fix(gallery): regenerate four terrain pieces' gate sheets; fail stale contact sheets

The 2026-10-08 quality passes re-rendered the heroes of terrain-scatter,
sea-stack-arch, river-delta-tile and canyon-mesa-tile but left their contact
and asset sheets showing the old models, so the committed gate evidence no
longer matched what ships.

Regenerated all eight sheets: scripts/contact_sheet.py, and
scripts/asset_sheet.py on Blender 5.2.1.
Contact sheets: stages sit with the calibration set (0.19-0.31). Candidate
luma (0.27-0.36) and canyon-mesa's warmth (+0.57) come from sandstone and
meadow, not the light. Asset sheets: river-delta, canyon-mesa and
sea-stack-arch hold up in the lineup. terrain-scatter is borderline: on the
neutral sweep, without its scatter, it reads as a slab with rocks and is the
likeliest pick for least designed. Flagged for a remodel rather than waved
through.

tests/check_contact_sheets.py (Validate) compares each sheet's candidate
tile with the current hero resized the same way. Current sheets differ by
0.6-1.9; the four stale ones by 4.0-34.2. The threshold is 3.0, and
restoring the old sea-stack-arch sheet fails it.

Closes #487

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

Author: TMHSDigital

.github/workflows/validate.yml

@@ -109,6 +109,9 @@ jobs:
       - name: Check gallery hero and preview sizes
         run: python3 tests/check_gallery_images.py
 
+      - name: Check every contact sheet shows the hero that ships (#487)
+        run: python3 tests/check_contact_sheets.py
+
       - name: Validate template Python syntax
         run: |
           echo "Checking template Python syntax..."

CLAUDE.md

@@ -163,7 +163,7 @@ Stage with **explicit paths only** — never `git add -A` or `git add .`. Cursor
 
 - `docs/VISUAL-STYLE.md` is the **binding** render standard; deviations are defects.
 - **Framing gate:** Layer 1 framing is measured, not eyeballed — the example's `--output` render path calls the shared helper `examples/gallery_framing.py` (`check_framing`, exit 10 on violation) before writing the still: hero fill 0.70–0.90 of frame in at least one axis, every element that matters clearing all four edges by ≥ 0.02. The check-only path never invokes it, so smoke runtimes are unaffected. The helper measures; call sites enforce. Bleed compositions call `measure_framing_deviation` and assert their own cap at the call site — `check_framing` has no `deviation=` flag.
-- **Contact-sheet gate:** composite the candidate hero beside the pinned calibration set — currently `armature-bend`, `damped-track-aim`, `bmesh-gear` — commit the composite under `docs/gallery/contact-sheets/`, link it in the PR body, and report per-criterion verdicts (stage darkness, wedge warmth, subject fill, saturation, thumbnail legibility) including mean luminance versus the calibration images. A claim without the committed composite is not acceptable evidence. **This list is the canonical home of the pinned set** — update it here when a new example outclasses a member; `docs/new-example-prompt.md` points here rather than naming members. The longer "calibration references" list in `docs/VISUAL-STYLE.md` is a style reference, not this contact-sheet set. Tooling: `python scripts/render_hero.py --blender PATH --only NAME` renders the README `--output` command and writes the hero, its 640 card variant, and the preview webps (the one committed PNG-to-webp path); `python scripts/contact_sheet.py NAME` builds the composite in the committed format and prints each tile's luma, stage, wedge warmth and saturation; `python scripts/measure_hero_drift.py` checks committed heroes against what the code renders now.
+- **Contact-sheet gate:** composite the candidate hero beside the pinned calibration set — currently `armature-bend`, `damped-track-aim`, `bmesh-gear` — commit the composite under `docs/gallery/contact-sheets/`, link it in the PR body, and report per-criterion verdicts (stage darkness, wedge warmth, subject fill, saturation, thumbnail legibility) including mean luminance versus the calibration images. A claim without the committed composite is not acceptable evidence. Re-rendering a hero means regenerating its sheet: `tests/check_contact_sheets.py` (Validate) fails when a sheet's candidate tile no longer matches the hero that ships (#487), and an asset-type piece's asset sheet must be re-rendered in the same commit. **This list is the canonical home of the pinned set** — update it here when a new example outclasses a member; `docs/new-example-prompt.md` points here rather than naming members. The longer "calibration references" list in `docs/VISUAL-STYLE.md` is a style reference, not this contact-sheet set. Tooling: `python scripts/render_hero.py --blender PATH --only NAME` renders the README `--output` command and writes the hero, its 640 card variant, and the preview webps (the one committed PNG-to-webp path); `python scripts/contact_sheet.py NAME` builds the composite in the committed format and prints each tile's luma, stage, wedge warmth and saturation; `python scripts/measure_hero_drift.py` checks committed heroes against what the code renders now.
 - **Asset-sheet gate (asset-type examples — game props/kits):** composite the hero asset rendered alone (neutral three-quarter view, plain studio lighting, no staging tricks, no labels, no comparison props) beside the pinned asset-quality reference set — currently `collision-hull-proxy`, `socket-attach-points`, `vertex-color-ao`, `wheelbarrow`, `apothecary-shelf` — rendered the same way; commit under `docs/gallery/asset-sheets/`, link it in the PR body, and report a verdict. The asset ships only if it is not identifiable as the least-designed object in that lineup — a strong scene can carry a weak model; this gate removes the scene. **This list is the canonical home of the reference set** — update it here when a new asset outclasses a member. A reference may be an example or a showcase piece. Tooling: `python scripts/asset_sheet.py --blender PATH NAME` renders the candidate and this set (read from this line) through `scripts/asset_sheet_panel.py` and writes the composite. The measurable floors behind the gate (naming, material variation, edge treatment) live in `examples/gallery_asset_quality.py` — render path only, same call pattern as `gallery_framing`, exit 11 on violation — with the calibration table and dropped-floor evidence in `docs/VISUAL-STYLE.md` § Asset quality.
 - **Falsification:** every check must be proven to fail once — break the contract, observe the non-zero exit, restore — with the probe and the measured error reported in the PR body. An assertion that cannot fail witnesses nothing.
 - **After gallery regeneration** (`python scripts/build_gallery.py`), read the **generated HTML** character by character — the `<img alt>` text and witnesses callouts in `docs/gallery/index.html` and `docs/gallery/<name>/index.html` — not just `examples/gallery.json`. Precedent: the `teaches.split(".")[0]` bug truncated 14/21 card alts at dotted API paths like `bmesh.ops` while the source JSON looked fine (fixed in PR #68).