VoxelForge/Standalone/Research/WorldAssemblerM3/Research2/REPORT.md

Research R2 — Unreal compile and behavior review

Read-only static review; no builds or tests run.

Build baseline and Source history

The last recorded Windows BuildHost UBT pass is Round 18/S14, source commit ec2afe9 (BuildHost UBT passed on its first attempt; the report lists Source/VoxelForge/Private/VoxelWorld.cpp). The older commit explicitly labelled “owner build” is 48fa028; the newer BuildHost pass is the better compile baseline. No later UBT pass is recorded for these Source edits.

Since ec2afe9, the Unreal-side edits are:

• L11 b1cfaf5: Private/VoxelWorld.cpp
• L18 dcf0763: Private/VoxelForgeCoreAdapter.cpp, Public/VoxelDensityPrimitives.h
• L21 8753f6d: adapter
• L22 55c26a0: adapter, Private/VoxelStrateManager.cpp, Public/VoxelSettings.h, Public/VoxelStrateManager.h
• L23 71d09a8: adapter
• L24 cb9236c: adapter, Public/VoxelStrateTypes.h
• L25 ef789aa: adapter
• L27 07b3fe2: adapter
• L29 63c7e56: adapter, Public/VoxelStrateTypes.h
• L37 3e443bf: adapter

That is seven changed Source files: VoxelForgeCoreAdapter.cpp, VoxelWorld.cpp, VoxelStrateManager.cpp, VoxelDensityPrimitives.h, VoxelSettings.h, VoxelStrateManager.h, and VoxelStrateTypes.h.

Findings

File:line	Issue	Confidence	Suggested fix
Source/VoxelForge/Private/VoxelForgeCoreAdapter.cpp:822	Calls non-const SetHardTransitionFallbackForAssembly through const UVoxelStrateManager*; this is a C++ compile error and remains in the current worktree.	certain	Pass a mutable manager through the serializer/attach path, or perform the state change at a non-const caller.
Standalone/Core/src/ShapeWorldInternal.h (tracked HEAD line 1554)	Tracked HEAD has an extra ) in its mouth-support if; the current L38 worktree replaces that passage-mouth block in a larger Core rewrite.	certain (HEAD only)	Preserve and review the current L38 diff before the owner builds.
Source/VoxelForge/Private/VoxelStrateManager.cpp:1179	New std::llround call has no direct <cmath> include; it may currently arrive transitively.	check	Add <cmath> to this translation unit.
Source/VoxelForge/Private/VoxelWorld.cpp:13048	New unordered_set::contains requires C++20; VoxelForge.Build.cs does not pin the standard.	check	Pin CppStandard=Cpp20 here or use find(...) != end() if older language modes must work.
Source/VoxelForge/Private/VoxelForgeCoreAdapter.cpp:137, 489, 543	Route capsule dimensions are fixed in Core subvoxels; the Floating Islands recipe leaves routeConstraints.version zero, so Core fills 25 cm-sized defaults. At smaller Core voxel sizes, the proofs shrink in centimetres.	likely (when Core voxel size < 25 cm)	Set both route constraint sets from fixed gameplay dimensions in cm divided by CoreVoxelSizeCm.
Source/VoxelForge/Private/VoxelWorld.cpp:7761	Failed Core startup switches to legacy generation but does not clear the hard-transition flag set by the adapter at line 822; legacy parameter lookups then keep the Core-only hard fallback.	likely	Clear the flag in FallBackToLegacyAfterCoreInitializationFailure.

No likely UHT blocker found in the changed headers: the new reflected setting is a float with numeric clamp metadata; the Blueprint enums remain : uint8; changed reflected declarations add no uint64/int64 properties. UE documents uint32/int64 as property integer types and metres as a supported unit. UE Properties · UE Units. VoxelDensityPrimitives.h adds inline shared helpers; the other header changes are layout state, comments, or the intentional Worm default. No designated initializers, __restrict, or suspicious new narrowing were found.

Core’s module pins C++20 and precise FP semantics. CoreNamespacePreamble.h selects a compiler-specific contraction control; the MSVC branch uses #pragma fp_contract(off), and World::compile rejects a build if its FMA self-test fails. MS documents that pragma from VS2022 17.0 and that older compilers could contract under /fp:precise; confirm the owner’s toolset and check the startup self-test. UE C++ standard · MSVC /fp · MSVC fp_contract. Core unordered containers appear to serve lookup, membership, statistics, or lookup-table construction; I found no output-affecting hash iteration.

At final review, L38 had an uncommitted worktree diff across six files (136 insertions / 1,002 deletions), including removal of terrainFollowingRoute from the Core recipe and both plan producers; no live code references remain. This is a substantial in-progress evaluator change with no UBT confirmation. No other stale Core/adapter recipe-field mismatch was found in the current worktree.

Behavior risks

• SurfaceWorld and FloatingIslands intentionally use different historical voxel conventions: SurfaceWorld layout chunks are 32 Core voxels (8 m at 25 cm); FloatingIslands converts 32 owner voxels (12.5 cm) through the owner/Core ratio (4 m at 25 cm). The L20/L22 research records this split. Do not blanket-apply the FI scale to SurfaceWorld; compare physical anchors and route clearances if using a non-25 cm Core size.
• Route proofs assume a 34 cm radius, 176 cm tall player capsule at 25 cm Core voxels. At 12.5 cm, the fixed Q values represent half those physical dimensions; the FI Core fallback also silently supplies fixed defaults because the adapter never sets routeConstraints.
• On adapter validation/export failure, the hard-transition flag set at adapter line 822 can leak into the legacy fallback path. This can make the fallback world differ from the normal legacy generator.
• FP behavior is fail-closed rather than silently divergent on unsupported MSVC: if contraction is detected, Core initialization refuses to generate. Linux1’s Clang/GCC checks do not validate the owner’s MSVC binary.

What the owner should check first when he builds

1. Build the current worktree (including the current L38 Core rewrite); expect the adapter constness error first unless the implementation fixes it.
2. Check UHT, then confirm the owner project’s language mode accepts unordered_set::contains; add the direct <cmath> include if MSVC reports llround unresolved.
3. Confirm Core startup passes the FP self-test. Then validate one SurfaceWorld and one FloatingIslands route at the configured Core voxel size, especially if it is below 25 cm; inspect startup plan errors and the route capsule/support clearance.

Orchestrator follow-up (Claude)

Both "certain" findings were confirmed and fixed in the same commit:

• ShapeWorldInternal.h:1554 stray ) — L37's committed Core did not compile. It was left when a temporary support-off diagnostic was restored after the final build. Fixed; a clang build of the fixed HEAD reproduces L37's verified owner-world hashes exactly (SurfaceWorld and FloatingIslands, L25 W12).
• Adapter constness (VoxelForgeCoreAdapter.cpp:823) — the setter is now const over a mutable runtime flag.
• Also applied: the legacy fallback clears that flag, and <cmath> is included in VoxelStrateManager.cpp.
• Left for the owner's build: unordered_set::contains (UE5 modules default to C++20), and the FI route-constraint scaling at Core voxel sizes other than 25 cm (only matters if he changes it).