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