fix(ui): bind radar to streamed world state

Resolve the live-entity spatial broadphase at snapshot time so retained UI construction cannot capture GameWindow's empty bootstrap GpuWorldState. Add a replacement-owner regression test covering the exact compass-without-blips failure.

Co-authored-by: OpenAI Codex <codex@openai.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -2264,7 +2264,7 @@ public sealed class GameWindow : IDisposable
                 coordinatesOnRadar: () => _persistedGameplay.CoordinatesOnRadar,
                 uiLocked: () => _persistedGameplay.LockUI,
                 playerEntities: () => _entitiesByServerGuid,
-                copySpatialCandidates: _worldState.CopyLiveEntitiesNearLandblock);
+                spatialQuery: () => _worldState);
             var retailChatVm = new AcDream.UI.Abstractions.Panels.Chat.ChatVM(Chat, displayLimit: 200);
             _retailChatVm = retailChatVm;
             AcDream.App.UI.RetailUiPersistenceBindings? persistence = _settingsStore is null

src/AcDream.App/Streaming/GpuWorldState.cs

@@ -3,6 +3,7 @@ using System.Linq;
 using System.Numerics;
 using AcDream.App.Rendering.Vfx;
 using AcDream.App.Rendering.Wb;
+using AcDream.App.World;
 using AcDream.Core.World;
 
 namespace AcDream.App.Streaming;
@@ -39,7 +40,7 @@ namespace AcDream.App.Streaming;
 /// Threading: not thread-safe. All calls must happen on the render thread.
 /// </remarks>
 /// </summary>
-public sealed class GpuWorldState
+public sealed class GpuWorldState : ILiveEntitySpatialQuery
 {
     private readonly LandblockSpawnAdapter? _wbSpawnAdapter;
     private readonly EntityScriptActivator? _entityScriptActivator;

src/AcDream.App/UI/Layout/RadarSnapshotProvider.cs

@@ -1,4 +1,5 @@
 using System.Numerics;
+using AcDream.App.World;
 using AcDream.Core.Items;
 using AcDream.Core.Net;
 using AcDream.Core.Physics.Motion;
@@ -29,7 +30,7 @@ public sealed class RadarSnapshotProvider
     private readonly Func<bool> _coordinatesOnRadar;
     private readonly Func<bool> _uiLocked;
     private readonly Func<uint, RadarRelationshipTraits>? _relationshipFor;
-    private readonly Action<uint, int, List<KeyValuePair<uint, WorldEntity>>>? _copySpatialCandidates;
+    private readonly Func<ILiveEntitySpatialQuery?>? _spatialQuery;
     private readonly List<KeyValuePair<uint, WorldEntity>> _candidateScratch = new();
 
     public RadarSnapshotProvider(
@@ -44,7 +45,7 @@ public sealed class RadarSnapshotProvider
         Func<bool> uiLocked,
         Func<uint, RadarRelationshipTraits>? relationshipFor = null,
         Func<IReadOnlyDictionary<uint, WorldEntity>>? playerEntities = null,
-        Action<uint, int, List<KeyValuePair<uint, WorldEntity>>>? copySpatialCandidates = null)
+        Func<ILiveEntitySpatialQuery?>? spatialQuery = null)
     {
         _objects = objects ?? throw new ArgumentNullException(nameof(objects));
         _worldEntities = worldEntities ?? throw new ArgumentNullException(nameof(worldEntities));
@@ -57,7 +58,7 @@ public sealed class RadarSnapshotProvider
         _coordinatesOnRadar = coordinatesOnRadar ?? throw new ArgumentNullException(nameof(coordinatesOnRadar));
         _uiLocked = uiLocked ?? throw new ArgumentNullException(nameof(uiLocked));
         _relationshipFor = relationshipFor;
-        _copySpatialCandidates = copySpatialCandidates;
+        _spatialQuery = spatialQuery;
     }
 
     public UiRadarSnapshot BuildSnapshot()
@@ -90,12 +91,16 @@ public sealed class RadarSnapshotProvider
         float range = RetailRadar.GetRangeMeters(isOutside);
 
         _candidateScratch.Clear();
-        if (_copySpatialCandidates is not null)
+        // Retained UI mounts before the production GpuWorldState. Resolve the
+        // spatial owner per snapshot just like the live dictionaries above;
+        // retaining a method group here binds forever to the empty bootstrap
+        // state and produces a working compass with no object blips.
+        if (_spatialQuery?.Invoke() is { } spatialQuery)
         {
             // Retail radar is at most 75 metres while a landblock is 192
             // metres wide. The current block plus its eight neighbours is a
             // complete broadphase (the cheap spatial pre-filter).
-            _copySpatialCandidates(playerCellId, 1, _candidateScratch);
+            spatialQuery.CopyLiveEntitiesNearLandblock(playerCellId, 1, _candidateScratch);
         }
         else
         {

src/AcDream.App/World/ILiveEntitySpatialQuery.cs

@@ -0,0 +1,16 @@
+using AcDream.Core.World;
+
+namespace AcDream.App.World;
+
+/// <summary>
+/// Read-only spatial broadphase for live server-object projections.
+/// Consumers resolve this owner late because <c>GameWindow</c> replaces its
+/// empty bootstrap world state after retained UI construction.
+/// </summary>
+public interface ILiveEntitySpatialQuery
+{
+    void CopyLiveEntitiesNearLandblock(
+        uint centerCellOrLandblockId,
+        int landblockRadius,
+        List<KeyValuePair<uint, WorldEntity>> destination);
+}