proto: liminal looks - pool rooms, backrooms grid, staircase to nowhere, terraced hills (L161)

Stamp vocabulary v7 (opt-in fillBox, carveBox, fillSteps; carveArch reused); flat-field liminal stamp fixtures; capsule
walk audit with doorway-width gate (1.2 m control fails as expected). Clang/GCC W1/W8/W12 identical; owner canonical
hashes unchanged; fast tier 273/273. Terraced wide view not yet legible.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Research/WorldAssemblerM3/Linux161/REPORT.md

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+# L161 — More liminal looks
+
+| Look | Eye height | Wide |
+|---|---|---|
+| Pool rooms | ![Pool rooms at eye height](captures/pool-rooms-eye.jpg) | ![Pool rooms wide](captures/pool-rooms-wide.jpg) |
+| Backrooms grid | ![Backrooms corridor at eye height](captures/backrooms-grid-eye.jpg) | ![Backrooms grid wide](captures/backrooms-grid-wide.jpg) |
+| Staircase to nowhere | ![Staircase at eye height](captures/staircase-to-nowhere-eye.jpg) | ![Staircase wide](captures/staircase-to-nowhere-wide.jpg) |
+| Terraced hills | ![Terraced hills at eye height](captures/terraced-hills-eye.jpg) | ![Terraced hills wide](captures/terraced-hills-wide.jpg) |
+
+## Result
+
+Four standalone SurfaceWorld fixtures resolve from the shared stamp vocabulary. They use repeated rooms and basins, a doorway grid, a freestanding stair and arch, and nine stepped ridges. This round authored no inter-strate passages or owner content.
+
+## Changes
+
+- Stamp vocabulary v7 adds `fillBox`, `carveBox`, and `fillSteps`; the existing `carveArch` is reused. The new kinds are opt-in.
+- Added a flat-field liminal stamp-fixture override and a capsule walk audit with doorway-width gates. The audit checks support, collision, grade, and authored opening widths.
+- Fixtures contain 275 pool-room stamps, 129 backrooms stamps, 4 staircase/arch stamps, and 18 terrace stamps.
+
+## Verification
+
+- Clang 19 and GCC 14 builds passed with FP contraction off. Both binaries carry source stamp `8e9e114c1357`.
+- Each fixture matched across Clang/GCC at W1, W8, and W12: manifest, resolved-layout identity, and tile hashes were identical in all six cells.
+- Positive capsule audits passed. Pool doorways measured 7.2 m, backrooms doorways 4.0 m, and the arch opening 10.0 m. The narrow 1.2 m backrooms control failed the 1.5 m minimum as expected. The terrace walk had zero blocked samples, unsupported samples, or grade failures.
+- All eight 1600×900 captures passed image quality checks; files are 25.3–58.4 KB. Capture and audit logs are under `Saved/Linux/l161/logs/`.
+- Fast tier passed: 273 checks in 346.6 s. Both owner generators matched their pinned L130/v227 canonical baselines exactly (12/12 rows), and W1/W12 signatures matched. Summary: `Saved/Linux/l161/fast-tier/fast-summary.json`.
+- `git diff --check` passed. No Unreal `Source/` files changed; no Unreal build or medium/full verification tier was run.
+
+## Remaining risk
+
+The captures show untextured geometry with simple fog. The terraced wide capture uses clip radius 3 and max LOD 1 to stay within the standalone shape-build bound, so the long-range horizon read still needs an art review.