wip(L28): passage columns/routes culled per tile (BVH); cost back near L24, bit-identical to L27

GenerateMesh scopes passage queries to the tile's sample bounds with a feature AABB BVH plus
per-passage segment BVHs; L9 proof boxes use a passage-bound BVH. Whole view vs L24: FI ~0%, SW
+3.7% (reviewer interleaved). All hashes equal L27; all passage/route/proof audits pass.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

ARCHITECTURE.md

@@ -2034,6 +2034,23 @@ adapter edit is required. The L26 report contains the eight-style table, hashes,
 [`Standalone/Research/WorldAssemblerM3/Linux26/REPORT.md`](Standalone/Research/WorldAssemblerM3/Linux26/REPORT.md)
 records the final evidence.
 
+### 8.45 Tile-bounded passage evaluation — World Assembler M3 Linux L28
+
+Each mesh tile scopes passage composition to the inclusive density-sample AABB, including the
+mesher's normal halo. A conservative feature AABB BVH selects route segments, columns and mouth
+support for that tile. A per-passage nearest-segment BVH bounds the long helix search; a separate
+passage-bound BVH rejects far L9 proof boxes. An unindexed native-only proof object uses a conservative
+linear fallback. No field, union order, serialized layout or recipe version changes.
+
+The column's exact complex SDF is evaluated only in XY/Z feature candidates. A cheap density-aware
+radial guard remains for samples sharing the column's Z slab: a positive column distance can still
+lower positive base density, so skipping that guard needs an exact bound on the base field. This is
+the remaining SurfaceWorld cost noted in the Linux L28 report. The passage candidate lists and
+proof bounds preserve the L27 output.
+
+[Linux28 report](Standalone/Research/WorldAssemblerM3/Linux28/REPORT.md)
+records counts, parity, costs and audit caveats.
+
 ## 9. Multiplayer model (listen-server first, dedicated-friendly)
 
 > **Status: transport is DESIGN ONLY — nothing is networked in-tree yet** (no `Replicated`/`HasAuthority`/RPCs; a