wip(assembler): round L11 -- fix 24 m+ crossing crash; near ring ready 2x sooner at spawn

Crash: crossing tiles were coalesced into one huge rectangle, and BuildSpatialBins tried to
resize to ~4.3e17 bytes (std::bad_alloc; the L7 32 m failure had the same cause). Analytic
regions now skip unread dense bins and compile in world-aligned 128-voxel pages, published
together; out-of-range keys error before allocation. 24 m, 32 m and 1 km crossings pass
(1 km: 72 pages, peak RSS 700 MiB).
Spawn: World::isTileShapeFree proves LOD0 SurfaceWorld tiles that never read the cave shape;
those start before shape compile, and all others wait. Reviewer W12 no-hash: near ring 0.337 ->
0.159 s, whole view +2.1%. All SurfaceWorld/FloatingIslands hashes unchanged (W1/W8/W12, both
compilers, forced-overlap run). Unreal VoxelWorld.cpp adapter changed but NOT built here.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

Source/VoxelForge/Private/VoxelWorld.cpp

@@ -146,6 +146,10 @@ public:
     FVoxelForgeCoreTaskScheduler Scheduler;
     std::unordered_set<VoxelForgeCore::TileKey, VoxelForgeCore::TileKeyHash> RetainedTiles;
     FCriticalSection RetainedTilesLock;
+    FCriticalSection ShapeReadinessLock;
+    std::unordered_set<VoxelForgeCore::TileKey, VoxelForgeCore::TileKeyHash> ShapeFreeTiles;
+    std::unordered_set<VoxelForgeCore::TileKey, VoxelForgeCore::TileKeyHash> ShapeDependentTiles;
+    std::atomic<bool> bSnapshotReady{false};
     std::atomic<bool> bReady{false};
     std::atomic<bool> bInitialFailed{false};
     std::atomic<bool> bRegionCompileInFlight{false};
@@ -7689,6 +7693,7 @@ bool AVoxelWorld::InitializeVoxelForgeCoreWorld(FString& OutFailureReason)
     Request.includeFarWorld = true;
 
     VoxelForgeCoreState = State;
+    State->bSnapshotReady.store(true, std::memory_order_release);
     ActiveTaskCount.fetch_add(1, std::memory_order_relaxed);
     UE::Tasks::Launch(TEXT("VoxelForgeCoreCompile"),
         [this, State, Request, InitialDesired, ActiveCoreClipRadius, ActiveCoreMaxClipLevel,
@@ -7708,10 +7713,17 @@ bool AVoxelWorld::InitializeVoxelForgeCoreWorld(FString& OutFailureReason)
 
         std::string Error;
         bool bCompiled = false;
+        bCompiled = State->World->compile(Request, State->Scheduler, Error);
+        if (bCompiled)
         {
+            // The initial compile builds into local state and atomically publishes an immutable
+            // shape. Proven native-only tiles may hold shared WorldLock readers during this work;
+            // take the writer only for region retention after publication.
+            // La compilation initiale construit un etat local puis publie une forme immuable.
+            // Les tuiles natives validees gardent le verrou lecteur partage; le verrou ecrivain
+            // ne sert qu'a retenir les regions apres publication.
             FWriteScopeLock Lock(State->WorldLock);
-            bCompiled = State->World->compile(Request, State->Scheduler, Error);
-            if (bCompiled)
+            if (State->World)
             {
                 State->World->retainTileRegions(InitialDesired);
                 FScopeLock RetainedLock(&State->RetainedTilesLock);
@@ -13019,9 +13031,33 @@ void AVoxelWorld::LoadCoreTile(const FVoxelTileKey& Tile, EVoxelTileWorkPriority
             return;
         }
     }
-    if (PendingTiles.Contains(Tile) || !IsVoxelForgeCoreReady()) return;
+    if (PendingTiles.Contains(Tile)) return;
     const TSharedPtr<FVoxelForgeCoreRuntimeState, ESPMode::ThreadSafe> State = VoxelForgeCoreState;
-    if (!State.IsValid() || State->bRegionCompileFailed.load(std::memory_order_acquire)) return;
+    if (!State.IsValid()||State->bInitialFailed.load(std::memory_order_acquire)
+        ||State->bRegionCompileFailed.load(std::memory_order_acquire)
+        ||State->bShuttingDown.load(std::memory_order_acquire))return;
+    const bool bShapeReady=State->bReady.load(std::memory_order_acquire);
+    if(!bShapeReady)
+    {
+        if(!State->bSnapshotReady.load(std::memory_order_acquire))return;
+        const VoxelForgeCore::TileKey CoreKey{
+            {Tile.Coord.X,Tile.Coord.Y,Tile.Coord.Z},Tile.Level};
+        bool bShapeFree=false;
+        {
+            FScopeLock ReadinessLock(&State->ShapeReadinessLock);
+            if(State->ShapeFreeTiles.contains(CoreKey))bShapeFree=true;
+            else if(State->ShapeDependentTiles.contains(CoreKey))return;
+            else
+            {
+                FReadScopeLock WorldReadLock(State->WorldLock);
+                if(!State->World)return;
+                bShapeFree=State->World->isTileShapeFree(CoreKey);
+                if(bShapeFree)State->ShapeFreeTiles.insert(CoreKey);
+                else State->ShapeDependentTiles.insert(CoreKey);
+            }
+        }
+        if(!bShapeFree)return;
+    }
     if (IsStreamingResultBacklogCapped())
     {
         StreamingResultBacklogCapStops.fetch_add(1, std::memory_order_relaxed);