fix(physics): keep remote placement and targeting in one world frame

CreateObject positions are landblock-local, but Runtime first-entry previously submitted remotes with a zero world offset. Runtime now owns the accepted local-player world-frame center and converts remote placements before SetPosition. The local physics host also publishes body.Position rather than CellPosition's landblock-local origin, so TargetManager no longer directs monsters toward a phantom player position. User gate: monster/static placement, chase, and attacks accepted outside Tusker Barracks.

src/AcDream.Runtime/Physics/RuntimePhysicsState.cs

@@ -448,6 +448,7 @@ public sealed class RuntimePhysicsState : IDisposable
     private int _collisionMutationThreadId;
     private long _nextCollisionPreparationSequence;
     private ulong _collisionWorldAuthority = 1UL;
+    private uint _worldFrameCenterLandblockId;
     private readonly List<Action<RuntimeCollisionGenerationCommitted>>
         _collisionGenerationCommittedObservers = new();
     private bool _disposed;
@@ -524,6 +525,52 @@ public sealed class RuntimePhysicsState : IDisposable
     internal double PlacementSimulationTime(double fallback) =>
         _gameClock?.SimulationTimeSeconds ?? fallback;
 
+    /// <summary>
+    /// Establishes the landblock that maps to world-frame XY (0,0). The
+    /// local-player Create initializes it before remote first-entry work;
+    /// only an accepted teleport moves it afterward. Ordinary walking across
+    /// a landblock boundary does not rebase the streamed world.
+    /// </summary>
+    internal void ObserveLocalWorldFrame(
+        uint fullCellId,
+        bool teleportAdvanced)
+    {
+        EnsureNotDisposed();
+        if (fullCellId == 0u)
+            return;
+        if (_worldFrameCenterLandblockId == 0u || teleportAdvanced)
+        {
+            _worldFrameCenterLandblockId =
+                (fullCellId & 0xFFFF0000u) | 0xFFFFu;
+        }
+    }
+
+    /// <summary>
+    /// Converts a retail landblock-local network frame into the Runtime's
+    /// current world frame without consulting presentation or waiting for
+    /// the destination collision package.
+    /// </summary>
+    internal bool TryGetWorldFrameOffset(
+        uint fullCellId,
+        out float worldOffsetX,
+        out float worldOffsetY)
+    {
+        if (_worldFrameCenterLandblockId == 0u || fullCellId == 0u)
+        {
+            worldOffsetX = 0f;
+            worldOffsetY = 0f;
+            return false;
+        }
+
+        int centerX = (int)((_worldFrameCenterLandblockId >> 24) & 0xFFu);
+        int centerY = (int)((_worldFrameCenterLandblockId >> 16) & 0xFFu);
+        int landblockX = (int)((fullCellId >> 24) & 0xFFu);
+        int landblockY = (int)((fullCellId >> 16) & 0xFFu);
+        worldOffsetX = (landblockX - centerX) * 192f;
+        worldOffsetY = (landblockY - centerY) * 192f;
+        return true;
+    }
+
     public RuntimePhysicsOwnershipSnapshot CaptureOwnership()
     {
         RuntimeSetPositionOwnershipSnapshot setPosition =
@@ -1315,6 +1362,7 @@ public sealed class RuntimePhysicsState : IDisposable
         _collisionAdmissions.Clear();
         SetPosition.ResetSession();
         CollisionReports.ResetSession();
+        _worldFrameCenterLandblockId = 0u;
         AdvanceCollisionWorldAuthority();
         Volatile.Write(ref _collisionMutationThreadId, 0);
     }
@@ -2007,6 +2055,7 @@ public sealed class RuntimePhysicsState : IDisposable
         _collisionPrefixMutations.Clear();
         _collisionAdmissions.Clear();
         _collisionGenerations.Clear();
+        _worldFrameCenterLandblockId = 0u;
         CellCommitted = null;
         _collisionGenerationCommittedObservers.Clear();
         _disposed = true;

src/AcDream.Runtime/Physics/RuntimeSetPositionMoverPreparation.cs

@@ -57,7 +57,8 @@ internal readonly record struct RuntimeSetPositionMoverPreparation(
     uint ScatterAttempts = 0u,
     float ShadowWorldOffsetX = 0f,
     float ShadowWorldOffsetY = 0f,
-    RuntimePortalPlacementAuthority Portal = default);
+    RuntimePortalPlacementAuthority Portal = default,
+    bool ResolveWorldOffsetFromRuntimeFrame = false);
 
 /// <summary>
 /// Pure preparation port of the mover inputs consumed by retail

src/AcDream.Runtime/Physics/RuntimeSetPositionState.cs

@@ -1522,6 +1522,32 @@ internal sealed class RuntimeSetPositionState : IDisposable
                 .RetrySetupUnavailable;
         }
 
+        RuntimeSetPositionMoverPreparation effectivePreparation = preparation;
+        if (preparation.ResolveWorldOffsetFromRuntimeFrame)
+        {
+            // CreateObject/Position origins are local to their authored
+            // landblock. Resolve them through Runtime's accepted world frame,
+            // which is initialized by the local-player Create and advanced
+            // only by authoritative teleport transitions. This is available
+            // before streaming publishes the target collision generation, so
+            // remote admission cannot starve world loading while still using
+            // the exact same coordinate frame that generation will publish.
+            if (!_physics.TryGetWorldFrameOffset(
+                    authority.AcceptedPosition.LandblockId,
+                    out float worldOffsetX,
+                    out float worldOffsetY))
+            {
+                return RuntimeSetPositionMoverPreparationStatus
+                    .RetrySetupUnavailable;
+            }
+
+            effectivePreparation = preparation with
+            {
+                ShadowWorldOffsetX = worldOffsetX,
+                ShadowWorldOffsetY = worldOffsetY,
+            };
+        }
+
         if (!RuntimeSetPositionMoverPreparer.TryBuild(
                 operation.Record,
                 authority.AcceptedPosition,
@@ -1529,7 +1555,7 @@ internal sealed class RuntimeSetPositionState : IDisposable
                 operation.Kind,
                 operation.Portal,
                 authority.VelocityAuthorityVersion,
-                preparation,
+                effectivePreparation,
                 out command)
             || !IsStructurallyValid(command.Physics))
         {
@@ -1586,7 +1612,8 @@ internal sealed class RuntimeSetPositionState : IDisposable
         float scatterRadiusY = 0f,
         uint scatterAttempts = 0u,
         float shadowWorldOffsetX = 0f,
-        float shadowWorldOffsetY = 0f)
+        float shadowWorldOffsetY = 0f,
+        bool resolveWorldOffsetFromRuntimeFrame = false)
     {
         outcome = default;
 
@@ -1606,7 +1633,8 @@ internal sealed class RuntimeSetPositionState : IDisposable
                 scatterRadiusY,
                 scatterAttempts,
                 shadowWorldOffsetX,
-                shadowWorldOffsetY);
+                shadowWorldOffsetY,
+                resolveWorldOffsetFromRuntimeFrame);
         if (status != RuntimeSetPositionMoverPreparationStatus.Prepared)
             return status;
 
@@ -1644,7 +1672,8 @@ internal sealed class RuntimeSetPositionState : IDisposable
         float scatterRadiusY = 0f,
         uint scatterAttempts = 0u,
         float shadowWorldOffsetX = 0f,
-        float shadowWorldOffsetY = 0f)
+        float shadowWorldOffsetY = 0f,
+        bool resolveWorldOffsetFromRuntimeFrame = false)
     {
         EnsureNotDisposed();
         ArgumentNullException.ThrowIfNull(record);
@@ -1683,7 +1712,8 @@ internal sealed class RuntimeSetPositionState : IDisposable
             scatterAttempts,
             shadowWorldOffsetX,
             shadowWorldOffsetY,
-            portal);
+            portal,
+            resolveWorldOffsetFromRuntimeFrame);
         return PrepareMover(token, preparation, out command);
     }