fix(portal): synchronize destination presentation state

tests/AcDream.Core.Tests/Physics/PhysicsBodyCellSyncTests.cs

@@ -66,15 +66,56 @@ public class PhysicsBodyCellSyncTests
         Assert.Equal(0u, body.CellPosition.ObjCellId);
     }
 
+    [Fact]
+    public void PositionDelta_InsideEnvCell_AdvancesCanonicalLocalFrame()
+    {
+        var body = new PhysicsBody();
+        body.SnapToCell(
+            0x8C0401ADu,
+            worldPos: new Vector3(12f, -30f, 4f),
+            cellLocal: new Vector3(80f, 40f, 4f));
+
+        body.Position += new Vector3(3f, -2f, 0.5f);
+
+        Assert.Equal(0x8C0401ADu, body.CellPosition.ObjCellId);
+        Assert.Equal(new Vector3(83f, 38f, 4.5f), body.CellPosition.Frame.Origin);
+    }
+
+    [Fact]
+    public void CommitTransitionPosition_InsideDungeon_AdoptsResolvedEnvCellAndFrame()
+    {
+        var body = new PhysicsBody();
+        body.SnapToCell(
+            0x8C0401ADu,
+            worldPos: new Vector3(12f, -30f, 4f),
+            cellLocal: new Vector3(80f, 40f, 4f));
+
+        body.CommitTransitionPosition(
+            0x8C0401AEu,
+            new Vector3(17f, -27f, 4f));
+
+        Assert.Equal(0x8C0401AEu, body.CellPosition.ObjCellId);
+        Assert.Equal(new Vector3(85f, 43f, 4f), body.CellPosition.Frame.Origin);
+        Assert.Equal(new Vector3(17f, -27f, 4f), body.Position);
+    }
+
+    [Fact]
+    public void CommitTransitionPosition_WithoutSeed_DoesNotInventCanonicalCell()
+    {
+        var body = new PhysicsBody();
+
+        body.CommitTransitionPosition(0x8C0401ADu, new Vector3(1f, 2f, 3f));
+
+        Assert.Equal(0u, body.CellPosition.ObjCellId);
+        Assert.Equal(new Vector3(1f, 2f, 3f), body.Position);
+    }
+
     [Fact]
     public void ContinuousTracking_LongWalkAcrossCellsAndBlock_NeverGoesStale()
     {
-        // Refutes the "CellPosition goes stale" concern (incl. the indoor-transit case):
-        // because the Position setter re-derives the cell via AdjustToOutside on EVERY
-        // write, CellPosition continuously tracks the outdoor cell under the body's WORLD
-        // position. The body is always world-space, so the world delta is frame-invariant —
-        // there is no separate "interior" frame to desync. On any exit it is the correct
-        // cell, never stale.
+        // Refutes outdoor CellPosition drift: the Position setter re-derives the
+        // cell via AdjustToOutside on every write, so the carried (cell, local)
+        // pair continuously tracks the body across cells and landblocks.
         var body = new PhysicsBody();
         body.SnapToCell(0xC95B0001u, new Vector3(1000f, 2000f, 12f), new Vector3(10f, 10f, 12f));