wip(assembler): M3 round 3 -- separated islands + Unreal island route (owner build 18:46)

Islands read as separate (91.89% open sky at mid-height), underside cavity closed,
rim teeth were capture shading. Island manifest import + BuildHost proof passed on the
pre-cache tree; M1 SurfaceWorld and M2 V1/V2 gates passed.

Known open: final XY-column cache compiled in the owner build but is unverified;
island LOD0 p95 ~155 ms misses the 133 ms sprint deadline (legacy ~43 ms); the island
manifest only fits the BuildHost fixture layout (owner's world: Core init fails,
empty world) -> round 4 builds plans inside Unreal.

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

@@ -1063,3 +1063,8 @@ match; the M2 mesher hash matrix was not replayed. No editor/viewer, project bui
 New source file this round: `RenderFloatingIslandRound2.py`.
 
 — Luna
+## World assembler M3 round 3 — 2026-10-10
+
+The owner's scale is settled at 12.5 cm per legacy voxel and 25 cm per Core voxel (owner-to-Core length ratio 0.5). The Round 3 shape review reads as four separated masses; sampled mid-height open sky is 91.89% of the XY bounding box. The underside center is solid, and the crust rim no longer shows the earlier sawtooth appearance in the matched offline captures.
+
+The manifest import and Core route passed the recorded BuildHost checks, along with SurfaceWorld M1 and HybridV1/V2 M2. Island/span collision contact, anchors/height/strate, Blueprint carve/fill, Core-off legacy behavior, W1/W8/W16 determinism, and tile hash parity passed on the verified source state. The recorded LOD0 island and mixed-tile sprint p95s still exceeded the 133.333 ms deadline by about 24 ms and 20 ms. A follow-up XY-column cache was added to target meshing/density cost but could not be compiled after the Windows command runner began returning `0xC0000142`; therefore I am not calling the current tree verified. The detailed measurements, hand-off, and run ledger are in `Standalone/Research/WorldAssemblerM3/Round3/REPORT.md`.