "template_id": "foo", "slot_payload": {"a": 1, "b": 2}}]
+    _emit_diag_zones_shape("Step 12 slot_payload emit", zones)
+    captured = capsys.readouterr().out.strip().splitlines()
+    assert len(captured) == 1
+    payload = _parse_diag_line(captured[0], "Step 12 slot_payload emit")
+    assert payload["zones_count"] == 1
+    assert payload["zones"][0]["position"] == "primary"
+    assert payload["zones"][0]["template_id"] == "foo"
+
+
+def test_helper_slot_keys_is_sorted_key_list_not_values(capsys):
+    # Raw values ("secret content") must not leak into the diag line.
+    zones = [{
+        "position": "primary",
+        "template_id": "foo",
+        "slot_payload": {"z_last": "secret content", "a_first": "another secret"},
+    }]
+    _emit_diag_zones_shape("Step 12 slot_payload emit", zones)
+    line = capsys.readouterr().out.strip()
+    assert "secret content" not in line
+    assert "another secret" not in line
+    payload = _parse_diag_line(line, "Step 12 slot_payload emit")
+    assert payload["zones"][0]["slot_keys"] == ["a_first", "z_last"]
+
+
+def test_helper_slot_keys_null_when_slot_payload_missing(capsys):
+    zones = [{"position": "primary", "template_id": "__empty__"}]
+    _emit_diag_zones_shape("Step 13 render_slide entry", zones)
+    payload = _parse_diag_line(capsys.readouterr().out.strip(), "Step 13 render_slide entry")
+    assert payload["zones"][0]["slot_keys"] is None
+
+
+def test_helper_slot_keys_null_when_slot_payload_non_dict(capsys):
+    zones = [{"position": "primary", "template_id": "foo", "slot_payload": ["not", "dict"]}]
+    _emit_diag_zones_shape("Step 13 render_slide entry", zones)
+    payload = _parse_diag_line(capsys.readouterr().out.strip(), "Step 13 render_slide entry")
+    assert payload["zones"][0]["slot_keys"] is None
+
+
+def test_helper_per_zone_index_threading(capsys):
+    zones = [
+        {"position": "top", "template_id": "alpha", "slot_payload": {}},
+        {"position": "bottom_l", "template_id": "beta", "slot_payload": {"k": "v"}},
+        {"position": "bottom_r", "template_id": "gamma", "slot_payload": {"k": "v"}},
+    ]
+    _emit_diag_zones_shape("Step 12 slot_payload emit", zones)
+    payload = _parse_diag_line(capsys.readouterr().out.strip(), "Step 12 slot_payload emit")
+    assert payload["zones_count"] == 3
+    assert [z["i"] for z in payload["zones"]] == [0, 1, 2]
+    assert [z["position"] for z in payload["zones"]] == ["top", "bottom_l", "bottom_r"]
+    assert [z["template_id"] for z in payload["zones"]] == ["alpha", "beta", "gamma"]
+
+
+def test_helper_extra_fields_merged_into_payload(capsys):
+    zones = [{"position": "primary", "template_id": "__empty__"}]
+    _emit_diag_zones_shape(
+        "Step 13 render_slide entry",
+        zones,
+        layout_preset="single",
+        embedded_mode="embedded",
+    )
+    payload = _parse_diag_line(capsys.readouterr().out.strip(), "Step 13 render_slide entry")
+    assert payload["layout_preset"] == "single"
+    assert payload["embedded_mode"] == "embedded"
+
+
+def test_helper_empty_zones_list_still_emits_line(capsys):
+    # No zones is a valid (degenerate) shape — diag must still fire, never silent.
+    _emit_diag_zones_shape("Step 12 slot_payload emit", [])
+    payload = _parse_diag_line(capsys.readouterr().out.strip(), "Step 12 slot_payload emit")
+    assert payload["zones_count"] == 0
+    assert payload["zones"] == []
+
+
+# ─── render_slide entry call site integration ────────────────────
+
+
+def _layout_css() -> dict:
+    return {"areas": '"primary"', "cols": "1fr", "rows": "1fr"}
+
+
+def test_render_slide_entry_emits_step13_diag_on_every_call(capsys):
+    zones = [{"position": "primary", "template_id": "__empty__"}]
+    render_slide(
+        slide_title="t",
+        slide_footer=None,
+        zones_data=zones,
+        layout_preset="single",
+        layout_css=_layout_css(),
+        gap_px=14,
+        embedded_mode="embedded",
+    )
+    out = capsys.readouterr().out
+    step13_lines = [
+        ln for ln in out.splitlines()
+        if ln.startswith("[DIAG] phase_z2 Step 13 render_slide entry ")
+    ]
+    assert len(step13_lines) == 1, (
+        f"expected exactly 1 Step 13 DIAG line, got {len(step13_lines)} from out={out!r}"
+    )
+    payload = _parse_diag_line(step13_lines[0], "Step 13 render_slide entry")
+    assert payload["layout_preset"] == "single"
+    assert payload["embedded_mode"] == "embedded"
+    assert payload["zones_count"] == 1
+
+
+def test_render_slide_fires_step13_diag_before_template_lookup(capsys):
+    # Diag must fire even when the precondition (u1) later raises — the diag
+    # is at entry, so the user sees the zone shape even on failure.
+    zones = [{"position": "primary", "slot_payload": {}}]
+    with pytest.raises(TypeError):
+        render_slide(
+            slide_title="t",
+            slide_footer=None,
+            zones_data=zones,
+            layout_preset="single",
+            layout_css=_layout_css(),
+            gap_px=14,
+            embedded_mode="embedded",
+        )
+    out = capsys.readouterr().out
+    assert "[DIAG] phase_z2 Step 13 render_slide entry " in out
+
+
+# ─── Step 12 emit call site source-slice ──────────────────────────
+
+
+def test_step12_emit_call_site_invokes_helper_after_artifact_write():
+    # The Step 12 emit site is buried inside the orchestrator; rather than
+    # spin up the full pipeline, assert by source-slice that the helper is
+    # invoked with the "Step 12 slot_payload emit" label *after* the
+    # _write_step_artifact(... step12 ... "slot_payload" ...) call.
+    src = Path(phase_z2_pipeline.__file__).read_text(encoding="utf-8")
+    artifact_marker = '_write_step_artifact(\n        run_dir, 12, "slot_payload"'
+    helper_marker = '_emit_diag_zones_shape("Step 12 slot_payload emit", zones_data)'
+    artifact_pos = src.find(artifact_marker)
+    helper_pos = src.find(helper_marker)
+    assert artifact_pos != -1, "Step 12 slot_payload artifact write not found"
+    assert helper_pos != -1, "Step 12 DIAG helper call not found"
+    assert helper_pos > artifact_pos, (
+        "Step 12 DIAG helper call must appear after the slot_payload artifact write "
+        f"(artifact_pos={artifact_pos}, helper_pos={helper_pos})"
+    )
+
+
+def test_step13_entry_call_site_invokes_helper_inside_render_slide():
+    src = Path(phase_z2_pipeline.__file__).read_text(encoding="utf-8")
+    render_slide_def = src.find("def render_slide(")
+    assert render_slide_def != -1, "render_slide definition not found"
+    # Bound the search to the function body — find next def or class after it.
+    next_def = src.find("\ndef ", render_slide_def + len("def render_slide("))
+    body = src[render_slide_def:next_def if next_def != -1 else len(src)]
+    assert '_emit_diag_zones_shape(\n        "Step 13 render_slide entry"' in body, (
+        "Step 13 DIAG helper call not found inside render_slide()"
+    )
+
+
+# ─── unconditional contract (no env-gate) ────────────────────────
+
+
+def test_diag_helper_has_no_env_gate(monkeypatch, capsys):
+    # Stage 1 contract: diag is unconditional. Setting any plausible
+    # "verbose off" env var must not silence the line. We test the most
+    # common gate names a future contributor might be tempted to add.
+    for env_name in (
+        "PHASE_Z_DIAG_VERBOSE",
+        "DIAG_VERBOSE",
+        "VERBOSE",
+        "DEBUG",
+        "PYTHON_NO_DIAG",
+    ):
+        monkeypatch.setenv(env_name, "0")
+    _emit_diag_zones_shape("Step 12 slot_payload emit", [])
+    out = capsys.readouterr().out
+    assert "[DIAG] phase_z2 Step 12 slot_payload emit" in out
@@ -77,10 +77,14 @@ def test_three_new_salvage_failure_types_route_to_expected_cascade_actions():
    assert NEXT_ACTION_BY_FAILURE["glue_absorption_insufficient"] == "font_step_compression"
    assert NEXT_ACTION_BY_FAILURE["font_step_insufficient"] == "layout_adjust"

-    # Implementation status (u7): 2 cascade entries IMPLEMENTED, layout_adjust MISSING
+    # Implementation status: 3 cascade entries IMPLEMENTED.
+    # layout_adjust was MISSING pre-IMP-88; IMP-88 u7 (2026-05-24) flipped it
+    # to IMPLEMENTED on the failure-router surface alongside the primary
+    # router surface (u3 plan_layout_adjust + u6 dispatcher branch + u7
+    # cascade entry trigger).
    assert NEXT_ACTION_IMPLEMENTATION_STATUS["glue_compression"] == "IMPLEMENTED"
    assert NEXT_ACTION_IMPLEMENTATION_STATUS["font_step_compression"] == "IMPLEMENTED"
-    assert NEXT_ACTION_IMPLEMENTATION_STATUS["layout_adjust"] == "MISSING"
+    assert NEXT_ACTION_IMPLEMENTATION_STATUS["layout_adjust"] == "IMPLEMENTED"

    # Classifier path via salvage_steps[-1].action → failure_type → next action
    cases = [
@@ -0,0 +1,483 @@
+"""IMP-88 u6 — Step 17 salvage cascade dispatcher tests for the two
+new branches (`layout_adjust` + `frame_internal_fit_candidate`).
+
+Stage 2 binding contract (u6):
+  - Extend `_SALVAGE_FAIL_BY_ACTION` to include the two IMP-88 actions so
+    the salvage loop range adapts and the cascade does not exit early at
+    `layout_adjust` / `frame_internal_fit_candidate` (previously terminal
+    in the 3-entry map, now executable).
+  - `layout_adjust` takes a distinct render path: it calls `render_slide`
+    with the NEW preset + remapped zones_data + new layout_css (built via
+    `apply_layout_adjust_layout_css`). No CSS overlay — topology swap only
+    (honors `[[feedback_phase_z_spacing_direction]]`: no common margin
+    shrink, no slide-body shrink).
+  - `frame_internal_fit_candidate` uses the shared CSS-overlay path
+    (same as font_step_compression / glue_compression) because the
+    planner emits a frame-scoped CSS rule via
+    `apply_frame_internal_fit_candidate_css`.
+
+Test surfaces (8 tests):
+  1. `_SALVAGE_FAIL_BY_ACTION` map registers the two new actions with
+     the failure_type names the failure_router (u2) cascade rows expect.
+  2. `layout_adjust` PASS — out_path promoted with the swapped render,
+     step records new_layout_preset, cascade exits.
+  3. `layout_adjust` infeasible (no sibling for `single` preset) — step
+     records failure_reason without invoking render_slide; cascade
+     advances to frame_internal_fit_candidate.
+  4. `layout_adjust` rerender FAIL — cascade advances to
+     frame_internal_fit_candidate (which then PASSes via patched
+     envelope).
+  5. `frame_internal_fit_candidate` PASS via patched envelope — out_path
+     promoted with CSS-overlay candidate.
+  6. `frame_internal_fit_candidate` no-envelope — step records
+     envelope_present=False; cascade exits via frame_reselect terminal.
+  7. Full 5-step cascade all fail — loop cap (range(len(map))=5)
+     respected; exactly 5 steps recorded; out_path preserved.
+  8. `layout_adjust` uses no CSS-overlay path (css_override field is
+     absent from the layout_adjust step; new_layout_preset is present).
+"""
+from __future__ import annotations
+
+import shutil
+import tempfile
+from pathlib import Path
+
+import pytest
+
+import src.phase_z2_mapper as _pz_mapper
+import src.phase_z2_pipeline as _pz_pipeline
+from src.phase_z2_pipeline import _SALVAGE_FAIL_BY_ACTION, _attempt_salvage_chain
+
+
+_PROJECT_ROOT = _pz_pipeline.PROJECT_ROOT
+
+
+@pytest.fixture
+def project_tmp(tmp_path_factory):
+    """Temp dir under PROJECT_ROOT so `_attempt_salvage_chain` can call
+    `candidate_path.relative_to(PROJECT_ROOT)` without ValueError on a
+    cross-drive Windows tmp path (default pytest tmp_path lives under
+    %LOCALAPPDATA% which is on a different drive from the project root).
+    Mirrors the fixture pattern in test_phase_z2_step17_salvage_chain.py.
+    """
+    base = _PROJECT_ROOT / ".orchestrator" / "tmp"
+    base.mkdir(parents=True, exist_ok=True)
+    d = Path(tempfile.mkdtemp(prefix="imp88_u6_", dir=str(base)))
+    try:
+        yield d
+    finally:
+        shutil.rmtree(d, ignore_errors=True)
+
+
+# IMP-09 gate-passing layout_css envelope. _attempt_salvage_chain skips
+# the cascade when dynamic_cols=True or dynamic_rows=False. Mirror of the
+# fixture in test_phase_z2_step17_salvage_chain.py so this test file
+# stays consistent with the existing u15 cascade surface.
+_LAYOUT_CSS_GATE_PASS = {
+    "areas": '"top" "bottom"',
+    "cols": "1fr",
+    "rows": "1fr 1fr",
+    "heights_px": [300, 290],
+    "widths_px": [1180],
+    "ratios": [0.508, 0.491],
+    "width_ratios": [1.0],
+    "dynamic_rows": True,
+    "dynamic_cols": False,
+}
+
+
+def _patch_render(monkeypatch):
+    """Stub render_slide → deterministic HTML envelope. Counter exposes
+    invocation count so tests can assert render_slide was (or was not)
+    called per branch."""
+    counter = {"n": 0}
+
+    def _stub(slide_title, slide_footer, zones_data, layout_preset, layout_css, gap_px=14):
+        counter["n"] += 1
+        return (
+            f"<html><head><meta charset='utf-8'></head>"
+            f"<body><div data-slide-title='{slide_title}' "
+            f"data-rendered-preset='{layout_preset}'></div></body></html>"
+        )
+
+    monkeypatch.setattr(_pz_pipeline, "render_slide", _stub)
+    return counter
+
+
+def _horizontal_zones() -> list[dict]:
+    """horizontal-2 zones with content_weight.score so the vertical-2
+    swap path can call _build_cols_dynamic → compute_zone_layout_cols
+    inside apply_layout_adjust_layout_css → build_layout_css."""
+    return [
+        {"position": "top", "template_id": "t-top",
+         "content_weight": {"score": 1.0}},
+        {"position": "bottom", "template_id": "t-bottom",
+         "content_weight": {"score": 1.0}},
+    ]
+
+
+def _ci_image() -> dict:
+    """Minimal cascade_inputs for the cascade chain — covers the keys
+    every branch reads (fit_analysis is None to deliberately keep the
+    cross_zone branch infeasible when the cascade enters there, since
+    full FitAnalysis assembly is the u15 cascade test's domain not u6's)."""
+    return {
+        "fit_analysis": None, "containers": {}, "min_margin_px": 10,
+        "excess_px": 40.0, "excess_after_glue_px": 40.0,
+        "block_count": 3, "zone_position": "top",
+        "current_font_px": 15.2, "available_lines": 10, "chars_per_line": 40,
+    }
+
+
+# ── 1. _SALVAGE_FAIL_BY_ACTION map registration ─────────────────────
+
+
+def test_salvage_fail_map_registers_imp88_actions():
+    """u6 extends the salvage-action → failure_type map from 3 to 5
+    entries so the loop cap (range(len(map))) covers the IMP-88
+    cascade depth. failure_type names mirror failure_router u2's
+    SALVAGE_FAILURE_TYPE_BY_ACTION rows."""
+    assert _SALVAGE_FAIL_BY_ACTION["layout_adjust"] == "layout_adjust_insufficient"
+    assert _SALVAGE_FAIL_BY_ACTION["frame_internal_fit_candidate"] == "frame_internal_fit_candidate_insufficient"
+    assert len(_SALVAGE_FAIL_BY_ACTION) == 5
+    # u4 image_fit stays OUT of the salvage chain map — u7 handles it as a
+    # Step 17 entry single-pass (not a cascade salvage stage). Guard against
+    # accidental future registration that would change cascade semantics.
+    assert "image_fit" not in _SALVAGE_FAIL_BY_ACTION
+
+
+# ── 2. layout_adjust PASS branch ────────────────────────────────────
+
+
+def test_layout_adjust_pass_promotes_final_html(project_tmp, monkeypatch):
+    """initial_failure_type=font_step_insufficient routes to layout_adjust;
+    plan_layout_adjust swaps horizontal-2 → vertical-2 (rows ↔ cols, swap
+    priority 0). render_slide is invoked with the NEW preset; overflow
+    passes → out_path promoted; step records new_layout_preset; cascade
+    exits with salvage_passed=True. No CSS overlay path was used."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")
+    counter = _patch_render(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": True, "fail_reasons": []},
+    )
+
+    trace = _attempt_salvage_chain(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="imp88-u6", slide_footer=None,
+        zones_data=_horizontal_zones(),
+        layout_preset="horizontal-2", layout_css=_LAYOUT_CSS_GATE_PASS,
+        cascade_inputs=_ci_image(),
+        initial_failure_type="font_step_insufficient", gap_px=14,
+    )
+
+    assert trace["salvage_attempted"] is True
+    assert trace["salvage_passed"] is True
+    assert len(trace["salvage_steps"]) == 1
+    step0 = trace["salvage_steps"][0]
+    assert step0["action"] == "layout_adjust"
+    assert step0["passed"] is True
+    assert step0["new_layout_preset"] == "vertical-2"
+    assert step0["plan"]["feasible"] is True
+    # layout_adjust uses the distinct render path — NOT the CSS-overlay path.
+    assert "css_override" not in step0
+    # render_slide was invoked exactly once with the NEW preset.
+    assert counter["n"] == 1
+    promoted = out_path.read_text(encoding="utf-8")
+    assert "ORIGINAL_BEFORE_SALVAGE" not in promoted
+    assert "data-rendered-preset='vertical-2'" in promoted
+
+
+# ── 3. layout_adjust infeasible (no sibling) ────────────────────────
+
+
+def test_layout_adjust_infeasible_no_sibling_cascade_advances(project_tmp, monkeypatch):
+    """`single` preset has no render-ready unit_count=1 sibling (catalog
+    design — single and grid-2x2 have no swap target). layout_adjust
+    returns feasible=False; render_slide is NOT invoked; cascade
+    advances to frame_internal_fit_candidate. Patched get_contract
+    returns no envelope → that branch also infeasible → cascade exits
+    at the frame_reselect terminal action."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")
+    counter = _patch_render(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: pytest.fail(
+            "run_overflow_check must not run when no candidate is emitted"
+        ),
+    )
+    monkeypatch.setattr(
+        _pz_mapper, "get_contract", lambda _tid: None,
+    )
+
+    trace = _attempt_salvage_chain(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="imp88-u6", slide_footer=None,
+        zones_data=[{"position": "primary", "template_id": "t-only",
+                     "content_weight": {"score": 1.0}}],
+        layout_preset="single", layout_css=_LAYOUT_CSS_GATE_PASS,
+        cascade_inputs={**_ci_image(), "zone_position": "primary"},
+        initial_failure_type="font_step_insufficient", gap_px=14,
+    )
+
+    assert trace["salvage_attempted"] is True
+    assert trace["salvage_passed"] is False
+    actions = [s["action"] for s in trace["salvage_steps"]]
+    assert actions == ["layout_adjust", "frame_internal_fit_candidate"]
+    s0, s1 = trace["salvage_steps"]
+    assert s0["plan"]["feasible"] is False
+    assert "no render-ready" in (s0["plan"]["failure_reason"] or "")
+    assert s0["new_layout_preset"] is None
+    assert s1["plan"]["feasible"] is False
+    assert s1["plan"]["envelope_present"] is False
+    # No candidate ever rendered (layout_adjust infeasible → no render call;
+    # frame_internal_fit_candidate infeasible → no render call).
+    assert counter["n"] == 0
+    # frame_reselect is the next routing target after
+    # frame_internal_fit_candidate_insufficient — not in salvage map → terminal.
+    assert trace.get("salvage_terminal_action") == "frame_reselect"
+    # Original final.html unchanged.
+    assert out_path.read_text(encoding="utf-8") == "ORIGINAL_BEFORE_SALVAGE"
+
+
+# ── 4. layout_adjust rerender FAIL → frame_internal_fit_candidate PASS ──
+
+
+def test_layout_adjust_fail_cascade_to_frame_internal_fit_pass(project_tmp, monkeypatch):
+    """layout_adjust feasible but post-swap overflow persists →
+    failure_type=layout_adjust_insufficient → routes to
+    frame_internal_fit_candidate. Patched contract provides an envelope
+    variant that absorbs the excess; that branch PASSes → out_path
+    promoted with the CSS-overlay candidate."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")
+    counter = _patch_render(monkeypatch)
+
+    # First overflow check (after layout_adjust render) FAILS,
+    # second (after frame_internal_fit CSS overlay) PASSes.
+    overflow_results = iter([
+        {"passed": False, "fail_reasons": ["zone overflow persists"]},
+        {"passed": True, "fail_reasons": []},
+    ])
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: next(overflow_results),
+    )
+
+    # Stub contract with a feasible internal_envelope variant covering 40px excess.
+    stub_contract = {
+        "internal_envelope": {
+            "variants": [
+                {"name": "internal_grid_row",
+                 "excess_budget_px": 60,
+                 "css_overrides": {"padding-top": "0px"}},
+            ],
+        },
+    }
+    monkeypatch.setattr(
+        _pz_mapper, "get_contract", lambda _tid: stub_contract,
+    )
+
+    trace = _attempt_salvage_chain(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="imp88-u6", slide_footer=None,
+        zones_data=_horizontal_zones(),
+        layout_preset="horizontal-2", layout_css=_LAYOUT_CSS_GATE_PASS,
+        cascade_inputs=_ci_image(),
+        initial_failure_type="font_step_insufficient", gap_px=14,
+    )
+
+    assert trace["salvage_passed"] is True
+    assert len(trace["salvage_steps"]) == 2
+    s0, s1 = trace["salvage_steps"]
+    assert s0["action"] == "layout_adjust"
+    assert s0["passed"] is False
+    assert s0["plan"]["feasible"] is True
+    assert s1["action"] == "frame_internal_fit_candidate"
+    assert s1["passed"] is True
+    assert s1["plan"]["selected_variant"] == "internal_grid_row"
+    assert s1["css_override"]
+    assert 'data-template-id="t-top"' in s1["css_override"]
+    # Two render_slide calls (one per dispatched branch).
+    assert counter["n"] == 2
+    assert "ORIGINAL_BEFORE_SALVAGE" not in out_path.read_text(encoding="utf-8")
+
+
+# ── 5. frame_internal_fit_candidate PASS (direct entry) ─────────────
+
+
+def test_frame_internal_fit_candidate_pass_promotes_final_html(project_tmp, monkeypatch):
+    """initial_failure_type=layout_adjust_insufficient routes directly to
+    frame_internal_fit_candidate. Patched contract envelope variant
+    covers excess; CSS-overlay candidate PASSes → out_path promoted."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")
+    counter = _patch_render(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": True, "fail_reasons": []},
+    )
+    monkeypatch.setattr(
+        _pz_mapper, "get_contract",
+        lambda _tid: {
+            "internal_envelope": {
+                "variants": [
+                    {"name": "density_envelope",
+                     "excess_budget_px": 80,
+                     "css_overrides": {"line-height": "1.4"}},
+                ],
+            },
+        },
+    )
+
+    trace = _attempt_salvage_chain(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="imp88-u6", slide_footer=None,
+        zones_data=_horizontal_zones(),
+        layout_preset="horizontal-2", layout_css=_LAYOUT_CSS_GATE_PASS,
+        cascade_inputs=_ci_image(),
+        initial_failure_type="layout_adjust_insufficient", gap_px=14,
+    )
+
+    assert trace["salvage_passed"] is True
+    assert len(trace["salvage_steps"]) == 1
+    step0 = trace["salvage_steps"][0]
+    assert step0["action"] == "frame_internal_fit_candidate"
+    assert step0["passed"] is True
+    assert step0["plan"]["selected_variant"] == "density_envelope"
+    assert step0["css_override"] and "line-height: 1.4" in step0["css_override"]
+    assert counter["n"] == 1
+
+
+# ── 6. frame_internal_fit_candidate no envelope → terminal exit ─────
+
+
+def test_frame_internal_fit_candidate_no_envelope_cascade_terminal(project_tmp, monkeypatch):
+    """initial=layout_adjust_insufficient routes to
+    frame_internal_fit_candidate. Patched contract has NO
+    internal_envelope → planner returns feasible=False with
+    envelope_present=False; failure_type=
+    frame_internal_fit_candidate_insufficient → routes to
+    frame_reselect (not in salvage map) → terminal exit recorded."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")
+    counter = _patch_render(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: pytest.fail("no candidate emitted — overflow_check must not run"),
+    )
+    # Contract present but no internal_envelope → envelope_present=False branch.
+    monkeypatch.setattr(
+        _pz_mapper, "get_contract", lambda _tid: {"some_other_key": "value"},
+    )
+
+    trace = _attempt_salvage_chain(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="imp88-u6", slide_footer=None,
+        zones_data=_horizontal_zones(),
+        layout_preset="horizontal-2", layout_css=_LAYOUT_CSS_GATE_PASS,
+        cascade_inputs=_ci_image(),
+        initial_failure_type="layout_adjust_insufficient", gap_px=14,
+    )
+
+    assert trace["salvage_passed"] is False
+    assert len(trace["salvage_steps"]) == 1
+    step0 = trace["salvage_steps"][0]
+    assert step0["action"] == "frame_internal_fit_candidate"
+    assert step0["plan"]["feasible"] is False
+    assert step0["plan"]["envelope_present"] is False
+    assert trace["salvage_terminal_action"] == "frame_reselect"
+    assert counter["n"] == 0
+    assert out_path.read_text(encoding="utf-8") == "ORIGINAL_BEFORE_SALVAGE"
+
+
+# ── 7. Loop cap respected — 5 stages all fail ───────────────────────
+
+
+def test_full_5_step_cascade_all_fail_loop_cap_respected(project_tmp, monkeypatch):
+    """Start at donor_slack_insufficient and force every cascade stage to
+    fail: cross_zone (no fit_analysis), glue (excess > envelope), font_step
+    (no headroom), layout_adjust (single → no sibling), frame_internal_fit
+    (no contract). Loop iterates exactly len(_SALVAGE_FAIL_BY_ACTION)=5
+    times → salvage_steps has 5 entries in the exact cascade order."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")
+    counter = _patch_render(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: pytest.fail("no CSS emitted in any branch — overflow_check must not run"),
+    )
+    monkeypatch.setattr(
+        _pz_mapper, "get_contract", lambda _tid: None,
+    )
+
+    trace = _attempt_salvage_chain(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="imp88-u6", slide_footer=None,
+        # single preset → layout_adjust will be infeasible (no sibling)
+        zones_data=[{"position": "primary", "template_id": "t-only",
+                     "content_weight": {"score": 1.0}}],
+        layout_preset="single", layout_css=_LAYOUT_CSS_GATE_PASS,
+        cascade_inputs={
+            "fit_analysis": None, "containers": {}, "min_margin_px": 10,
+            # excess_px=200 > glue envelope at block_count=1 (max ~28) → infeasible
+            "excess_px": 200.0, "excess_after_glue_px": 200.0,
+            "block_count": 1, "zone_position": "primary",
+            # current_font_px cannot absorb 200px even at 8px floor → infeasible
+            "current_font_px": 15.2, "available_lines": 10, "chars_per_line": 40,
+        },
+        initial_failure_type="donor_slack_insufficient", gap_px=14,
+    )
+
+    assert trace["salvage_passed"] is False
+    assert len(trace["salvage_steps"]) == 5
+    actions = [s["action"] for s in trace["salvage_steps"]]
+    assert actions == [
+        "cross_zone_redistribute",
+        "glue_compression",
+        "font_step_compression",
+        "layout_adjust",
+        "frame_internal_fit_candidate",
+    ]
+    # All 5 are infeasible — no candidate rendering anywhere.
+    assert counter["n"] == 0
+    # Loop exhausted at cap (no mid-cascade terminal_action since each
+    # next_action stayed in _SALVAGE_FAIL_BY_ACTION through 5 stages).
+    assert "salvage_terminal_action" not in trace
+    assert out_path.read_text(encoding="utf-8") == "ORIGINAL_BEFORE_SALVAGE"
+
+
+# ── 8. layout_adjust uses the distinct render path (no CSS overlay) ──
+
+
+def test_layout_adjust_step_has_no_css_overlay_field(project_tmp, monkeypatch):
+    """layout_adjust's render path is qualitatively different from the
+    CSS-overlay planners (glue / font_step / cross_zone / frame_internal_fit):
+    it calls render_slide with the NEW preset + remapped zones_data + new
+    layout_css. The step dict therefore omits `css_override` and surfaces
+    `new_layout_preset` instead — observability for downstream classifiers."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")
+    _patch_render(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": True, "fail_reasons": []},
+    )
+
+    trace = _attempt_salvage_chain(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="imp88-u6", slide_footer=None,
+        zones_data=_horizontal_zones(),
+        layout_preset="horizontal-2", layout_css=_LAYOUT_CSS_GATE_PASS,
+        cascade_inputs=_ci_image(),
+        initial_failure_type="font_step_insufficient", gap_px=14,
+    )
+
+    step0 = trace["salvage_steps"][0]
+    assert step0["action"] == "layout_adjust"
+    # Distinct render path observability contract:
+    assert "css_override" not in step0
+    assert "new_layout_preset" in step0
+    assert "candidate_path" in step0
@@ -0,0 +1,542 @@
+"""IMP-88 u7 — Step 17 entry runtime caller tests.
+
+Stage 2 binding contract (u7):
+  - `_attempt_step17_image_fit_single_pass` executes the image_fit Step 17
+    entry single-pass: per-event plan_image_fit → apply_image_fit_css →
+    aggregated CSS overlay → single re-render → run_overflow_check.
+    PASS promotes final.html and returns a salvage_steps-shaped entry with
+    post_salvage_overflow; FAIL returns the same shape with failure_reason
+    (NO out_path mutation on FAIL).
+  - image_fit stays OUT of `_SALVAGE_FAIL_BY_ACTION` (u6 guard). The Step 17
+    entry single-pass is NOT a cascade stage — it runs BEFORE the cascade
+    direct-entry block in pipeline §11.7.2.
+  - Honors `[[feedback_phase_z_spacing_direction]]` — img-scoped CSS only,
+    no common margin / slide-body shrink. Honors AI isolation contract
+    (PZ-1) — deterministic data-surface, no AI call.
+  - Step 17/18/19 artifact refresh: the pipeline §11.7.1 wrapper around the
+    helper re-runs classify_visual_runtime_check + route_fit_classification +
+    enrich_retry_trace_with_failure_classification on PASS so Step 18
+    failure_classification + Step 19 next_action_proposal reflect the
+    post-image_fit state (not the stale pre-image_fit state).
+  - direct entry triggers (§11.7.2) for layout_adjust /
+    frame_internal_fit_candidate / image_fit_insufficient route into
+    `_attempt_salvage_chain` with a synthetic initial_failure_type that
+    failure_router u2 NEXT_ACTION_BY_FAILURE maps onto the proposed action.
+
+Test surfaces (12 tests):
+  1. helper returns triggered=False when no image_events.
+  2. helper returns triggered=False when every image_event is below tol
+     (delta=None or |delta|<=tol).
+  3. helper returns triggered=False when plan_image_fit emits no CSS for
+     any feasible event (rendered_w/h missing — apply returns None).
+  4. helper PASS — out_path promoted, step shape correct (action=image_fit,
+     passed=True, image_fit_event_plans recorded, post_salvage_overflow).
+  5. helper FAIL — out_path NOT promoted, step records failure_reason +
+     no post_salvage_overflow key.
+  6. helper aggregates CSS chunks from multiple events into ONE candidate
+     re-render (render_slide called exactly once).
+  7. helper writes candidate to run_dir as `salvage_image_fit_candidate.html`
+     and step.candidate_path is the project-root-relative form.
+  8. helper passes delta_tol through to plan_image_fit (override threshold
+     filters which events get planned/applied).
+  9. image_fit stays OUT of `_SALVAGE_FAIL_BY_ACTION` (u6 guard re-asserted
+     so u7 does not accidentally register image_fit as a cascade stage).
+  10. helper guards out_path mutation strictly under PASS (FAIL = no write).
+  11. helper exposes every plan_image_fit result through `event_plans`
+      even when no CSS was emitted (telemetry continuity for Step 17/18/19).
+  12. helper honors frame-scoped img CSS only — emitted CSS contains an
+      img selector and does NOT touch shared margins / slide-body / zone gap.
+"""
+from __future__ import annotations
+
+import shutil
+import tempfile
+from pathlib import Path
+
+import pytest
+
+import src.phase_z2_pipeline as _pz_pipeline
+from src.phase_z2_pipeline import (
+    _SALVAGE_FAIL_BY_ACTION,
+    _attempt_step17_image_fit_single_pass,
+)
+
+
+_PROJECT_ROOT = _pz_pipeline.PROJECT_ROOT
+
+
+@pytest.fixture
+def project_tmp(tmp_path_factory):
+    """Temp dir under PROJECT_ROOT so candidate_path.relative_to(PROJECT_ROOT)
+    does not raise ValueError on a cross-drive Windows tmp path. Mirrors the
+    fixture in test_phase_z2_pipeline_salvage_imp88.py."""
+    base = _PROJECT_ROOT / ".orchestrator" / "tmp"
+    base.mkdir(parents=True, exist_ok=True)
+    d = Path(tempfile.mkdtemp(prefix="imp88_u7_", dir=str(base)))
+    try:
+        yield d
+    finally:
+        shutil.rmtree(d, ignore_errors=True)
+
+
+# IMP-09 gate-passing layout_css envelope — kept for parity even though the
+# image_fit single-pass helper does not consult the gate (gate is internal
+# to _attempt_salvage_chain). Reserved for §11.7.2 direct-entry tests.
+_LAYOUT_CSS_GATE_PASS = {
+    "areas": '"top" "bottom"',
+    "cols": "1fr",
+    "rows": "1fr 1fr",
+    "heights_px": [300, 290],
+    "widths_px": [1180],
+    "ratios": [0.508, 0.491],
+    "width_ratios": [1.0],
+    "dynamic_rows": True,
+    "dynamic_cols": False,
+}
+
+
+def _stub_render_capture(monkeypatch):
+    """Stub render_slide → deterministic HTML envelope; counter exposes
+    invocation count + a recorder of the (preset, css overlay observed via
+    candidate_html) tuple per call."""
+    state = {"n": 0, "calls": []}
+
+    def _stub(slide_title, slide_footer, zones_data, layout_preset, layout_css, gap_px=14):
+        state["n"] += 1
+        state["calls"].append({
+            "preset": layout_preset, "zones_count": len(zones_data),
+            "gap_px": gap_px,
+        })
+        return (
+            f"<html><head><meta charset='utf-8'></head>"
+            f"<body><div data-rendered-preset='{layout_preset}'>"
+            f"<img src='zoneA.png'/></div></body></html>"
+        )
+
+    monkeypatch.setattr(_pz_pipeline, "render_slide", _stub)
+    return state
+
+
+def _zones() -> list[dict]:
+    return [
+        {"position": "top", "template_id": "t-top",
+         "content_weight": {"score": 1.0}},
+        {"position": "bottom", "template_id": "t-bottom",
+         "content_weight": {"score": 1.0}},
+    ]
+
+
+def _image_event(*, src: str, zone_position: str = "top",
+                 zone_template_id: str = "t-top",
+                 natural_w: int = 1600, natural_h: int = 900,
+                 rendered_w: int = 800, rendered_h: int = 600,
+                 delta: float | None = 0.20) -> dict:
+    """Mirror the shape pipeline JS injection emits at lines 3019-3060."""
+    natural_ratio = natural_w / natural_h if natural_h else None
+    rendered_ratio = rendered_w / rendered_h if rendered_h else None
+    return {
+        "src": src,
+        "zone_position": zone_position,
+        "zone_template_id": zone_template_id,
+        "natural_w": natural_w, "natural_h": natural_h,
+        "rendered_w": rendered_w, "rendered_h": rendered_h,
+        "natural_ratio": natural_ratio,
+        "rendered_ratio": rendered_ratio,
+        "delta": delta,
+    }
+
+
+# ── 1. No image_events → not triggered ──────────────────────────────
+
+
+def test_helper_not_triggered_when_no_image_events(project_tmp, monkeypatch):
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_U7", encoding="utf-8")
+    counter = _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: pytest.fail("must not run overflow_check when not triggered"),
+    )
+
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-empty", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS, image_events=[], gap_px=14,
+    )
+
+    assert res["triggered"] is False
+    assert res["passed"] is False
+    assert res["step"] is None
+    assert res["candidate_html"] is None
+    assert res["candidate_overflow"] is None
+    assert res["event_plans"] == []
+    assert counter["n"] == 0
+    assert out_path.read_text(encoding="utf-8") == "ORIGINAL_BEFORE_U7"
+
+
+# ── 2. All events sub-tolerance → not triggered ─────────────────────
+
+
+def test_helper_not_triggered_when_all_events_under_tolerance(project_tmp, monkeypatch):
+    """delta=None (image not loaded) + |delta|<=tol (no aspect mismatch
+    above threshold) both should produce feasible=False plans, no CSS,
+    and triggered=False at the helper level."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_U7", encoding="utf-8")
+    counter = _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: pytest.fail("must not run overflow_check when not triggered"),
+    )
+
+    events = [
+        _image_event(src="zoneA.png", delta=None),         # not loaded
+        _image_event(src="zoneB.png", delta=0.03),         # under tol
+    ]
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-undertol", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS, image_events=events, gap_px=14,
+    )
+
+    assert res["triggered"] is False
+    assert len(res["event_plans"]) == 2
+    assert all(p.get("feasible") is False for p in res["event_plans"])
+    assert counter["n"] == 0
+    assert out_path.read_text(encoding="utf-8") == "ORIGINAL_BEFORE_U7"
+
+
+# ── 3. Feasible but apply_image_fit_css returns None ─────────────────
+
+
+def test_helper_not_triggered_when_apply_returns_none(project_tmp, monkeypatch):
+    """rendered_w/h missing on a feasible-shaped event means apply_image_fit_css
+    would emit empty CSS — but plan_image_fit treats missing rendered dims as
+    infeasible (per u4 contract), so this stays triggered=False."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_U7", encoding="utf-8")
+    counter = _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: pytest.fail("must not run overflow_check when not triggered"),
+    )
+
+    bad_event = _image_event(src="zoneA.png", delta=0.20)
+    bad_event["rendered_w"] = 0  # invalidates apply path → plan infeasible
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-noapply", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS, image_events=[bad_event], gap_px=14,
+    )
+
+    assert res["triggered"] is False
+    assert res["event_plans"][0].get("feasible") is False
+    assert counter["n"] == 0
+
+
+# ── 4. helper PASS — out_path promoted, step shape correct ──────────
+
+
+def test_helper_pass_promotes_final_html(project_tmp, monkeypatch):
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_U7", encoding="utf-8")
+    counter = _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": True, "fail_reasons": []},
+    )
+
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-pass", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS,
+        image_events=[_image_event(src="zoneA.png", delta=0.30)],
+        gap_px=14,
+    )
+
+    assert res["triggered"] is True
+    assert res["passed"] is True
+    assert res["step"]["action"] == "image_fit"
+    assert res["step"]["passed"] is True
+    assert res["step"]["post_salvage_overflow"] == {"passed": True, "fail_reasons": []}
+    assert "failure_reason" not in res["step"]
+    assert res["step"]["image_fit_event_plans"]
+    assert res["step"]["image_fit_event_plans"][0]["feasible"] is True
+    assert counter["n"] == 1
+    # out_path promoted with the candidate HTML (style overlay injected).
+    promoted = out_path.read_text(encoding="utf-8")
+    assert "ORIGINAL_BEFORE_U7" not in promoted
+    assert "data-rendered-preset='vertical-2'" in promoted
+    assert "<style>" in promoted
+
+
+# ── 5. helper FAIL — out_path NOT promoted, failure_reason recorded ──
+
+
+def test_helper_fail_leaves_out_path_untouched(project_tmp, monkeypatch):
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_U7", encoding="utf-8")
+    _stub_render_capture(monkeypatch)
+    fail_payload = {
+        "passed": False,
+        "fail_reasons": ["zone--top (t-top) overflowed by 30px (vert) / 0px (horiz)"],
+    }
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check", lambda p: fail_payload,
+    )
+
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-fail", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS,
+        image_events=[_image_event(src="zoneA.png", delta=0.30)],
+        gap_px=14,
+    )
+
+    assert res["triggered"] is True
+    assert res["passed"] is False
+    assert res["step"]["passed"] is False
+    assert "post_salvage_overflow" not in res["step"]
+    assert res["step"]["failure_reason"] == fail_payload["fail_reasons"]
+    # out_path stays at the pre-helper value — strict PASS-only promotion.
+    assert out_path.read_text(encoding="utf-8") == "ORIGINAL_BEFORE_U7"
+
+
+# ── 6. helper aggregates multi-event CSS into one re-render ─────────
+
+
+def test_helper_aggregates_multi_event_css_into_single_render(project_tmp, monkeypatch):
+    """Three feasible image events → CSS chunks concatenated → ONE render_slide
+    call (not three). The aggregated style block is injected before </head>."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL_BEFORE_U7", encoding="utf-8")
+    counter = _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": True, "fail_reasons": []},
+    )
+
+    events = [
+        _image_event(src="zoneA.png", zone_position="top", delta=0.20),
+        _image_event(src="zoneB.png", zone_position="top", delta=0.25),
+        _image_event(src="zoneC.png", zone_position="bottom",
+                     zone_template_id="t-bottom", delta=0.18),
+    ]
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-multi", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS, image_events=events, gap_px=14,
+    )
+
+    assert res["triggered"] is True
+    assert res["passed"] is True
+    assert counter["n"] == 1
+    promoted = out_path.read_text(encoding="utf-8")
+    # All three image src selectors should appear in the merged overlay.
+    assert "zoneA.png" in promoted
+    assert "zoneB.png" in promoted
+    assert "zoneC.png" in promoted
+
+
+# ── 7. candidate_path is project-relative ───────────────────────────
+
+
+def test_helper_candidate_path_is_project_root_relative(project_tmp, monkeypatch):
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL", encoding="utf-8")
+    _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": False, "fail_reasons": ["nope"]},
+    )
+
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-relpath", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS,
+        image_events=[_image_event(src="zoneA.png", delta=0.20)],
+        gap_px=14,
+    )
+
+    assert res["triggered"] is True
+    cp = res["step"]["candidate_path"]
+    # project-relative path ending with the salvage candidate filename.
+    assert cp.endswith("salvage_image_fit_candidate.html")
+    assert not Path(cp).is_absolute()
+    # Concrete file actually exists on disk.
+    assert (project_tmp / "salvage_image_fit_candidate.html").exists()
+
+
+# ── 8. delta_tol override threads through ────────────────────────────
+
+
+def test_helper_passes_delta_tol_through_to_plan_image_fit(project_tmp, monkeypatch):
+    """An event with |delta|=0.10 is OVER default tol (0.05) but UNDER an
+    override tol of 0.20. With override the helper should see infeasible
+    plans → triggered=False; with default it should see feasible plans."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL", encoding="utf-8")
+    _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": True, "fail_reasons": []},
+    )
+
+    ev = _image_event(src="zoneA.png", delta=0.10)
+    # Default tol = IMAGE_ASPECT_DELTA_TOL = 0.05 → plan feasible, triggered.
+    res_default = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-tol", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS, image_events=[ev], gap_px=14,
+    )
+    assert res_default["triggered"] is True
+    assert res_default["event_plans"][0].get("feasible") is True
+
+    # Override tol = 0.20 → plan infeasible (delta 0.10 within tol).
+    out_path.write_text("ORIGINAL", encoding="utf-8")  # reset
+    res_override = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-tol", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS, image_events=[ev], gap_px=14,
+        delta_tol=0.20,
+    )
+    assert res_override["triggered"] is False
+    assert res_override["event_plans"][0].get("feasible") is False
+
+
+# ── 9. image_fit stays OUT of _SALVAGE_FAIL_BY_ACTION ────────────────
+
+
+def test_image_fit_stays_out_of_salvage_fail_map():
+    """u7 entry single-pass is NOT a cascade salvage stage. The u6 guard
+    asserted this; re-assert here so u7's wiring does not accidentally
+    register image_fit into the cascade map."""
+    assert "image_fit" not in _SALVAGE_FAIL_BY_ACTION
+    # Cascade stages stay as u6 left them: 5 entries, image_fit absent.
+    assert len(_SALVAGE_FAIL_BY_ACTION) == 5
+    assert set(_SALVAGE_FAIL_BY_ACTION) == {
+        "cross_zone_redistribute",
+        "glue_compression",
+        "font_step_compression",
+        "layout_adjust",
+        "frame_internal_fit_candidate",
+    }
+
+
+# ── 10. PASS-only out_path mutation (strict gate) ────────────────────
+
+
+def test_helper_strictly_promotes_only_on_pass(project_tmp, monkeypatch):
+    """Defensive — assert the helper does NOT write out_path on FAIL even
+    after rendering a candidate. Mutation must be strictly gated on
+    passed=True from run_overflow_check."""
+    out_path = project_tmp / "final.html"
+    canary = "STRICT_PROMOTION_CANARY_DO_NOT_OVERWRITE"
+    out_path.write_text(canary, encoding="utf-8")
+    _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": False, "fail_reasons": ["persists"]},
+    )
+
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-strict", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS,
+        image_events=[_image_event(src="zoneA.png", delta=0.30)],
+        gap_px=14,
+    )
+
+    assert res["triggered"] is True
+    assert res["passed"] is False
+    # The candidate file IS written (telemetry continuity); out_path is NOT.
+    assert (project_tmp / "salvage_image_fit_candidate.html").exists()
+    assert out_path.read_text(encoding="utf-8") == canary
+
+
+# ── 11. event_plans telemetry continuity even when no CSS emitted ───
+
+
+def test_helper_event_plans_recorded_even_when_not_triggered(project_tmp, monkeypatch):
+    """Step 17 telemetry must surface every plan_image_fit result via
+    event_plans so Step 18 / Step 19 can read planner-side decisions
+    even when the single-pass did not render a candidate."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL", encoding="utf-8")
+    _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: pytest.fail("not triggered → overflow_check must not run"),
+    )
+
+    events = [
+        _image_event(src="zoneA.png", delta=None),    # not loaded
+        _image_event(src="zoneB.png", delta=0.02),    # under default tol
+    ]
+    res = _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-telemetry", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS, image_events=events, gap_px=14,
+    )
+
+    assert res["triggered"] is False
+    assert res["step"] is None
+    # Every event still surfaces a plan — telemetry continuity invariant.
+    assert len(res["event_plans"]) == 2
+    failure_reasons = [p.get("failure_reason") for p in res["event_plans"]]
+    assert any("not loaded" in (r or "") for r in failure_reasons)
+    assert any("delta_tol" in (r or "") for r in failure_reasons)
+
+
+# ── 12. Emitted CSS is img-scoped (Phase Z spacing guardrail) ────────
+
+
+def test_helper_emits_img_scoped_css_only(project_tmp, monkeypatch):
+    """[[feedback_phase_z_spacing_direction]] — image_fit must NOT shrink
+    common margins / slide-body / zone gap. The emitted CSS overlay must
+    target img selectors only."""
+    out_path = project_tmp / "final.html"
+    out_path.write_text("ORIGINAL", encoding="utf-8")
+    _stub_render_capture(monkeypatch)
+    monkeypatch.setattr(
+        _pz_pipeline, "run_overflow_check",
+        lambda p: {"passed": True, "fail_reasons": []},
+    )
+
+    _attempt_step17_image_fit_single_pass(
+        run_dir=project_tmp, out_path=out_path,
+        slide_title="u7-scope", slide_footer=None,
+        zones_data=_zones(), layout_preset="vertical-2",
+        layout_css=_LAYOUT_CSS_GATE_PASS,
+        image_events=[_image_event(src="zoneA.png", delta=0.20)],
+        gap_px=14,
+    )
+
+    candidate = (project_tmp / "salvage_image_fit_candidate.html").read_text(
+        encoding="utf-8",
+    )
+    style_block_start = candidate.find("<style>")
+    style_block_end = candidate.find("</style>", style_block_start)
+    assert style_block_start >= 0 and style_block_end > style_block_start
+    style_body = candidate[style_block_start + len("<style>"):style_block_end]
+    # img-scoped selector present.
+    assert "img" in style_body
+    # Phase Z spacing guardrail — none of these shared-spacing tokens
+    # may appear in the image_fit overlay.
+    assert ".slide-body" not in style_body
+    assert "slide-base" not in style_body
+    assert "--spacing-page" not in style_body
+    assert "--spacing-block" not in style_body
+    assert "grid-gap" not in style_body
+    assert "padding-page" not in style_body
@@ -0,0 +1,252 @@
+"""IMP-88 u5 — plan_frame_internal_fit_candidate / apply tests (Step 17).
+
+Stage 2 contract (unit u5):
+  - plan_frame_internal_fit_candidate operates ONLY inside the frame
+    contract's declared `internal_envelope` (PHASE-Z-PIPELINE-OVERVIEW.md
+    :333 lock). No internal_envelope → infeasible(envelope_present=False).
+    Envelope present + variant.excess_budget_px >= overflow_zone.excess_y
+    → feasible with selected_variant + frame-scoped css_overrides.
+  - apply_frame_internal_fit_candidate_css(plan) emits a frame-scoped CSS
+    rule (`.zone[data-template-id="<template_id>"]` selector) from the
+    selected variant's css_overrides. None on infeasible.
+  - Honors feedback_phase_z_spacing_direction — frame-scoped only, no
+    common margin / slide-body / zone gap shrink.
+  - Default contract loader (mapper.get_contract) overridable as kwarg so
+    tests stay free of the catalog cache / pipeline import cycle.
+"""
+from __future__ import annotations
+
+from src.phase_z2_retry import (
+    apply_frame_internal_fit_candidate_css,
+    plan_frame_internal_fit_candidate,
+)
+
+
+def _contract(*, variants=None, with_envelope=True) -> dict:
+    """Build a synthetic frame contract for u5 planner tests."""
+    c: dict = {
+        "template_id": "frame_internal_fit_test",
+        "source_shape": "top_bullets",
+        "cardinality": {"strict": 3},
+    }
+    if with_envelope:
+        c["internal_envelope"] = {
+            "variants": list(variants or []),
+        }
+    return c
+
+
+def _variant(*, name: str, budget_px: int, css: dict | None = None) -> dict:
+    return {
+        "name": name,
+        "excess_budget_px": budget_px,
+        "css_overrides": dict(css or {"--frame-density": "compact"}),
+    }
+
+
+# ─── planner: no-envelope infeasible paths ──────────────────────
+
+
+def test_no_contract_infeasible_with_clear_reason():
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="non_existent_frame",
+        frame_contract={},  # caller passed empty dict — explicit no-contract
+    )
+    # Empty dict counts as "contract present but no internal_envelope" → present=False.
+    assert plan["action"] == "frame_internal_fit_candidate"
+    assert plan["feasible"] is False
+    assert plan["envelope_present"] is False
+    assert plan["selected_variant"] is None
+    assert plan["css_overrides"] is None
+    assert "internal_envelope" in plan["failure_reason"]
+
+
+def test_contract_lookup_none_returns_no_contract_failure():
+    # Simulate mapper.get_contract returning None: caller passes None explicitly
+    # via overriding kwarg path — planner falls back to mapper path then returns
+    # the dedicated "no frame contract registered" failure.
+    # We exercise this directly by passing a sentinel template_id that has no
+    # entry; the planner default-loads via mapper.get_contract.
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="__sentinel_unregistered_template__",
+    )
+    assert plan["feasible"] is False
+    assert plan["envelope_present"] is False
+    assert "no frame contract registered" in plan["failure_reason"]
+    assert "__sentinel_unregistered_template__" in plan["failure_reason"]
+
+
+def test_contract_without_internal_envelope_infeasible():
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test",
+        frame_contract=_contract(with_envelope=False),
+    )
+    assert plan["feasible"] is False
+    assert plan["envelope_present"] is False
+    assert "does not declare internal_envelope" in plan["failure_reason"]
+    assert "frame_reselect" in plan["failure_reason"]
+
+
+def test_envelope_present_but_empty_variants_infeasible():
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test",
+        frame_contract=_contract(variants=[]),
+    )
+    assert plan["feasible"] is False
+    assert plan["envelope_present"] is True
+    assert plan["candidates_considered"] == []
+    assert "no variants" in plan["failure_reason"]
+
+
+# ─── planner: feasible paths ────────────────────────────────────
+
+
+def test_single_variant_within_budget_is_selected():
+    contract = _contract(variants=[
+        _variant(name="density_compact", budget_px=40,
+                 css={"--frame-density": "compact", "font-size": "0.95em"}),
+    ])
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test",
+        frame_contract=contract,
+        overflow_zone={"excess_y": 24.0},
+    )
+    assert plan["feasible"] is True
+    assert plan["envelope_present"] is True
+    assert plan["selected_variant"] == "density_compact"
+    assert plan["selected_variant_budget_px"] == 40
+    assert plan["excess_y"] == 24
+    assert plan["css_overrides"]["font-size"] == "0.95em"
+    assert plan["css_overrides"]["--frame-density"] == "compact"
+
+
+def test_greedy_walk_picks_first_variant_that_fits_in_catalog_order():
+    # density_compact only absorbs 10px; line_rhythm 60px; grid_row 200px.
+    # excess_y=45 → density_compact rejected, line_rhythm selected (first fit).
+    contract = _contract(variants=[
+        _variant(name="density_compact", budget_px=10),
+        _variant(name="line_rhythm_tight", budget_px=60),
+        _variant(name="grid_row_collapse", budget_px=200),
+    ])
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test",
+        frame_contract=contract,
+        overflow_zone={"excess_y": 45.0},
+    )
+    assert plan["feasible"] is True
+    assert plan["selected_variant"] == "line_rhythm_tight"
+    assert plan["selected_variant_budget_px"] == 60
+    assert plan["candidates_considered"] == [
+        "density_compact", "line_rhythm_tight", "grid_row_collapse",
+    ]
+
+
+def test_no_overflow_zone_picks_first_variant():
+    # excess_y default = 0 → every variant qualifies; first catalog entry wins.
+    contract = _contract(variants=[
+        _variant(name="first", budget_px=5),
+        _variant(name="second", budget_px=100),
+    ])
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test", frame_contract=contract,
+    )
+    assert plan["feasible"] is True
+    assert plan["selected_variant"] == "first"
+    assert plan["excess_y"] == 0
+
+
+def test_all_variants_below_budget_returns_infeasible_with_excess():
+    contract = _contract(variants=[
+        _variant(name="small", budget_px=10),
+        _variant(name="medium", budget_px=25),
+    ])
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test", frame_contract=contract,
+        overflow_zone={"excess_y": 80.0},
+    )
+    assert plan["feasible"] is False
+    assert plan["envelope_present"] is True
+    assert plan["excess_y"] == 80
+    assert plan["selected_variant"] is None
+    assert "excess_y=80px" in plan["failure_reason"]
+    assert plan["candidates_considered"] == ["small", "medium"]
+
+
+def test_excess_y_is_ceil_rounded():
+    # Sub-pixel overflow rounds up so a budget exactly matching the integer
+    # excess covers the case. 23.4 → 24 → variant(budget=24) is selected.
+    contract = _contract(variants=[
+        _variant(name="exact_fit", budget_px=24),
+    ])
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test", frame_contract=contract,
+        overflow_zone={"excess_y": 23.4},
+    )
+    assert plan["feasible"] is True
+    assert plan["excess_y"] == 24
+    assert plan["selected_variant"] == "exact_fit"
+
+
+def test_envelope_keys_recorded_for_telemetry():
+    contract = _contract(variants=[_variant(name="v1", budget_px=100)])
+    # Inject an extra envelope key to ensure planner surfaces them.
+    contract["internal_envelope"]["envelope_kind"] = "density_grid"
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test", frame_contract=contract,
+    )
+    assert "envelope_kind" in plan["envelope_keys"]
+    assert "variants" in plan["envelope_keys"]
+
+
+# ─── apply: frame-scoped CSS snippet ────────────────────────────
+
+
+def test_apply_emits_frame_template_scoped_selector():
+    contract = _contract(variants=[
+        _variant(name="density_compact", budget_px=100, css={
+            "--frame-density": "compact",
+            "font-size": "0.92em",
+            "line-height": "1.35",
+        }),
+    ])
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="three_parallel_requirements",
+        frame_contract=contract,
+    )
+    css = apply_frame_internal_fit_candidate_css(plan)
+    assert css is not None
+    assert ".zone[data-template-id=\"three_parallel_requirements\"]" in css
+    assert "--frame-density: compact;" in css
+    assert "font-size: 0.92em;" in css
+    assert "line-height: 1.35;" in css
+
+
+def test_apply_infeasible_returns_none():
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test",
+        frame_contract=_contract(with_envelope=False),
+    )
+    assert apply_frame_internal_fit_candidate_css(plan) is None
+
+
+def test_apply_does_not_shrink_shared_spacing():
+    # feedback_phase_z_spacing_direction: emitted CSS must scope to the frame
+    # only and MUST NOT touch slide-body / outer zone / gap / common margin /
+    # padding tokens. The selector is frame-scoped; body comes from author-
+    # declared envelope css_overrides. We sanity-check that nothing in the
+    # apply helper introduces shared-spacing properties of its own.
+    contract = _contract(variants=[
+        _variant(name="density_compact", budget_px=100,
+                 css={"--frame-density": "compact"}),
+    ])
+    plan = plan_frame_internal_fit_candidate(
+        frame_template_id="f_test", frame_contract=contract,
+    )
+    css = apply_frame_internal_fit_candidate_css(plan)
+    assert css is not None
+    for forbidden in (".slide-body", ".zone-container", "grid-gap", "gap:",
+                      "padding:", "margin:"):
+        assert forbidden not in css, (
+            f"frame_internal_fit CSS leaked shared-spacing token "
+            f"'{forbidden}' — see feedback_phase_z_spacing_direction."
+        )
@@ -0,0 +1,198 @@
+"""IMP-88 u4 — plan_image_fit / apply_image_fit_css tests (Step 17 entry).
+
+Stage 2 contract (unit u4):
+  - plan_image_fit consumes a single image_event (overflow_metrics.image_
+    events shape: natural_w/h, rendered_w/h, natural_ratio, rendered_ratio,
+    delta, src, zone_position, zone_template_id) and returns:
+      success  : {feasible=True, css_overrides={object_fit, max_width_px,
+                  max_height_px, width, height}, delta, correction_axis,
+                  natural_*, rendered_*}
+      no-op    : {feasible=False, failure_reason} when |delta| <= tol or
+                 delta is None
+      infeas   : {feasible=False, failure_reason} when rendered_w/h missing
+                 or non-positive
+  - apply_image_fit_css(plan) returns a frame-scoped CSS rule string for
+    feasible plans (object-fit + max-w/h constraints scoped to the zone +
+    src image), None for infeasible plans.
+  - Honors feedback_phase_z_spacing_direction — image-scoped CSS only, no
+    common margin / frame envelope shrink.
+"""
+from __future__ import annotations
+
+from src.phase_z2_retry import apply_image_fit_css, plan_image_fit
+
+
+def _image_event(
+    *, delta: float | None = 0.20, src: str = "/images/diagram.png",
+    zone_position: str = "top", zone_template_id: str = "frame_07",
+    natural_w: int = 1200, natural_h: int = 800,
+    rendered_w: int = 600, rendered_h: int = 300,
+) -> dict:
+    """image_event shape mirroring runtime overflow_metrics.image_events[i]."""
+    natural_ratio = natural_w / natural_h if natural_h else None
+    rendered_ratio = rendered_w / rendered_h if rendered_h else None
+    return {
+        "src": src,
+        "zone_position": zone_position,
+        "zone_template_id": zone_template_id,
+        "natural_w": natural_w,
+        "natural_h": natural_h,
+        "rendered_w": rendered_w,
+        "rendered_h": rendered_h,
+        "natural_ratio": natural_ratio,
+        "rendered_ratio": rendered_ratio,
+        "delta": delta,
+        "bbox": {"x": 0, "y": 0, "w": rendered_w, "h": rendered_h},
+    }
+
+
+# ─── planner: success paths ─────────────────────────────────────
+
+
+def test_positive_delta_emits_width_correction_axis():
+    # natural 1200x800 (1.5), rendered 600x300 (2.0) → delta = +0.5
+    ev = _image_event(
+        delta=0.5,
+        natural_w=1200, natural_h=800,
+        rendered_w=600, rendered_h=300,
+    )
+    plan = plan_image_fit(image_event=ev)
+    assert plan["action"] == "image_fit"
+    assert plan["feasible"] is True
+    assert plan["correction_axis"] == "width"
+    assert plan["delta"] == 0.5
+    assert plan["natural_w"] == 1200
+    assert plan["rendered_w"] == 600
+    overrides = plan["css_overrides"]
+    assert overrides["object_fit"] == "contain"
+    assert overrides["max_width_px"] == 600
+    assert overrides["max_height_px"] == 300
+    assert overrides["width"] == "auto"
+    assert overrides["height"] == "auto"
+
+
+def test_negative_delta_emits_height_correction_axis():
+    # natural 800x1200 (~0.667), rendered 600x600 (1.0) → delta = +0.333 not -;
+    # use rendered taller than natural for negative delta.
+    ev = _image_event(
+        delta=-0.40,
+        natural_w=1600, natural_h=800,
+        rendered_w=400, rendered_h=400,
+    )
+    plan = plan_image_fit(image_event=ev)
+    assert plan["feasible"] is True
+    assert plan["correction_axis"] == "height"
+    assert plan["css_overrides"]["max_width_px"] == 400
+    assert plan["css_overrides"]["max_height_px"] == 400
+
+
+def test_planner_passes_through_zone_and_template_metadata():
+    ev = _image_event(
+        delta=0.20,
+        src="/img/policy.png",
+        zone_position="bottom-right",
+        zone_template_id="f23",
+    )
+    plan = plan_image_fit(image_event=ev)
+    assert plan["feasible"] is True
+    assert plan["src"] == "/img/policy.png"
+    assert plan["zone_position"] == "bottom-right"
+    assert plan["zone_template_id"] == "f23"
+
+
+# ─── planner: infeasible / no-op paths ──────────────────────────
+
+
+def test_delta_none_infeasible_with_clear_reason():
+    ev = _image_event(delta=None)
+    plan = plan_image_fit(image_event=ev)
+    assert plan["feasible"] is False
+    assert plan["css_overrides"] is None
+    assert "delta is None" in plan["failure_reason"]
+
+
+def test_delta_within_tolerance_returns_planner_noop():
+    ev = _image_event(delta=0.02)
+    plan = plan_image_fit(image_event=ev)
+    assert plan["feasible"] is False
+    assert "no image_aspect_mismatch to correct" in plan["failure_reason"]
+    # No-op path still records delta + action for telemetry continuity.
+    assert plan["delta"] == 0.02
+    assert plan["action"] == "image_fit"
+
+
+def test_delta_at_boundary_is_planner_noop():
+    # |delta| == delta_tol is treated as no-op (strict greater-than is the
+    # emission threshold in the classifier).
+    ev = _image_event(delta=0.05)
+    plan = plan_image_fit(image_event=ev, delta_tol=0.05)
+    assert plan["feasible"] is False
+
+
+def test_rendered_w_zero_infeasible():
+    ev = _image_event(rendered_w=0)
+    plan = plan_image_fit(image_event=ev)
+    assert plan["feasible"] is False
+    assert "rendered_w / rendered_h" in plan["failure_reason"]
+
+
+def test_rendered_h_missing_infeasible():
+    ev = _image_event()
+    ev.pop("rendered_h", None)
+    plan = plan_image_fit(image_event=ev)
+    assert plan["feasible"] is False
+    assert plan["css_overrides"] is None
+
+
+def test_custom_delta_tol_widens_noop_band():
+    ev = _image_event(delta=0.10)
+    # default tol=0.05 → feasible, but caller-supplied tol=0.20 → no-op.
+    assert plan_image_fit(image_event=ev)["feasible"] is True
+    assert plan_image_fit(image_event=ev, delta_tol=0.20)["feasible"] is False
+
+
+# ─── apply: frame-scoped CSS snippet ────────────────────────────
+
+
+def test_apply_image_fit_css_emits_zone_and_src_scoped_selector():
+    plan = plan_image_fit(image_event=_image_event(
+        delta=0.30,
+        src="/images/process.png",
+        zone_position="top",
+        rendered_w=520, rendered_h=240,
+    ))
+    css = apply_image_fit_css(plan)
+    assert css is not None
+    assert ".zone[data-zone-position=\"top\"]" in css
+    assert "img[src=\"/images/process.png\"]" in css
+    assert "object-fit: contain;" in css
+    assert "max-width: 520px;" in css
+    assert "max-height: 240px;" in css
+    assert "width: auto;" in css
+    assert "height: auto;" in css
+
+
+def test_apply_image_fit_css_without_src_falls_back_to_zone_only_selector():
+    ev = _image_event(delta=0.30, src="")
+    css = apply_image_fit_css(plan_image_fit(image_event=ev))
+    assert css is not None
+    assert ".zone[data-zone-position=\"top\"] img {" in css
+    assert "img[src=" not in css
+
+
+def test_apply_image_fit_css_infeasible_returns_none():
+    plan = plan_image_fit(image_event=_image_event(delta=None))
+    assert apply_image_fit_css(plan) is None
+
+
+def test_apply_image_fit_css_does_not_shrink_shared_spacing():
+    # feedback_phase_z_spacing_direction: CSS must scope to image only and
+    # MUST NOT touch slide-body / zone / frame / gap / margin / padding.
+    plan = plan_image_fit(image_event=_image_event(delta=0.30))
+    css = apply_image_fit_css(plan)
+    assert css is not None
+    for forbidden in (".slide-body", ".zone-container", "padding:", "margin:",
+                      "gap:", "grid-gap"):
+        assert forbidden not in css, (
+            f"image_fit CSS leaked shared-spacing token '{forbidden}'"
+        )
@@ -0,0 +1,168 @@
+"""IMP-88 u3 — plan_layout_adjust tests (Step 17 retry chain).
+
+Stage 2 contract (unit u3):
+  - planner returns {feasible, new_layout_preset, new_zones_data,
+    position_remap, candidates_considered, swap_topology_from/to} on success;
+    {feasible=False, failure_reason} on infeasible (no sibling, unknown
+    preset, zone-count mismatch).
+  - apply_layout_adjust_layout_css(plan, gap_px) builds a fresh layout_css
+    via build_layout_css with the swapped preset + remapped zones_data; raw_
+    zone_layout records layout_adjust_applied/from/to provenance. Infeasible
+    plan -> None (dispatcher u6 skips re-render).
+  - Honors feedback_phase_z_spacing_direction — preset swap only, no shared
+    spacing shrink claim.
+"""
+from __future__ import annotations
+
+from src.phase_z2_composition import LAYOUT_PRESETS
+from src.phase_z2_retry import (
+    apply_layout_adjust_layout_css,
+    plan_layout_adjust,
+)
+
+
+def _zones(positions: list[str]) -> list[dict]:
+    """Minimal zones_data shape for planner consumption."""
+    return [
+        {
+            "position": pos,
+            "template_id": f"frame_{i}",
+            "min_height_px": 120,
+            "content_weight": {"score": 1.0},
+            "slot_payload": {"title": f"zone_{i}"},
+        }
+        for i, pos in enumerate(positions)
+    ]
+
+
+# ─── planner: success paths ─────────────────────────────────────
+
+
+def test_horizontal_2_swaps_to_vertical_2_orientation_axis():
+    plan = plan_layout_adjust(
+        current_layout_preset="horizontal-2",
+        zones_data=_zones(["top", "bottom"]),
+    )
+    assert plan["action"] == "layout_adjust"
+    assert plan["feasible"] is True
+    assert plan["new_layout_preset"] == "vertical-2"
+    assert plan["unit_count"] == 2
+    assert plan["swap_topology_from"] == "rows"
+    assert plan["swap_topology_to"] == "cols"
+    assert plan["position_remap"] == {"top": "left", "bottom": "right"}
+    new_zd = plan["new_zones_data"]
+    assert [z["position"] for z in new_zd] == ["left", "right"]
+    # Non-position payload preserved through remap.
+    assert new_zd[0]["template_id"] == "frame_0"
+    assert new_zd[1]["slot_payload"] == {"title": "zone_1"}
+
+
+def test_vertical_2_swaps_back_to_horizontal_2():
+    plan = plan_layout_adjust(
+        current_layout_preset="vertical-2",
+        zones_data=_zones(["left", "right"]),
+    )
+    assert plan["feasible"] is True
+    assert plan["new_layout_preset"] == "horizontal-2"
+    assert plan["position_remap"] == {"left": "top", "right": "bottom"}
+
+
+def test_T_swaps_to_inverted_T_first_by_topology_priority():
+    plan = plan_layout_adjust(
+        current_layout_preset="top-1-bottom-2",
+        zones_data=_zones(["top", "bottom-left", "bottom-right"]),
+    )
+    assert plan["feasible"] is True
+    # 3-unit siblings: top-2-bottom-1, left-1-right-2, left-2-right-1.
+    # _layout_swap_priority puts T<->inverted-T at priority 1 (before side-T).
+    assert plan["new_layout_preset"] == "top-2-bottom-1"
+    assert plan["candidates_considered"] == [
+        "top-2-bottom-1", "left-1-right-2", "left-2-right-1",
+    ]
+
+
+# ─── planner: infeasible paths ──────────────────────────────────
+
+
+def test_single_preset_infeasible_no_sibling():
+    plan = plan_layout_adjust(
+        current_layout_preset="single",
+        zones_data=_zones(["primary"]),
+    )
+    assert plan["feasible"] is False
+    assert plan["new_layout_preset"] is None
+    assert plan["unit_count"] == 1
+    assert plan["candidates_considered"] == []
+    assert "no render-ready 8-preset sibling" in plan["failure_reason"]
+    assert "single (1)" in plan["failure_reason"]
+
+
+def test_grid_2x2_preset_infeasible_no_sibling():
+    plan = plan_layout_adjust(
+        current_layout_preset="grid-2x2",
+        zones_data=_zones(["top-left", "top-right", "bottom-left", "bottom-right"]),
+    )
+    assert plan["feasible"] is False
+    assert plan["candidates_considered"] == []
+    assert "grid-2x2 (4)" in plan["failure_reason"]
+
+
+def test_unknown_preset_infeasible_with_clear_reason():
+    plan = plan_layout_adjust(
+        current_layout_preset="not-a-real-preset",
+        zones_data=_zones(["top", "bottom"]),
+    )
+    assert plan["feasible"] is False
+    assert plan["new_layout_preset"] is None
+    assert "not in LAYOUT_PRESETS catalog" in plan["failure_reason"]
+
+
+def test_zone_count_mismatch_infeasible():
+    plan = plan_layout_adjust(
+        current_layout_preset="horizontal-2",
+        zones_data=_zones(["top", "bottom", "extra"]),
+    )
+    assert plan["feasible"] is False
+    assert "length 3" in plan["failure_reason"]
+    assert "horizontal-2" in plan["failure_reason"]
+
+
+# ─── apply: layout_css construction + provenance ─────────────────
+
+
+def test_apply_layout_adjust_builds_new_layout_css_with_provenance():
+    plan = plan_layout_adjust(
+        current_layout_preset="horizontal-2",
+        zones_data=_zones(["top", "bottom"]),
+    )
+    layout_css = apply_layout_adjust_layout_css(plan, gap_px=20)
+    assert layout_css is not None
+    # Mirrors build_layout_css(vertical-2, ...) output shape.
+    assert layout_css["areas"] == LAYOUT_PRESETS["vertical-2"]["css_areas"]
+    assert "heights_px" in layout_css and "widths_px" in layout_css
+    raw = layout_css["raw_zone_layout"]
+    assert raw["layout_adjust_applied"] is True
+    assert raw["layout_adjust_from"] == "horizontal-2"
+    assert raw["layout_adjust_to"] == "vertical-2"
+
+
+def test_apply_layout_adjust_infeasible_returns_none():
+    plan = plan_layout_adjust(
+        current_layout_preset="single",
+        zones_data=_zones(["primary"]),
+    )
+    assert apply_layout_adjust_layout_css(plan, gap_px=20) is None
+
+
+def test_apply_layout_adjust_T_swap_produces_2d_dynamic_css():
+    plan = plan_layout_adjust(
+        current_layout_preset="top-1-bottom-2",
+        zones_data=_zones(["top", "bottom-left", "bottom-right"]),
+    )
+    layout_css = apply_layout_adjust_layout_css(plan, gap_px=20)
+    assert layout_css is not None
+    # top-2-bottom-1 is a 2-D dynamic preset.
+    assert layout_css["dynamic_rows"] is True
+    assert layout_css["dynamic_cols"] is True
+    assert layout_css["areas"] == LAYOUT_PRESETS["top-2-bottom-1"]["css_areas"]
+    assert layout_css["raw_zone_layout"]["layout_adjust_to"] == "top-2-bottom-1"
@@ -198,10 +198,19 @@ def test_case_b_cross_zone_fails_glue_passes_second_promoted(project_tmp, monkey


 def test_case_c_all_three_fail_revert_preserved(project_tmp, monkeypatch):
-    """(c) All three cascade actions are infeasible (no CSS emitted by any
-    planner) → run_overflow_check is never invoked, salvage_passed=False,
-    salvage_steps has three failed entries, and out_path is unchanged
-    (original final.html intact — (b)-revert preserved)."""
+    """(c) All cascade actions are infeasible (no CSS / no candidate emitted
+    by any planner) → run_overflow_check is never invoked, salvage_passed=
+    False, out_path is unchanged (original final.html intact — (b)-revert
+    preserved).
+
+    IMP-88 u6 extends the cascade depth from 3 to 5 stages (layout_adjust +
+    frame_internal_fit_candidate added). When all stages are infeasible the
+    cascade now runs through all five — the empty zones_data carried by
+    _kwargs() makes plan_layout_adjust infeasible (length mismatch) and the
+    empty resulting template_id makes plan_frame_internal_fit_candidate
+    infeasible (no contract). The (b)-revert contract this test locks
+    (out_path untouched + salvage_passed=False) is unchanged.
+    """
    out_path = project_tmp / "final.html"
    out_path.write_text("ORIGINAL_BEFORE_SALVAGE", encoding="utf-8")

@@ -231,18 +240,24 @@ def test_case_c_all_three_fail_revert_preserved(project_tmp, monkeypatch):

    assert trace["salvage_attempted"] is True
    assert trace["salvage_passed"] is False
-    assert len(trace["salvage_steps"]) == 3
+    # IMP-88 u6 — cascade depth extended from 3 to 5; see _SALVAGE_FAIL_BY_ACTION.
+    assert len(trace["salvage_steps"]) == 5
    actions = [s["action"] for s in trace["salvage_steps"]]
    assert actions == [
        "cross_zone_redistribute",
        "glue_compression",
        "font_step_compression",
+        "layout_adjust",
+        "frame_internal_fit_candidate",
    ]
    for step in trace["salvage_steps"]:
        assert step["passed"] is False
-        assert step["css_override"] is None
+        # layout_adjust uses a distinct render path → its step dict has no
+        # css_override key (new_layout_preset is the observability field
+        # instead). All other branches use the shared CSS-overlay path.
+        assert step.get("css_override") is None
        assert step["failure_reason"]
-    # No CSS emitted anywhere → no render_slide calls either.
+    # No CSS / candidate emitted anywhere → no render_slide calls either.
    assert render_counter["n"] == 0
    # (b) revert: out_path is untouched.
    assert out_path.read_text(encoding="utf-8") == "ORIGINAL_BEFORE_SALVAGE"
@@ -0,0 +1,223 @@
+"""IMP-88 (#88) u1 — Step 17 retry chain router rows + status surface.
+
+Stage 2 binding contract (unit u1, data-surface only):
+  - NEW row `image_aspect_mismatch → image_fit` in ACTION_BY_CATEGORY.
+    Closes the unmapped classifier emission gap at
+    src/phase_z2_classifier.py:434-447 where image_aspect_mismatch was
+    emitted with proposed_action=None (verified Stage 1).
+  - REMAP `frame_capacity_mismatch → frame_internal_fit_candidate`
+    (previously frame_reselect) per PHASE-Z-PIPELINE-OVERVIEW.md:321.
+    frame_reselect remains a valid downstream action via the
+    failure_router cascade (rerender_still_fails → frame_reselect).
+  - NEW ACTION_RATIONALE rows for image_aspect_mismatch +
+    frame_internal_fit_candidate (rationale text for trace surface).
+  - NEW ACTION_IMPLEMENTATION_STATUS rows for image_fit +
+    frame_internal_fit_candidate. layout_adjust is also registered.
+    u1 initial state was MISSING for all three. u7 completion flips the
+    rows to IMPLEMENTED once the end-to-end path (u3/u4/u5 planners +
+    u6 dispatcher + u7 Step 17 entry) is wired (same convention as
+    IMP-12 u7 cascade rows + IMP-35 u3 details_popup_escalation flip).
+
+Out of scope for u1 (locked in Stage 2 exit report):
+  - failure_router cascade rows for the three actions → u2.
+  - planner stubs (plan_layout_adjust / plan_image_fit /
+    plan_frame_internal_fit_candidate) → u3 / u4 / u5.
+  - salvage dispatcher branches + Step 17 entry triggers → u6 / u7.
+
+Post u7 completion (2026-05-24): status assertions in this file reflect
+the IMPLEMENTED end-state. Test names that previously referenced "_missing"
+are renamed to "_implemented_after_u7" so the surface contract is honest
+about the post-u7 state.
+"""
+from __future__ import annotations
+
+from src.phase_z2_router import (
+    ACTION_BY_CATEGORY,
+    ACTION_IMPLEMENTATION_STATUS,
+    ACTION_RATIONALE,
+    route_action,
+    route_fit_classification,
+)
+
+
+# ─── ACTION_BY_CATEGORY rows ──────────────────────────────────────
+
+
+def test_image_aspect_mismatch_maps_to_image_fit():
+    """u1 — NEW row closes the classifier→router gap.
+
+    Stage 1 verified that route_action('image_aspect_mismatch') returned
+    proposed_action=None with implementation_status='unknown'. u1 must
+    register the row so the classifier emission is routable.
+    """
+    assert ACTION_BY_CATEGORY["image_aspect_mismatch"] == "image_fit"
+
+
+def test_frame_capacity_mismatch_remaps_to_frame_internal_fit_candidate():
+    """u1 — REMAP per PHASE-Z-PIPELINE-OVERVIEW.md:321.
+
+    Spec lock: frame_internal_fit_candidate is the per-zone first-pass
+    salvage inside the declared frame envelope. frame_reselect (V4 top-k
+    alternate frame swap) remains downstream via the failure_router
+    cascade (rerender_still_fails → frame_reselect).
+    """
+    assert ACTION_BY_CATEGORY["frame_capacity_mismatch"] == "frame_internal_fit_candidate"
+
+
+def test_existing_action_by_category_rows_unchanged():
+    """u1 — non-IMP-88 rows must NOT be touched (regression guard).
+
+    Only two edits are allowed in u1: NEW image_aspect_mismatch row and
+    REMAP frame_capacity_mismatch row. Everything else is locked.
+    """
+    assert ACTION_BY_CATEGORY["minor_overflow"] == "zone_ratio_retry"
+    assert ACTION_BY_CATEGORY["moderate_overflow"] == "layout_adjust"
+    assert ACTION_BY_CATEGORY["structural_minor_overflow"] == "zone_ratio_retry"
+    assert ACTION_BY_CATEGORY["structural_major_overflow"] == "details_popup_escalation"
+    assert ACTION_BY_CATEGORY["tabular_overflow"] == "details_popup_escalation"
+    assert ACTION_BY_CATEGORY["layout_zone_mismatch"] == "layout_adjust"
+    assert ACTION_BY_CATEGORY["hard_visual_fail"] == "abort"
+
+
+# ─── ACTION_RATIONALE rows ────────────────────────────────────────
+
+
+def test_image_aspect_mismatch_rationale_present():
+    """u1 — trace surface must explain *why* image_aspect_mismatch routes
+    onto image_fit (frame-scoped, no global image CSS shrink — honors
+    feedback_phase_z_spacing_direction)."""
+    rationale = ACTION_RATIONALE.get("image_aspect_mismatch", "")
+    assert rationale.strip(), "image_aspect_mismatch rationale must be non-empty"
+    assert "image" in rationale.lower()
+
+
+def test_frame_capacity_mismatch_rationale_updated_for_internal_fit():
+    """u1 — rationale text must reflect the new internal-fit-first
+    routing. The text must no longer claim frame_reselect as the primary
+    action for this category (it's now the downstream cascade step)."""
+    rationale = ACTION_RATIONALE.get("frame_capacity_mismatch", "")
+    assert rationale.strip(), "frame_capacity_mismatch rationale must be non-empty"
+    # Mentions the new internal-fit direction.
+    assert "internal" in rationale.lower() or "envelope" in rationale.lower()
+
+
+# ─── ACTION_IMPLEMENTATION_STATUS rows ────────────────────────────
+
+
+def test_layout_adjust_status_implemented_after_u7():
+    """u1 registered layout_adjust row (initial MISSING). After u3
+    (plan_layout_adjust + apply_layout_adjust_layout_css) + u6 (salvage
+    dispatcher branch) + u7 (cascade entry trigger) land the end-to-end
+    deterministic path, the status flips to IMPLEMENTED."""
+    assert ACTION_IMPLEMENTATION_STATUS["layout_adjust"] == "IMPLEMENTED"
+
+
+def test_image_fit_status_implemented_after_u7():
+    """u1 registered image_fit row (initial MISSING). After u4 (plan_image_fit
+    + apply_image_fit_css) + u7 (_attempt_step17_image_fit_single_pass entry)
+    land the end-to-end deterministic path, the status flips to IMPLEMENTED."""
+    assert "image_fit" in ACTION_IMPLEMENTATION_STATUS
+    assert ACTION_IMPLEMENTATION_STATUS["image_fit"] == "IMPLEMENTED"
+
+
+def test_frame_internal_fit_candidate_status_implemented_after_u7():
+    """u1 registered frame_internal_fit_candidate row (initial MISSING). After
+    u5 (plan_frame_internal_fit_candidate + apply) + u6 (salvage dispatcher
+    branch) + u7 (cascade entry trigger) land the end-to-end deterministic
+    path, the status flips to IMPLEMENTED."""
+    assert "frame_internal_fit_candidate" in ACTION_IMPLEMENTATION_STATUS
+    assert ACTION_IMPLEMENTATION_STATUS["frame_internal_fit_candidate"] == "IMPLEMENTED"
+
+
+def test_existing_action_implementation_status_rows_unchanged():
+    """u1 — non-IMP-88 status rows must NOT regress. zone_ratio_retry,
+    cascade-only salvage actions, details_popup_escalation (IMP-35 u3),
+    and frame_reselect must keep their current statuses."""
+    assert ACTION_IMPLEMENTATION_STATUS["zone_ratio_retry"] == "IMPLEMENTED"
+    assert ACTION_IMPLEMENTATION_STATUS["details_popup_escalation"] == "IMPLEMENTED"
+    assert ACTION_IMPLEMENTATION_STATUS["frame_reselect"] == "PARTIAL"
+    assert ACTION_IMPLEMENTATION_STATUS["adapter_needed"] == "PARTIAL"
+    assert ACTION_IMPLEMENTATION_STATUS["abort"] == "IMPLEMENTED"
+    assert ACTION_IMPLEMENTATION_STATUS["cross_zone_redistribute"] == "IMPLEMENTED"
+    assert ACTION_IMPLEMENTATION_STATUS["glue_compression"] == "IMPLEMENTED"
+    assert ACTION_IMPLEMENTATION_STATUS["font_step_compression"] == "IMPLEMENTED"
+
+
+# ─── route_action + route_fit_classification integration ──────────
+
+
+def test_route_action_image_aspect_mismatch_returns_image_fit_implemented():
+    """u1 — route_action surface composes the new mapping correctly.
+
+    Stage 1 evidence: previously this call returned proposed_action=None
+    and implementation_status='unknown'. After u1 + u4 + u7, the call must
+    return image_fit with status IMPLEMENTED (end-to-end deterministic path
+    via plan_image_fit + apply_image_fit_css + Step 17 single-pass entry)."""
+    routing = route_action("image_aspect_mismatch")
+    assert routing["proposed_action"] == "image_fit"
+    assert routing["implementation_status"] == "IMPLEMENTED"
+    assert routing["mapping_source"] == "spec §4 ACTION_BY_CATEGORY"
+    assert routing["rationale"], "rationale must be carried through route_action"
+
+
+def test_route_action_frame_capacity_mismatch_returns_frame_internal_fit_candidate_implemented():
+    """u1 — route_action surface reflects the REMAP. After u1 + u5 + u6 + u7
+    the status is IMPLEMENTED (end-to-end deterministic path via
+    plan_frame_internal_fit_candidate + apply + salvage dispatcher branch +
+    cascade entry trigger)."""
+    routing = route_action("frame_capacity_mismatch")
+    assert routing["proposed_action"] == "frame_internal_fit_candidate"
+    assert routing["implementation_status"] == "IMPLEMENTED"
+    assert routing["mapping_source"] == "spec §4 ACTION_BY_CATEGORY"
+
+
+def test_route_fit_classification_surfaces_imp88_actions_as_implemented():
+    """End-to-end: when classifier emits the two IMP-88 categories alongside
+    an already-implemented one, route_fit_classification:
+      - attaches proposed_action onto each row
+      - lists all three actions in proposed_actions_summary
+      - reports an empty missing_actions_pending_impl for the IMP-88 actions
+        (u7 completion flipped image_fit + frame_internal_fit_candidate to
+        IMPLEMENTED alongside layout_adjust)
+      - all three rows count as IMPLEMENTED in the status summary."""
+    fit_classification = {
+        "visual_check_passed": False,
+        "classifications": [
+            {
+                "source": "image_event",
+                "zone_position": "bottom",
+                "category": "image_aspect_mismatch",
+            },
+            {
+                "source": "composition",
+                "zone_position": "top",
+                "category": "frame_capacity_mismatch",
+            },
+            {
+                "source": "clipped_inner",
+                "zone_position": "bottom",
+                "category": "minor_overflow",
+            },
+        ],
+    }
+    summary = route_fit_classification(fit_classification)
+    assert summary["router_active"] is True
+    assert summary["routed_count"] == 3
+    assert "image_fit" in summary["proposed_actions_summary"]
+    assert "frame_internal_fit_candidate" in summary["proposed_actions_summary"]
+    assert "zone_ratio_retry" in summary["proposed_actions_summary"]
+    # After u7 completion, both new IMP-88 actions are IMPLEMENTED on the
+    # router-surface — they no longer surface as missing pending impl.
+    assert "image_fit" not in summary["missing_actions_pending_impl"]
+    assert "frame_internal_fit_candidate" not in summary["missing_actions_pending_impl"]
+    # All three (zone_ratio_retry IMPLEMENTED + 2 IMP-88 IMPLEMENTED) count
+    # together. zone_ratio_retry was IMPLEMENTED since A3 cascade.
+    assert summary["implementation_status_summary"].get("IMPLEMENTED", 0) == 3
+    assert summary["implementation_status_summary"].get("MISSING", 0) == 0
+    # Per-row enrichment carries the new proposed actions onto entries.
+    cats = {c["category"]: c for c in fit_classification["classifications"]}
+    assert cats["image_aspect_mismatch"]["proposed_action"] == "image_fit"
+    assert (
+        cats["frame_capacity_mismatch"]["proposed_action"]
+        == "frame_internal_fit_candidate"
+    )
@@ -0,0 +1,151 @@
+"""IMP-90 (#90) u17 — slide_base.html print-mode contract tests.
+
+Stage 2 plan contract (unit u17):
+  Step 22 user-edit + Export track. The Phase Z2 print path MUST
+  auto-expand <details> popups so the FULL raw_content (MDX 원문 무손실
+  보존) is included when the user prints / exports from the browser.
+
+  u17 introduces two coordinated surfaces in
+  ``templates/phase_z2/slide_base.html``:
+
+    1. ``@media print`` CSS block — neutralizes the on-screen-only body
+       centering / box-shadow / 280px popup card clipping so the slide
+       prints at 1280×720 with the expanded popup body in static flow.
+
+    2. ``beforeprint`` / ``afterprint`` JavaScript hook at body level —
+       toggles ``details.open`` to ``true`` before the print snapshot
+       and restores the user's prior open/closed state afterwards. Body
+       level (outside any ``<details>...</details>`` block) preserves
+       the IMP-35 u8 popup-render JS-free invariant
+       (tests/phase_z2/test_slide_base_popup_render.py
+       ``test_popup_emits_no_javascript_on_render_path``).
+
+Invariants locked here:
+  P-1: ``@media print`` block is emitted exactly once in the render.
+  P-2: ``@page`` size matches the 1280×720 slide canvas.
+  P-3: ``.slide`` box-shadow + body padding/min-height neutralized at
+       print time.
+  P-4: ``.zone__popup-summary`` hidden, popup body switches from
+       absolute to static flow with unconstrained height — the popup
+       card chrome (border / shadow / 280px max-height) is unset.
+  P-5: ``beforeprint`` + ``afterprint`` listeners are wired at body
+       level (NOT inside the per-zone details block) so the popup
+       render path stays JS-free.
+  P-6: Restore semantics — the script preserves the user's prior
+       open/closed state via a single ``dataset.imp90PrintRestore`` key
+       (no global state, no event-bus mutation).
+"""
+from __future__ import annotations
+
+import re
+
+from src.phase_z2_pipeline import render_slide
+
+
+def _layout_css() -> dict:
+    return {"areas": '"primary"', "cols": "1fr", "rows": "1fr"}
+
+
+def _zone(**overrides) -> dict:
+    base = {
+        "position": "primary",
+        "template_id": "__empty__",
+        "slot_payload": {},
+    }
+    base.update(overrides)
+    return base
+
+
+def _render() -> str:
+    return render_slide(
+        slide_title="t",
+        slide_footer=None,
+        zones_data=[_zone()],
+        layout_preset="single",
+        layout_css=_layout_css(),
+        gap_px=14,
+    )
+
+
+# ─── P-1 ─ media print block presence ───────────────────────────────
+
+
+def test_media_print_block_emitted_once():
+    html = _render()
+    matches = re.findall(r"@media\s+print\s*\{", html)
+    assert len(matches) == 1
+
+
+# ─── P-2 ─ @page size matches slide canvas ──────────────────────────
+
+
+def test_page_size_matches_slide_canvas():
+    html = _render()
+    flat = re.sub(r"\s+", " ", html)
+    assert "@page { size: 1280px 720px; margin: 0; }" in flat
+
+
+# ─── P-3 ─ standalone chrome neutralized at print ───────────────────
+
+
+def test_slide_box_shadow_neutralized_at_print():
+    html = _render()
+    flat = re.sub(r"\s+", " ", html)
+    print_block = re.search(r"@media\s+print\s*\{(.*?)\}\s*</style>", flat)
+    assert print_block is not None
+    body = print_block.group(1)
+    assert "box-shadow: none !important" in body
+    assert "padding: 0 !important" in body
+    assert "min-height: 0 !important" in body
+
+
+# ─── P-4 ─ popup body switches to static flow, summary hidden ───────
+
+
+def test_popup_card_chrome_unset_at_print():
+    html = _render()
+    flat = re.sub(r"\s+", " ", html)
+    print_block = re.search(r"@media\s+print\s*\{(.*?)\}\s*</style>", flat)
+    assert print_block is not None
+    body = print_block.group(1)
+    assert ".zone__popup-summary { display: none !important; }" in body
+    assert "position: static !important" in body
+    assert "max-height: none !important" in body
+    assert "overflow: visible !important" in body
+
+
+# ─── P-5 ─ beforeprint hook is body-level (NOT inside <details>) ────
+
+
+def test_beforeprint_and_afterprint_listeners_present():
+    html = _render()
+    assert "addEventListener('beforeprint'" in html
+    assert "addEventListener('afterprint'" in html
+
+
+def test_print_script_is_outside_any_details_block():
+    """The IMP-35 u8 popup render path is JS-free. Our print script
+    sits at body level after the slide div, so no <script> appears
+    inside a <details>...</details> popup block."""
+    html = _render(
+    )
+    # No <details> in the no-popup baseline — but the assertion still
+    # holds defensively: locate every <details>...</details> block (if
+    # any) and confirm no <script> tag appears inside.
+    for block in re.findall(r"<details[\s>].*?</details>", html, re.DOTALL):
+        assert "<script" not in block
+        assert "addEventListener" not in block
+
+
+# ─── P-6 ─ restore semantics ────────────────────────────────────────
+
+
+def test_restore_uses_single_dataset_key():
+    """Restore strategy uses one dataset key
+    (``dataset.imp90PrintRestore``) — no global Set/Map, no mutation
+    of any other DOM attribute. Locks the minimal-surface contract."""
+    html = _render()
+    assert "imp90PrintRestore" in html
+    # Restore branch only sets open=false when the prior state was '0'.
+    assert "imp90PrintRestore === '0'" in html
+    assert "d.open = true" in html
@@ -40,8 +40,8 @@
    "04.mdx": {
      "mdx_file": "04.mdx",
      "run_id": "89a_baseline_04",
-      "final_html_size_bytes": 27707,
-      "sha256": "2bce45041cdcca6518cd92586c1be9e051a5c98f5a0ad61fdde02604618a1d80",
+      "final_html_size_bytes": 28042,
+      "sha256": "ddb6bf2f8d76ca1f56588a50dd4af5aeb5f45e0a83d5241b83b5932d0c66d41c",
      "pipeline_exit_code": null
    },
    "05.mdx": {
@@ -0,0 +1,62 @@
+"""IMP-#91 u14 — unit tests for the status-board marker updater.
+
+Exercises ``parse_outcomes`` (nodeid → axis/mdx outcome mapping) and
+``update_board_text`` (idempotent marker rewrite). u15 will wire the CLI
+into the GitHub Actions workflow; these tests guard the contract.
+"""
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+import update_status_board as usb  # noqa: E402
+
+
+SAMPLE_REPORT = {
+    "tests": [
+        {
+            "nodeid": "tests/integration/test_multi_mdx_regression.py::test_normalize_snapshot_matches[01]",
+            "outcome": "passed",
+        },
+        {
+            "nodeid": "tests/integration/test_multi_mdx_regression.py::test_v4_ranking_snapshot_matches[02]",
+            "outcome": "passed",
+        },
+        {
+            "nodeid": "tests/integration/test_multi_mdx_regression.py::test_layout_snapshot_matches[03]",
+            "outcome": "failed",
+        },
+        {
+            "nodeid": "tests/integration/test_multi_mdx_regression.py::test_pipeline_run_produces_step20_status[02]",
+            "outcome": "passed",
+        },
+    ]
+}
+
+
+def test_parse_outcomes_maps_known_axes_only() -> None:
+    outcomes = usb.parse_outcomes(SAMPLE_REPORT)
+    assert outcomes == {
+        ("F0", "01"): "PASS",
+        ("F1", "02"): "PASS",
+        ("F4", "03"): "FAIL",
+    }
+
+
+def test_update_board_text_rewrites_markers() -> None:
+    board = "F0/01: <!-- IMP-91:F0:01 -->?<!-- /IMP-91 --> F1/02: <!-- IMP-91:F1:02 -->old<!-- /IMP-91 -->"
+    outcomes = {("F0", "01"): "PASS"}
+    result = usb.update_board_text(board, outcomes)
+    assert "<!-- IMP-91:F0:01 -->PASS<!-- /IMP-91 -->" in result
+    assert "<!-- IMP-91:F1:02 -->?<!-- /IMP-91 -->" in result
+
+
+def test_update_board_text_is_idempotent() -> None:
+    board = "<!-- IMP-91:F2:05 -->old<!-- /IMP-91 -->"
+    outcomes = {("F2", "05"): "PASS"}
+    once = usb.update_board_text(board, outcomes)
+    twice = usb.update_board_text(once, outcomes)
+    assert once == twice == "<!-- IMP-91:F2:05 -->PASS<!-- /IMP-91 -->"
@@ -0,0 +1,107 @@
+"""IMP-45 (#74) u2 — frontmatter ``slide_overrides`` surfacing.
+
+Covers ``src.mdx_normalizer.normalize_mdx_content`` and the helper
+``_extract_slide_overrides``. The Stage 2 plan enumerates four cases:
+
+1. Present — nested ``slide_overrides.css`` survives normalization verbatim.
+2. Absent — return dict carries an empty ``slide_overrides`` mapping.
+3. Non-string ``css`` — dropped (fail-closed against typo'd YAML shapes).
+4. Title-only frontmatter — no ``slide_overrides`` key in metadata → ``{}``.
+
+Scope-lock: this unit only adds the new key to the return dict. The four
+pre-existing return keys (``clean_text``/``title``/``images``/``popups``/
+``tables``/``sections``) are asserted unchanged at the structural level.
+"""
+from __future__ import annotations
+
+from src.mdx_normalizer import _extract_slide_overrides, normalize_mdx_content
+
+
+_CSS_BLOCK = "<style>.f29b__col_right { width: 320px; }</style>"
+
+
+def _mdx_with_frontmatter(fm_body: str, body: str = "# 제목\n\n본문 한 줄.\n") -> str:
+    return f"---\n{fm_body}---\n{body}"
+
+
+# -- case 1: present (nested css string survives verbatim) ------------------
+
+
+def test_normalize_surfaces_nested_slide_overrides_css():
+    raw = _mdx_with_frontmatter(
+        "title: 04 sample\n"
+        "slide_overrides:\n"
+        f"  css: \"{_CSS_BLOCK}\"\n"
+    )
+
+    result = normalize_mdx_content(raw)
+
+    assert result["slide_overrides"] == {"css": _CSS_BLOCK}
+    # Other axes unaffected by the new key.
+    assert result["title"] == "04 sample"
+    assert "본문" in result["clean_text"]
+
+
+# -- case 2: absent (no slide_overrides key in frontmatter) -----------------
+
+
+def test_normalize_returns_empty_slide_overrides_when_key_absent():
+    raw = _mdx_with_frontmatter("title: 03 sample\n")
+
+    result = normalize_mdx_content(raw)
+
+    assert result["slide_overrides"] == {}
+    # Confirm key is always present (callers can rely on .get without default).
+    assert "slide_overrides" in result
+
+
+# -- case 3: non-string css (fail-closed drop) ------------------------------
+
+
+def test_normalize_drops_non_string_css_under_slide_overrides():
+    # YAML list under .css should be dropped; sibling unknown keys survive
+    # so the future generalization path (e.g., slide_overrides.js) stays
+    # forward-compatible per the Stage 2 plan.
+    raw = _mdx_with_frontmatter(
+        "title: typo case\n"
+        "slide_overrides:\n"
+        "  css:\n"
+        "    - .f29b__col_right { width: 320px; }\n"
+        "  note: experimental sibling\n"
+    )
+
+    result = normalize_mdx_content(raw)
+
+    assert "css" not in result["slide_overrides"]
+    assert result["slide_overrides"].get("note") == "experimental sibling"
+
+
+# -- case 4: title-only frontmatter (no slide_overrides at all) -------------
+
+
+def test_normalize_title_only_frontmatter_yields_empty_slide_overrides():
+    raw = _mdx_with_frontmatter("title: title only\n")
+
+    result = normalize_mdx_content(raw)
+
+    assert result["title"] == "title only"
+    assert result["slide_overrides"] == {}
+
+
+# -- direct helper coverage (defensive against future return-shape drift) ---
+
+
+def test_extract_slide_overrides_non_mapping_returns_empty_dict():
+    # Frontmatter parsers can yield odd types if the user writes
+    # ``slide_overrides: 42`` or ``slide_overrides: ".x{}"``. The helper
+    # must coerce to ``{}`` rather than raise.
+    for bad in (None, 42, "literal string", ["css"]):
+        assert _extract_slide_overrides({"slide_overrides": bad}) == {}
+
+
+def test_extract_slide_overrides_passes_through_unknown_siblings():
+    payload = {"slide_overrides": {"css": ".a{}", "js": "console.log(1)"}}
+    assert _extract_slide_overrides(payload) == {
+        "css": ".a{}",
+        "js": "console.log(1)",
+    }
@@ -56,6 +56,8 @@ def _exec_main_block(
        override_zone_geometries=None,
        override_section_assignments=None,
        override_image_overrides=None,
+        override_slide_css=None,
+        reuse_from=None,
    ):
        captured["mdx_path"] = mdx_path
        captured["run_id"] = run_id
@@ -64,6 +66,8 @@ def _exec_main_block(
        captured["override_zone_geometries"] = override_zone_geometries
        captured["override_section_assignments"] = override_section_assignments
        captured["override_image_overrides"] = override_image_overrides
+        captured["override_slide_css"] = override_slide_css
+        captured["reuse_from"] = reuse_from

    monkeypatch.setattr(_pz2, "run_phase_z2_mvp1", _fake_run)
    monkeypatch.setattr(sys, "argv", argv)
@@ -346,3 +350,136 @@ def test_image_override_does_not_leak_into_sibling_axes(tmp_path, monkeypatch):
    assert captured["override_frames"] is None
    assert captured["override_zone_geometries"] is None
    assert captured["override_section_assignments"] is None
+
+
+# -- IMP-45 (#74) u5 — slide-level CSS override CLI surface ----------------
+#
+# Six focused cases mirror the --override-image pattern above:
+#   1. neither flag      → kwarg None (fall-back to MDX frontmatter at u4)
+#   2. --override-slide-css inline TEXT → kwarg passes verbatim
+#   3. --slide-css-file PATH UTF-8 read → kwarg = file contents
+#   4. both flags set    → sys.exit(2) with mutual-exclusion stderr
+#   5. --slide-css-file missing path    → sys.exit(2) with not-found stderr
+#   6. --slide-css-file non-UTF-8 bytes → sys.exit(2) with utf-8 stderr
+
+
+def test_no_slide_css_override_forwards_none(tmp_path, monkeypatch):
+    """Neither --override-slide-css nor --slide-css-file → kwarg = None."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    _exec_main_block(
+        captured, ["src.phase_z2_pipeline", "03.mdx"], monkeypatch,
+    )
+
+    assert captured["override_slide_css"] is None
+
+
+def test_inline_slide_css_override_forwards_verbatim(tmp_path, monkeypatch):
+    """--override-slide-css TEXT → kwarg = TEXT (verbatim, no `<style>` wrap)."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    _exec_main_block(
+        captured,
+        [
+            "src.phase_z2_pipeline",
+            "03.mdx",
+            "--override-slide-css",
+            ".slide { background: red; }",
+        ],
+        monkeypatch,
+    )
+
+    assert captured["override_slide_css"] == ".slide { background: red; }"
+
+
+def test_slide_css_file_override_reads_utf8(tmp_path, monkeypatch):
+    """--slide-css-file PATH → kwarg = UTF-8 decoded file contents."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    css_payload = ".slide-body { color: #1e293b; } /* 한글 주석 */\n"
+    css_path = tmp_path / "slide_override.css"
+    css_path.write_text(css_payload, encoding="utf-8")
+    captured: dict[str, Any] = {}
+    _exec_main_block(
+        captured,
+        [
+            "src.phase_z2_pipeline",
+            "03.mdx",
+            "--slide-css-file",
+            str(css_path),
+        ],
+        monkeypatch,
+    )
+
+    assert captured["override_slide_css"] == css_payload
+
+
+def test_slide_css_both_flags_set_exits(tmp_path, monkeypatch, capsys):
+    """--override-slide-css + --slide-css-file → sys.exit(2)."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    css_path = tmp_path / "slide_override.css"
+    css_path.write_text(".slide { color: red; }\n", encoding="utf-8")
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--override-slide-css",
+                ".slide { color: blue; }",
+                "--slide-css-file",
+                str(css_path),
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--override-slide-css and --slide-css-file are mutually exclusive" in err
+
+
+def test_slide_css_file_missing_path_exits(tmp_path, monkeypatch, capsys):
+    """--slide-css-file with non-existent PATH → sys.exit(2)."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    missing_path = tmp_path / "does_not_exist.css"
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--slide-css-file",
+                str(missing_path),
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--slide-css-file path does not exist" in err
+    assert str(missing_path) in err
+
+
+def test_slide_css_file_non_utf8_exits(tmp_path, monkeypatch, capsys):
+    """--slide-css-file with non-UTF-8 bytes → sys.exit(2)."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    bad_path = tmp_path / "latin1.css"
+    # 0xff is a stand-alone invalid UTF-8 start byte; strict decode raises.
+    bad_path.write_bytes(b".slide { color: \xff; }\n")
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--slide-css-file",
+                str(bad_path),
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--slide-css-file must be UTF-8 encoded" in err
@@ -0,0 +1,385 @@
+"""IMP-43 (#72) u1 + u5 — focused tests for the ``--reuse-from`` CLI surface.
+
+u1 scope (per the Stage 2 Exit Report):
+
+- argparse flag ``--reuse-from PREV_RUN_ID`` parses without error.
+- Fail-closed precondition guard runs AFTER the ``user_overrides.json``
+  merge and BEFORE dispatch. With ``--reuse-from`` set, the guard
+  must:
+    * accept frame-only overrides (or no overrides at all);
+    * reject layout / zone-geometry / zone-section / image overrides
+      with ``sys.exit(2)`` whose stderr names every rejected axis.
+
+u5 scope (added 2026-05-24):
+
+- ``reuse_from`` is keyword-only on ``run_phase_z2_mvp1`` and defaults
+  to ``None`` so the absent-flag path preserves pre-u5 behaviour.
+- The CLI dispatch forwards ``args.reuse_from`` verbatim — both
+  ``None`` (flag absent) and ``"PREV_RUN_ID"`` (flag present) reach
+  the kwarg unchanged.
+- The fake ``run_phase_z2_mvp1`` stub below mirrors the production
+  signature so the forwarding lock would fail loudly on any
+  forwarding regression.
+
+The harness mirrors ``tests/test_phase_z2_cli_overrides.py`` — the
+``if __name__ == "__main__"`` block of ``src.phase_z2_pipeline`` is
+exec'd inside the module's namespace after monkeypatching
+``run_phase_z2_mvp1`` with a recording stub. The persistence fallback
+is silenced by redirecting ``src.user_overrides_io.DEFAULT_OVERRIDES_ROOT``
+to a clean tmp directory so persisted state from prior runs cannot bleed
+into the parser-only assertions here.
+"""
+from __future__ import annotations
+
+import ast
+import sys
+from pathlib import Path
+from typing import Any
+
+import pytest
+
+import src.phase_z2_pipeline as _pz2
+import src.user_overrides_io as _io
+
+
+# -- harness ---------------------------------------------------------------
+
+
+def _exec_main_block(
+    captured: dict[str, Any], argv: list[str], monkeypatch
+) -> None:
+    """Run the ``__main__`` body of phase_z2_pipeline.py with a fake
+    ``run_phase_z2_mvp1`` so its kwargs are observable. Captures the
+    presence of the call (``called=True``) so guard-driven early exits
+    can be distinguished from a successful parse + dispatch."""
+
+    def _fake_run(
+        mdx_path,
+        run_id,
+        *,
+        override_layout=None,
+        override_frames=None,
+        override_zone_geometries=None,
+        override_section_assignments=None,
+        override_image_overrides=None,
+        override_slide_css=None,
+        reuse_from=None,
+    ):
+        captured["called"] = True
+        captured["mdx_path"] = mdx_path
+        captured["run_id"] = run_id
+        captured["override_layout"] = override_layout
+        captured["override_frames"] = override_frames
+        captured["override_zone_geometries"] = override_zone_geometries
+        captured["override_section_assignments"] = override_section_assignments
+        captured["override_image_overrides"] = override_image_overrides
+        captured["override_slide_css"] = override_slide_css
+        captured["reuse_from"] = reuse_from
+
+    monkeypatch.setattr(_pz2, "run_phase_z2_mvp1", _fake_run)
+    monkeypatch.setattr(sys, "argv", argv)
+
+    src_path = Path(_pz2.__file__)
+    source = src_path.read_text(encoding="utf-8")
+    tree = ast.parse(source)
+    for node in tree.body:
+        if (
+            isinstance(node, ast.If)
+            and isinstance(node.test, ast.Compare)
+            and isinstance(node.test.left, ast.Name)
+            and node.test.left.id == "__name__"
+        ):
+            block = ast.Module(body=node.body, type_ignores=[])
+            exec(compile(block, str(src_path), "exec"), _pz2.__dict__)
+            return
+    raise AssertionError("no `if __name__ == '__main__'` block found")
+
+
+def _redirect_overrides_root(tmp_path: Path, monkeypatch) -> None:
+    """Isolate the persistence fallback so file state never leaks in."""
+    monkeypatch.setattr(_io, "DEFAULT_OVERRIDES_ROOT", tmp_path)
+
+
+# -- success paths --------------------------------------------------------
+
+
+def test_reuse_from_alone_parses_and_dispatches(tmp_path, monkeypatch):
+    """``--reuse-from`` with no other overrides must parse cleanly and
+    fall through to dispatch (frame-only / empty override is allowed).
+    u5 (2026-05-24): also asserts the CLI threads ``args.reuse_from``
+    verbatim into the ``reuse_from`` kwarg."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    _exec_main_block(
+        captured,
+        [
+            "src.phase_z2_pipeline",
+            "03.mdx",
+            "--reuse-from",
+            "03__DX_20260508025134",
+        ],
+        monkeypatch,
+    )
+
+    assert captured.get("called") is True
+    # u5 — verbatim threading.
+    assert captured["reuse_from"] == "03__DX_20260508025134"
+
+
+def test_reuse_from_with_frame_override_dispatches(tmp_path, monkeypatch):
+    """Frame overrides ARE preserved across Step 0/1/2/5/6 reuse, so
+    ``--reuse-from`` + ``--override-frame`` must reach dispatch.
+    u5: forwards both ``reuse_from`` and ``override_frames`` in the
+    same call."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    _exec_main_block(
+        captured,
+        [
+            "src.phase_z2_pipeline",
+            "03.mdx",
+            "--reuse-from",
+            "03__DX_20260508025134",
+            "--override-frame",
+            "03-1=frame_foo",
+        ],
+        monkeypatch,
+    )
+
+    assert captured.get("called") is True
+    assert captured["override_frames"] == {"03-1": "frame_foo"}
+    # u5 — frame override + reuse_from reach the kwarg simultaneously.
+    assert captured["reuse_from"] == "03__DX_20260508025134"
+
+
+# -- u5 — flag-absent default + signature surface ------------------------
+
+
+def test_no_reuse_from_threads_none_kwarg(tmp_path, monkeypatch):
+    """u5 — when ``--reuse-from`` is absent, the kwarg must reach
+    ``run_phase_z2_mvp1`` as ``None`` (not omitted, not ``""``). This
+    locks the "default None preserves current behavior" requirement
+    from the Stage 2 plan §u5."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    _exec_main_block(
+        captured,
+        ["src.phase_z2_pipeline", "03.mdx"],
+        monkeypatch,
+    )
+
+    assert captured.get("called") is True
+    assert captured["reuse_from"] is None
+
+
+def test_run_phase_z2_mvp1_signature_includes_reuse_from():
+    """Production signature lock — ``reuse_from`` must be a keyword-only
+    parameter with default ``None``. Mirror of the entry-tests
+    invariant; kept here so the CLI-surface test file fails loudly if
+    the production signature drifts away from the dispatch contract."""
+    import inspect
+
+    sig = inspect.signature(_pz2.run_phase_z2_mvp1)
+    assert "reuse_from" in sig.parameters, list(sig.parameters)
+    param = sig.parameters["reuse_from"]
+    assert param.kind is inspect.Parameter.KEYWORD_ONLY, param.kind
+    assert param.default is None, param.default
+
+
+# -- fail-closed (single-axis rejection) ----------------------------------
+
+
+def test_reuse_from_with_layout_override_exits(tmp_path, monkeypatch, capsys):
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--reuse-from",
+                "03__DX_20260508025134",
+                "--override-layout",
+                "horizontal-2",
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--reuse-from incompatible with override axes" in err
+    assert "layout" in err
+    assert captured.get("called") is not True
+
+
+def test_reuse_from_with_zone_geometry_override_exits(
+    tmp_path, monkeypatch, capsys
+):
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--reuse-from",
+                "03__DX_20260508025134",
+                "--override-zone-geometry",
+                "top=0,0,1,0.3",
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--reuse-from incompatible with override axes" in err
+    assert "zone_geometry" in err
+    assert captured.get("called") is not True
+
+
+def test_reuse_from_with_zone_section_override_exits(
+    tmp_path, monkeypatch, capsys
+):
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--reuse-from",
+                "03__DX_20260508025134",
+                "--override-section-assignment",
+                "top=03-1",
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--reuse-from incompatible with override axes" in err
+    assert "zone_section" in err
+    assert captured.get("called") is not True
+
+
+def test_reuse_from_with_image_override_exits(tmp_path, monkeypatch, capsys):
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--reuse-from",
+                "03__DX_20260508025134",
+                "--override-image",
+                "img-abc=10,15,30,25",
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--reuse-from incompatible with override axes" in err
+    assert "image" in err
+    assert captured.get("called") is not True
+
+
+# -- fail-closed (multi-axis aggregation) ---------------------------------
+
+
+def test_reuse_from_with_multiple_rejected_axes_lists_all(
+    tmp_path, monkeypatch, capsys
+):
+    """Stderr must enumerate every rejected axis (not stop at first)."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--reuse-from",
+                "03__DX_20260508025134",
+                "--override-layout",
+                "horizontal-2",
+                "--override-zone-geometry",
+                "top=0,0,1,0.3",
+                "--override-image",
+                "img-abc=10,15,30,25",
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "layout" in err
+    assert "zone_geometry" in err
+    assert "image" in err
+    assert captured.get("called") is not True
+
+
+# -- guard inactive when --reuse-from absent ------------------------------
+
+
+def test_no_reuse_from_layout_override_still_dispatches(
+    tmp_path, monkeypatch
+):
+    """Without ``--reuse-from``, the guard must be silent — existing
+    override behaviour is preserved end-to-end."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    captured: dict[str, Any] = {}
+    _exec_main_block(
+        captured,
+        [
+            "src.phase_z2_pipeline",
+            "03.mdx",
+            "--override-layout",
+            "horizontal-2",
+        ],
+        monkeypatch,
+    )
+
+    assert captured.get("called") is True
+    assert captured["override_layout"] == "horizontal-2"
+
+
+# -- fail-closed honours persisted overrides ------------------------------
+
+
+def test_reuse_from_with_persisted_layout_override_exits(
+    tmp_path, monkeypatch, capsys
+):
+    """The guard runs AFTER the user_overrides.json merge, so a layout
+    persisted on disk (not on the CLI) must still reject when
+    ``--reuse-from`` is set. This locks the Stage 2 placement rule."""
+    _redirect_overrides_root(tmp_path, monkeypatch)
+    # Persist a layout override keyed by the MDX stem ``03``.
+    overrides_dir = tmp_path
+    overrides_dir.mkdir(parents=True, exist_ok=True)
+    (overrides_dir / "03.json").write_text(
+        '{"layout": "vertical-2"}', encoding="utf-8"
+    )
+    captured: dict[str, Any] = {}
+    with pytest.raises(SystemExit) as excinfo:
+        _exec_main_block(
+            captured,
+            [
+                "src.phase_z2_pipeline",
+                "03.mdx",
+                "--reuse-from",
+                "03__DX_20260508025134",
+            ],
+            monkeypatch,
+        )
+
+    assert excinfo.value.code == 2
+    err = capsys.readouterr().err
+    assert "--reuse-from incompatible with override axes" in err
+    assert "layout" in err
+    assert captured.get("called") is not True
@@ -676,12 +676,20 @@ def test_u5_zone_without_provisional_key_treated_as_non_provisional():
 # ─── u5 case 2 : provisional zone renders class + badge + data attr ───


-def test_u5_provisional_zone_renders_class_and_badge():
-    """Opt-in path. zones[i].provisional=True must:
-      1. Append `zone--provisional` class to the zone div.
-      2. Set `data-provisional="1"` data attribute (for downstream selectors).
-      3. Render a `<span class="zone__needs-adaptation-badge">` element with
-         the literal text "needs adaptation" (aria-label included for a11y).
+def test_imp84_provisional_zone_silent_no_class_no_badge():
+    """IMP-84 silent-automation inversion of the prior IMP-30 u5 contract.
+    Under the silent contract, zones[i].provisional=True must:
+      1. NOT append `zone--provisional` class to the zone div (no user-visible
+         outline / striped wash).
+      2. Still set `data-provisional="1"` data attribute as silent telemetry
+         for downstream selectors / inspection.
+      3. NOT render any `<span class="zone__needs-adaptation-badge">` element
+         and NOT surface the literal text "needs adaptation" or its
+         aria-label (no user-facing badge).
+
+    Scope: assertions target the zone div body. The CSS <style> block must
+    likewise not carry the removed visual selectors — that surface is pinned
+    in `test_imp84_slide_base_css_strips_provisional_visual_selectors` below.
    """
    zones = [
        {
@@ -694,21 +702,26 @@ def test_u5_provisional_zone_renders_class_and_badge():
        }
    ]
    html = _render_slide_base(zones)
-    # zone--provisional class must appear on the zone div for position=single.
-    assert "zone--provisional" in html
-    # data-provisional="1" attribute must be present.
-    assert 'data-provisional="1"' in html
-    # Badge element with the required label text.
-    assert 'class="zone__needs-adaptation-badge"' in html
-    assert "needs adaptation" in html
-    assert 'aria-label="needs user or AI adaptation"' in html
+    zone_divs = _all_zone_div_openings(html)
+    assert len(zone_divs) == 1
+    # No zone--provisional class on the zone div (visual removed).
+    assert "zone--provisional" not in zone_divs[0]
+    # data-provisional="1" attribute still present as silent telemetry.
+    assert 'data-provisional="1"' in zone_divs[0]
+    # No badge <span> element and no badge label text anywhere in the body.
+    assert _all_badge_spans(html) == []
+    assert "needs adaptation" not in html
+    assert 'aria-label="needs user or AI adaptation"' not in html


-def test_u5_provisional_badge_appears_inside_provisional_zone_only():
-    """Mixed-zone slide: one provisional zone + one normal zone. The badge
-    + class must appear ONLY in the provisional zone, not bleed into the
-    normal one (CSS-level isolation should already prevent this, but the
-    template must not emit the badge for both)."""
+def test_imp84_provisional_badge_never_rendered_in_mixed_zones():
+    """IMP-84 silent-automation inversion of the prior IMP-30 u5 mixed-zone
+    contract. Mixed-zone slide: one provisional zone + one normal zone. The
+    silent contract requires that NO badge span and NO `zone--provisional`
+    class be emitted on either zone div. The provisional zone is identifiable
+    only through the silent `data-provisional="1"` telemetry attribute, which
+    must be scoped to the provisional zone alone (no bleed onto the normal
+    zone)."""
    zones = [
        {
            "position": "top",
@@ -735,21 +748,21 @@ def test_u5_provisional_badge_appears_inside_provisional_zone_only():
    html = _render_slide_base(
        zones, layout_preset="vertical-2", layout_css=layout_css
    )
-    # Exactly one badge span element should be present in the rendered body
-    # (CSS selector in <style> excluded by the helper).
-    assert len(_all_badge_spans(html)) == 1
-    # zone--provisional must appear on exactly one zone div (CSS selector
-    # in <style> excluded by the helper).
+    # No badge <span> element should be rendered anywhere in the body
+    # (silent-automation policy).
+    assert _all_badge_spans(html) == []
+    # No zone div should carry the zone--provisional class (visual removed).
    zone_divs = _all_zone_div_openings(html)
    assert len(zone_divs) == 2
-    provisional_zone_divs = [d for d in zone_divs if "zone--provisional" in d]
-    assert len(provisional_zone_divs) == 1
-    # The provisional class must be associated with the bottom zone.
+    assert all("zone--provisional" not in d for d in zone_divs)
+    # data-provisional="1" telemetry must be present on the bottom (provisional)
+    # zone only — never on the top (non-provisional) zone.
    bottom_zone_open = _zone_div_for_position(html, "bottom")
-    assert "zone--provisional" in bottom_zone_open
-    assert "zone__needs-adaptation-badge" in bottom_zone_open
-    # The top zone must NOT carry the provisional class.
+    assert 'data-provisional="1"' in bottom_zone_open
+    assert "zone--provisional" not in bottom_zone_open
+    assert "zone__needs-adaptation-badge" not in bottom_zone_open
    top_zone_open = _zone_div_for_position(html, "top")
+    assert 'data-provisional="1"' not in top_zone_open
    assert "zone--provisional" not in top_zone_open
    assert "zone__needs-adaptation-badge" not in top_zone_open

@@ -779,15 +792,19 @@ def test_u5_zones_data_provisional_field_defaults_false_in_template():
    assert _all_badge_spans(html) == []


-def test_u5_slide_base_css_carries_provisional_marker_styles():
-    """The provisional visual contract (dashed outline + striped wash + badge)
-    is defined in slide_base.html <style>. Pin that the relevant CSS class
-    selectors exist in the rendered HTML so a refactor that removes them
-    breaks this test rather than silently rendering an unstyled badge.
+def test_imp84_slide_base_css_strips_provisional_visual_selectors():
+    """IMP-84 silent-automation inversion of the prior IMP-30 u5 CSS-presence
+    contract. The provisional visual treatment (dashed outline + striped wash
+    + badge) was deleted from `slide_base.html <style>` by IMP-84 u2. Pin
+    that the CSS class selectors `.zone--provisional` and
+    `.zone__needs-adaptation-badge` no longer appear in the rendered HTML —
+    a refactor that re-introduces them must break this test rather than
+    silently re-surfacing the removed visual signal.

-    This is a class-selector existence check; it does not validate the
-    specific color / dash pattern, which is a design decision intentionally
-    left malleable (e.g., palette swap for a different theme)."""
+    Scope: the assertion targets the entire rendered HTML (style block plus
+    body). Since the body badge span is also gone (covered separately above),
+    any occurrence of these strings in the rendered output would only come
+    from a regressed style block."""
    zones = [
        {
            "position": "single",
@@ -799,9 +816,9 @@ def test_u5_slide_base_css_carries_provisional_marker_styles():
        }
    ]
    html = _render_slide_base(zones)
-    # Style block must define .zone--provisional and the badge selector.
-    assert ".zone--provisional" in html
-    assert ".zone__needs-adaptation-badge" in html
+    # Style block must NOT define .zone--provisional or the badge selector.
+    assert ".zone--provisional" not in html
+    assert ".zone__needs-adaptation-badge" not in html


 # ════════════════════════════════════════════════════════════════════════
@@ -0,0 +1,555 @@
+"""IMP-43 (#72) u4 — focused tests for the --reuse-from entry helpers.
+
+u4 scope (per the Stage 2 Exit Report):
+
+- Pure path resolution, file copy, snapshot load+validate, MdxSection +
+  CompositionUnit rehydration, and reuse-marker writing.
+- Helpers RAISE on missing artifacts / corrupt snapshot / mdx_sha256
+  mismatch — u4b adds the stderr + sys.exit(2) translation and the
+  prev_run_dir == new_run_dir accidental-write guard around them.
+- The kwarg threading + the in-``run_phase_z2_mvp1`` branch that
+  invokes these helpers land in u5.
+
+Tested helpers (``src/phase_z2_pipeline.py``):
+  * ``_resolve_reuse_from_prev_run_dir``
+  * ``_copy_reuse_artifacts_from_prev_run``
+  * ``_load_and_validate_reuse_snapshot``
+  * ``_rehydrate_mdx_sections_from_snapshot``
+  * ``_rehydrate_composition_units_from_snapshot``
+  * ``_write_reuse_marker``
+  * ``_RehydratedV4Candidate`` (V4Match-shape duck type)
+  * ``_REUSE_STEP_ARTIFACTS`` / ``REUSE_MARKER_FILENAME`` /
+    ``REUSE_MARKER_SCHEMA_VERSION``
+"""
+from __future__ import annotations
+
+import hashlib
+import json
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Any, Optional
+
+import pytest
+
+import src.phase_z2_pipeline as _pz2
+from src.phase_z2_composition import CompositionUnit
+from src.phase_z2_reuse_snapshot import (
+    SNAPSHOT_FILENAME,
+    SNAPSHOT_VERSION,
+    SnapshotValidationError,
+    build_snapshot,
+)
+
+
+# -- synthetic duck-typed inputs (mirror u3 test fixture) -----------------
+
+
+@dataclass
+class _Section:
+    section_id: str
+    section_num: int
+    title: str
+    raw_content: str
+    heading_number: Optional[str] = None
+    v4_alias_keys: list = field(default_factory=list)
+    sub_sections: list = field(default_factory=list)
+
+
+@dataclass
+class _V4Candidate:
+    template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+
+
+@dataclass
+class _Unit:
+    source_section_ids: list
+    merge_type: str
+    frame_template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+    phase_z_status: str
+    raw_content: str
+    title: str
+    score: float
+    v4_rank: Optional[int] = 1
+    selection_path: str = "rank_1"
+    fallback_reason: Optional[str] = None
+    rationale: dict = field(default_factory=dict)
+    auto_selectable: bool = True
+    filter_reasons: list = field(default_factory=list)
+    notes: list = field(default_factory=list)
+    v4_candidates: list = field(default_factory=list)
+    provisional: bool = False
+
+
+def _mdx_text() -> str:
+    return "# Slide\n\n## 03-1 DX status\n\n- bullet one\n- bullet two\n"
+
+
+def _build_canonical_snapshot(
+    *,
+    mdx_source_text: Optional[str] = None,
+    layout_preset: str = "single",
+) -> dict:
+    text = mdx_source_text if mdx_source_text is not None else _mdx_text()
+    cand = _V4Candidate(
+        template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+    )
+    section = _Section(
+        section_id="03-1",
+        section_num=1,
+        title="DX status",
+        raw_content="- bullet one\n- bullet two",
+        heading_number="3.1",
+        v4_alias_keys=["03-1.1"],
+        sub_sections=[],
+    )
+    unit = _Unit(
+        source_section_ids=["03-1"],
+        merge_type="single",
+        frame_template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+        phase_z_status="auto_renderable",
+        raw_content="- bullet one\n- bullet two",
+        title="DX status",
+        score=0.91,
+        v4_candidates=[cand],
+        provisional=False,
+        auto_selectable=True,
+        filter_reasons=[],
+        notes=["a note"],
+        rationale={"weight": 1.0},
+    )
+    return build_snapshot(
+        mdx_sha256=hashlib.sha256(text.encode("utf-8")).hexdigest(),
+        slide_title="Slide",
+        slide_footer=None,
+        sections=[section],
+        stage0_adapter_diagnostics={"used": True, "fallback_reason": None},
+        stage0_normalized_assets={"popups": [], "images": [], "tables": []},
+        v4_evidence=[
+            {
+                "section_id": "03-1",
+                "v4_candidates": [
+                    {
+                        "template_id": "tpl_a",
+                        "frame_id": "fid_a",
+                        "frame_number": 13,
+                        "confidence": 0.91,
+                        "label": "use_as_is",
+                    }
+                ],
+                "candidate_status": "ok",
+            }
+        ],
+        layout_preset_pre_override=layout_preset,
+        units=[unit],
+        comp_debug={"v4_fallback_summary": {"fallback_used_count": 0}},
+        v4_fallback_traces={"03-1": {"selection_path": "rank_1"}},
+        ai_preflight={"enabled": False, "skipped": True},
+    )
+
+
+def _seed_prev_run_dir(prev_run_dir: Path, *, snapshot: dict) -> None:
+    """Populate ``prev_run_dir`` with the Step 0/1/2/5/6 artifacts plus
+    the reuse snapshot — minimal but valid surface for u4 helpers."""
+    (prev_run_dir / "steps").mkdir(parents=True, exist_ok=True)
+    for fname in _pz2._REUSE_STEP_ARTIFACTS:
+        # JSON-shaped surface — exact shape doesn't matter for u4 (the
+        # copy helper doesn't introspect contents); just must exist.
+        (prev_run_dir / "steps" / fname).write_text(
+            f'{{"name": "{fname}"}}'
+            if fname.endswith(".json")
+            else "raw mdx body bytes",
+            encoding="utf-8",
+        )
+    (prev_run_dir / SNAPSHOT_FILENAME).write_text(
+        json.dumps(snapshot, ensure_ascii=False, indent=2),
+        encoding="utf-8",
+    )
+
+
+# -- _REUSE_STEP_ARTIFACTS constant ---------------------------------------
+
+
+def test_reuse_step_artifacts_locks_stage2_boundary():
+    """Stage 2 boundary lock — Step 0/1/2/5/6 artifacts only.
+    Step 3/4 deliberately absent: step03 / step04 ARE written after
+    Step 6 (around src/phase_z2_pipeline.py:5931 / 5964) before the
+    Step 7 artifact (~6294), but both are emitted with
+    step_status='trace-only' / pipeline_path_connected=False — they
+    are diagnostic projections of the Step 6 debug_zones, not
+    pipeline-path-connected inputs that Step 7+ rehydrate from."""
+    assert _pz2._REUSE_STEP_ARTIFACTS == (
+        "step00_preconditions.json",
+        "step01_mdx_upload.json",
+        "step01_mdx_source.md",
+        "step02_normalized.json",
+        "step05_v4_evidence.json",
+        "step06_composition_plan.json",
+    )
+
+
+def test_reuse_marker_filename_is_dotfile_at_run_dir_root():
+    assert _pz2.REUSE_MARKER_FILENAME == "_reuse_marker.json"
+
+
+# -- _resolve_reuse_from_prev_run_dir -------------------------------------
+
+
+def test_resolve_prev_run_dir_returns_runs_dir_phase_z2_path():
+    rv = _pz2._resolve_reuse_from_prev_run_dir("20260524_120000_phase_z2")
+    expected = _pz2.RUNS_DIR / "20260524_120000_phase_z2" / "phase_z2"
+    assert rv == expected
+
+
+def test_resolve_prev_run_dir_does_not_check_existence(tmp_path: Path):
+    """Pure path computation — must NOT touch the filesystem (u4b
+    handles the missing-prev-run case)."""
+    rv = _pz2._resolve_reuse_from_prev_run_dir("never_existed_run_id")
+    assert isinstance(rv, Path)
+    # The path does not actually exist; helper still returned cleanly.
+    assert not rv.exists()
+
+
+# -- _copy_reuse_artifacts_from_prev_run ----------------------------------
+
+
+def test_copy_reuse_artifacts_copies_all_step_files(tmp_path: Path):
+    prev = tmp_path / "prev" / "phase_z2"
+    new = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev, snapshot=snap)
+
+    copied = _pz2._copy_reuse_artifacts_from_prev_run(prev, new)
+
+    for fname in _pz2._REUSE_STEP_ARTIFACTS:
+        assert (new / "steps" / fname).exists(), f"missing copy: {fname}"
+        assert copied[fname] == f"steps/{fname}"
+
+
+def test_copy_reuse_artifacts_copies_snapshot_to_run_dir_root(tmp_path: Path):
+    prev = tmp_path / "prev" / "phase_z2"
+    new = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev, snapshot=snap)
+
+    copied = _pz2._copy_reuse_artifacts_from_prev_run(prev, new)
+
+    # Snapshot lives at run_dir root (NOT under steps/) per u3 contract.
+    assert (new / SNAPSHOT_FILENAME).exists()
+    assert copied[SNAPSHOT_FILENAME] == SNAPSHOT_FILENAME
+
+
+def test_copy_reuse_artifacts_creates_steps_subdir_if_absent(tmp_path: Path):
+    prev = tmp_path / "prev" / "phase_z2"
+    new = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev, snapshot=snap)
+
+    # new_run_dir / steps does not yet exist
+    assert not (new / "steps").exists()
+    _pz2._copy_reuse_artifacts_from_prev_run(prev, new)
+    assert (new / "steps").is_dir()
+
+
+def test_copy_reuse_artifacts_missing_step_raises_filenotfound(
+    tmp_path: Path,
+):
+    prev = tmp_path / "prev" / "phase_z2"
+    new = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev, snapshot=snap)
+    # Delete one of the required step artifacts.
+    (prev / "steps" / "step05_v4_evidence.json").unlink()
+
+    with pytest.raises(FileNotFoundError) as ei:
+        _pz2._copy_reuse_artifacts_from_prev_run(prev, new)
+    msg = str(ei.value)
+    assert "step05_v4_evidence.json" in msg
+    assert "prev_run_dir" in msg
+
+
+def test_copy_reuse_artifacts_missing_snapshot_raises_filenotfound(
+    tmp_path: Path,
+):
+    prev = tmp_path / "prev" / "phase_z2"
+    new = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev, snapshot=snap)
+    (prev / SNAPSHOT_FILENAME).unlink()
+
+    with pytest.raises(FileNotFoundError) as ei:
+        _pz2._copy_reuse_artifacts_from_prev_run(prev, new)
+    assert SNAPSHOT_FILENAME in str(ei.value)
+
+
+def test_copy_reuse_artifacts_byte_identical_copy(tmp_path: Path):
+    """Bytes must match exactly — copy, not transform."""
+    prev = tmp_path / "prev" / "phase_z2"
+    new = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev, snapshot=snap)
+
+    _pz2._copy_reuse_artifacts_from_prev_run(prev, new)
+
+    for fname in _pz2._REUSE_STEP_ARTIFACTS:
+        assert (
+            (prev / "steps" / fname).read_bytes()
+            == (new / "steps" / fname).read_bytes()
+        )
+    assert (
+        (prev / SNAPSHOT_FILENAME).read_bytes()
+        == (new / SNAPSHOT_FILENAME).read_bytes()
+    )
+
+
+# -- _load_and_validate_reuse_snapshot ------------------------------------
+
+
+def test_load_and_validate_returns_snapshot_dict(tmp_path: Path):
+    text = _mdx_text()
+    snap = _build_canonical_snapshot(mdx_source_text=text)
+    (tmp_path / SNAPSHOT_FILENAME).write_text(
+        json.dumps(snap, ensure_ascii=False, indent=2), encoding="utf-8"
+    )
+
+    loaded = _pz2._load_and_validate_reuse_snapshot(
+        tmp_path, mdx_source_text=text
+    )
+    assert loaded["schema_version"] == SNAPSHOT_VERSION
+    assert loaded["slide_title"]["value"] == "Slide"
+
+
+def test_load_and_validate_mdx_sha256_mismatch_raises(tmp_path: Path):
+    """Snapshot was built for ``text_a`` but caller passes ``text_b``;
+    u2 validator raises ``SnapshotValidationError`` (subclass of
+    ``ValueError``). u4b translates to exit 2 — here we only assert the
+    raise."""
+    text_a = "# Slide A\n"
+    text_b = "# Slide B (different bytes)\n"
+    snap = _build_canonical_snapshot(mdx_source_text=text_a)
+    (tmp_path / SNAPSHOT_FILENAME).write_text(
+        json.dumps(snap, ensure_ascii=False, indent=2), encoding="utf-8"
+    )
+
+    with pytest.raises(SnapshotValidationError) as ei:
+        _pz2._load_and_validate_reuse_snapshot(
+            tmp_path, mdx_source_text=text_b
+        )
+    assert "mdx_sha256 mismatch" in str(ei.value)
+
+
+def test_load_and_validate_corrupt_json_raises(tmp_path: Path):
+    (tmp_path / SNAPSHOT_FILENAME).write_text(
+        "{ not valid json", encoding="utf-8"
+    )
+    with pytest.raises(json.JSONDecodeError):
+        _pz2._load_and_validate_reuse_snapshot(
+            tmp_path, mdx_source_text=_mdx_text()
+        )
+
+
+def test_load_and_validate_missing_snapshot_file_raises(tmp_path: Path):
+    """No snapshot at all — bare ``read_text`` raises FileNotFoundError.
+    u4b translates this to exit 2 with a provenance message."""
+    with pytest.raises(FileNotFoundError):
+        _pz2._load_and_validate_reuse_snapshot(
+            tmp_path, mdx_source_text=_mdx_text()
+        )
+
+
+def test_load_and_validate_schema_version_mismatch_raises(tmp_path: Path):
+    text = _mdx_text()
+    snap = _build_canonical_snapshot(mdx_source_text=text)
+    snap["schema_version"] = SNAPSHOT_VERSION + 1  # force mismatch
+    (tmp_path / SNAPSHOT_FILENAME).write_text(
+        json.dumps(snap, ensure_ascii=False, indent=2), encoding="utf-8"
+    )
+    with pytest.raises(SnapshotValidationError) as ei:
+        _pz2._load_and_validate_reuse_snapshot(
+            tmp_path, mdx_source_text=text
+        )
+    assert "schema_version" in str(ei.value)
+
+
+# -- _rehydrate_mdx_sections_from_snapshot --------------------------------
+
+
+def test_rehydrate_sections_returns_mdxsection_instances():
+    snap = _build_canonical_snapshot()
+    sections = _pz2._rehydrate_mdx_sections_from_snapshot(snap)
+    assert len(sections) == 1
+    assert isinstance(sections[0], _pz2.MdxSection)
+    assert sections[0].section_id == "03-1"
+    assert sections[0].title == "DX status"
+    assert sections[0].raw_content == "- bullet one\n- bullet two"
+
+
+def test_rehydrate_sections_preserves_heading_number_and_aliases():
+    snap = _build_canonical_snapshot()
+    sections = _pz2._rehydrate_mdx_sections_from_snapshot(snap)
+    assert sections[0].heading_number == "3.1"
+    assert sections[0].v4_alias_keys == ["03-1.1"]
+    assert sections[0].sub_sections == []
+
+
+# -- _rehydrate_composition_units_from_snapshot ---------------------------
+
+
+def test_rehydrate_units_returns_composition_unit_instances():
+    snap = _build_canonical_snapshot()
+    units = _pz2._rehydrate_composition_units_from_snapshot(snap)
+    assert len(units) == 1
+    assert isinstance(units[0], CompositionUnit)
+
+
+def test_rehydrate_units_preserves_core_fields():
+    snap = _build_canonical_snapshot()
+    units = _pz2._rehydrate_composition_units_from_snapshot(snap)
+    u = units[0]
+    assert u.source_section_ids == ["03-1"]
+    assert u.merge_type == "single"
+    assert u.frame_template_id == "tpl_a"
+    assert u.frame_id == "fid_a"
+    assert u.frame_number == 13
+    assert u.confidence == pytest.approx(0.91)
+    assert u.label == "use_as_is"
+    assert u.phase_z_status == "auto_renderable"
+    assert u.title == "DX status"
+    assert u.score == pytest.approx(0.91)
+
+
+def test_rehydrate_units_preserves_provisional_and_auto_selectable():
+    snap = _build_canonical_snapshot()
+    units = _pz2._rehydrate_composition_units_from_snapshot(snap)
+    assert units[0].provisional is False
+    assert units[0].auto_selectable is True
+    assert units[0].filter_reasons == []
+    assert units[0].notes == ["a note"]
+    assert units[0].rationale == {"weight": 1.0}
+
+
+def test_rehydrate_units_v4_candidates_expose_attribute_access():
+    """``_apply_frame_override_to_unit`` reads
+    ``cand.template_id`` / ``cand.frame_id`` / etc. off
+    ``unit.v4_candidates`` — restored entries MUST expose attribute
+    access, not raw dict access."""
+    snap = _build_canonical_snapshot()
+    units = _pz2._rehydrate_composition_units_from_snapshot(snap)
+    cands = units[0].v4_candidates
+    assert len(cands) == 1
+    c = cands[0]
+    assert isinstance(c, _pz2._RehydratedV4Candidate)
+    assert c.template_id == "tpl_a"
+    assert c.frame_id == "fid_a"
+    assert c.frame_number == 13
+    assert c.confidence == pytest.approx(0.91)
+    assert c.label == "use_as_is"
+
+
+def test_rehydrate_units_empty_v4_candidates_yields_empty_list():
+    snap = _build_canonical_snapshot()
+    snap["units"]["value"][0]["v4_candidates"] = []
+    units = _pz2._rehydrate_composition_units_from_snapshot(snap)
+    assert units[0].v4_candidates == []
+
+
+# -- _write_reuse_marker --------------------------------------------------
+
+
+def test_write_reuse_marker_writes_json_with_prev_run_id(tmp_path: Path):
+    copied = {
+        "step00_preconditions.json": "steps/step00_preconditions.json",
+        SNAPSHOT_FILENAME: SNAPSHOT_FILENAME,
+    }
+    rv = _pz2._write_reuse_marker(
+        tmp_path,
+        prev_run_id="20260524_010101_phase_z2",
+        copied_artifacts=copied,
+    )
+    assert rv == tmp_path / _pz2.REUSE_MARKER_FILENAME
+    marker = json.loads(rv.read_text(encoding="utf-8"))
+    assert marker["schema_version"] == _pz2.REUSE_MARKER_SCHEMA_VERSION
+    assert marker["reuse_from_prev_run_id"] == "20260524_010101_phase_z2"
+    assert marker["snapshot_filename"] == SNAPSHOT_FILENAME
+
+
+def test_write_reuse_marker_records_copied_artifacts_and_boundary(
+    tmp_path: Path,
+):
+    copied = {
+        fname: f"steps/{fname}" for fname in _pz2._REUSE_STEP_ARTIFACTS
+    }
+    copied[SNAPSHOT_FILENAME] = SNAPSHOT_FILENAME
+    _pz2._write_reuse_marker(
+        tmp_path,
+        prev_run_id="20260524_010101_phase_z2",
+        copied_artifacts=copied,
+    )
+    marker = json.loads(
+        (tmp_path / _pz2.REUSE_MARKER_FILENAME).read_text(encoding="utf-8")
+    )
+    assert marker["copied_artifacts"] == copied
+    assert marker["boundary_steps"] == list(_pz2._REUSE_STEP_ARTIFACTS)
+    assert marker["resume_at_step"] == 7
+
+
+# -- module surface anchors -----------------------------------------------
+
+
+def test_pipeline_exposes_all_u4_helpers():
+    """u5 wires these into ``run_phase_z2_mvp1`` — they must remain
+    module-level callable surface on ``phase_z2_pipeline``."""
+    for name in (
+        "_resolve_reuse_from_prev_run_dir",
+        "_copy_reuse_artifacts_from_prev_run",
+        "_load_and_validate_reuse_snapshot",
+        "_rehydrate_mdx_sections_from_snapshot",
+        "_rehydrate_composition_units_from_snapshot",
+        "_write_reuse_marker",
+        "_RehydratedV4Candidate",
+        "_REUSE_STEP_ARTIFACTS",
+        "REUSE_MARKER_FILENAME",
+        "REUSE_MARKER_SCHEMA_VERSION",
+    ):
+        assert hasattr(_pz2, name), f"u4 surface missing: {name}"
+
+
+def test_pipeline_run_signature_reuse_from_is_kw_only_optional_none():
+    """u5 — ``reuse_from`` is now part of ``run_phase_z2_mvp1``'s public
+    signature. The kwarg MUST be keyword-only (after the ``*`` barrier),
+    default to ``None`` (so absent flag preserves the pre-u5 behaviour),
+    and sit alongside the existing override kwargs. The locked
+    ``until_u5`` regression has flipped — keep this assertion as the
+    forward-direction lock so future signature drift (e.g. a positional
+    promotion or a default change) trips loudly."""
+    import inspect
+
+    sig = inspect.signature(_pz2.run_phase_z2_mvp1)
+    assert "reuse_from" in sig.parameters, (
+        "u5 must thread reuse_from into run_phase_z2_mvp1 — kwarg missing. "
+        f"current params: {list(sig.parameters)}"
+    )
+    param = sig.parameters["reuse_from"]
+    assert param.kind is inspect.Parameter.KEYWORD_ONLY, (
+        f"reuse_from must be keyword-only (after the ``*`` barrier); "
+        f"got kind={param.kind}"
+    )
+    assert param.default is None, (
+        f"reuse_from must default to None to preserve pre-u5 behaviour; "
+        f"got default={param.default!r}"
+    )
@@ -0,0 +1,261 @@
+"""IMP-43 (#72) u7b — Opt-in sweep equivalence test for full rerun vs
+``--reuse-from`` across 3 layouts × 3 mdx samples × per-baseline frame pins.
+
+u7b scope (per the Stage 2 Exit Report):
+
+  * Three mdx samples — ``01.mdx``, ``02.mdx``, ``03.mdx`` (the baseline
+    full run for each must exit 0 to give step13 equivalence something
+    to compare; ``04.mdx`` / ``05.mdx`` are deliberately excluded per
+    the u7a docstring — adapter_needed / EMPTY_SHELL_NO_CONTENT).
+  * Three ``--override-layout`` axes — ``None`` (auto), ``horizontal-2``,
+    ``vertical-2``. ``None`` exercises the natural layout for that mdx;
+    the explicit pins exercise the layout-locked branch (Step 7-B
+    ``select_layout_preset`` honors ``--override-layout`` per
+    ``src/phase_z2_pipeline.py:5210``). The reuse path (C) inherits the
+    locked layout via the Step 6 snapshot ``layout_preset_pre_override``
+    (u2) — it MUST NOT pass ``--override-layout`` itself (u1 fail-closed
+    guard at ``src/phase_z2_pipeline.py:8181-8199`` rejects layout
+    overrides combined with ``--reuse-from``).
+  * "All 32 frames" coverage axis — each test case discovers ALL pinnable
+    ``(unit_id, frame_template_id)`` pairs from its baseline ``step06_
+    composition_plan.json`` and uses every pin in (B) and (C). Union of
+    pins across the 9 (mdx, layout) cases approximates the V4 catalog
+    coverage; pure Cartesian 3×3×32 = 288 parametrize combos × 3
+    subprocess runs ≈ 864 pipeline runs is impractical even opt-in.
+
+Three subprocess pipeline runs per case (same shape as u7a):
+  (A) baseline full run — no frame overrides — reuse seed.
+  (B) full rerun with the discovered frame overrides — independent
+      control path that does NOT touch ``--reuse-from``.
+  (C) ``--reuse-from <seed_id>`` with the same frame overrides — the
+      reuse path.
+
+Assert: ``step13_render.json`` from (B) and (C) is byte-equal modulo the
+Stage 2 whitelist (only ``run_id`` substring inside
+``data.final_html_path`` is normalized — see u7a docstring for the full
+whitelist rationale).
+
+Opt-in:
+  * ``@pytest.mark.sweep`` — marker registered in ``pyproject.toml``.
+    Default CI must run ``pytest -m 'not sweep'``; explicit opt-in is
+    ``pytest -m sweep tests/test_phase_z2_reuse_from_equivalence_sweep.py``.
+  * If an mdx / layout combo's baseline (A) returns non-zero (e.g., a
+    layout pin incompatible with the mdx's natural unit_count produces
+    a pipeline error), the case is skipped — u7b is a reuse-equivalence
+    test, not a baseline-correctness test (those live elsewhere).
+
+Persisted ``data/user_overrides/<stem>.json`` isolation:
+  IMP-52 (#80) u2 introduced an MDX-keyed persistence fallback at
+  ``src/phase_z2_pipeline.py:8075-8168`` that merges the on-disk file
+  into the subprocess overrides regardless of CLI flags. For mdx stems
+  whose persistence file carries non-frame axes (e.g.,
+  ``data/user_overrides/03.json`` holds ``layout`` + ``zone_geometries``),
+  two orthogonality problems break u7b:
+
+    1. (A) and (B) absorb the persisted ``layout`` / ``zone_geometries``
+       independent of the ``layout_pin`` parameter, collapsing the test
+       matrix — the parametrized layout axis stops being a real axis.
+    2. (C) on the reuse path receives the persisted non-frame axes via
+       the same merge, which the u1 fail-closed guard at
+       ``src/phase_z2_pipeline.py:8181-8199`` rejects with exit code 2
+       before step13 equivalence can be measured.
+
+  The ``_isolated_persisted_overrides`` context manager renames the
+  persistence file out of the way for the duration of each parametrized
+  case (try/finally restore; crash-resistant via a startup recovery
+  branch). The hidden backup filename starts with ``.`` so
+  ``user_overrides_io.validate_key`` (``src/user_overrides_io.py:72``)
+  cannot accidentally re-load it mid-run. The pipeline subprocess does
+  not write the persistence file (writes are gated to the Vite
+  ``/api/user-overrides`` endpoint), so the rename is safe across the
+  three subprocess spawns. The real-world reuse-from × persistence
+  interaction (where ``--reuse-from`` should arguably suppress
+  non-frame persistence injection rather than fail closed) is a
+  follow-up issue candidate, surfaced in this unit's unit_executed
+  Gitea comment.
+"""
+from __future__ import annotations
+
+import contextlib
+import json
+import os
+import subprocess
+import sys
+import uuid
+from pathlib import Path
+
+import pytest
+
+from tests.test_phase_z2_reuse_from_equivalence_unit import (
+    _assert_run_ok,
+    _frame_override_args,
+    _normalize_step13,
+    _read_step_artifact,
+    _spawn_pipeline,
+)
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+SAMPLES_DIR = REPO_ROOT / "samples" / "mdx_batch"
+RUNS_DIR = REPO_ROOT / "data" / "runs"
+OVERRIDES_DIR = REPO_ROOT / "data" / "user_overrides"
+
+MDX_FILES = ("01.mdx", "02.mdx", "03.mdx")
+LAYOUT_PINS = (None, "horizontal-2", "vertical-2")
+
+
+def _unique(prefix: str) -> str:
+    return f"{prefix}_imp43_u7b_{uuid.uuid4().hex[:8]}"
+
+
+@contextlib.contextmanager
+def _isolated_persisted_overrides(mdx_name: str):
+    """Temporarily rename ``data/user_overrides/<stem>.json`` so the
+    three subprocess runs see a clean persistence state.
+
+    Rationale: see module docstring "Persisted ... isolation" section.
+    The pipeline reads the file at
+    ``src/phase_z2_pipeline.py:8098`` via ``load(key)`` which resolves
+    to ``DEFAULT_OVERRIDES_ROOT`` (``src/user_overrides_io.py:54``);
+    moving the file out of the way reduces ``load(key) -> {}`` and
+    prevents the merge from injecting persisted axes.
+
+    Crash recovery: a prior run that crashed between rename and
+    restore would leave ``.<stem>.imp43_u7b_isolation.bak`` next to
+    the missing ``<stem>.json``. The recovery branch at startup
+    restores the backup before proceeding so we never lose the
+    original on a second invocation.
+    """
+    stem = Path(mdx_name).stem
+    src = OVERRIDES_DIR / f"{stem}.json"
+    backup = OVERRIDES_DIR / f".{stem}.imp43_u7b_isolation.bak"
+    if backup.is_file() and not src.is_file():
+        os.replace(backup, src)
+    moved = False
+    if src.is_file():
+        OVERRIDES_DIR.mkdir(parents=True, exist_ok=True)
+        os.replace(src, backup)
+        moved = True
+    try:
+        yield
+    finally:
+        if moved and backup.is_file():
+            os.replace(backup, src)
+
+
+def _discover_all_frame_pins(seed_run_id: str) -> list[tuple[str, str]]:
+    """Discover ALL ``(unit_id, frame_template_id)`` pins from baseline plan.
+
+    Unlike u7a (capped at 2 for fast CI), u7b uses every pin so the sweep
+    naturally exercises the union of frame templates produced across the
+    9 (mdx, layout) cases — the practical realization of the Stage 2
+    plan's "all 32 frames" axis (full Cartesian 3×3×32 would be 288×3 =
+    864 pipeline runs; impractical even opt-in).
+
+    Schema source: ``src/phase_z2_pipeline.py:5530-5560`` — step06 artifact
+    emits ``data.selected_units[*].{source_section_ids, frame_template_id}``;
+    ``unit_id = "+".join(source_section_ids)`` per the ``--override-frame``
+    contract documented at ``src/phase_z2_pipeline.py:7827-7832``.
+    """
+    step06 = _read_step_artifact(seed_run_id, "step06_composition_plan.json")
+    selected_units = step06.get("data", {}).get("selected_units") or []
+    pins: list[tuple[str, str]] = []
+    for u in selected_units:
+        sids = u.get("source_section_ids") or []
+        tpl_id = u.get("frame_template_id")
+        if not isinstance(sids, list) or not sids:
+            continue
+        if not isinstance(tpl_id, str) or not tpl_id:
+            continue
+        unit_id = "+".join(str(s) for s in sids)
+        if unit_id:
+            pins.append((unit_id, tpl_id))
+    return pins
+
+
+@pytest.mark.sweep
+@pytest.mark.parametrize("layout_pin", LAYOUT_PINS)
+@pytest.mark.parametrize("mdx_name", MDX_FILES)
+def test_full_rerun_vs_reuse_from_step13_equivalence_sweep(
+    mdx_name: str, layout_pin: str | None
+) -> None:
+    """Stage 2 §u7b binding contract: across the (mdx × layout) sweep,
+    full rerun (B) with discovered frame overrides and ``--reuse-from``
+    (C) with the same overrides yield byte-equal ``step13_render.json``
+    modulo the u7a whitelist.
+
+    Skip semantics: if baseline (A) fails for a (mdx, layout) combo
+    (e.g., layout pin incompatible with mdx unit_count), the case is
+    skipped — baseline correctness is not the equivalence axis under
+    test here.
+    """
+    mdx_path = SAMPLES_DIR / mdx_name
+    if not mdx_path.is_file():
+        pytest.skip(f"sample missing: {mdx_path}")
+
+    layout_args: list[str] = (
+        [] if layout_pin is None else ["--override-layout", layout_pin]
+    )
+
+    # Isolate any persisted ``data/user_overrides/<stem>.json`` for this
+    # mdx before spawning the three subprocesses; see module docstring
+    # "Persisted ... isolation" section for the orthogonality and
+    # fail-closed-guard rationale.
+    with _isolated_persisted_overrides(mdx_name):
+        # (A) baseline full run — no frame overrides — reuse seed.
+        seed_id = _unique("seed")
+        cp_a = _spawn_pipeline([str(mdx_path), seed_id, *layout_args])
+        if cp_a.returncode != 0:
+            pytest.skip(
+                f"baseline (A) non-zero for mdx={mdx_name} layout={layout_pin} "
+                f"(returncode={cp_a.returncode}); not a reuse-equivalence axis. "
+                f"stderr tail: {cp_a.stderr[-400:]}"
+            )
+
+        pins = _discover_all_frame_pins(seed_id)
+        if not pins:
+            pytest.skip(
+                f"no pinnable (unit_id, frame_template_id) pairs in baseline "
+                f"step06 for mdx={mdx_name} layout={layout_pin}; nothing to "
+                f"exercise on the override-frame surface"
+            )
+        override_args = _frame_override_args(pins)
+
+        # (B) full rerun with the discovered frame overrides — independent control.
+        full_id = _unique("full")
+        cp_b = _spawn_pipeline([str(mdx_path), full_id, *layout_args, *override_args])
+        _assert_run_ok(
+            f"full rerun (B) mdx={mdx_name} layout={layout_pin} pins={len(pins)}",
+            cp_b,
+        )
+
+        # (C) --reuse-from seed with the same frame overrides — reuse path.
+        # NOTE: must NOT pass --override-layout here — u1 fail-closed guard
+        # rejects layout+reuse combination. Layout is restored from the Step 6
+        # snapshot (u2 layout_preset_pre_override) instead.
+        reuse_id = _unique("reuse")
+        cp_c = _spawn_pipeline([
+            str(mdx_path),
+            reuse_id,
+            "--reuse-from", seed_id,
+            *override_args,
+        ])
+        _assert_run_ok(
+            f"reuse rerun (C) mdx={mdx_name} layout={layout_pin} pins={len(pins)}",
+            cp_c,
+        )
+
+        # Step 13 equivalence — apply whitelist + compare byte-for-byte.
+        full_step13 = _read_step_artifact(full_id, "step13_render.json")
+        reuse_step13 = _read_step_artifact(reuse_id, "step13_render.json")
+        full_norm = _normalize_step13(full_step13, full_id)
+        reuse_norm = _normalize_step13(reuse_step13, reuse_id)
+
+        assert full_norm == reuse_norm, (
+            f"step13_render.json equivalence violated for IMP-43 #72 u7b "
+            f"(mdx={mdx_name}, layout={layout_pin}, full={full_id}, "
+            f"reuse={reuse_id}, seed={seed_id}, pins={pins}):\n"
+            f"--- full (normalized) ---\n"
+            f"{json.dumps(full_norm, ensure_ascii=False, indent=2)}\n"
+            f"--- reuse (normalized) ---\n"
+            f"{json.dumps(reuse_norm, ensure_ascii=False, indent=2)}"
+        )
@@ -0,0 +1,204 @@
+"""IMP-43 (#72) u7a — Fast CI equivalence test for full rerun vs ``--reuse-from``.
+
+u7a scope (per the Stage 2 Exit Report):
+
+  * One mdx (``samples/mdx_batch/02.mdx``), one layout (auto), two
+    ``--override-frame`` pins self-discovered from the baseline's
+    ``step06_composition_plan.json`` (each pin re-states the unit's
+    own ``frame_template_id`` — semantically a no-op, but it
+    exercises the full ``--override-frame`` CLI surface through both
+    paths, satisfying the "two frames" axis of the Stage 2 plan).
+  * Three subprocess pipeline runs:
+        (A) baseline full run — no overrides — reuse seed
+        (B) full rerun with the two ``--override-frame`` pins — the
+            independent control path that does NOT touch ``--reuse-from``
+        (C) ``--reuse-from <seed_id>`` with the same two
+            ``--override-frame`` pins — the reuse path
+  * Assert: ``step13_render.json`` from (B) and (C) is byte-equal modulo
+    the Stage 2 whitelist — only ``run_id`` (as a substring of
+    ``data.final_html_path``), ``timestamps``, and ``prev_run_id`` may
+    legitimately differ. ``step13_render.json`` has no timestamps and
+    no ``prev_run_id`` field (the latter surfaces via the separate
+    ``_reuse_marker.json`` sidecar instead — out of scope for this
+    step13 equivalence axis), so the only effective normalization
+    target is the ``run_id`` substring inside ``data.final_html_path``.
+
+Per Stage 2 plan: the sweep equivalence coverage (3 layouts × 3 mdx ×
+all 32 frames) lives in u7b under ``pytest.mark.sweep`` — u7a stays
+fast (3 pipeline runs on a single small mdx) so it can run in default
+CI without an opt-in marker.
+
+Why mdx02:
+  * ``test_pipeline_smoke_imp85.py::test_non_vp_smoke_runs_clean`` already
+    pins mdx02 as a non-VP exit-0 path (the baseline (A) run must
+    exit 0 for the equivalence axis to even have something to
+    compare against).
+  * mdx04 / mdx05 are deliberately excluded — mdx04 routes zones to
+    ``adapter_needed`` per IMP-#85 u1 and mdx05 exits 1 with
+    ``EMPTY_SHELL_NO_CONTENT`` per IMP-#87 u3, neither of which gives
+    a stable step13 equivalence surface for a fast CI lock.
+"""
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+import uuid
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+SAMPLES_DIR = REPO_ROOT / "samples" / "mdx_batch"
+RUNS_DIR = REPO_ROOT / "data" / "runs"
+MDX_FILENAME = "02.mdx"
+
+
+def _unique_run_id(prefix: str) -> str:
+    return f"{prefix}_imp43_u7a_{uuid.uuid4().hex[:8]}"
+
+
+def _spawn_pipeline(extra_args: list[str], timeout: int = 600) -> subprocess.CompletedProcess:
+    """Spawn ``python -m src.phase_z2_pipeline <args>`` and capture I/O."""
+    return subprocess.run(
+        [sys.executable, "-m", "src.phase_z2_pipeline", *extra_args],
+        capture_output=True,
+        text=True,
+        timeout=timeout,
+        cwd=str(REPO_ROOT),
+    )
+
+
+def _assert_run_ok(label: str, cp: subprocess.CompletedProcess) -> None:
+    assert cp.returncode == 0, (
+        f"{label} pipeline returncode={cp.returncode}\n"
+        f"--- stderr tail ---\n{cp.stderr[-2000:]}\n"
+        f"--- stdout tail ---\n{cp.stdout[-2000:]}"
+    )
+
+
+def _read_step_artifact(run_id: str, fname: str) -> dict:
+    p = RUNS_DIR / run_id / "phase_z2" / "steps" / fname
+    assert p.is_file(), f"missing artifact: {p}"
+    return json.loads(p.read_text(encoding="utf-8"))
+
+
+def _discover_two_frame_pins(seed_run_id: str) -> list[tuple[str, str]]:
+    """Self-discover two ``(unit_id, frame_template_id)`` pins from the
+    baseline's ``step06_composition_plan.json``.
+
+    Schema source: ``src/phase_z2_pipeline.py`` ~L5530-L5560 — the step06
+    artifact emits ``data.selected_units[*].{source_section_ids,
+    frame_template_id}``. ``unit_id`` is derived as
+    ``"+".join(source_section_ids)`` per the
+    ``--override-frame UNIT_ID=TEMPLATE_ID`` contract documented at
+    ``src/phase_z2_pipeline.py:7827-7832`` and computed by ``_unit_id``
+    at ``src/phase_z2_pipeline.py:2328``. Pinning the unit's own
+    template is a no-op semantically but exercises the
+    ``--override-frame`` CLI surface end-to-end in both (B) and (C).
+    """
+    step06 = _read_step_artifact(seed_run_id, "step06_composition_plan.json")
+    selected_units = step06.get("data", {}).get("selected_units") or []
+    pinnable: list[tuple[str, str]] = []
+    for u in selected_units:
+        sids = u.get("source_section_ids") or []
+        tpl_id = u.get("frame_template_id")
+        if not isinstance(sids, list) or not sids:
+            continue
+        if not isinstance(tpl_id, str) or not tpl_id:
+            continue
+        unit_id = "+".join(str(s) for s in sids)
+        if not unit_id:
+            continue
+        pinnable.append((unit_id, tpl_id))
+        if len(pinnable) >= 2:
+            break
+    assert len(pinnable) >= 2, (
+        f"baseline {seed_run_id} step06_composition_plan.json must expose "
+        f">= 2 (unit_id, frame_template_id) pairs for the u7a two-frames "
+        f"axis; got {pinnable}"
+    )
+    return pinnable
+
+
+def _frame_override_args(pins: list[tuple[str, str]]) -> list[str]:
+    out: list[str] = []
+    for unit_id, tpl_id in pins:
+        out.extend(["--override-frame", f"{unit_id}={tpl_id}"])
+    return out
+
+
+def _normalize_step13(payload: dict, run_id: str) -> dict:
+    """Apply the Stage 2 equivalence whitelist to step13_render.json.
+
+    Whitelist axes (Stage 2 plan §u7a):
+      * ``run_id``      — appears only as a substring of
+                          ``data.final_html_path`` in the step13 schema
+                          (``src/phase_z2_pipeline.py:7174-7192``).
+      * ``timestamps``  — ``_write_step_artifact``
+                          (``src/phase_z2_pipeline.py:3826``) does not
+                          stamp a timestamp on the payload, so no
+                          normalization is needed for this axis.
+      * ``prev_run_id`` — surfaces via ``_reuse_marker.json`` (separate
+                          sidecar), NOT via step13_render.json. No
+                          normalization needed on the step13 surface.
+
+    Returns a deep copy of ``payload`` with the ``run_id`` substring of
+    ``data.final_html_path`` replaced by the sentinel ``<RUN_ID>`` so
+    the (B) and (C) step13 payloads can be compared byte-for-byte.
+    """
+    normalized = json.loads(json.dumps(payload, ensure_ascii=False))
+    data = normalized.get("data")
+    if isinstance(data, dict):
+        fhp = data.get("final_html_path")
+        if isinstance(fhp, str) and run_id in fhp:
+            data["final_html_path"] = fhp.replace(run_id, "<RUN_ID>")
+    return normalized
+
+
+def test_full_rerun_vs_reuse_from_step13_equivalence_one_mdx_two_frames() -> None:
+    """Stage 2 §u7a binding contract: full rerun (B) with two
+    ``--override-frame`` pins and ``--reuse-from`` (C) with the same
+    pins yield byte-equal ``step13_render.json`` modulo the whitelist.
+    """
+    mdx_path = SAMPLES_DIR / MDX_FILENAME
+    assert mdx_path.is_file(), f"sample missing: {mdx_path}"
+
+    # (A) baseline full run — no overrides — reuse seed.
+    seed_id = _unique_run_id("seed")
+    cp_a = _spawn_pipeline([str(mdx_path), seed_id])
+    _assert_run_ok("baseline (A)", cp_a)
+
+    # Self-discover two (unit_id, frame_template_id) pins.
+    pins = _discover_two_frame_pins(seed_id)
+    override_args = _frame_override_args(pins)
+
+    # (B) full rerun with the two frame overrides — independent control.
+    full_id = _unique_run_id("full")
+    cp_b = _spawn_pipeline([str(mdx_path), full_id, *override_args])
+    _assert_run_ok("full rerun (B)", cp_b)
+
+    # (C) --reuse-from seed with the same frame overrides — reuse path.
+    reuse_id = _unique_run_id("reuse")
+    cp_c = _spawn_pipeline([
+        str(mdx_path),
+        reuse_id,
+        "--reuse-from", seed_id,
+        *override_args,
+    ])
+    _assert_run_ok("reuse rerun (C)", cp_c)
+
+    # Step 13 equivalence — apply whitelist + compare byte-for-byte.
+    full_step13 = _read_step_artifact(full_id, "step13_render.json")
+    reuse_step13 = _read_step_artifact(reuse_id, "step13_render.json")
+    full_norm = _normalize_step13(full_step13, full_id)
+    reuse_norm = _normalize_step13(reuse_step13, reuse_id)
+
+    assert full_norm == reuse_norm, (
+        "step13_render.json equivalence violated for IMP-43 #72 u7a "
+        f"(full={full_id}, reuse={reuse_id}, seed={seed_id}, pins={pins}):\n"
+        f"--- full (normalized) ---\n"
+        f"{json.dumps(full_norm, ensure_ascii=False, indent=2)}\n"
+        f"--- reuse (normalized) ---\n"
+        f"{json.dumps(reuse_norm, ensure_ascii=False, indent=2)}"
+    )
@@ -0,0 +1,748 @@
+"""IMP-43 (#72) u4b — fail-closed wrapper tests for ``--reuse-from``.
+
+u4b scope (per the Stage 2 Exit Report):
+
+- Translate the u4 raise surface (``FileNotFoundError`` /
+  ``SnapshotValidationError`` / ``json.JSONDecodeError`` / ``OSError``)
+  into the CLI fail-closed contract: stderr message + ``sys.exit(2)``.
+- Add the ``prev_run_dir == new_run_dir`` accidental-write guard BEFORE
+  any copy attempt (prev_run_dir must stay read-only).
+- Add the missing-prev-run-dir surface (clean axis, not raw stack).
+- Surface ``mdx_sha256 mismatch`` as its OWN axis (distinct from
+  generic snapshot validation failures).
+
+The signature threading + the in-``run_phase_z2_mvp1`` branch that
+invokes the wrapper land in u5. u4b adds the wrapper function only.
+
+Tested surface (``src/phase_z2_pipeline.py``):
+  * ``execute_reuse_from_or_fail_closed``
+  * ``_abort_reuse_from``
+  * ``_paths_equivalent``
+  * ``REUSE_FAIL_CLOSED_AXES`` (closed enum)
+"""
+from __future__ import annotations
+
+import hashlib
+import json
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Optional
+
+import pytest
+
+import src.phase_z2_pipeline as _pz2
+from src.phase_z2_reuse_snapshot import (
+    SNAPSHOT_FILENAME,
+    SNAPSHOT_VERSION,
+    build_snapshot,
+)
+
+
+# -- synthetic snapshot inputs (mirror u4 test fixture) ------------------
+
+
+@dataclass
+class _Section:
+    section_id: str
+    section_num: int
+    title: str
+    raw_content: str
+    heading_number: Optional[str] = None
+    v4_alias_keys: list = field(default_factory=list)
+    sub_sections: list = field(default_factory=list)
+
+
+@dataclass
+class _V4Candidate:
+    template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+
+
+@dataclass
+class _Unit:
+    source_section_ids: list
+    merge_type: str
+    frame_template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+    phase_z_status: str
+    raw_content: str
+    title: str
+    score: float
+    v4_rank: Optional[int] = 1
+    selection_path: str = "rank_1"
+    fallback_reason: Optional[str] = None
+    rationale: dict = field(default_factory=dict)
+    auto_selectable: bool = True
+    filter_reasons: list = field(default_factory=list)
+    notes: list = field(default_factory=list)
+    v4_candidates: list = field(default_factory=list)
+    provisional: bool = False
+
+
+def _mdx_text() -> str:
+    return "# Slide\n\n## 03-1 DX status\n\n- bullet one\n- bullet two\n"
+
+
+def _build_canonical_snapshot(*, mdx_source_text: Optional[str] = None) -> dict:
+    text = mdx_source_text if mdx_source_text is not None else _mdx_text()
+    cand = _V4Candidate(
+        template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+    )
+    section = _Section(
+        section_id="03-1",
+        section_num=1,
+        title="DX status",
+        raw_content="- bullet one\n- bullet two",
+        heading_number="3.1",
+        v4_alias_keys=["03-1.1"],
+    )
+    unit = _Unit(
+        source_section_ids=["03-1"],
+        merge_type="single",
+        frame_template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+        phase_z_status="auto_renderable",
+        raw_content="- bullet one\n- bullet two",
+        title="DX status",
+        score=0.91,
+        v4_candidates=[cand],
+    )
+    return build_snapshot(
+        mdx_sha256=hashlib.sha256(text.encode("utf-8")).hexdigest(),
+        slide_title="Slide",
+        slide_footer=None,
+        sections=[section],
+        stage0_adapter_diagnostics={"used": True, "fallback_reason": None},
+        stage0_normalized_assets={"popups": [], "images": [], "tables": []},
+        v4_evidence=[],
+        layout_preset_pre_override="single",
+        units=[unit],
+        comp_debug={},
+        v4_fallback_traces={},
+        ai_preflight={"enabled": False, "skipped": True},
+    )
+
+
+def _seed_prev_run_dir(prev_run_dir: Path, *, snapshot: dict) -> None:
+    (prev_run_dir / "steps").mkdir(parents=True, exist_ok=True)
+    for fname in _pz2._REUSE_STEP_ARTIFACTS:
+        (prev_run_dir / "steps" / fname).write_text(
+            f'{{"name": "{fname}"}}'
+            if fname.endswith(".json")
+            else "raw mdx body bytes",
+            encoding="utf-8",
+        )
+    (prev_run_dir / SNAPSHOT_FILENAME).write_text(
+        json.dumps(snapshot, ensure_ascii=False, indent=2),
+        encoding="utf-8",
+    )
+
+
+# -- REUSE_FAIL_CLOSED_AXES vocab lock ------------------------------------
+
+
+def test_fail_closed_axes_is_closed_enum():
+    """The nine axes are the entire fail-closed vocabulary; if a new
+    axis lands without test coverage update, this lock breaks.
+
+    ``reuse_copy_os_error`` / ``snapshot_read_os_error`` were added in
+    the Codex #6 stage_3_edit rewind to cover OSError != FNF that the
+    earlier u4b implementation let escape as a raw traceback.
+    """
+    assert _pz2.REUSE_FAIL_CLOSED_AXES == frozenset({
+        "prev_run_dir_missing",
+        "prev_run_dir_equals_new_run_dir",
+        "reuse_artifact_missing",
+        "reuse_copy_os_error",
+        "snapshot_missing_after_copy",
+        "snapshot_corrupt_json",
+        "snapshot_read_os_error",
+        "mdx_sha256_mismatch",
+        "snapshot_validation_failed",
+    })
+
+
+# -- _abort_reuse_from -----------------------------------------------------
+
+
+def test_abort_reuse_from_exits_with_code_two(capsys):
+    with pytest.raises(SystemExit) as ei:
+        _pz2._abort_reuse_from(
+            axis="prev_run_dir_missing",
+            value="never_existed",
+            path="D:/nope",
+            upstream="--reuse-from CLI argument",
+        )
+    assert ei.value.code == 2
+
+
+def test_abort_reuse_from_stderr_contains_value_path_upstream(capsys):
+    with pytest.raises(SystemExit):
+        _pz2._abort_reuse_from(
+            axis="prev_run_dir_missing",
+            value="never_existed",
+            path="D:/nope",
+            upstream="--reuse-from CLI argument",
+        )
+    err = capsys.readouterr().err
+    assert "prev_run_dir_missing" in err
+    assert "value:" in err
+    assert "path:" in err
+    assert "upstream:" in err
+    assert "never_existed" in err
+    assert "D:/nope" in err
+    assert "--reuse-from CLI argument" in err
+
+
+def test_abort_reuse_from_includes_reason_when_exc_passed(capsys):
+    """The optional ``exc`` field surfaces the underlying type +
+    message so operators can distinguish e.g. JSONDecodeError line/col
+    info from a generic 'snapshot broken'."""
+    try:
+        raise ValueError("schema_version mismatch: expected 1, got 99")
+    except ValueError as exc:
+        with pytest.raises(SystemExit):
+            _pz2._abort_reuse_from(
+                axis="snapshot_validation_failed",
+                value=str(exc),
+                path="D:/some/path",
+                upstream="validate_snapshot",
+                exc=exc,
+            )
+    err = capsys.readouterr().err
+    assert "reason:" in err
+    assert "ValueError" in err
+    assert "schema_version mismatch" in err
+
+
+def test_abort_reuse_from_rejects_unknown_axis():
+    """Unknown axis = programmer error, not user error; must trip
+    AssertionError, not silently emit a malformed stderr line."""
+    with pytest.raises(AssertionError):
+        _pz2._abort_reuse_from(
+            axis="totally_made_up_axis",
+            value="x",
+            path="y",
+            upstream="z",
+        )
+
+
+# -- _paths_equivalent -----------------------------------------------------
+
+
+def test_paths_equivalent_same_path_returns_true(tmp_path: Path):
+    a = tmp_path / "x" / "y"
+    a.mkdir(parents=True)
+    assert _pz2._paths_equivalent(a, a) is True
+
+
+def test_paths_equivalent_different_paths_returns_false(tmp_path: Path):
+    a = tmp_path / "alpha"
+    b = tmp_path / "beta"
+    a.mkdir()
+    b.mkdir()
+    assert _pz2._paths_equivalent(a, b) is False
+
+
+def test_paths_equivalent_handles_nonexistent_paths(tmp_path: Path):
+    """``Path.resolve(strict=False)`` should still normalize ``..``
+    even when the leaf does not yet exist (new_run_dir before mkdir)."""
+    a = tmp_path / "new_run" / "phase_z2"
+    b = tmp_path / "new_run" / "phase_z2"
+    assert _pz2._paths_equivalent(a, b) is True
+
+
+# -- execute_reuse_from_or_fail_closed: happy path -----------------------
+
+
+def test_happy_path_returns_prev_run_dir_copied_snapshot(
+    tmp_path: Path, monkeypatch
+):
+    text = _mdx_text()
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_id_001"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+
+    snap = _build_canonical_snapshot(mdx_source_text=text)
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    rv = _pz2.execute_reuse_from_or_fail_closed(
+        reuse_from=prev_run_id,
+        new_run_dir=new_run_dir,
+        mdx_source_text=text,
+    )
+    prev_dir_ret, copied_ret, snap_ret = rv
+
+    assert prev_dir_ret == prev_run_dir
+    assert SNAPSHOT_FILENAME in copied_ret
+    assert snap_ret["schema_version"] == SNAPSHOT_VERSION
+    # snapshot wrapper survives (value/source_path/upstream_step)
+    assert snap_ret["slide_title"]["value"] == "Slide"
+
+
+# -- prev_run_dir_missing axis --------------------------------------------
+
+
+def test_prev_run_dir_missing_aborts(tmp_path: Path, monkeypatch, capsys):
+    runs_root = tmp_path / "runs"
+    runs_root.mkdir()
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from="does_not_exist_anywhere",
+            new_run_dir=tmp_path / "new" / "phase_z2",
+            mdx_source_text=_mdx_text(),
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "prev_run_dir_missing" in err
+    assert "does_not_exist_anywhere" in err
+
+
+# -- prev_run_dir_equals_new_run_dir axis ---------------------------------
+
+
+def test_prev_run_dir_equals_new_run_dir_aborts(
+    tmp_path: Path, monkeypatch, capsys
+):
+    """Accidental collision: if the new run_id resolves to the same
+    phase_z2 dir as prev_run_id, the copy step would overwrite
+    prev_run_dir in place. u4b must reject BEFORE the copy attempt."""
+    runs_root = tmp_path / "runs"
+    prev_run_id = "shared_run_id"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    # new_run_dir resolves to the SAME phase_z2 dir as prev_run_dir.
+    new_run_dir = prev_run_dir
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "prev_run_dir_equals_new_run_dir" in err
+
+
+def test_prev_run_dir_equals_new_run_dir_does_not_mutate_prev(
+    tmp_path: Path, monkeypatch
+):
+    """Critical RO guarantee — the abort must fire BEFORE
+    ``_copy_reuse_artifacts_from_prev_run`` runs, so the seeded prev
+    artifact bytes survive untouched."""
+    runs_root = tmp_path / "runs"
+    prev_run_id = "shared_run_id"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    sentinel_text = '{"name": "step02_normalized.json"}'
+    target = prev_run_dir / "steps" / "step02_normalized.json"
+    assert target.read_text(encoding="utf-8") == sentinel_text
+
+    with pytest.raises(SystemExit):
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=prev_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    # prev_run_dir bytes still intact.
+    assert target.read_text(encoding="utf-8") == sentinel_text
+
+
+# -- reuse_artifact_missing axis ------------------------------------------
+
+
+def test_reuse_artifact_missing_aborts(tmp_path: Path, monkeypatch, capsys):
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_001"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    # Remove one required step file → triggers FileNotFoundError in
+    # _copy_reuse_artifacts_from_prev_run.
+    (prev_run_dir / "steps" / "step05_v4_evidence.json").unlink()
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "reuse_artifact_missing" in err
+    assert "step05_v4_evidence.json" in err
+    assert "reason:" in err
+    assert "FileNotFoundError" in err
+
+
+def test_reuse_artifact_missing_snapshot_sidecar(
+    tmp_path: Path, monkeypatch, capsys
+):
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_002"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    (prev_run_dir / SNAPSHOT_FILENAME).unlink()
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "reuse_artifact_missing" in err
+    assert SNAPSHOT_FILENAME in err
+
+
+# -- snapshot_corrupt_json axis -------------------------------------------
+
+
+def test_snapshot_corrupt_json_aborts(tmp_path: Path, monkeypatch, capsys):
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_corrupt"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    # Overwrite the snapshot with invalid JSON; copy will succeed,
+    # validate_snapshot will fail with JSONDecodeError (raised inside
+    # _load_and_validate_reuse_snapshot before validate_snapshot).
+    (prev_run_dir / SNAPSHOT_FILENAME).write_text(
+        "{ not valid json", encoding="utf-8"
+    )
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "snapshot_corrupt_json" in err
+    assert SNAPSHOT_FILENAME in err
+    assert "JSONDecodeError" in err
+
+
+# -- mdx_sha256_mismatch axis (own surface) -------------------------------
+
+
+def test_mdx_sha256_mismatch_aborts_with_own_axis(
+    tmp_path: Path, monkeypatch, capsys
+):
+    """Distinct from generic snapshot_validation_failed — operator
+    must be able to tell 'wrong --mdx-path for this prev_run_id' apart
+    from 'snapshot file is broken'."""
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_diff_mdx"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+
+    text_a = "# Slide A\n"
+    text_b = "# Slide B (different bytes)\n"
+    snap = _build_canonical_snapshot(mdx_source_text=text_a)
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=text_b,
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "mdx_sha256_mismatch" in err
+    # Must NOT be reported as generic snapshot_validation_failed —
+    # the mdx-sha case has its own axis.
+    assert "snapshot_validation_failed" not in err
+    assert "mdx_source_text" in err or "mdx_sha256" in err
+
+
+# -- snapshot_validation_failed axis --------------------------------------
+
+
+def test_snapshot_validation_failed_schema_version_aborts(
+    tmp_path: Path, monkeypatch, capsys
+):
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_schema_mismatch"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+
+    text = _mdx_text()
+    snap = _build_canonical_snapshot(mdx_source_text=text)
+    snap["schema_version"] = SNAPSHOT_VERSION + 1
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=text,
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "snapshot_validation_failed" in err
+    assert "schema_version" in err
+    # NOT the mdx-sha axis — separate fingerprint.
+    assert "mdx_sha256_mismatch" not in err
+
+
+def test_snapshot_validation_failed_missing_required_key_aborts(
+    tmp_path: Path, monkeypatch, capsys
+):
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_missing_key"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+
+    text = _mdx_text()
+    snap = _build_canonical_snapshot(mdx_source_text=text)
+    del snap["units"]
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=text,
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "snapshot_validation_failed" in err
+    assert "units" in err
+
+
+# -- reuse_copy_os_error axis (OSError != FileNotFoundError) -------------
+
+
+def test_copy_os_error_aborts_with_own_axis(
+    tmp_path: Path, monkeypatch, capsys
+):
+    """Codex #6 stage_3_edit fixup — OSError raised inside
+    ``_copy_reuse_artifacts_from_prev_run`` (e.g. PermissionError on
+    the destination, OSError(errno.EXDEV) on cross-device copy) must
+    translate to fail-closed (stderr + SystemExit(2)) instead of
+    escaping as a raw traceback.
+
+    Implementation must catch ``FileNotFoundError`` BEFORE the bare
+    ``OSError`` handler (FNF is a subclass of OSError), otherwise the
+    missing-artifact case would be mis-bucketed under
+    ``reuse_copy_os_error``.
+    """
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_perm_denied"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    def _raise_perm(src, dst, *args, **kwargs):
+        raise PermissionError(f"simulated permission denied: {dst}")
+
+    monkeypatch.setattr(_pz2.shutil, "copyfile", _raise_perm)
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "reuse_copy_os_error" in err
+    assert "value:" in err
+    assert "path:" in err
+    assert "upstream:" in err
+    assert "reason:" in err
+    assert "PermissionError" in err
+    assert "simulated permission denied" in err
+    # Must NOT be mis-bucketed as the missing-artifact case.
+    assert "reuse_artifact_missing" not in err
+
+
+def test_copy_filenotfounderror_still_uses_artifact_missing_axis(
+    tmp_path: Path, monkeypatch, capsys
+):
+    """Subclass ordering regression guard — ``FileNotFoundError`` IS an
+    ``OSError`` subclass. If the bare-OSError handler ever moves above
+    the FNF handler, the missing-artifact case would be mis-bucketed
+    under ``reuse_copy_os_error``; this test pins the dispatch.
+    """
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_fnf_ordering"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    (prev_run_dir / "steps" / "step05_v4_evidence.json").unlink()
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    with pytest.raises(SystemExit):
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    err = capsys.readouterr().err
+    assert "reuse_artifact_missing" in err
+    assert "reuse_copy_os_error" not in err
+
+
+# -- snapshot_read_os_error axis (OSError != FileNotFoundError) ----------
+
+
+def test_snapshot_read_os_error_aborts_with_own_axis(
+    tmp_path: Path, monkeypatch, capsys
+):
+    """OSError raised inside ``_load_and_validate_reuse_snapshot``
+    (e.g. PermissionError on ``Path.read_text``, IsADirectoryError if
+    the snapshot path resolves to a directory after copy) must
+    translate to fail-closed instead of escaping as a raw traceback.
+    """
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_snapshot_perm"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    def _raise_perm(*args, **kwargs):
+        raise PermissionError("simulated read denied on snapshot")
+
+    monkeypatch.setattr(
+        _pz2, "_load_and_validate_reuse_snapshot", _raise_perm
+    )
+
+    with pytest.raises(SystemExit) as ei:
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    assert ei.value.code == 2
+    err = capsys.readouterr().err
+    assert "snapshot_read_os_error" in err
+    assert "value:" in err
+    assert "path:" in err
+    assert "upstream:" in err
+    assert "reason:" in err
+    assert "PermissionError" in err
+    assert "simulated read denied on snapshot" in err
+    # Must NOT be mis-bucketed as missing-after-copy or corrupt-json.
+    assert "snapshot_missing_after_copy" not in err
+    assert "snapshot_corrupt_json" not in err
+
+
+def test_snapshot_filenotfounderror_still_uses_missing_after_copy_axis(
+    tmp_path: Path, monkeypatch, capsys
+):
+    """Subclass ordering regression guard for the load surface — FNF
+    must keep its own ``snapshot_missing_after_copy`` axis even though
+    the new bare-OSError branch sits below it.
+    """
+    runs_root = tmp_path / "runs"
+    prev_run_id = "prev_run_load_fnf_ordering"
+    prev_run_dir = runs_root / prev_run_id / "phase_z2"
+    new_run_dir = tmp_path / "new" / "phase_z2"
+    snap = _build_canonical_snapshot()
+    _seed_prev_run_dir(prev_run_dir, snapshot=snap)
+    monkeypatch.setattr(_pz2, "RUNS_DIR", runs_root)
+
+    def _raise_fnf(*args, **kwargs):
+        raise FileNotFoundError("simulated FNF on snapshot read")
+
+    monkeypatch.setattr(
+        _pz2, "_load_and_validate_reuse_snapshot", _raise_fnf
+    )
+
+    with pytest.raises(SystemExit):
+        _pz2.execute_reuse_from_or_fail_closed(
+            reuse_from=prev_run_id,
+            new_run_dir=new_run_dir,
+            mdx_source_text=_mdx_text(),
+        )
+    err = capsys.readouterr().err
+    assert "snapshot_missing_after_copy" in err
+    assert "snapshot_read_os_error" not in err
+
+
+# -- module surface anchor ------------------------------------------------
+
+
+def test_pipeline_exposes_u4b_surface():
+    """u5 wires ``execute_reuse_from_or_fail_closed`` into the entry
+    point — the public callable + the closed-axis vocabulary must
+    remain module-level attributes."""
+    for name in (
+        "execute_reuse_from_or_fail_closed",
+        "_abort_reuse_from",
+        "_paths_equivalent",
+        "REUSE_FAIL_CLOSED_AXES",
+    ):
+        assert hasattr(_pz2, name), f"u4b surface missing: {name}"
+
+
+def test_pipeline_run_signature_reuse_from_threaded_after_u5():
+    """u5 has now threaded ``reuse_from`` into ``run_phase_z2_mvp1`` as
+    a keyword-only parameter with default ``None``. The previous
+    ``until_u5`` lock has flipped — this forward-direction lock
+    ensures the kwarg never silently drifts (positional promotion,
+    default change to a string, kind change). Mirror of the
+    equivalent lock in test_phase_z2_reuse_from_entry.py and
+    test_phase_z2_cli_reuse_from.py — kept in this file too so the
+    fail-closed regression suite is self-contained."""
+    import inspect
+
+    sig = inspect.signature(_pz2.run_phase_z2_mvp1)
+    assert "reuse_from" in sig.parameters, (
+        "u5 must thread reuse_from into run_phase_z2_mvp1 — kwarg missing. "
+        f"current params: {list(sig.parameters)}"
+    )
+    param = sig.parameters["reuse_from"]
+    assert param.kind is inspect.Parameter.KEYWORD_ONLY, (
+        f"reuse_from must be keyword-only (after the ``*`` barrier); "
+        f"got kind={param.kind}"
+    )
+    assert param.default is None, (
+        f"reuse_from must default to None to preserve pre-u5 behaviour; "
+        f"got default={param.default!r}"
+    )
@@ -0,0 +1,493 @@
+"""IMP-43 (#72) u2 — unit tests for ``src.phase_z2_reuse_snapshot``.
+
+Scope mirror of the production module (Stage 2 u2):
+
+* ``build_snapshot`` shape, provenance, JSON round-trip, required keys.
+* ``serialize_section`` / ``serialize_unit`` field preservation, including
+  the duck-typed ``v4_candidates`` shape (template_id / frame_id /
+  frame_number / confidence / label).
+* ``validate_snapshot`` fail-closed paths: non-dict input, schema
+  version mismatch, missing/empty/non-string ``mdx_sha256``, sha
+  mismatch, missing required keys, unwrapped wrapper, wrapper missing
+  a provenance field.
+* Module-level constants exposed for u3 / u4 / u4b consumers.
+
+The tests use synthetic duck-typed dataclasses so the snapshot module's
+external surface is exercised without coupling to the production
+``MdxSection`` / ``CompositionUnit`` / ``V4Match`` dataclass layouts.
+That mirrors the production module's intentional duck-typing (no
+imports from ``phase_z2_pipeline`` / ``phase_z2_composition``).
+"""
+from __future__ import annotations
+
+import json
+from dataclasses import dataclass, field
+from typing import Any, Optional
+
+import pytest
+
+from src.phase_z2_reuse_snapshot import (
+    REQUIRED_TOP_LEVEL_KEYS,
+    SNAPSHOT_FILENAME,
+    SNAPSHOT_VERSION,
+    SnapshotValidationError,
+    build_snapshot,
+    serialize_section,
+    serialize_unit,
+    validate_snapshot,
+)
+
+
+# -- synthetic duck-typed inputs ------------------------------------------
+
+
+@dataclass
+class _Section:
+    section_id: str
+    section_num: int
+    title: str
+    raw_content: str
+    heading_number: Optional[str] = None
+    v4_alias_keys: list = field(default_factory=list)
+    sub_sections: list = field(default_factory=list)
+
+
+@dataclass
+class _V4Candidate:
+    template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+    v4_rank: Optional[int] = None
+
+
+@dataclass
+class _Unit:
+    source_section_ids: list
+    merge_type: str
+    frame_template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+    phase_z_status: str
+    raw_content: str
+    title: str
+    score: float
+    v4_rank: Optional[int] = 1
+    selection_path: str = "rank_1"
+    fallback_reason: Optional[str] = None
+    rationale: dict = field(default_factory=dict)
+    auto_selectable: bool = True
+    filter_reasons: list = field(default_factory=list)
+    notes: list = field(default_factory=list)
+    v4_candidates: list = field(default_factory=list)
+    provisional: bool = False
+
+
+def _make_section(**overrides: Any) -> _Section:
+    base = dict(
+        section_id="03-1",
+        section_num=1,
+        title="DX status",
+        raw_content="- bullet one\n- bullet two",
+    )
+    base.update(overrides)
+    return _Section(**base)
+
+
+def _make_unit(**overrides: Any) -> _Unit:
+    cand = _V4Candidate(
+        template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+    )
+    base: dict[str, Any] = dict(
+        source_section_ids=["03-1"],
+        merge_type="single",
+        frame_template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+        phase_z_status="auto_renderable",
+        raw_content="- bullet one\n- bullet two",
+        title="DX status",
+        score=0.91,
+        v4_candidates=[cand],
+    )
+    base.update(overrides)
+    return _Unit(**base)
+
+
+def _make_build_kwargs(**overrides: Any) -> dict[str, Any]:
+    kwargs: dict[str, Any] = dict(
+        mdx_sha256="a" * 64,
+        slide_title="Title",
+        slide_footer="Footer",
+        sections=[_make_section()],
+        stage0_adapter_diagnostics={"used": True, "fallback_reason": None},
+        stage0_normalized_assets={"popups": [], "images": [], "tables": []},
+        v4_evidence=[{"section_id": "03-1", "v4_candidates": []}],
+        layout_preset_pre_override="horizontal-2",
+        units=[_make_unit()],
+        comp_debug={"v4_fallback_summary": {"fallback_used_count": 0}},
+        v4_fallback_traces={"03-1": {"selection_path": "rank_1"}},
+        ai_preflight={"enabled": False, "skipped": True},
+    )
+    kwargs.update(overrides)
+    return kwargs
+
+
+# -- module constants -----------------------------------------------------
+
+
+def test_snapshot_filename_constant():
+    assert SNAPSHOT_FILENAME == "_reuse_snapshot.json"
+
+
+def test_snapshot_version_is_positive_int():
+    assert isinstance(SNAPSHOT_VERSION, int)
+    assert SNAPSHOT_VERSION >= 1
+
+
+def test_required_keys_include_contract_and_payload():
+    # Bare contract / integrity keys.
+    assert "schema_version" in REQUIRED_TOP_LEVEL_KEYS
+    assert "mdx_sha256" in REQUIRED_TOP_LEVEL_KEYS
+    # Payload axes per Stage 2 plan.
+    for k in (
+        "slide_title",
+        "slide_footer",
+        "sections",
+        "stage0_adapter_diagnostics",
+        "stage0_normalized_assets",
+        "v4_evidence",
+        "layout_preset_pre_override",
+        "units",
+        "comp_debug",
+        "v4_fallback_traces",
+        "ai_preflight",
+    ):
+        assert k in REQUIRED_TOP_LEVEL_KEYS, f"missing from REQUIRED_TOP_LEVEL_KEYS: {k}"
+
+
+# -- build_snapshot -------------------------------------------------------
+
+
+def test_build_snapshot_round_trips_through_json():
+    snap = build_snapshot(**_make_build_kwargs())
+    payload = json.dumps(snap)
+    loaded = json.loads(payload)
+    assert loaded["schema_version"] == SNAPSHOT_VERSION
+    assert loaded["mdx_sha256"] == "a" * 64
+
+
+def test_build_snapshot_has_all_required_keys():
+    snap = build_snapshot(**_make_build_kwargs())
+    for key in REQUIRED_TOP_LEVEL_KEYS:
+        assert key in snap, f"build_snapshot missing required key: {key}"
+
+
+def test_build_snapshot_bare_keys_are_unwrapped_scalars():
+    snap = build_snapshot(**_make_build_kwargs())
+    assert snap["schema_version"] == SNAPSHOT_VERSION
+    assert snap["mdx_sha256"] == "a" * 64
+    # bare keys MUST NOT be wrapped — u4b mdx_sha256 check reads directly.
+    assert not isinstance(snap["schema_version"], dict)
+    assert not isinstance(snap["mdx_sha256"], dict)
+
+
+def test_build_snapshot_provenance_wrapper_shape():
+    snap = build_snapshot(**_make_build_kwargs())
+    bare = {"schema_version", "mdx_sha256"}
+    for key, entry in snap.items():
+        if key in bare:
+            continue
+        assert isinstance(entry, dict), f"{key} is not wrapped"
+        assert set(entry.keys()) == {"value", "source_path", "upstream_step"}, key
+        assert isinstance(entry["source_path"], str) and entry["source_path"]
+        assert isinstance(entry["upstream_step"], str)
+        assert entry["upstream_step"].startswith("step"), entry["upstream_step"]
+
+
+def test_build_snapshot_upstream_steps_stay_inside_reuse_boundary():
+    """No ``upstream_step`` may point outside the Step 0/2/5/6 reuse
+    boundary (Stage 1 root_cause). A drift to e.g. ``step09`` would
+    silently invite work outside the reuse window — fail loudly.
+
+    Step 01's contribution is the ``mdx_sha256`` integrity key (a bare
+    contract scalar with no wrapper) so step01 does not need to appear
+    in payload provenance.
+    """
+    snap = build_snapshot(**_make_build_kwargs())
+    allowed = {"step00", "step02", "step05", "step06"}
+    for key, entry in snap.items():
+        if key in {"schema_version", "mdx_sha256"}:
+            continue
+        assert entry["upstream_step"] in allowed, (
+            f"key {key!r}: upstream_step {entry['upstream_step']!r} outside reuse boundary"
+        )
+
+
+def test_build_snapshot_units_carry_v4_candidates():
+    snap = build_snapshot(**_make_build_kwargs())
+    units = snap["units"]["value"]
+    assert len(units) == 1
+    assert units[0]["v4_candidates"][0]["template_id"] == "tpl_a"
+    assert units[0]["v4_candidates"][0]["frame_number"] == 13
+    assert units[0]["v4_candidates"][0]["confidence"] == pytest.approx(0.91)
+
+
+def test_build_snapshot_sections_preserve_alias_keys_and_subsections():
+    sec = _make_section(
+        section_id="04-2",
+        v4_alias_keys=["04-2.1"],
+        sub_sections=[{"id": "04-2-sub-1"}],
+        heading_number="2.1",
+    )
+    snap = build_snapshot(**_make_build_kwargs(sections=[sec]))
+    payload = snap["sections"]["value"]
+    assert payload[0]["section_id"] == "04-2"
+    assert payload[0]["v4_alias_keys"] == ["04-2.1"]
+    assert payload[0]["sub_sections"] == [{"id": "04-2-sub-1"}]
+    assert payload[0]["heading_number"] == "2.1"
+
+
+def test_build_snapshot_units_provenance_points_at_step06():
+    snap = build_snapshot(**_make_build_kwargs())
+    assert "step06_composition_plan.json" in snap["units"]["source_path"]
+    assert snap["units"]["upstream_step"] == "step06"
+
+
+def test_build_snapshot_v4_evidence_provenance_points_at_step05():
+    snap = build_snapshot(**_make_build_kwargs())
+    assert "step05_v4_evidence.json" in snap["v4_evidence"]["source_path"]
+    assert snap["v4_evidence"]["upstream_step"] == "step05"
+
+
+def test_build_snapshot_ai_preflight_provenance_points_at_step00():
+    snap = build_snapshot(**_make_build_kwargs())
+    assert "step00_preconditions.json" in snap["ai_preflight"]["source_path"]
+    assert snap["ai_preflight"]["upstream_step"] == "step00"
+
+
+def test_build_snapshot_rejects_unjsonable_input():
+    bad_unit = _make_unit()
+    bad_unit.notes.append(object())  # not JSON-safe
+    with pytest.raises(TypeError):
+        build_snapshot(**_make_build_kwargs(units=[bad_unit]))
+
+
+def test_build_snapshot_handles_none_optional_fields():
+    snap = build_snapshot(
+        **_make_build_kwargs(
+            slide_title=None,
+            slide_footer=None,
+            stage0_adapter_diagnostics=None,
+            stage0_normalized_assets=None,
+            comp_debug=None,
+            v4_fallback_traces=None,
+            ai_preflight=None,
+        )
+    )
+    # None inputs land as None / {} consistently — never raise.
+    assert snap["slide_title"]["value"] is None
+    assert snap["slide_footer"]["value"] is None
+    assert snap["stage0_adapter_diagnostics"]["value"] == {}
+    assert snap["stage0_normalized_assets"]["value"] == {}
+    assert snap["comp_debug"]["value"] == {}
+    assert snap["v4_fallback_traces"]["value"] == {}
+    assert snap["ai_preflight"]["value"] == {}
+
+
+# -- serializer helpers ---------------------------------------------------
+
+
+def test_serialize_section_preserves_all_documented_fields():
+    sec = _make_section(
+        heading_number="1.1",
+        v4_alias_keys=["03-1.x"],
+        sub_sections=[{"id": "s"}],
+    )
+    out = serialize_section(sec)
+    assert out["section_id"] == "03-1"
+    assert out["section_num"] == 1
+    assert out["title"] == "DX status"
+    assert out["raw_content"].startswith("- bullet")
+    assert out["heading_number"] == "1.1"
+    assert out["v4_alias_keys"] == ["03-1.x"]
+    assert out["sub_sections"] == [{"id": "s"}]
+
+
+def test_serialize_section_works_with_missing_optional_attrs():
+    class _Minimal:
+        section_id = "x"
+        section_num = 0
+        title = "t"
+        raw_content = "r"
+    out = serialize_section(_Minimal())
+    assert out["heading_number"] is None
+    assert out["v4_alias_keys"] == []
+    assert out["sub_sections"] == []
+
+
+def test_serialize_unit_v4_candidates_unwrap_to_named_attrs():
+    unit = _make_unit()
+    out = serialize_unit(unit)
+    cand = out["v4_candidates"][0]
+    assert cand == {
+        "template_id": "tpl_a",
+        "frame_id": "fid_a",
+        "frame_number": 13,
+        "confidence": pytest.approx(0.91),
+        "label": "use_as_is",
+        # u4 follow-up — Step 9 application-plan payload reads
+        # ``c.v4_rank`` off each rehydrated candidate. Snapshot
+        # serializer persists it via ``getattr(c, 'v4_rank', None)`` so
+        # legacy duck types (no v4_rank attr) get None and modern V4Match
+        # instances carry their rank (1/2/3/...).
+        "v4_rank": None,
+    }
+
+
+def test_serialize_unit_v4_candidates_persist_v4_rank_when_present():
+    """A v4_candidate with v4_rank=2 (V4Match-shape duck type) round-trips."""
+    ranked_cand = _V4Candidate(
+        template_id="tpl_b",
+        frame_id="fid_b",
+        frame_number=14,
+        confidence=0.82,
+        label="light_edit",
+        v4_rank=2,
+    )
+    unit = _make_unit(v4_candidates=[ranked_cand])
+    out = serialize_unit(unit)
+    assert out["v4_candidates"][0]["v4_rank"] == 2
+
+
+def test_serialize_unit_handles_empty_v4_candidates():
+    unit = _make_unit(v4_candidates=[])
+    out = serialize_unit(unit)
+    assert out["v4_candidates"] == []
+
+
+def test_serialize_unit_provisional_default_false():
+    unit = _make_unit()
+    assert serialize_unit(unit)["provisional"] is False
+
+
+def test_serialize_unit_provisional_true_preserved():
+    unit = _make_unit(provisional=True)
+    assert serialize_unit(unit)["provisional"] is True
+
+
+def test_serialize_unit_round_trips_through_json():
+    out = serialize_unit(_make_unit())
+    reloaded = json.loads(json.dumps(out))
+    assert reloaded["source_section_ids"] == ["03-1"]
+    assert reloaded["frame_template_id"] == "tpl_a"
+
+
+# -- validate_snapshot ----------------------------------------------------
+
+
+def test_validate_snapshot_accepts_well_formed():
+    snap = build_snapshot(**_make_build_kwargs())
+    validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+
+
+def test_validate_snapshot_rejects_non_dict_input():
+    with pytest.raises(SnapshotValidationError):
+        validate_snapshot("not a dict", expected_mdx_sha256="a" * 64)
+
+
+def test_validate_snapshot_rejects_version_mismatch():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["schema_version"] = SNAPSHOT_VERSION + 999
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "schema_version" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_missing_sha():
+    snap = build_snapshot(**_make_build_kwargs())
+    del snap["mdx_sha256"]
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "mdx_sha256" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_empty_sha():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["mdx_sha256"] = ""
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "mdx_sha256" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_non_string_sha():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["mdx_sha256"] = 12345
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "mdx_sha256" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_sha_mismatch():
+    snap = build_snapshot(**_make_build_kwargs())
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="b" * 64)
+    assert "mdx_sha256 mismatch" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_missing_required_key():
+    snap = build_snapshot(**_make_build_kwargs())
+    del snap["units"]
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "units" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_unwrapped_payload_key():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["units"] = "not a dict"
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "units" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_wrapper_missing_value():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["units"] = {"source_path": "x", "upstream_step": "step06"}
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "value" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_wrapper_missing_source_path():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["units"] = {"value": [], "upstream_step": "step06"}
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "source_path" in str(exc.value)
+
+
+def test_validate_snapshot_rejects_wrapper_missing_upstream_step():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["units"] = {"value": [], "source_path": "x"}
+    with pytest.raises(SnapshotValidationError) as exc:
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
+    assert "upstream_step" in str(exc.value)
+
+
+def test_validate_snapshot_error_subclasses_value_error():
+    snap = build_snapshot(**_make_build_kwargs())
+    snap["schema_version"] = 999
+    # u4b will pre-catch SnapshotValidationError, but the broader
+    # `except ValueError` net must still pick this up.
+    with pytest.raises(ValueError):
+        validate_snapshot(snap, expected_mdx_sha256="a" * 64)
@@ -0,0 +1,282 @@
+"""IMP-43 (#72) u3 — focused tests for the Step 6 reuse snapshot writer.
+
+u3 scope (per the Stage 2 Exit Report):
+
+- ``_write_reuse_snapshot`` writes ``run_dir/_reuse_snapshot.json`` *after*
+  the Step 6 artifact lands; failure WARNS and CONTINUES (the helper does
+  NOT raise out of the main pipeline run).
+- The Step 6 artifact data dict records the run_dir-relative sidecar path
+  as ``data.reuse_snapshot_path`` (additive informational field, always
+  set to ``SNAPSHOT_FILENAME`` regardless of write success — u4 will
+  fail-closed on missing / invalid sidecar via u2's ``validate_snapshot``).
+
+The helper is tested in isolation (no full pipeline run) — pipeline call
+site presence is asserted structurally so we exercise behaviour without
+re-running Step 0~6 inside the test process. End-to-end equivalence under
+``--reuse-from`` is u7a / u7b scope.
+"""
+from __future__ import annotations
+
+import json
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Any, Optional
+
+import pytest
+
+import src.phase_z2_pipeline as _pz2
+from src.phase_z2_reuse_snapshot import (
+    SNAPSHOT_FILENAME,
+    SNAPSHOT_VERSION,
+    SnapshotValidationError,
+    validate_snapshot,
+)
+
+
+# -- synthetic duck-typed inputs ------------------------------------------
+
+
+@dataclass
+class _Section:
+    section_id: str
+    section_num: int
+    title: str
+    raw_content: str
+    heading_number: Optional[str] = None
+    v4_alias_keys: list = field(default_factory=list)
+    sub_sections: list = field(default_factory=list)
+
+
+@dataclass
+class _V4Candidate:
+    template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+
+
+@dataclass
+class _Unit:
+    source_section_ids: list
+    merge_type: str
+    frame_template_id: str
+    frame_id: str
+    frame_number: int
+    confidence: float
+    label: str
+    phase_z_status: str
+    raw_content: str
+    title: str
+    score: float
+    v4_rank: Optional[int] = 1
+    selection_path: str = "rank_1"
+    fallback_reason: Optional[str] = None
+    rationale: dict = field(default_factory=dict)
+    auto_selectable: bool = True
+    filter_reasons: list = field(default_factory=list)
+    notes: list = field(default_factory=list)
+    v4_candidates: list = field(default_factory=list)
+    provisional: bool = False
+
+
+def _make_kwargs(**overrides: Any) -> dict[str, Any]:
+    cand = _V4Candidate(
+        template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+    )
+    section = _Section(
+        section_id="03-1",
+        section_num=1,
+        title="DX status",
+        raw_content="- bullet one\n- bullet two",
+    )
+    unit = _Unit(
+        source_section_ids=["03-1"],
+        merge_type="single",
+        frame_template_id="tpl_a",
+        frame_id="fid_a",
+        frame_number=13,
+        confidence=0.91,
+        label="use_as_is",
+        phase_z_status="auto_renderable",
+        raw_content="- bullet one\n- bullet two",
+        title="DX status",
+        score=0.91,
+        v4_candidates=[cand],
+    )
+    kwargs: dict[str, Any] = dict(
+        mdx_source_text="# Slide\n\n## 03-1 DX status\n\n- bullet one\n- bullet two\n",
+        slide_title="Slide",
+        slide_footer=None,
+        sections=[section],
+        stage0_adapter_diagnostics={"used": True, "fallback_reason": None},
+        stage0_normalized_assets={"popups": [], "images": [], "tables": []},
+        v4_evidence=[
+            {
+                "section_id": "03-1",
+                "v4_candidates": [
+                    {
+                        "template_id": "tpl_a",
+                        "frame_id": "fid_a",
+                        "frame_number": 13,
+                        "confidence": 0.91,
+                        "label": "use_as_is",
+                    }
+                ],
+                "candidate_status": "ok",
+            }
+        ],
+        layout_preset_pre_override="single",
+        units=[unit],
+        comp_debug={"v4_fallback_summary": {"fallback_used_count": 0}},
+        v4_fallback_traces={"03-1": {"selection_path": "rank_1"}},
+        ai_preflight={"enabled": False, "skipped": True},
+    )
+    kwargs.update(overrides)
+    return kwargs
+
+
+# -- success path ---------------------------------------------------------
+
+
+def test_writes_snapshot_file_at_run_dir_root(tmp_path: Path):
+    rv = _pz2._write_reuse_snapshot(tmp_path, **_make_kwargs())
+    assert rv == SNAPSHOT_FILENAME
+    fpath = tmp_path / SNAPSHOT_FILENAME
+    assert fpath.exists(), f"snapshot not written at {fpath}"
+
+
+def test_written_snapshot_validates(tmp_path: Path):
+    kwargs = _make_kwargs()
+    rv = _pz2._write_reuse_snapshot(tmp_path, **kwargs)
+    assert rv == SNAPSHOT_FILENAME
+    snap = json.loads((tmp_path / SNAPSHOT_FILENAME).read_text(encoding="utf-8"))
+
+    # mdx_sha256 is derived from mdx_source_text — recompute to verify
+    # the helper is hashing the UTF-8 bytes of the same source we passed.
+    import hashlib as _hl
+
+    expected_sha = _hl.sha256(
+        kwargs["mdx_source_text"].encode("utf-8")
+    ).hexdigest()
+    validate_snapshot(snap, expected_mdx_sha256=expected_sha)
+
+
+def test_snapshot_has_correct_schema_version(tmp_path: Path):
+    _pz2._write_reuse_snapshot(tmp_path, **_make_kwargs())
+    snap = json.loads((tmp_path / SNAPSHOT_FILENAME).read_text(encoding="utf-8"))
+    assert snap["schema_version"] == SNAPSHOT_VERSION
+
+
+def test_snapshot_records_layout_preset_pre_override(tmp_path: Path):
+    _pz2._write_reuse_snapshot(
+        tmp_path, **_make_kwargs(layout_preset_pre_override="horizontal-2")
+    )
+    snap = json.loads((tmp_path / SNAPSHOT_FILENAME).read_text(encoding="utf-8"))
+    assert snap["layout_preset_pre_override"]["value"] == "horizontal-2"
+
+
+def test_snapshot_is_utf8_encoded_with_non_ascii_content(tmp_path: Path):
+    _pz2._write_reuse_snapshot(
+        tmp_path,
+        **_make_kwargs(
+            slide_title="설계 방식의 왜곡",
+            mdx_source_text="# 설계 방식\n\n- 한글 bullet\n",
+        ),
+    )
+    # ensure_ascii=False is intentional so Korean text round-trips
+    # readable; if a future refactor drops it the bytes change but the
+    # JSON still parses — we assert the file is decodable AS utf-8 and
+    # the value survives the round trip.
+    raw = (tmp_path / SNAPSHOT_FILENAME).read_text(encoding="utf-8")
+    snap = json.loads(raw)
+    assert snap["slide_title"]["value"] == "설계 방식의 왜곡"
+
+
+# -- failure path ---------------------------------------------------------
+
+
+def test_failure_warns_and_returns_none(tmp_path: Path, monkeypatch, capsys):
+    """When ``build_snapshot`` raises, the helper must NOT propagate the
+    exception — it WARNS on stderr and returns ``None`` so the main
+    pipeline run continues."""
+
+    def _boom(**_kwargs):
+        raise RuntimeError("synthetic build failure")
+
+    monkeypatch.setattr(_pz2, "build_snapshot", _boom)
+
+    rv = _pz2._write_reuse_snapshot(tmp_path, **_make_kwargs())
+
+    assert rv is None
+    captured = capsys.readouterr()
+    assert "reuse-snapshot" in captured.err
+    assert "WARN" in captured.err
+    assert "RuntimeError" in captured.err
+    # File MUST NOT exist on failure (no partial JSON on disk).
+    assert not (tmp_path / SNAPSHOT_FILENAME).exists()
+
+
+def test_failure_on_unwritable_run_dir_warns_and_returns_none(
+    tmp_path: Path, monkeypatch, capsys
+):
+    """Simulate disk write failure: helper warns + returns None, never
+    raises out to the caller (Stage 2 guardrail: optional sidecar)."""
+    nonexistent = tmp_path / "does" / "not" / "exist"
+    # nonexistent.exists() is False — Path.write_text raises FileNotFoundError.
+
+    rv = _pz2._write_reuse_snapshot(nonexistent, **_make_kwargs())
+
+    assert rv is None
+    captured = capsys.readouterr()
+    assert "reuse-snapshot" in captured.err
+    assert "WARN" in captured.err
+    # FileNotFoundError specifically — sanity-check the type surfaces in
+    # the warning so debugging is not blind.
+    assert "FileNotFoundError" in captured.err
+
+
+# -- pipeline integration anchors -----------------------------------------
+
+
+def test_pipeline_imports_helper_and_constant():
+    """The pipeline module must expose the helper for the post-Step-6
+    call site, and the constant must round-trip from the snapshot
+    module (single source of truth)."""
+    assert hasattr(_pz2, "_write_reuse_snapshot")
+    assert callable(_pz2._write_reuse_snapshot)
+    assert _pz2.SNAPSHOT_FILENAME == "_reuse_snapshot.json"
+
+
+def test_pipeline_call_site_follows_step06_artifact_write():
+    """Structural guard: the helper must be invoked AFTER the Step 6
+    artifact write in ``run_phase_z2_mvp1`` so the sidecar lands next
+    to ``steps/step06_composition_plan.json`` (Stage 2 spec)."""
+    source = Path(_pz2.__file__).read_text(encoding="utf-8")
+    # Locate the step06 artifact write call site by its locked name arg.
+    step06_marker = '6, "composition_plan"'
+    idx_step06 = source.find(step06_marker)
+    assert idx_step06 != -1, "step06 artifact write call site missing"
+    # The helper call must appear AFTER the step06 marker.
+    idx_helper = source.find("_write_reuse_snapshot(", idx_step06)
+    assert idx_helper != -1, "u3 helper call missing after step06 write"
+
+
+def test_pipeline_step06_artifact_data_records_snapshot_path():
+    """Structural guard: the Step 6 artifact data dict must include the
+    ``reuse_snapshot_path`` field so a future ``--reuse-from`` consumer
+    can locate the expected sidecar via the canonical step artifact
+    (Stage 2 spec — informational; absence of the file is u4's
+    fail-closed concern)."""
+    source = Path(_pz2.__file__).read_text(encoding="utf-8")
+    step06_marker = '6, "composition_plan"'
+    idx_step06 = source.find(step06_marker)
+    assert idx_step06 != -1
+    # Search a generous window after the marker for the field key.
+    window = source[idx_step06 : idx_step06 + 8000]
+    assert '"reuse_snapshot_path"' in window
+    assert "SNAPSHOT_FILENAME" in window
@@ -0,0 +1,101 @@
+"""IMP-45 (#74) u6 — subprocess smoke for the slide-level CSS override axis.
+
+End-to-end guard that the ``slide_overrides.css`` frontmatter axis added
+in u2 propagates through the pipeline (u4) and lands in ``final.html``
+via :func:`src.slide_css_injector.inject_slide_css` (u3).
+
+The fixture is the new ``slide_overrides.css`` frontmatter block in
+``samples/mdx_batch/04.mdx`` (u6 migration of the legacy frontend-only
+``MDX04_DEFAULT_OVERRIDE_CSS`` constant). The pipeline is spawned via
+``python -m src.phase_z2_pipeline 04.mdx <run_id>`` so the assertion
+applies to the on-disk artifact CI / CLI / regression all observe, not
+to a live iframe view.
+
+The subprocess returncode is intentionally NOT asserted: mdx04 has known
+downstream issues (see ``test_pipeline_smoke_imp85.py`` —
+``test_mdx04_no_longer_emits_imp85_crash_signature``) that are tracked
+on a separate axis. Step 13 runs before the downstream failure surface,
+so ``final.html`` is written with the injected slide CSS marker
+regardless. The test asserts ``final.html`` exists and contains both
+the IMP-45 sentinel marker and a distinctive CSS substring from the
+migrated frontmatter block.
+"""
+from __future__ import annotations
+
+import subprocess
+import sys
+import uuid
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+SAMPLES_DIR = REPO_ROOT / "samples" / "mdx_batch"
+RUNS_DIR = REPO_ROOT / "data" / "runs"
+
+# IMP-45 (#74) u3 marker sentinel emitted by
+# :func:`src.slide_css_injector.inject_slide_css` around the injected
+# ``<style>`` block. Match the ``_IMP45_STYLE_MARKER_OPEN`` constant in
+# ``src/slide_css_injector.py`` byte-for-byte.
+IMP45_OPEN_MARKER = "<!--IMP45-SLIDE-CSS:OPEN-->"
+IMP45_CLOSE_MARKER = "<!--IMP45-SLIDE-CSS:CLOSE-->"
+
+# Distinctive substring from the migrated frontmatter block in
+# ``samples/mdx_batch/04.mdx``. ``f29b__cell:nth-child(n+3)`` is unique
+# to the MDX04 slide-level override CSS and does not appear elsewhere in
+# the slide_base / partial templates, so its presence in ``final.html``
+# is sufficient evidence that the frontmatter axis fed the injector.
+MDX04_DISTINCTIVE_CSS_SUBSTRING = ".f29b__cell:nth-child(n+3)"
+
+
+def _run_pipeline(mdx_name: str, run_id: str, timeout: int = 240) -> subprocess.CompletedProcess:
+    """Spawn ``python -m src.phase_z2_pipeline <mdx> <run_id>``."""
+    return subprocess.run(
+        [
+            sys.executable,
+            "-m",
+            "src.phase_z2_pipeline",
+            str(SAMPLES_DIR / mdx_name),
+            run_id,
+        ],
+        capture_output=True,
+        text=True,
+        timeout=timeout,
+        cwd=str(REPO_ROOT),
+    )
+
+
+def _unique_run_id(prefix: str) -> str:
+    return f"{prefix}_imp45_slide_css_smoke_{uuid.uuid4().hex[:8]}"
+
+
+def test_mdx04_slide_overrides_css_lands_in_final_html() -> None:
+    """mdx04 ``slide_overrides.css`` frontmatter must reach ``final.html``.
+
+    Contract pins both the IMP-45 marker sentinel and a distinctive CSS
+    substring from the migrated frontmatter block so a regression in
+    either the frontmatter extractor (u2), the kwarg forwarding (u4),
+    or the injector (u3) is caught by this single smoke.
+    """
+    run_id = _unique_run_id("mdx04")
+    cp = _run_pipeline("04.mdx", run_id)
+
+    final_html_path = RUNS_DIR / run_id / "phase_z2" / "final.html"
+    assert final_html_path.is_file(), (
+        f"final.html not found at {final_html_path}\n"
+        f"--- stderr tail ---\n{cp.stderr[-1500:]}\n"
+        f"--- stdout tail ---\n{cp.stdout[-1500:]}"
+    )
+    html = final_html_path.read_text(encoding="utf-8")
+
+    assert IMP45_OPEN_MARKER in html, (
+        f"IMP-45 open marker missing from mdx04 final.html ({final_html_path}).\n"
+        f"slide_overrides.css frontmatter axis did not reach the injector."
+    )
+    assert IMP45_CLOSE_MARKER in html, (
+        f"IMP-45 close marker missing from mdx04 final.html ({final_html_path}).\n"
+        f"Marker wrap appears unbalanced — check inject_slide_css() output."
+    )
+    assert MDX04_DISTINCTIVE_CSS_SUBSTRING in html, (
+        f"Migrated frontmatter CSS substring "
+        f"{MDX04_DISTINCTIVE_CSS_SUBSTRING!r} missing from mdx04 final.html "
+        f"({final_html_path}). The slide_overrides.css block did not propagate."
+    )
@@ -0,0 +1,216 @@
+"""IMP-56 (#90) u7 — Step 12 ``structure_overrides`` apply unit tests.
+
+Synthetic — exercises ``_apply_structure_overrides_to_zones`` directly
+without running the full Phase Z 22-step pipeline. The helper is
+decoupled from ``MdxSection`` / ``CompositionUnit`` graphs and only
+consumes a minimal ``[{position, slot_payload}, ...]`` zone list, so a
+synthetic fixture is sufficient to lock the contract.
+
+Coverage axes (Stage 2 plan u7 + Stage 1 binding contract) :
+
+  - reorder happy path : ``slot_order`` partial reorder mutates
+    ``zone['slot_payload']`` key order in place (caller reference stays
+    valid via clear+update rebuild contract documented at u6).
+  - hide happy path : ``hidden_slots`` pops the listed keys.
+  - stale slot_key : absent slot_keys silently no-op (count toward
+    ``skipped_zones`` if the whole override produces no mutation).
+  - SCOPE LOCK : frame-swap-shaped inner keys (``frame_id``,
+    ``template_id``) are dropped by the u6 validate gate and therefore
+    never reach the apply path here.
+  - raw_content preservation : per-slot ``list[str]`` line content
+    untouched; out-of-band sentinels (mirror of ``debug_zones`` graph)
+    stay byte-identical.
+  - audit shape : ``applied_zones`` / ``skipped_zones`` / ``per_zone``
+    keys present and counts consistent with the input batch.
+  - empty / ``None`` batch is a no-op (empty audit).
+
+Fully synthetic per Codex generalization guardrail (MOCK_ prefix).
+NO real catalog template_id / frame_id, NO ``v4_full32_result.yaml``
+dependency.
+"""
+from __future__ import annotations
+
+import pytest
+
+from src.phase_z2_pipeline import _apply_structure_overrides_to_zones
+
+
+# ─── Synthetic fixture helpers ──────────────────────────────────────
+
+
+def _zone(position: str, slot_payload: dict) -> dict:
+    """Minimal zone dict mirroring the Step 12 ``zones_data[i]`` shape."""
+    return {
+        "position": position,
+        "template_id": "MOCK_T_phase_z2_structure_overrides",
+        "slot_payload": slot_payload,
+        "content_weight": 1.0,
+        "min_height_px": 200,
+    }
+
+
+# ─── Case 1 : reorder happy path ──────────────────────────────────────
+
+
+def test_apply_reorders_slot_payload_keys_in_place():
+    payload = {"slot_a": ["A"], "slot_b": ["B"], "slot_c": ["C"]}
+    zones = [_zone("top", payload)]
+    overrides = {"top": {"slot_order": ["slot_c", "slot_a"]}}
+
+    audit = _apply_structure_overrides_to_zones(overrides, zones)
+
+    # Caller reference (payload) stays valid via clear+update rebuild.
+    assert zones[0]["slot_payload"] is payload
+    assert list(payload.keys()) == ["slot_c", "slot_a", "slot_b"]
+    # Per-slot list[str] content untouched (raw_content invariant).
+    assert payload["slot_a"] == ["A"]
+    assert payload["slot_b"] == ["B"]
+    assert payload["slot_c"] == ["C"]
+    assert audit["applied_zones"] == 1
+    assert audit["skipped_zones"] == 0
+    assert audit["per_zone"] == [{"position": "top", "mutated": True}]
+
+
+# ─── Case 2 : hide happy path ─────────────────────────────────────────
+
+
+def test_apply_hides_listed_slot_keys():
+    payload = {"slot_a": ["A"], "slot_b": ["B"], "slot_c": ["C"]}
+    zones = [_zone("top", payload)]
+    overrides = {"top": {"hidden_slots": ["slot_b"]}}
+
+    audit = _apply_structure_overrides_to_zones(overrides, zones)
+
+    assert "slot_b" not in payload
+    assert list(payload.keys()) == ["slot_a", "slot_c"]
+    assert audit["applied_zones"] == 1
+    assert audit["per_zone"] == [{"position": "top", "mutated": True}]
+
+
+# ─── Case 3 : stale slot_key — frame swap / layout regression ─────────
+
+
+def test_stale_slot_key_silently_no_op():
+    """Absent slot_keys produce no mutation; the zone counts toward skipped_zones."""
+    payload = {"slot_a": ["A"]}
+    zones = [_zone("top", payload)]
+    overrides = {
+        "top": {
+            "hidden_slots": ["slot_missing"],          # absent — no-op
+            "slot_order": ["slot_also_missing"],       # absent — no-op
+        },
+    }
+
+    audit = _apply_structure_overrides_to_zones(overrides, zones)
+
+    assert list(payload.keys()) == ["slot_a"]
+    assert audit["applied_zones"] == 0
+    assert audit["skipped_zones"] == 1
+    assert audit["per_zone"] == [{"position": "top", "mutated": False}]
+
+
+# ─── Case 4 : SCOPE LOCK — frame swap shape dropped at validate ───────
+
+
+def test_frame_swap_keys_dropped_at_validate_no_mutation():
+    payload = {"slot_a": ["A"], "slot_b": ["B"]}
+    zones = [_zone("top", payload)]
+    # frame_id / template_id / slot_payload as inner keys are the canonical
+    # frame-swap / DOM-rebuild shapes the SCOPE LOCK rejects.
+    overrides = {
+        "top": {
+            "frame_id": "MOCK_OTHER_FRAME",
+            "template_id": "MOCK_OTHER_TEMPLATE",
+            "slot_payload": {"slot_a": ["overwritten"]},
+        },
+    }
+
+    audit = _apply_structure_overrides_to_zones(overrides, zones)
+
+    # No mutation: validate gate drops the whole zone payload (no allowed
+    # inner key remains), so the zone never reaches the apply loop.
+    assert payload == {"slot_a": ["A"], "slot_b": ["B"]}
+    assert audit["applied_zones"] == 0
+    assert audit["skipped_zones"] == 0
+    assert audit["per_zone"] == []
+
+
+# ─── Case 5 : raw_content preservation invariant ──────────────────────
+
+
+def test_raw_content_sentinel_untouched():
+    """Helper must not mutate anything outside zone['slot_payload']
+    AND must not mutate per-slot list[str] line content."""
+    raw_sentinel = ["MOCK_S1", "MOCK_S2"]
+    payload = {"slot_a": ["line 1", "line 2"], "slot_b": ["line 3"]}
+    zones = [_zone("top", payload)]
+    zones[0]["source_section_ids_sentinel"] = raw_sentinel  # out-of-band
+    zones[0]["raw_content_sentinel"] = "- line 1\n- line 2\n"
+
+    _apply_structure_overrides_to_zones(
+        {"top": {"slot_order": ["slot_b", "slot_a"]}}, zones,
+    )
+
+    # Out-of-band fields untouched.
+    assert zones[0]["source_section_ids_sentinel"] is raw_sentinel
+    assert zones[0]["source_section_ids_sentinel"] == ["MOCK_S1", "MOCK_S2"]
+    assert zones[0]["raw_content_sentinel"] == "- line 1\n- line 2\n"
+    # Per-slot list[str] line content byte-identical.
+    assert payload["slot_a"] == ["line 1", "line 2"]
+    assert payload["slot_b"] == ["line 3"]
+
+
+# ─── Case 6 : empty / None / irrelevant batch is no-op ────────────────
+
+
+@pytest.mark.parametrize(
+    "batch",
+    [
+        None,
+        {},
+        {"top": {}},                                            # empty per-zone
+        {"missing_zone": {"slot_order": ["slot_a"]}},           # stale zone_id
+    ],
+)
+def test_empty_or_irrelevant_batch_is_noop(batch):
+    payload = {"slot_a": ["A"]}
+    zones = [_zone("top", payload)]
+    audit = _apply_structure_overrides_to_zones(batch, zones)
+
+    assert list(payload.keys()) == ["slot_a"]
+    assert audit["applied_zones"] == 0
+    assert audit["skipped_zones"] == 0
+    assert audit["per_zone"] == []
+
+
+# ─── Case 7 : zone without slot_payload skipped (defensive) ───────────
+
+
+def test_zone_without_slot_payload_skipped():
+    zones = [{"position": "top"}]  # no slot_payload key (defensive contract)
+    audit = _apply_structure_overrides_to_zones(
+        {"top": {"slot_order": ["slot_a"]}}, zones,
+    )
+    assert audit["per_zone"] == []
+    assert audit["applied_zones"] == 0
+    assert audit["skipped_zones"] == 0
+
+
+# ─── Case 8 : combined reorder + hide in a single zone ────────────────
+
+
+def test_combined_reorder_and_hide_in_one_zone():
+    payload = {"slot_a": ["A"], "slot_b": ["B"], "slot_c": ["C"]}
+    zones = [_zone("top", payload)]
+    overrides = {
+        "top": {
+            "hidden_slots": ["slot_b"],
+            "slot_order": ["slot_c", "slot_a"],
+        },
+    }
+
+    audit = _apply_structure_overrides_to_zones(overrides, zones)
+
+    assert list(payload.keys()) == ["slot_c", "slot_a"]
+    assert audit["applied_zones"] == 1
+    assert audit["per_zone"] == [{"position": "top", "mutated": True}]
@@ -0,0 +1,158 @@
+"""IMP-56 (#90) u5 — Step 12 ``text_overrides`` apply unit tests.
+
+Synthetic — exercises ``_apply_text_overrides_to_zones`` directly without
+running the full Phase Z 22-step pipeline. The helper is decoupled from
+``MdxSection`` / ``CompositionUnit`` graphs and only consumes a minimal
+``[{position, slot_payload}, ...]`` zone list, so a synthetic fixture is
+sufficient to lock the contract.
+
+Coverage axes (Stage 2 plan u5 + Stage 1 binding contract) :
+
+  - sanitized batch : malformed text_path / non-string value drops per-row
+    (mirrors ``image_id_stamper.build_image_overrides_style`` u7 tolerance).
+  - stale path : frame swap / layout regression → ``skipped``, not error.
+  - raw_content preservation : helper never touches ``debug_zones`` / unit
+    graph (asserted by zero-mutation on an out-of-band sentinel mapping).
+  - audit shape : ``applied`` / ``skipped`` / ``per_zone`` keys present and
+    counts consistent with the input batch.
+  - empty / ``None`` override input is a no-op (empty audit).
+
+Fully synthetic per Codex generalization guardrail (MOCK_ prefix).
+NO real catalog template_id / frame_id, NO ``v4_full32_result.yaml``
+dependency.
+"""
+from __future__ import annotations
+
+import pytest
+
+from src.phase_z2_pipeline import _apply_text_overrides_to_zones
+
+
+# ─── Synthetic fixture helpers ──────────────────────────────────────
+
+
+def _zone(position: str, slot_payload: dict) -> dict:
+    """Minimal zone dict mirroring the Step 12 ``zones_data[i]`` shape."""
+    return {
+        "position": position,
+        "template_id": "MOCK_T_phase_z2_text_overrides",
+        "slot_payload": slot_payload,
+        "content_weight": 1.0,
+        "min_height_px": 200,
+    }
+
+
+# ─── Case 1 : happy path — list[str] slot mutation ────────────────────
+
+
+def test_apply_replaces_list_line_in_place():
+    zones = [
+        _zone("top", {"slot_title": ["original headline"], "slot_body": ["a", "b", "c"]}),
+        _zone("bottom", {"slot_caption": ["caption A"]}),
+    ]
+    overrides = {
+        "top": {"slot_title.0": "edited headline", "slot_body.1": "edited B"},
+    }
+
+    audit = _apply_text_overrides_to_zones(overrides, zones)
+
+    assert zones[0]["slot_payload"]["slot_title"] == ["edited headline"]
+    assert zones[0]["slot_payload"]["slot_body"] == ["a", "edited B", "c"]
+    # bottom zone untouched (no override entry)
+    assert zones[1]["slot_payload"]["slot_caption"] == ["caption A"]
+    assert audit["applied"] == 2
+    assert audit["skipped"] == 0
+    assert audit["per_zone"] == [{"position": "top", "applied": 2, "skipped": 0}]
+
+
+# ─── Case 2 : stale text_path — frame swap / layout regression ────────
+
+
+def test_stale_text_path_skipped_silently():
+    """Absent slot_key + out-of-range line_index both count as skipped, not errors."""
+    zones = [_zone("top", {"slot_title": ["only one line"]})]
+    overrides = {
+        "top": {
+            "slot_title.0": "ok",           # applied
+            "slot_title.99": "out of range", # skipped (idx > len)
+            "slot_missing.0": "stale frame", # skipped (slot absent)
+        },
+    }
+
+    audit = _apply_text_overrides_to_zones(overrides, zones)
+
+    assert zones[0]["slot_payload"]["slot_title"] == ["ok"]
+    assert "slot_missing" not in zones[0]["slot_payload"]
+    assert audit["applied"] == 1
+    assert audit["skipped"] == 2
+    assert audit["per_zone"][0] == {"position": "top", "applied": 1, "skipped": 2}
+
+
+# ─── Case 3 : malformed input — per-entry tolerance ────────────────────
+
+
+def test_malformed_entries_dropped_in_validate():
+    """Non-string value / malformed text_path drop in ``validate_text_overrides``."""
+    zones = [_zone("top", {"slot_title": ["original", "second"]})]
+    overrides = {
+        "top": {
+            "slot_title.0": "good",        # kept
+            "slot_title.bad": "ignored",   # dropped (non-int idx)
+            "slot_title.1": 123,           # dropped (non-str value)
+            "no_dot": "ignored",           # dropped (missing '.')
+        },
+        "": {"slot_title.0": "empty zone id dropped"},  # zone_id sanitization
+        123: {"slot_title.0": "non-string zone id dropped"},
+    }
+
+    audit = _apply_text_overrides_to_zones(overrides, zones)
+
+    # only the well-formed entry applied
+    assert zones[0]["slot_payload"]["slot_title"] == ["good", "second"]
+    assert audit["applied"] == 1
+    assert audit["skipped"] == 0
+
+
+# ─── Case 4 : raw_content preservation invariant ──────────────────────
+
+
+def test_raw_content_sentinel_untouched():
+    """Helper must not mutate anything outside ``zone['slot_payload']``.
+
+    Out-of-band fields (mirror of ``debug_zones[i].source_section_ids`` /
+    MdxSection graph) stay byte-identical — Stage 1 binding contract.
+    """
+    raw_sentinel = ["MOCK_S1", "MOCK_S2"]
+    zones = [_zone("top", {"slot_title": ["original"]})]
+    zones[0]["source_section_ids_sentinel"] = raw_sentinel  # out-of-band
+    zones[0]["raw_content_sentinel"] = "- original bullet\n- second\n"
+
+    _apply_text_overrides_to_zones({"top": {"slot_title.0": "edited"}}, zones)
+
+    assert zones[0]["source_section_ids_sentinel"] is raw_sentinel  # same object
+    assert zones[0]["source_section_ids_sentinel"] == ["MOCK_S1", "MOCK_S2"]
+    assert zones[0]["raw_content_sentinel"] == "- original bullet\n- second\n"
+
+
+# ─── Case 5 : empty / None batch is no-op ──────────────────────────────
+
+
+@pytest.mark.parametrize("payload", [None, {}, {"top": {}}, {"missing_zone": {"slot.0": "x"}}])
+def test_empty_or_irrelevant_batch_is_noop(payload):
+    zones = [_zone("top", {"slot_title": ["unchanged"]})]
+    audit = _apply_text_overrides_to_zones(payload, zones)
+
+    assert zones[0]["slot_payload"]["slot_title"] == ["unchanged"]
+    assert audit["applied"] == 0
+    assert audit["skipped"] == 0
+
+
+# ─── Case 6 : zone without slot_payload skipped (defensive) ───────────
+
+
+def test_zone_without_slot_payload_skipped():
+    zones = [{"position": "top"}]  # no slot_payload key (defensive contract)
+    audit = _apply_text_overrides_to_zones({"top": {"slot.0": "x"}}, zones)
+    assert audit["per_zone"] == []
+    assert audit["applied"] == 0
+    assert audit["skipped"] == 0
@@ -0,0 +1,212 @@
+"""IMP-56 (#90) u9 — Step 13 ``text_path_stamper`` wiring tests.
+
+Verifies that :func:`src.phase_z2_pipeline.render_slide` stamps each
+rendered ``text-line`` opening tag with
+``data-text-path="{slot_key}.{line_index}"`` via the u8 stamper
+(``src.text_path_stamper.stamp_zone_html``). This is the wiring unit
+companion to the u8 module-level tests at
+``tests/test_text_path_stamper.py``.
+
+Coverage axes (Stage 2 plan u9 + Stage 1 binding contract) :
+
+  - happy path : real ``bim_current_problems_paired`` template emits
+    ``text-line`` divs for list-valued slots; the stamper attaches
+    ``data-text-path`` with matching ``{slot_key}.{line_index}``.
+  - non-list slots skipped : ``title`` / ``row_*_left_label`` (scalars)
+    do NOT receive ``data-text-path`` attributes.
+  - empty list slots emit no stamps : rows whose body list is empty
+    contribute zero stamps.
+  - deterministic : repeated calls produce byte-identical HTML
+    (no nondeterministic mutation of ``slot_payload`` between renders).
+  - empty zone : the ``__empty__`` template_id short-circuit emits no
+    ``data-text-path`` (the stamper short-circuits on empty stamps).
+
+Fully synthetic slot_payload — no real Phase Z run, no
+``v4_full32_result.yaml`` dependency. Uses the real
+``bim_current_problems_paired`` family template only to exercise the
+genuine Jinja2 + slide_base render path.
+"""
+from __future__ import annotations
+
+import re
+
+import pytest
+
+from src.phase_z2_pipeline import render_slide
+
+
+# ─── Fixture helpers ────────────────────────────────────────────────
+
+
+def _layout_css() -> dict:
+    """Minimal valid layout_css for a single-zone slide.
+
+    Mirrors tests/phase_z2/test_slide_base_embedded_mode.py shape.
+    """
+    return {"areas": '"primary"', "cols": "1fr", "rows": "1fr"}
+
+
+def _paired_slot_payload(
+    *,
+    left_lines: list[str] | None = None,
+    right_lines: list[str] | None = None,
+) -> dict:
+    """Build a slot_payload for the bim_current_problems_paired family.
+
+    Only row_1 is populated by default; rows 2-4 stay empty so the
+    template short-circuits to zero text-line divs for them.
+    """
+    left_lines = left_lines if left_lines is not None else ["L1a", "L1b"]
+    right_lines = right_lines if right_lines is not None else ["R1a"]
+    payload: dict = {
+        "title": "Synthetic Title",
+        "row_1_left_label": "left pill 1",
+        "row_1_left_body": [{"text": t, "indent": 0} for t in left_lines],
+        "row_1_right_label": "right pill 1",
+        "row_1_right_body": [{"text": t, "indent": 0} for t in right_lines],
+    }
+    for r in (2, 3, 4):
+        payload[f"row_{r}_left_label"] = f"left pill {r}"
+        payload[f"row_{r}_left_body"] = []
+        payload[f"row_{r}_right_label"] = f"right pill {r}"
+        payload[f"row_{r}_right_body"] = []
+    return payload
+
+
+def _zone(template_id: str, slot_payload: dict) -> dict:
+    return {
+        "position": "primary",
+        "template_id": template_id,
+        "slot_payload": slot_payload,
+    }
+
+
+def _render(zones: list[dict]) -> str:
+    return render_slide(
+        slide_title="t",
+        slide_footer=None,
+        zones_data=zones,
+        layout_preset="single",
+        layout_css=_layout_css(),
+        gap_px=14,
+        embedded_mode="embedded",
+    )
+
+
+# ─── Case 1 : happy path — list-valued slots stamped ─────────────────
+
+
+def test_render_slide_stamps_text_path_per_line():
+    """Each list-valued slot line gets data-text-path={slot}.{index}."""
+    payload = _paired_slot_payload(
+        left_lines=["left line A", "left line B"],
+        right_lines=["right line A"],
+    )
+    html = _render([_zone("bim_current_problems_paired", payload)])
+
+    # left body 2 lines + right body 1 line = 3 stamps in row 1.
+    assert 'data-text-path="row_1_left_body.0"' in html
+    assert 'data-text-path="row_1_left_body.1"' in html
+    assert 'data-text-path="row_1_right_body.0"' in html
+    # row 2-4 are empty → no stamps for those slot_keys.
+    assert "row_2_left_body" not in html
+    assert "row_3_right_body" not in html
+
+
+def test_stamps_preserve_class_attribute():
+    """data-text-path injected before existing class attribute, both present."""
+    payload = _paired_slot_payload(left_lines=["only left"], right_lines=[])
+    html = _render([_zone("bim_current_problems_paired", payload)])
+
+    # The original class="text-line..." must survive verbatim alongside
+    # the injected data-text-path attribute on the same opening tag.
+    assert re.search(
+        r'<div\s+data-text-path="row_1_left_body\.0"\s+class="text-line[^"]*">',
+        html,
+    ) is not None
+
+
+# ─── Case 2 : non-list slots are NOT stamped ─────────────────────────
+
+
+def test_non_list_slots_not_stamped():
+    """Scalar slot values (title, *_label) get no data-text-path."""
+    payload = _paired_slot_payload(left_lines=["x"], right_lines=["y"])
+    html = _render([_zone("bim_current_problems_paired", payload)])
+
+    # Scalar slots present in slot_payload as strings — must not receive
+    # data-text-path stamps (u8 contract: scalar slots skipped silently
+    # because they render outside text-line divs).
+    assert 'data-text-path="title' not in html
+    assert 'data-text-path="row_1_left_label' not in html
+    assert 'data-text-path="row_1_right_label' not in html
+
+
+# ─── Case 3 : empty list slots contribute no stamps ──────────────────
+
+
+def test_empty_list_slots_no_stamps():
+    """Empty list slot yields zero stamps; template emits zero text-line divs."""
+    payload = _paired_slot_payload(left_lines=[], right_lines=[])
+    html = _render([_zone("bim_current_problems_paired", payload)])
+
+    # No row 1 lines at all (both bodies empty) → no row_1_*_body stamps.
+    assert "data-text-path" not in html
+
+
+# ─── Case 4 : deterministic — repeated render produces same HTML ─────
+
+
+def test_render_with_stamp_is_deterministic():
+    """Same slot_payload → byte-identical HTML across two render_slide calls.
+
+    Guards against the wiring layer accidentally mutating slot_payload
+    between renders (the stamper itself only reads slot_payload; it
+    operates on rendered_partial). Also guards against double-stamping.
+    """
+    payload_1 = _paired_slot_payload()
+    payload_2 = _paired_slot_payload()
+    html_1 = _render([_zone("bim_current_problems_paired", payload_1)])
+    html_2 = _render([_zone("bim_current_problems_paired", payload_2)])
+
+    assert html_1 == html_2
+    # Counts must match — no double-stamp side effect on shared module state.
+    assert html_1.count("data-text-path=") == html_2.count("data-text-path=")
+    # 2 left + 1 right = 3 stamps for the default fixture.
+    assert html_1.count("data-text-path=") == 3
+
+
+# ─── Case 5 : __empty__ short-circuit emits no stamps ────────────────
+
+
+def test_empty_template_short_circuit_no_stamps():
+    """``template_id=__empty__`` short-circuits before stamping; no stamps."""
+    html = _render([_zone("__empty__", {})])
+    assert "data-text-path" not in html
+
+
+# ─── Case 6 : slot_payload preserved (raw_content invariant) ─────────
+
+
+def test_render_does_not_mutate_slot_payload():
+    """Stamping must not mutate slot_payload list/dict contents.
+
+    The stamper operates on rendered_partial HTML; the source
+    slot_payload should be byte-identical before and after render_slide.
+    Locks the raw_content preservation invariant at the wiring layer.
+    """
+    payload = _paired_slot_payload(
+        left_lines=["preserved A", "preserved B"],
+        right_lines=["preserved C"],
+    )
+    # Snapshot key list/dict identities and content.
+    snapshot_left = list(payload["row_1_left_body"])
+    snapshot_left_text = [item["text"] for item in snapshot_left]
+    snapshot_right_text = [item["text"] for item in payload["row_1_right_body"]]
+
+    _ = _render([_zone("bim_current_problems_paired", payload)])
+
+    assert [item["text"] for item in payload["row_1_left_body"]] == snapshot_left_text
+    assert [item["text"] for item in payload["row_1_right_body"]] == snapshot_right_text
+    # Scalar slots untouched too.
+    assert payload["title"] == "Synthetic Title"
--- a/Show More
+++ b/Show More