fix(streaming): prepare quiesced destination entities

Separate loaded spatial residency from the world presentation gate so destination live objects acquire mesh owners behind portal space while drawing and simulation stay quiesced. Prevent unowned CPU-cache hits from recreating stale GPU staging work.

Co-authored-by: Erik Nilsson <erikn@users.noreply.github.com>

src/AcDream.App/Rendering/Wb/MeshUploadCaches.cs

@@ -8,6 +8,7 @@ internal enum MeshStageResult
     Staged,
     AlreadyStaged,
     HighWater,
+    NotOwned,
 }
 
 /// <summary>
@@ -282,7 +283,7 @@ internal sealed class CpuMeshUploadCache
     // review). Read via Stats from the diagnostics/checkpoint thread
     // without taking _data's lock, so plain fields with Interlocked
     // increments — the 4 concurrent preparation workers all consult
-    // TryGetAndStage.
+    // TryGetAndStageOwned.
     private long _hits;
     private long _misses;
     private long _evictions;
@@ -307,12 +308,15 @@ internal sealed class CpuMeshUploadCache
     internal int Capacity => _capacity;
     internal long ByteCapacity => _byteCapacity;
 
-    public bool TryGetAndStage(
+    public bool TryGetAndStageOwned(
         ulong id,
         MeshUploadStagingQueue staging,
+        MeshOwnershipCounter ownership,
         out ObjectMeshData? data,
         out MeshStageResult stageResult)
     {
+        ArgumentNullException.ThrowIfNull(staging);
+        ArgumentNullException.ThrowIfNull(ownership);
         lock (_data)
         {
             if (!_data.TryGetValue(id, out data)) {
@@ -323,7 +327,13 @@ internal sealed class CpuMeshUploadCache
             Interlocked.Increment(ref _hits);
             _lru.Remove(id);
             _lru.AddLast(id);
-            stageResult = staging.TryStage(data);
+            // Prepared payload residency is deliberately independent from
+            // live render ownership. A point-of-use lookup from a retiring
+            // world generation must never recreate GPU staging work after
+            // that generation released its final mesh reference.
+            stageResult = ownership.IsOwned(id)
+                ? staging.TryStage(data)
+                : MeshStageResult.NotOwned;
             return true;
         }
     }

src/AcDream.App/Rendering/Wb/ObjectMeshManager.cs

@@ -876,9 +876,10 @@ namespace AcDream.App.Rendering.Wb
             }
 
             ObjectMeshData? deferredCachedData = null;
-            if (_cpuMeshCache.TryGetAndStage(
+            if (_cpuMeshCache.TryGetAndStageOwned(
                     geomId,
                     _stagedMeshData,
+                    _ownership,
                     out ObjectMeshData? cachedData,
                     out MeshStageResult cacheStage))
             {
@@ -936,9 +937,10 @@ namespace AcDream.App.Rendering.Wb
                 _terminalPreparationFailures.Remove(id);
 
             ObjectMeshData? deferredCachedData = null;
-            if (_cpuMeshCache.TryGetAndStage(
+            if (_cpuMeshCache.TryGetAndStageOwned(
                     id,
                     _stagedMeshData,
+                    _ownership,
                     out ObjectMeshData? cachedData,
                     out MeshStageResult cacheStage))
             {

src/AcDream.App/Streaming/GpuWorldState.cs

@@ -153,10 +153,19 @@ public sealed class GpuWorldState : ILiveEntitySpatialQuery
     public bool IsRenderReady(uint landblockId) =>
         _loaded.ContainsKey(landblockId)
         && (_wbSpawnAdapter?.IsLandblockRenderReady(landblockId) ?? true);
+    /// <summary>
+    /// True when at least one projection for the server object belongs to a
+    /// loaded spatial bucket. This deliberately ignores the world-generation
+    /// presentation gate: destination objects must acquire their render
+    /// resources while portal/login reveal keeps normal world consumers closed.
+    /// </summary>
+    public bool IsLiveEntityProjectionResident(uint serverGuid) =>
+        serverGuid != 0
+        && _visibleLiveProjectionCounts.ContainsKey(serverGuid);
+
     public bool IsLiveEntityVisible(uint serverGuid) =>
         _availability.IsWorldAvailable
-        && serverGuid != 0
-        && _visibleLiveProjectionCounts.ContainsKey(serverGuid);
+        && IsLiveEntityProjectionResident(serverGuid);
 
     /// <summary>
     /// Try to grab the loaded record for a landblock — useful for callers

src/AcDream.App/World/LiveEntityRuntime.cs

@@ -843,7 +843,7 @@ public sealed class LiveEntityRuntime
                 runtimeNotificationFailure: null);
             return false;
         }
-        bool visible = _spatial.IsLiveEntityVisible(serverGuid);
+        bool visible = _spatial.IsLiveEntityProjectionResident(serverGuid);
         record.IsSpatiallyVisible = visible;
         if (record.ProjectionKind is LiveEntityProjectionKind.World)
             _materializedWorldEntitiesByGuid[serverGuid] = entity;
@@ -2584,7 +2584,7 @@ public sealed class LiveEntityRuntime
         // an older queued edge drains. Apply an edge only while it still
         // matches current spatial truth; otherwise it belongs to the displaced
         // projection and must not mutate the replacement generation.
-        if (_spatial.IsLiveEntityVisible(serverGuid) != visible)
+        if (_spatial.IsLiveEntityProjectionResident(serverGuid) != visible)
             return;
         if (!_recordsByGuid.TryGetValue(serverGuid, out LiveEntityRecord? record)
             || record.WorldEntity is not { } entity)