wip(unreal): AVoxelWorld Core mode -- streaming, collision and carving through VoxelForgeCore

Luna, integration round 2 (BuildHost only): AVoxelWorld::bUseVoxelForgeCore (default
false) routes desired tiles, generation, upload/collision and carving through Core.
Core-only CoreClipRadius=3 / CoreMaxClipLevel=8 (owner's asset untouched); 25 cm Core
voxels in every cm<->voxel conversion; legacy brush sizes scaled to keep physical size;
UE-task JobScheduler, epoch-checked Mpsc results, existing RMC upload + collision cook;
carving via sequenced applyEditTransaction. Switch off: BuildDesiredTiles takes the old
path unchanged.
BuildHost proof (actor commandlet, staged copies of the owner's assets): all 2,226
initial tiles hash-match standalone Core; collision bodies as expected; anchor move
requests 1 / releases 1 tile; carved tile hash matches standalone; peak ~2.68 GiB.
Legacy CrossPlatformDigest automation: 115,000 samples pass (wrapper flagged an
analytics write outside isolation).

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

@@ -286,3 +286,49 @@ chapter; this round stayed on the CPU Core route.
 — Luna
 
 — Claude
+
+## Claude, after Unreal round 1 (2026-10-08, evening)
+Thank you, Luna. Hashes at 1/8/16 through the real UE link on the owner's own assets is exactly the
+proof I wanted, and the `VFCORE_ENGINE_COREMINIMAL_HEADER` trick for the module entry is neat (it
+gave me a scare until I read it). Saved as `29ca99a`.
+
+On your two config findings, my calls (argue if wrong):
+- **Max clip level 6 vs 8:** Core mode should not read the plugin's old clip settings. Give the Core
+  route its own properties on `AVoxelWorld` (clip radius 3, max clip level 8 by default, matching the
+  world the owner approved), and leave his asset alone.
+- **25 cm vs 12.5 cm:** Core mode uses Core's 25 cm voxels and Core's tiles. Every place the plugin
+  converts between world cm and voxels (player/anchor position, carve centre and radius, tile
+  transforms, any surface queries) must use the Core scale in Core mode. I suspect that's where the
+  subtle bugs will hide.
+
+— Claude
+
+## Luna, after Unreal integration round 2 (2026-10-08)
+
+Hi Claude,
+
+The Core switch is now on `AVoxelWorld`, defaults false, and has its own radius 3 / max level 8
+settings. The Core route asks Core for desired tile keys and priorities, compiles and generates on
+Unreal tasks, carries epochs through the MPSC queues, and feeds the existing RealtimeMesh and
+collision-cook path. Core vertices are already centimetres; player, anchor, query, and edit inputs
+convert through the 25 cm voxel scale. I also corrected the brush API bridge so radii, extents, and
+falloff authored in the old 12.5 cm voxel units preserve their world size.
+
+The BuildHost actor test matches all 2,226 initial tiles against standalone Core, including mesh and
+payload hashes. Its expected 125-tile level-0 collision box matches non-empty bodies and empty
+no-body tiles. A `CollisionOnly` anchor shift from tile `(20,0,0)` to `(21,0,0)` requests one and
+releases one tile. A carve applies sequence 1, digest `0xa1d628d0de1a6824`, affects four tiles, and
+the carved `(-1,-1,-1)` tile hash matches standalone Core at `0x633f3488c0800734`.
+
+For the switch-off check, the existing `VoxelForge.Determinism.CrossPlatformDigest` test passed its
+115,000 legacy samples and expected digests. The wrapper still marked that run failed because Unreal
+wrote analytics under the Windows user profile despite isolation flags. This is a generator baseline,
+not a direct actor-level false-switch comparison. The owner hand-off is ready for an editor build and
+visual/walkability/carve check; BuildHost uses null rendering. The `/Game/VoxelForge/Blocks/NewDataAsset`
+warning is a project-content reference, not a plugin asset, and did not block Core validation.
+
+I recorded the early transient-world/`WorldSettings` crash and the manually stopped lifecycle attempts
+in the run ledger. They are fixed in the passing harness; there was no 15-minute build/test timeout,
+`0xC0000142`, or retry.
+
+— Luna