wip(assembler): round S2 (Sol) -- shared per-tile feature queries for every Core family; island placement 30x faster

Island-only worker context replaced by a shared worker-local candidate domain
(WorldAssemblyFeatureTileListV1 / ScopedWorldAssemblyFeatureQueriesV1) serving
SurfaceWorld, FloatingIslands and far-shell queries; a per-domain cost hint keeps the
full scan on small plans. Content placement prepares the same queries and skips proven
air: owner island cell p95 7.07 -> 0.24 ms; populated fixture 572 exact placements,
3.27 s -> 29 ms. Full/candidate hashes equal with dropped-feature controls on both
families; S1 default W1/W8/W16 hashes reproduced; Core-off and M2 fixtures pass.
Default contract for future families in ARCHITECTURE 8.23. Run on gpt-6.1-sol medium.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

CODEMAP.md

@@ -882,11 +882,25 @@ uses the owner/Core ratio as well. Edits use sequenced `applyEditTransaction` ca
 Core work drains, then regenerate Core's affected keys under a new epoch. Existing streaming anchors
 participate; the headless move proof covers `CollisionOnly` policy.
 
-The reusable `BuildWorldAssemblyFeatureTileListV1` accepts conservative inclusive feature bounds for
-future caves, shafts, pits, and passages. Floating Islands builds one `FloatingIslandTileFeatureListV1`
-per tile and the scoped worker context makes `FloatingIslandFieldV1::densityAt` evaluate only that
-candidate list. Candidate order stays canonical, the field hash remains bit-identical, and a dropped-
-feature negative control is part of the standalone Round 5 audit.
+The reusable `BuildWorldAssemblyFeatureTileListV1` accepts conservative inclusive feature bounds.
+`ScopedWorldAssemblyFeatureQueriesV1` replaces the island-only ShapeWorld worker context: meshing,
+derived shells, decoration cells and landmark columns share its nestable worker scope. Recipe/plan
+identity and an inclusive domain guard each query; outside queries fall back to the full evaluator.
+See ARCHITECTURE §8.23 and WorldAssemblerM3/Round6/REPORT.md.
+
+| Symbol | Canonical file | Role |
+|---|---|---|
+| `WorldAssemblyFeatureTileListV1`, `WorldAssemblyFeatureGroupBoundsV1`, `WorldAssemblyFeatureQueryV1` | `Standalone/Core/include/VoxelForgeCore/VoxelForgeCore.h` | Stable-order candidates, optional exact value-side group certificates and borrowed recipe/plan identity. Old island names remain aliases. |
+| `ScopedWorldAssemblyFeatureQueriesV1::{find,ScopedWorldAssemblyFeatureQueriesV1}`, `WorldAssemblyFeatureTileListV1::candidateEvaluationUseful` | `Standalone/Core/src/WorldAssemblerInternal.h` / public header | Worker-local domain, cost hint resolved once per query, forced validation, nested restoration and full-scan fallback; replaces ShapeWorld's island context. |
+| `Heightfield2D::buildFeatureTileList`, `world_assembly_detail::FeatureRange` | `Standalone/Core/src/WorldAssemblerInternal.h` | XY bounds for column writers; exact no-op bounds for finite boxes/shelves; canonical operation order. |
+| `FloatingIslandFieldV1::{solidSupportBounds,buildFeatureTileList,densitySubvoxels}` | `Standalone/Core/src/FloatingIslandsInternal.h` | Finite support declarations, root-aware distance certificates, automatic shared-scope consumption. |
+| `WorldAssemblyFeatureColumnRangeV1`, `BuildWorldAssemblyFeatureColumnRangeV1` | Public Core header / `Standalone/Core/src/WorldAssemblerInternal.h` | Conservative column support union for air-base families; invalid bounds are unknown. |
+| `VF_ContentFeatureQueries`, `VF_ConstrainContentMarch` | `Private/VoxelContentManager.cpp` | Immutable queries prepared per cell/landmark; skips proven air while preserving march phase and exact crossing refinement. |
+| `UVoxelContentManager::MeasurePlacementCostForValidation` | `Private/VoxelContentManager.cpp` | Authored/populated full-versus-candidate transforms, canonical anchor checks, batch and isolated HISM application cost. |
+| `UVoxelContentManager::ApplyRegion` | `Private/VoxelContentManager.cpp` / `Public/VoxelContentManager.h` | Normal region application retains landmark footprints; its default-true footprint flag isolates the temporary populated validation fixture. |
+| `RunCoreSharedFeatureCostAudit`, `RunCoreContentPlacementCostAudit` | `Source/VoxelForgeEditor/Private/VoxelForgeExploreCommandlet.cpp` | Paired owner-plan tile/shell timings and hashes, placement metrics and transient BuildHost plan exports. |
+| `TileGenerationOptions::useAssemblyFeatureQueries`, `TileGenerationStats::{featureListMilliseconds,farShellMilliseconds}` | Public Core header / `Standalone/Core/src/VoxelForgeCore.cpp` | Default-on candidate route, full-scan validation control and stage timing; no identity change. |
+| `SharedFeatureListAudit.cpp`, `BuildSharedFeatureListAudit.ps1` | `Standalone/Research/WorldAssemblerM3/Round6/` | Owner-plan/stress hashes, shared-scope probes and deliberately dropped needed features. |
 
 `-coreworldtest=1` in the BuildHost editor commandlet validates initial tiles, expected collision
 bodies/empty tiles, anchor movement, a carve transaction, travel to the B landing and native surface