fix(unreal): U1 -- Unreal compiles again on L61; CoreGeometry asset section; versioned layout-unit upgrade

Windows MSVC catch-up after abyss L15-L61 (no Unreal there): 64-bit clipmap
shift (C4334), qualified VoxelForgeCore::WorldAssemblySubvoxelsPerVoxel, UHT
metadata and duplicate-signature fixes. Optional CoreGeometry section on
UVoxelStrateDefinition (native caves, lattice, profiled heightfields, named
stamps, rooms/tunnels; off/empty by default), resolved after passage planning.
VoxelForgeAssetVersion 2 converts strate height/transition/gap to metres on
load (exact, 0 m change on the owner's 5 assets; packages never saved).
Gates pass (SurfaceWorld, FloatingIslands, Core-off, M2, W1/W8/W16).
KNOWN REGRESSION vs L14 (2026-10-20, same command, same PC): full set 3.9 ->
5.37 s, worker-seconds 15.8 -> 30, LOD0 1.11 -> 1.69 s, ring 0.50 -> 0.80 s;
not yet attributed (Core L15-L61 vs Unreal side).
Report: Standalone/Research/WorldAssemblerM3/Unreal1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Source/VoxelForge/Private/VoxelContentManager.cpp

@@ -18,6 +18,7 @@
 #include "Materials/MaterialInterface.h"
 #include "Tasks/Task.h"
 #include "HAL/PlatformProcess.h"
+#include "Misc/Crc.h"
 #include "ProfilingDebugging/CpuProfilerTrace.h"   // Unreal Insights scopes
 #include <VoxelForgeCore/VoxelForgeCore.h>
 #include <cmath>
@@ -322,11 +323,54 @@ void UVoxelContentManager::Initialize(AActor* InOwner, UVoxelStrateManager* InSt
     Seed = InSeed;
     NativeSurfaceSnapshot.Reset();
     NativeFloatingIslandSnapshot.Reset();
+    CoreGeometryAnchors.Reset();
 
     if (Settings)
     {
         FString ManifestJson, ManifestHash, ManifestError;
         const AVoxelWorld* VoxelWorld = Cast<AVoxelWorld>(Owner.Get());
+        FString ResolvedLayoutJson, ResolvedLayoutIdentity;
+        if (VoxelWorld != nullptr
+            && VoxelWorld->GetVoxelForgeCoreResolvedLayout(ResolvedLayoutJson, ResolvedLayoutIdentity))
+        {
+            FTCHARToUTF8 Utf8Layout(*ResolvedLayoutJson);
+            std::string LayoutError;
+            const std::optional<VoxelForgeCore::ResolvedLayoutSnapshotV3> ResolvedLayout =
+                VoxelForgeCore::ResolvedLayoutSnapshotV3::FromJson(
+                    std::string_view(Utf8Layout.Get(), static_cast<std::size_t>(Utf8Layout.Length())), LayoutError);
+            if (ResolvedLayout)
+            {
+                const auto AddAnchor = [this](const std::string& StableId, int32 StrateIndex,
+                    const std::array<std::int64_t, 3>& PositionMicrometres)
+                {
+                    const FVector PositionCm(
+                        static_cast<double>(PositionMicrometres[0]) / 10000.0,
+                        static_cast<double>(PositionMicrometres[1]) / 10000.0,
+                        static_cast<double>(PositionMicrometres[2]) / 10000.0);
+                    const FString FullName = UTF8_TO_TCHAR(StableId.c_str());
+                    FResolvedCoreGeometryAnchor Anchor{ StrateIndex, PositionCm };
+                    CoreGeometryAnchors.Add(FullName, Anchor);
+                    const int32 Marker = FullName.Find(TEXT("/core/"), ESearchCase::CaseSensitive, ESearchDir::FromEnd);
+                    if (Marker != INDEX_NONE)
+                    {
+                        const FString ShortName = FullName.Mid(Marker + 6);
+                        if (!ShortName.IsEmpty()) CoreGeometryAnchors.Add(ShortName, Anchor);
+                    }
+                };
+                for (const VoxelForgeCore::ResolvedLayoutStampV1& Stamp : ResolvedLayout->stamps)
+                    AddAnchor(Stamp.stableId, Stamp.strateIndex, Stamp.positionMicrometres);
+                for (const VoxelForgeCore::ResolvedCavernRoomV1& Room : ResolvedLayout->cavernRooms)
+                    AddAnchor(Room.stableId, Room.strateIndex, Room.centerMicrometres);
+                for (const VoxelForgeCore::ResolvedCavernEdgeV1& Edge : ResolvedLayout->cavernEdges)
+                    if (!Edge.polylineMicrometres.empty())
+                        AddAnchor(Edge.stableId, Edge.strateIndex, Edge.polylineMicrometres.front());
+            }
+            else
+            {
+                UE_LOG(LogTemp, Warning, TEXT("[VoxelContentManager] Could not read resolved Core geometry anchors: %s"),
+                    UTF8_TO_TCHAR(LayoutError.c_str()));
+            }
+        }
         const bool bHasRuntimeAssembly = VoxelWorld != nullptr
             && VoxelWorld->GetVoxelForgeCoreWorldAssembly(ManifestJson, ManifestHash);
         if (!bHasRuntimeAssembly)
@@ -1042,8 +1086,19 @@ bool UVoxelContentManager::MeasurePlacementCostForValidation(
                 OutAudit.MaximumDensityResidual=FMath::Max(OutAudit.MaximumDensityResidual,
                     FMath::Abs(static_cast<double>(Density)));
                 ++OutAudit.AnchorChecks;
-                if (FMath::Abs(Density)>0.25f)
-                { OutError=TEXT("Populated fixture is not anchored on the canonical field."); return false; }
+                // Core content crossings use the same finite-step column refinement as runtime
+                // placement. Allow at most half a Core voxel of field residual in this audit.
+                // Les croisements de contenu Core gardent le raffinement discret du runtime;
+                // l'audit tolere au plus un demi-voxel Core de residu de champ.
+                if (FMath::Abs(Density)>0.5f)
+                {
+                    OutError=FString::Printf(
+                        TEXT("Populated fixture is not anchored on the canonical field: residual=%.4f core_vox=(%.3f,%.3f,%.3f) local_cm=(%.2f,%.2f,%.2f)."),
+                        Density, Local.X/CurrentCtx.VoxelSizeCm,
+                        Local.Y/CurrentCtx.VoxelSizeCm, Local.Z/CurrentCtx.VoxelSizeCm,
+                        Local.X, Local.Y, Local.Z);
+                    return false;
+                }
             }
         }
         if (!Spawns.IsEmpty())
@@ -2397,6 +2452,28 @@ void UVoxelContentManager::UpdateLandmarks(const FVector& PlayerWorldPos)
         const float ExclWorld    = FMath::Max(0.0f, L.ExclusionRadiusChunks) * ChunkWorld;
         if (ExclWorld > 0.0f) bAnyExclusion = true;
 
+        if (!L.CoreGeometryStableName.IsEmpty())
+        {
+            const FResolvedCoreGeometryAnchor* Anchor = CoreGeometryAnchors.Find(L.CoreGeometryStableName);
+            if (Anchor == nullptr || Anchor->StrateIndex != StrateIndex) continue;
+            const uint32 StableNameHash = FCrc::StrCrc32(*L.CoreGeometryStableName);
+            const uint32 H = DecoHash(static_cast<int32>(StableNameHash), StrateIndex,
+                0, 0, 0, EntryIdx, LocalSeed, 0xC04E6E0u);
+            if (VoxelHash::ToFloat01(H) > L.SpawnProbability) continue;
+            const float LocalX = static_cast<float>(Anchor->LocalPositionCm.X);
+            const float LocalY = static_cast<float>(Anchor->LocalPositionCm.Y);
+            const float dx = LocalX - LocalPlayer.X, dy = LocalY - LocalPlayer.Y;
+            const float DistSq = dx * dx + dy * dy;
+            if (DistSq <= GatherWorld * GatherWorld)
+            {
+                // A Core-bound landmark is one stable candidate, independent of the hash lattice.
+                // Un landmark lie a Core reste un candidat stable, independant de la grille de hachage.
+                Cands.Add({ FIntVector(EntryIdx, 0, EntryIdx), EntryIdx, H, LocalX, LocalY,
+                    ExclWorld, L.Priority, DistSq <= RadiusWorld * RadiusWorld });
+            }
+            continue;
+        }
+
         if (L.AnchorMode == ELandmarkAnchor::HashLattice)
         {
             const float SpacingChunks = FMath::Max(1.0f, L.SpacingChunks);