checkpoint(render): preserve pre-overhaul investigation state

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

@@ -21,7 +21,9 @@ namespace AcDream.Core.Tests.Physics;
 public sealed class CellTransitFindTransitCellsBoxTests
 {
     private static CellPhysics MakeCellWithPortalAtRightWall(
-        Matrix4x4 worldTransform, uint otherCellId, ushort flags)
+        Matrix4x4 worldTransform,
+        uint otherCellId,
+        ushort flags)
     {
         // Portal poly at local x=2.5 (right wall), normal +X. Same shape as
         // CellTransitFindTransitCellsSphereTests' fixture, so the sphere-only
@@ -142,6 +144,47 @@ public sealed class CellTransitFindTransitCellsBoxTests
         Assert.DoesNotContain(0xA9B40101u, endToEnd);
     }
 
+    [Fact]
+    public void StaticPartArrayCrossesExteriorPortal_KeepsOutdoorCells()
+    {
+        // CPhysicsObj::calc_cross_cells_static sets do_not_load_cells before
+        // entering find_bbox_cell_list, but retail's bbox worklist returns
+        // the CELLARRAY directly. The post-pass prune at CObjCell::
+        // find_cell_list+0x18E belongs only to that separate sphere route.
+        // This is the cathedral-ramp shape: an indoor static box genuinely
+        // reaches an exterior portal and must remain registered in outdoor
+        // shadow cells even when the seed's stab list is empty.
+        var cache = new PhysicsDataCache();
+        const uint seedCell = 0xF4180112u;
+        cache.RegisterCellStructForTest(
+            seedCell,
+            MakeCellWithPortalAtRightWall(
+                Matrix4x4.Identity,
+                otherCellId: 0xFFFF,
+                flags: 0));
+
+        var partWorldPos = new Vector3(2.0f, 0f, 2.5f);
+        var sphere = new Sphere { Origin = partWorldPos, Radius = 0.7f };
+        var box = new[]
+        {
+            MakeBox(
+                new Vector3(-0.7f),
+                new Vector3(0.7f),
+                partWorldPos,
+                Quaternion.Identity),
+        };
+
+        IReadOnlyList<uint> cells = CellTransit.BuildShadowCellSetFromParts(
+            cache,
+            seedCell,
+            box,
+            new[] { sphere },
+            isStatic: true);
+
+        Assert.Contains(seedCell, cells);
+        Assert.Contains(cells, id => (id & 0xFFFFu) is >= 1u and <= 64u);
+    }
+
     // ── D3.2: inverse guard — a box that DOES cross admits, unchanged ──────
 
     /// <summary>