feat(core): deterministic bounded SDF landmark stamps, off by default (L43); research R10

Stamp vocabulary v1 (carve ellipsoid/arch, fill pillar/dais) with smooth CSG and seeded relief; the
director resolves records (stable ID, strate, micrometre position, conservative bounds) from
hash(seed, strate, ID) with up to 512 candidates and rejects any that touch a passage mouth, walk corridor,
content face or ceiling/bedrock band; a stamp BVH skips tiles outside all bounds. No requests: canonical
JSON and owner hashes unchanged. --landmark-chamber-demo adds a SW chamber (buried; see review).
fast/medium/full PASS on clean builds. Research R10 (read-only): ore/resource channel design.
Review also records a pre-existing W1/W12 determinism mismatch at a non-spawn camera (L37+, not S14).

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

ARCHITECTURE.md

@@ -2236,6 +2236,35 @@ also retains generator-specific anchor and default-mouth placement rules; those
 shared composition boundary policy. No Unreal source changed. See the L42 report for hashes, tier
 results and paired cost measurements.
 
+### 8.53 Shared Core landmark SDF stamps — World Assembler M3 L43
+
+`ResolvedLayoutStampV1` adds a small, version-1 SDF vocabulary to the shared resolved layout:
+carve ellipsoid, carve arch, fill pillar and fill dais. Requests and resolved records use integer
+micrometres and carry a stable ID, strate, position, conservative bounds, half extents, smooth-CSG
+width, bounded irregularity amplitude/wavelength and quarter-turn orientation. A stamp's seeded
+noise and bounded placement offsets derive from `(world seed, strate, stable ID)`; records are
+sorted by stable ID before the layout identity is finalized. If no request is made, the stamp fields
+are omitted from canonical JSON, preserving the no-stamp layout identity and density hashes.
+
+Resolution retries a finite, deterministic set of candidates and rejects a record if its complete
+bound intersects a passage mouth or walk corridor, reaches a strate content face, or overlaps the
+ceiling or bedrock band. The director reports failure if no safe candidate exists. The strict-layout
+negative control forces a candidate onto a route and into a ceiling band and expects both rejections.
+
+`FStandaloneShapeWorld` applies stamps after the shared resolved-strate boundary and passage
+composition. Carves use smooth maximum with the negated stamp SDF; fills use smooth minimum. Seeded
+trilinear value noise adds low-frequency relief without changing the conservative bound. The tile
+query scope builds a BVH candidate list from each tile's sample bounds. Samples in a tile outside
+every stamp box do no stamp SDF evaluation. Box classification marks stamp-intersecting boxes mixed,
+and native-only readiness refuses to skip them.
+
+The `--landmark-chamber-demo` recipe flag adds an irregular ellipsoid chamber, a separate arched
+entrance and a low fill dais in the owner SurfaceWorld strate, about 31 m from the passage arrival
+mouth and off the walk route. It stays disabled by default. Active records carry vocabulary version
+1 in the layout identity, making the demo an explicit world change; no Unreal adapter was added.
+L43's report records the off/on hashes, walk and interface audits, outside-stamp timing, tier
+results, captures and any failed runs.
+
 ## 9. Multiplayer model (listen-server first, dedicated-friendly)
 
 > **Status: transport is DESIGN ONLY — nothing is networked in-tree yet** (no `Replicated`/`HasAuthority`/RPCs; a