wip(assembler): M3 round 4 -- plans built inside Unreal from the owner's strates; no import needed

SurfaceWorld and FloatingIslands plans generate at startup from the resolved seed,
strate types and heights (hashed, cached). Imported JSON is an opt-in override (off by
default); an invalid override shows an on-screen notice and falls back to legacy.
BuildHost on staged owner assets: SurfaceWorld cross-system checks, islands at owner
height (route, collision, anchors, BP edits), seed 137501, W1/W8/W16, Core-off legacy.
XY-column cache verified (hashes kept); island LOD0 p95 91 ms vs 133 ms sprint deadline.
Not exercised: season-seed path (no Season in staged settings), rendered notice pixels.

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

@@ -1067,4 +1067,13 @@ New source file this round: `RenderFloatingIslandRound2.py`.
 
 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`.
+
+## World assembler M3 round 4 — 2026-10-10
+
+Round 4 moves SurfaceWorld and FloatingIslands planning into the Unreal startup adapter. It uses the resolved seed, actual strate type/height/layout, and authored parameters, then caches the canonical JSON and hash for that world. Imported JSON is now opt-in through **Use Imported World Assembly Override**. This makes the owner’s already-imported but mismatched round-3 payload harmless by default while preserving a deliberate debug override and its clear error/fallback behavior.
+
+The staged owner settings did contain the old manifest, and the plan test retained those bytes with override off: seed 137501 produced an identical canonical serialization and startup hash `15c54ba04b430e42`. SurfaceWorld passed height/water/atmosphere, biome, worker-hash, and Blueprint carve/fill checks. The owner-height FloatingIslands copy passed the route and W1/W8/W16 checks, island/span anchor agreement, cooked capsule contacts, Blueprint edits, and legacy switch-off. The exact Round 3 standalone probe also passed with its old recipe/plan/manifest and worker hashes unchanged. Its native 32K-sample timing measured 38.91 ms after the XY-column cache versus the recorded 46.30 ms; the owner-height LOD0 island p95 was 91.429 ms versus the 133.333 ms sprint deadline.
+
+One remaining fixture caveat is recorded in [`WorldAssemblerM3/Round4/REPORT.md`](../../WorldAssemblerM3/Round4/REPORT.md): the staged saved `DA_Settings` points to `DA_Strate4`, while the owner’s read-only Play log resolves the active single SurfaceWorld from `DA_Strate1`. The BuildHost commandlet therefore reconstructed that logged one-slot layout as a transient copy at the real `[0,-63]` bounds. No Season asset was assigned in the staged settings, so the season-seed path was not tested. The report includes this distinction, the full pass/fail ledger, crash check, and editor hand-off. No owner project/editor was touched, no `.uasset` was edited, and no commit, push, or stash was made.
+
+No new source file was added. The post-change UHT/BuildHost compile and Core link audit passed at four actions; the Core-only Standalone rebuild/audit passed. No `0xC0000142` retry or new UECC folder occurred.