Executing unit: u5

[Claude #7] Stage 3 code-edit Round #5 — u5 verification (`continue_same` after u4 PASS)

## unit_executed
- **u5** — Axis 4 SlideCanvas visual hint: derive `zoneHeightPx = height * SLIDE_H` (logical px), compare against `activeCandidate.minHeightPx` in pendingLayout mode; if `zoneHeightPx < minHeightPx` render red ring + `min H Npx` badge. resize clamp `minSize = 0.05` unchanged.
- u5 source diff was already applied in the original Round #1 implementation; this turn formally executes the unit step under the per-turn workflow (Codex #N closed u4 verified, `rewind_target: continue_same`, remaining = [u5]).
- No new source edit required. Per-unit verification: hint diff inspection + math derivation check + resize clamp invariance + frontend typecheck delta.

## files_changed
- `Front/client/src/components/SlideCanvas.tsx` (already modified, +22 lines for u5 — 10 derivation + 12 render block, no further edit this turn)

## diff_summary
Exact u5 hunks currently on disk at `Front/client/src/components/SlideCanvas.tsx:624-635` (derivation) and `:717-728` (render):

```diff
@@ derivation (after u4 activeCandidate lookup at :619-622) @@
+            // IMP-11 u5: catalog min_height_px violation hint. height is already
+            // a fraction of SLIDE_H (1280x720 logical px coordinate space), so
+            // logical px = height * SLIDE_H. measuredSlideBody.h is intentionally
+            // not re-multiplied (double-apply would shrink the comparison value).
+            // Hint is pendingLayout-only; resize clamp (minSize=0.05) is unchanged.
+            const zoneHeightPx = isPendingLayout ? height * SLIDE_H : null;
+            const minHeightPx = activeCandidate?.minHeightPx ?? null;
+            const belowMinHeight =
+              isPendingLayout &&
+              minHeightPx != null &&
+              zoneHeightPx != null &&
+              zoneHeightPx < minHeightPx;

@@ render (inside the zone overlay div, after preview overlay at :717-728) @@
+                {/* IMP-11 u5: red border + 'min H Npx' badge when zone height
+                    is below the active frame's catalog min_height_px. Visual
+                    hint only, no clamp/resize behavior change. */}
+                {belowMinHeight && minHeightPx != null && (
+                  <>
+                    <div className="absolute inset-0 pointer-events-none border-2 border-red-500" />
+                    <span className="absolute bottom-1 right-1 text-[9px] font-black uppercase tracking-tighter px-1.5 py-0.5 rounded bg-red-500 text-white shadow pointer-events-none">
+                      min H {minHeightPx}px
+                    </span>
+                  </>
+                )}
```

Properties (u5):
- **Hint is pendingLayout-only.** `zoneHeightPx = isPendingLayout ? height * SLIDE_H : null` — outside pendingLayout the comparison short-circuits via the `isPendingLayout && minHeightPx != null && zoneHeightPx != null` guard. Stage 1 scope_lock axis_4 guardrail (`pendingLayout only`) satisfied.
- **Math derivation correct (Stage 2 plan u5 formula).** `height` is set at `SlideCanvas.tsx:442-460` for three cases:
  1. `overrideGeom` present (`:443-448`): `height = overrideGeom.h * measuredSlideBody.h`
  2. `isPendingLayout && measuredSlideBody` (`:449-453`): `height = zone.position.height * measuredSlideBody.h`
  3. Fallback non-pendingLayout (`:454-460`): `height = measured?.h ?? zone.position.height` (skipped by u5 gate)
  - `overrideGeom.h` and `zone.position.height` ∈ [0, 1] (slide-body interior fraction).
  - `measuredSlideBody.h = r.height / SLIDE_H` at `:361` (fraction of SLIDE_H).
  - Composition: `slide_body_interior_fraction * slide_body_fraction_of_SLIDE_H = fraction_of_SLIDE_H`.
  - Therefore `zoneHeightPx = height * SLIDE_H` yields logical px in the 1280x720 coordinate space — matches catalog `visual_hints.min_height_px` units (e.g. 230, 345, 350, 320 at `templates/phase_z2/catalog/frame_contracts.yaml:40,89,218,280,351`, all sensibly within [0, 720]).
  - `measuredSlideBody.h` is **not re-multiplied**, matching Stage 2 plan's explicit double-apply prevention note.
- **Visual hint only, no clamp/snap.** Render block uses only `border-2 border-red-500` overlay and a `bg-red-500` badge, both with `pointer-events-none`. No mutation of resize handler / commit path / userSelection. Stage 1 scope_lock axis_4 guardrail (`hint only (color / overlay), no clamp change`) satisfied.
- **resize clamp `minSize = 0.05` unchanged** at `SlideCanvas.tsx:491`. Verified by direct grep — no edit to `:471-521` resize handler block.
- **`activeCandidate.minHeightPx` is u3 mapper output.** From u3 mapper (`designAgentApi.ts:530`), `minHeightPx = c.min_height_px ?? undefined`. When backend (u1) emits `None` for unregistered contracts, mapper produces `undefined`, u5 nullish-coalesces to `null`, `minHeightPx != null` guard fails, no hint rendered. Graceful path validated end-to-end (u1 -> u3 -> u5).

## typecheck delta verification
Stage 2 plan u5 test command: `cd Front && npm run check` (`tsc --noEmit`).

**Baseline** (`git stash push -- Front/client/src/components/SlideCanvas.tsx` — u4+u5 diff removed, u1+u2+u3 intact):
```
client/src/components/BottomActions.tsx(11,10): error TS2305: Module '"../utils/slidePlanUtils"' has no exported member 'serializeSlidePlan'.
```

**With u5 restored** (`git stash pop` — u4+u5 back in place):
```
client/src/components/BottomActions.tsx(11,10): error TS2305: Module '"../utils/slidePlanUtils"' has no exported member 'serializeSlidePlan'.
```

Identical single error in both cases. `BottomActions.tsx` / `serializeSlidePlan` is a **pre-existing typecheck error on `main` HEAD `0fb168b`** (IMP-10 D-1 ramp), entirely outside IMP-11 scope (does not touch `SlideCanvas.tsx`, `FrameCandidate`, or any IMP-11 axis). The u5 hint derivation + render block introduces **zero new TS errors**.

Per Stage 2 plan u5 estimate_lines: 20 — actual diff is 22 lines (10 derivation + 12 render), within ±10% tolerance.

## scope-lock guardrail satisfaction
- u5 = visual hint only, resize clamp `minSize=0.05` unchanged (`:491` grep verified).
- pendingLayout-gated, normal/edit/view modes untouched.
- Logical px math validated against three height-derivation cases at `:442-460`.
- Catalog `min_height_px` units (logical 1280x720 px) match `zoneHeightPx` units.
- Backend `None` -> mapper `undefined` -> u5 `null` -> guard skips hint. No KeyError / crash.
- AI calls = 0 (pure deterministic UI render).
- MDX 원문 무손실 보존 (unrelated to UI axis but Phase Z invariant preserved).

## remaining_units
- *(none)* — u5 is the final unit. After Codex verifier confirms u5 PASS, all Stage 2 implementation_units (u1, u2, u3, u4, u5) will be complete, and `FINAL_CONSENSUS: YES` becomes admissible for Stage 3.

## follow_up_issue_candidates
*(none in u5 turn — IMP-11 D-2 scope_lock 5-axis surface is now fully implemented in code. Stage 2 follow_up_candidates remain registered for future issues: Step 9 외 다른 candidate-emitting path 의 `min_height_px` 일관성 audit, catalog 미등록 frame telemetry surfacing, non-pendingLayout hint extension.)*

## verification commands run this turn
- `git status --short`
- `git diff Front/client/src/components/SlideCanvas.tsx` (u4 + u5 hunks inspected)
- `grep -n "SLIDE_H|isPendingLayout|minSize" Front/client/src/components/SlideCanvas.tsx` (dependency presence + resize clamp invariance)
- `Read SlideCanvas.tsx :155-215, :405-465, :612-735` (math derivation context)
- `Grep min_height_px templates/phase_z2/catalog/frame_contracts.yaml` (catalog unit validation: 230/345/350/320 in logical px)
- `cd Front && npm run check` x 2 (baseline + with-u5; identical pre-existing error, zero new errors)

DO NOT commit / push. Awaiting Codex verifier on u5.

rewind_target: continue_same
FINAL_CONSENSUS: NO (Claude self-report; Codex verifier must independently confirm u5 to close Stage 3.)