fix(physics): traverse prepared indoor portal topology

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

@@ -290,4 +290,88 @@ public class CameraCornerSealReplayTests
             "Viewer sweep through a verified-open doorway path was obstructed or cut short " +
             "(camera would wrongly pull in at openings) for: " + string.Join(", ", failures));
     }
+
+    [Fact]
+    public void HoltburgCottageExit_ViewerSweep_AdvancesFromAlcoveToOutdoor()
+    {
+        var datDir = ConformanceDats.ResolveDatDir();
+        if (datDir is null) return;
+
+        using var dats = new DatCollection(datDir, DatAccessType.Read);
+        var graphCache = new PhysicsDataCache();
+        var preparedCache = PhysicsDataCache.CreateProduction();
+        for (uint low = 0x013Fu; low <= 0x0150u; low++)
+        {
+            uint cellId = ConformanceDats.HoltburgLandblock | low;
+            ConformanceDats.LoadEnvCell(
+                dats,
+                graphCache,
+                cellId);
+
+            CellPhysics graphCell = Assert.IsType<CellPhysics>(
+                graphCache.GetCellStruct(cellId));
+            FlatCellCollisionAsset prepared =
+                FlatCollisionAssetBuilder.FlattenCell(graphCell);
+            var datCell = Assert.IsType<DatReaderWriter.DBObjs.EnvCell>(
+                dats.Get<DatReaderWriter.DBObjs.EnvCell>(cellId));
+            preparedCache.CacheCellStruct(
+                cellId,
+                datCell,
+                graphCell.WorldTransform,
+                prepared.Structure,
+                prepared.Topology);
+        }
+
+        var graphEngine = new PhysicsEngine { DataCache = graphCache };
+        var preparedEngine = new PhysicsEngine { DataCache = preparedCache };
+
+        var heights = new byte[81];
+        var heightTable = new float[256];
+        for (int i = 0; i < heightTable.Length; i++)
+            heightTable[i] = -1000f;
+        foreach (PhysicsEngine engine in new[] { graphEngine, preparedEngine })
+        {
+            engine.AddLandblock(
+                ConformanceDats.HoltburgLandblock,
+                new TerrainSurface(heights, heightTable),
+                Array.Empty<CellSurface>(),
+                Array.Empty<PortalPlane>(),
+                0f,
+                0f);
+        }
+
+        // Connected capture indoor-visibility-20260726-220007. The player is
+        // just inside the narrow 0x0150 vestibule, facing into the cottage.
+        // Its chase camera is behind it, outside the open doorway. Retail's
+        // viewer CTransition crosses 0x0150's 0xFFFF portal and carries the
+        // outdoor landcell as viewer_cell.
+        var player = new Vector3(132.70f, 16.80f, 94.00f);
+        var pivot = player + new Vector3(0f, 0f, PivotHeight);
+        var eye = new Vector3(131.30f, 19.97f, 96.25f);
+
+        var graphPivot = graphEngine.AdjustPosition(0xA9B40150u, pivot);
+        var preparedPivot = preparedEngine.AdjustPosition(0xA9B40150u, pivot);
+        Assert.True(graphPivot.found);
+        Assert.True(preparedPivot.found);
+        Assert.Equal(0xA9B40150u, graphPivot.cellId);
+        Assert.Equal(graphPivot.cellId, preparedPivot.cellId);
+
+        ResolveResult graphResult = SweepViewer(
+            graphEngine,
+            pivot,
+            eye,
+            0xA9B40150u);
+        ResolveResult preparedResult = SweepViewer(
+            preparedEngine,
+            pivot,
+            eye,
+            0xA9B40150u);
+
+        _out.WriteLine(FormattableString.Invariant(
+            $"graph=0x{graphResult.CellId:X8} prepared=0x{preparedResult.CellId:X8} graphPos=({graphResult.Position.X:F3},{graphResult.Position.Y:F3},{graphResult.Position.Z:F3}) preparedPos=({preparedResult.Position.X:F3},{preparedResult.Position.Y:F3},{preparedResult.Position.Z:F3})"));
+
+        Assert.Equal(0xA9B40029u, graphResult.CellId);
+        Assert.Equal(graphResult.CellId, preparedResult.CellId);
+        Assert.Equal(graphResult.Position, preparedResult.Position);
+    }
 }