passages: exact relief skip + per-tile BVH node masks (L82); FI/TN LOD0-2 -12%

- Wall relief noise is skipped when its hard-bounded contribution cannot change the final max;
  mouth surface/tread noise only on paths that use it.
- Exact active BVH-node masks cached per tile/passage/segment range; no per-sample lower_bound.
- Full-view audit imports the exported Core plan (not the stale 26-point root route): 21,425/21,425
  walkability samples pass.
Cold (L80 protocol, medians) LOD0-2: SW 1.16->1.11, FI 2.86->2.51, TN 2.88->2.54, VS 1.23->1.22 s.
Passage share FI 64.6->58.7%, TN 65.4->58.4%. Hashes identical (v214). TN "slowdown" from L81
not reproduced (5 pairs, 3.08 -> 2.75 s). Fast tier PASS; Linux UE host builds.

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

Standalone/Research/WorldAssemblerM3/Linux82/REPORT.md

@@ -0,0 +1,50 @@
+# Linux82 — samples near passages
+
+## Changes
+
+- Kept the 3D relief definition. The wall relief noise is skipped only when its hard-bounded maximum contribution (including mouth-floor relief and the bridge input) cannot change the final `max`. Mouth surface and tread noise are evaluated only on paths that use them. This is exact; no 2D relief approximation or world change was made.
+- Cached exact active BVH-node masks per tile, passage, segment range, and priority. Repeated samples reuse the mask and skip the per-sample `lower_bound`; candidate segment ordering and distance tests are unchanged.
+- The full-view audit now imports the exported Core plan and resolved layout without a recipe override. Snapshot creation preserves that export provenance so generated recipe overrides keep their own route audit.
+
+## Passage census
+
+Mean near-LOD passage share of weighted sampler ticks; L81 has two exact-mode runs and L82 has three.
+
+| World | L81 exact | L82 exact | Change |
+|---|---:|---:|---:|
+| FI | 64.56% | 58.67% | −5.89 pp |
+| TN | 65.35% | 58.40% | −6.95 pp |
+
+## Cold readiness
+
+Three interleaved measured pairs per stratum; medians in seconds.
+
+| Stratum | LOD0–2 L81 → L82 | Whole view L81 → L82 |
+|---|---:|---:|
+| SW | 1.158 → 1.110 | 2.525 → 2.414 |
+| FI | 2.864 → 2.505 | 4.240 → 3.797 |
+| TN | 2.879 → 2.535 | 4.042 → 3.632 |
+| VS | 1.232 → 1.224 | 2.261 → 2.227 |
+
+All 960 LOD0–1 tile hashes per stratum matched L81 for density, mesh, payload, and topology; whole signatures matched with zero mismatches. The exact path kept evaluator version 214 and made no world-data change.
+
+## TN comparison
+
+Five interleaved TN-only LOD0–2 pairs (`max-level=2`, default scheduling on both binaries): `90378a5` median 3.078 s; `9cb5e53` median 2.747 s. All five paired deltas favored `9cb5e53` (median −0.281 s). The 3.18→3.51 s slowdown was not reproduced in the requested comparison; this A/B does not isolate an L80-to-L81 pair.
+
+## Audit and verification
+
+- Canonical full-view walkability: 21,425/21,425 samples passed; all three resolved passage audits passed. The stale 26-point root route was not used.
+- Fast tier: PASS, 298.1 s.
+- Linux `VFHostEditor` build after timing: PASS, 27/27 actions in 70.98 s with `-NoUBA -MaxParallelActions=4`; log rotation was redirected to `/tmp` after the default config path proved read-only. Three existing RealtimeMesh deprecation warnings.
+- Final source stamp: `99fcbd2fd46e0bb3e250f3ad67e98ade0545e419193f987550356015714c6f1b`.
+
+## Failed attempts
+
+- The first TN harness expected the newer near-LOD marker, which `90378a5` does not emit. It was changed to use whole-view readiness with only LOD0–2 enabled; all five pairs then completed.
+- The first full-view audit used `--recipe=surface-world`, which rebuilt a recipe snapshot and hit the stale root route (65/5,310). Removing the override imported the canonical export and passed.
+- The first fast-tier launch lacked its round-specific binary. A later diagnostic exposed lost export provenance in snapshot creation; that was threaded through, and the final fast tier passed.
+- The first UE build could not rotate a log in the read-only user config directory. Retrying with `XDG_CONFIG_HOME` under `/tmp` succeeded.
+
+Logs and summaries are under `Saved/Linux/l82/`. No commit, push, or stash was made.
+All headless runs used the requested CPU affinity and 6 GiB address-space cap; UBT used the CPU affinity without the cap. No run reached 30 minutes.