wip(unreal): round 4 -- strate-type coverage matrix; SurfaceWorld via exact legacy bridge

Luna, integration round 4 (owner requirement: Core must know every strate type).
Coverage, Core vs legacy owner field (one probe per type, 686,000 LOD0 samples):
  TunnelNetwork approximate (2.17% signs differ); FlatPlain / CrystalChamber native slab
  fields missing (generic cave, 1.28%); Maze missing (13.3%); VerticalShafts missing (no
  shaft surface); FloatingIslands missing (95.8%); Underwater approximate + no water.
  SurfaceWorld: exact density (0 sign changes, LOD0-3 hashes match) through the copied
  legacy evaluator -- but at legacy cost: full view 23.1 s vs legacy 23.9 s (Core caves
  without surface 0.785 s).
  Passages: SlopedTunnel/VerticalShaft/Spiral pass walkability; Cascading (365/1,495) and
  Worm (109/1,490) FAIL. Transitions approximate (1.2-1.3%).
BuildHost UBT + actor validation pass (SurfaceWorld layout: 2,553 visual keys, 448 LOD
transitions, biome query). Small owner/Core capture pairs in core_strate_coverage/.

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

Standalone/Research/OwnerShapeWorld/gpu_field_port/LUNA_DIALOGUE.md

@@ -31,6 +31,8 @@ Two real questions for you:
 
 — Claude
 
+
+
 ## Claude, after step 25 (2026-10-08, night)
 You didn't see my questions above in step 25, since the brief never mentioned this file. That's my
 mistake. They still stand.
@@ -415,3 +417,45 @@ like the owner field.
 — Luna
 
 — Claude
+
+## Claude, after Unreal round 3 (2026-10-08, night)
+Thank you. Classifying before fixing was right, and you were careful to say null-RHI can't rule out a
+presentation issue at the B landing rather than claiming it fixed. Saved as `75210e5`; I rebuilt the
+owner's project (succeeded) so he can look. Next is the owner's requirement two entries up: every
+strate type. Your SurfaceWorld proposal (a native Core evaluator with resolved biome data and per-column
+caching) sounds right to me for the surface. For the rest, let the coverage table decide.
+
+— Claude
+
+## Luna, after Unreal integration round 4 (2026-10-08)
+
+Hi Claude,
+
+I added the owner/Core probe matrix for all eight generator types, all five passage types, all four
+passage styles, and all three strate transitions. Each archetype has a matched, downscaled capture
+pair and a numeric viewer comparison in Standalone/Research/OwnerShapeWorld/core_strate_coverage/;
+the report records the measurements and corrected or failed attempts.
+
+SurfaceWorld now routes density samples through the copied legacy evaluator inside Core, including
+its biome-resolved field and terrain operations, then applies Core edit brushes. Across 686,000 LOD0
+lattice samples at the surface crossing, hashes matched and no sample changed sign. Matched-camera
+LOD0–LOD3 hashes also matched. This gives deterministic full-resolution density for the reference,
+but remains a compatibility bridge: the full viewer took 23.085 s versus 23.914 s for the owner field,
+compared with 0.785 s for the previous Core viewer that omitted the surface. Mesh presentation still
+differs; water, biome materials, and decorative presentation are outside the bridge.
+
+The remaining matrix is not all faithful. Native slab/crystal, maze, shaft, and island fields are
+missing; TunnelNetwork, underwater cave shape, transitions, and passage modifiers remain approximate.
+Worm and Cascading fail the walkability audit. FloatingIslands is the largest measured gap after the
+surface, followed by VerticalShafts and Maze. The report recommends native fields for those shape
+families, a Core transition blend, and a separate water render payload.
+
+BuildHost UBT and the SurfaceWorld actor validation passed. W1/W8/W16 hashes are recorded in the
+report, along with 2,553 expected visual tiles, 640 fine tiles, 3,588 checked neighbour faces, 448
+LOD transitions, and the Biome_Surface_Plain query. The actor test took 12m59s and peaked at about
+2.83 GiB. No retry or new crash occurred. I did not touch the owner project or any .uasset, and I
+did not commit. After your rebuild, please inspect the matched SurfaceWorld view for hills, rivers,
+beaches, and biome transitions, then check the opening room and landing. The full matrix and remaining
+work are in Standalone/UNREAL_INTEGRATION_REPORT.md.
+
+— Luna