feat(#71): IMP-42 u1~u5 silent fail chain diagnostics (assert + invalid-char detector + DIAG log)

Stage 4 binding scope — diagnostic-only, fail-loud, sample-agnostic (RULE 0 / AI-isolation contract). No production behavior change beyond fail-loud raises on previously-silent failure classes. u1 src/phase_z2_pipeline.py:2747-2772 — render_slide precondition assert (template_id non-empty str + slot_payload dict), placed after the `__empty__` short-circuit at 2740 to preserve empty-zone grid behavior. u2 src/phase_z2_pipeline.py:2681-2710 — _scan_rendered_html_for_invalid_path_chars helper covering src / href / url(...) values for backslash, &, '. Invoked on partial render (2778) and slide_base assembly (2798). u3 src/phase_z2_pipeline.py:2638-2676,2733,5509 — _emit_diag_zones_shape shape-only [DIAG] JSON at Step 12 slot_payload emit and Step 13 render_slide entry. No env gate — silence is the bug. u4 Front/client/src/pages/Home.tsx:388-392 — unconditional [DIAG raw overrides] console.log on handleGenerate boundary, after flushUserOverrides() and immediately before runPipeline. u5 tests/phase_z2/test_phase_z2_diag_smoke_general.py — 32-frame general smoke driven by load_frame_contracts() registry (not literal MDX 03/04/05), parametrizes u1/u2/u3 across the full frame_contracts.yaml top-level. Tests (Stage 4 verification PASS): - u1 8 passed, u2 14 passed, u3 12 passed, u4 5 passed, u5 97 passed. - Backend full regression tests/phase_z2/ 499 passed in 110.84s. - Frontend full regression 182 passed in 1.10s. Out of scope (separate axes): - Path normalization / as_posix migration. - Autoescape policy change. - build_layout_css refactor (Stage 1 category-error rejection). - Recovery / auto-fix on detected invalid path. - MDX content / frame-selection / zone-composition change. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-24 08:28:54 +09:00
parent c59864eb9a
commit 5deeb97cf6
7 changed files with 818 additions and 4 deletions
--- a/Front/client/src/pages/Home.tsx
+++ b/Front/client/src/pages/Home.tsx
@@ -384,6 +384,14 @@ 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) {
--- a/Front/client/tests/handle_generate_diag.test.ts
+++ b/Front/client/tests/handle_generate_diag.test.ts
@@ -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);
+  });
+});
--- a/src/phase_z2_pipeline.py
+++ b/src/phase_z2_pipeline.py
@@ -2632,6 +2632,84 @@ def _remeasure_after_frame_reselect(
    }


+# ─── IMP-42 u3 (#71) — unconditional Step 12 / Step 13 DIAG log helper ──
+
+
+def _emit_diag_zones_shape(stage_label: str, zones_data: list[dict], **extra_fields) -> None:
+    """IMP-42 u3 (#71) — emit shape-only zone metadata to stdout.
+
+    Used at the Step 12 slot_payload emit site and the Step 13 render_slide
+    entry site to make the silent 3-hop handoff visible in the terminal.
+    Shape-only — never logs raw slot_payload values — so the diag is
+    sample-agnostic (RULE 0) and never leaks user content.
+
+    No env gate: silence is the bug this IMP fights, so the log fires
+    unconditionally on every slide loop.
+    """
+    payload = {
+        "zones_count": len(zones_data),
+        "zones": [
+            {
+                "i": i,
+                "position": z.get("position"),
+                "template_id": z.get("template_id"),
+                "slot_keys": (
+                    sorted(z["slot_payload"].keys())
+                    if isinstance(z.get("slot_payload"), dict) else None
+                ),
+            }
+            for i, z in enumerate(zones_data)
+        ],
+    }
+    payload.update(extra_fields)
+    print(
+        f"[DIAG] phase_z2 {stage_label} "
+        + json.dumps(payload, ensure_ascii=False, sort_keys=True),
+        flush=True,
+    )
+
+
+# ─── IMP-42 u2 (#71) — post-render HTML invalid path char detector ──
+
+_INVALID_PATH_ATTR_RE = re.compile(
+    r"""(src|href)\s*=\s*["']([^"']*)["']|url\(\s*['"]?([^)'"\s]+)['"]?\s*\)""",
+    re.IGNORECASE,
+)
+_INVALID_PATH_CHARS = ("\\", "&amp;", "&#39;")
+
+
+def _scan_rendered_html_for_invalid_path_chars(html: str, context: str) -> None:
+    """IMP-42 u2 (#71) — fail loud when rendered HTML asset references
+    contain invalid path characters in src / href / url(...) values.
+
+    Catches three silent fail vectors at the rendered HTML boundary that
+    surface downstream as 404 / asset-load failures far from upstream cause:
+      - Windows backslash from str(Path) (e.g. ``assets\\img.png``).
+      - Autoescape entity ``&amp;`` (raw ``&`` in raw path source string).
+      - Autoescape entity ``&#39;`` (raw ``'`` in raw path source string).
+
+    Raises ValueError on first hit, citing context, attr type, value snippet.
+    Scope-locked to rendered HTML asset attrs only; never inspects CSS grid
+    metadata or static template strings.
+    """
+    for match in _INVALID_PATH_ATTR_RE.finditer(html):
+        if match.group(3) is not None:
+            attr_label = "url(...)"
+            value = match.group(3)
+        else:
+            attr_label = match.group(1).lower()
+            value = match.group(2)
+        for bad in _INVALID_PATH_CHARS:
+            if bad in value:
+                snippet = value if len(value) <= 120 else value[:117] + "..."
+                raise ValueError(
+                    f"render_slide: {context} — invalid path char {bad!r} in "
+                    f"{attr_label} value (value={snippet}). "
+                    "Likely upstream: Windows backslash from str(Path) or "
+                    "autoescape of '&' / \"'\" in raw path string."
+                )
+
+
 def render_slide(slide_title: str, slide_footer: Optional[str],
                 zones_data: list[dict], layout_preset: str,
                 layout_css: dict, gap_px: int = GRID_GAP,
@@ -2651,22 +2729,60 @@ def render_slide(slide_title: str, slide_footer: Optional[str],
            f"render_slide: invalid embedded_mode={embedded_mode!r}; "
            "expected one of 'auto', 'embedded', 'standalone'"
        )
+    # IMP-42 u3 (#71) — unconditional Step 13 entry DIAG log.
+    _emit_diag_zones_shape(
+        "Step 13 render_slide entry",
+        zones_data,
+        layout_preset=layout_preset,
+        embedded_mode=embedded_mode,
+    )
    env = Environment(
        loader=FileSystemLoader(str(TEMPLATE_DIR)),
        autoescape=select_autoescape(["html"]),
    )
-    for zone in zones_data:
+    for zone_index, zone in enumerate(zones_data):
        # Stage 4 Part 2 (Codex #10 Catch N) — empty zone produced by section
        # assignment override has no partial template; render an empty string so
        # the slide_base zones loop preserves grid identity without TemplateNotFound.
        if zone.get("template_id") == "__empty__":
            zone["partial_html"] = ""
            continue
-        partial = env.get_template(f"families/{zone['template_id']}.html")
-        zone["partial_html"] = partial.render(slot_payload=zone["slot_payload"])
+        # IMP-42 u1 (#71) — fail-loud precondition for Step 13 partial render.
+        # Catches the silent fail vector where Step 12 emits a zone dict missing
+        # `template_id` / `slot_payload`. Error message cites zone_index +
+        # missing key so the diag is actionable (vs Jinja TemplateNotFound /
+        # KeyError surfacing far from the upstream emit site).
+        template_id = zone.get("template_id")
+        if not isinstance(template_id, str) or not template_id:
+            raise TypeError(
+                f"render_slide: zones_data[{zone_index}] precondition failed — "
+                f"`template_id` must be a non-empty str, got {type(template_id).__name__}={template_id!r}"
+            )
+        if "slot_payload" not in zone:
+            raise TypeError(
+                f"render_slide: zones_data[{zone_index}] precondition failed — "
+                f"`slot_payload` key missing (template_id={template_id!r})"
+            )
+        slot_payload = zone["slot_payload"]
+        if not isinstance(slot_payload, dict):
+            raise TypeError(
+                f"render_slide: zones_data[{zone_index}] precondition failed — "
+                f"`slot_payload` must be a dict, got {type(slot_payload).__name__} "
+                f"(template_id={template_id!r})"
+            )
+        partial = env.get_template(f"families/{template_id}.html")
+        rendered_partial = partial.render(slot_payload=slot_payload)
+        # IMP-42 u2 (#71) — fail loud on invalid path chars in rendered HTML
+        # asset refs (src / href / url(...)). Catches Windows backslash and
+        # autoescape entity vectors before they reach the browser as 404.
+        _scan_rendered_html_for_invalid_path_chars(
+            rendered_partial,
+            f"zones_data[{zone_index}] template_id={template_id!r}",
+        )
+        zone["partial_html"] = rendered_partial

    base = env.get_template("slide_base.html")
-    return base.render(
+    rendered_base = base.render(
        slide_title=slide_title,
        slide_footer=slide_footer,
        zones=zones_data,
@@ -2676,6 +2792,11 @@ def render_slide(slide_title: str, slide_footer: Optional[str],
        token_css=_read_token_css(),
        embedded_mode=embedded_mode,
    )
+    # IMP-42 u2 (#71) — also scan the assembled slide_base output to cover
+    # asset refs introduced by the slide-base shell itself (title / footer /
+    # popup slots) outside the per-zone partial scope.
+    _scan_rendered_html_for_invalid_path_chars(rendered_base, "slide_base")
+    return rendered_base


 # ─── Selenium check (single slide + per-zone) ──────────────────
@@ -5384,6 +5505,8 @@ def run_phase_z2_mvp1(
        outputs=["step12_slot_payload.json"],
        note="map_with_contract 결과 — actual slot_payload 값 그대로 (key 만 X).",
    )
+    # IMP-42 u3 (#71) — unconditional Step 12 slot_payload emit DIAG log.
+    _emit_diag_zones_shape("Step 12 slot_payload emit", zones_data)

    # 6. Build layout CSS — horizontal-2 = dynamic heights (regression preserve), 그 외 = fr default.
    #    Step D-ext : override_zone_geometries 가 들어오면 layout_css 강제.
--- a/tests/phase_z2/test_phase_z2_diag_invalid_char.py
+++ b/tests/phase_z2/test_phase_z2_diag_invalid_char.py
@@ -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
--- a/tests/phase_z2/test_phase_z2_diag_render_assertions.py
+++ b/tests/phase_z2/test_phase_z2_diag_render_assertions.py
@@ -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
--- a/tests/phase_z2/test_phase_z2_diag_smoke_general.py
+++ b/tests/phase_z2/test_phase_z2_diag_smoke_general.py
@@ -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"] == []
--- a/tests/phase_z2/test_phase_z2_diag_terminal_logs.py
+++ b/tests/phase_z2/test_phase_z2_diag_terminal_logs.py
@@ -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