diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index a2531674..a42ba321 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -6890,12 +6890,16 @@ public sealed class GameWindow : IDisposable
             // window otherwise pulls in ~129 unrelated ocean-grid dungeons. Building
             // interiors (cottage/inn) have SeenOutside cells, so they are NOT gated
             // and keep their surrounding terrain.
-            // Mirrors the playerInsideCell computation below (CurrCell → registry
-            // LoadedCell.SeenOutside): true only for a sealed indoor cell.
+            // True only for a sealed indoor cell. Read the physics CurrCell's own
+            // SeenOutside (ObjCell.SeenOutside, set from the EnvCell dat flags) rather
+            // than the render registry: the registry lookup only succeeds AFTER the
+            // landblock FINALIZES (~tens of seconds for a 205-cell dungeon), which
+            // delayed the collapse and let the full 25×25 neighbor window churn in
+            // first (the "~30s to stabilize" report). CurrCell.SeenOutside is set the
+            // moment the player is placed, so the collapse now engages at the snap.
             bool insideDungeon = false;
             if (_physicsEngine.DataCache?.CellGraph.CurrCell is AcDream.Core.World.Cells.EnvCell pcEnv
-                && _cellVisibility.TryGetCell(pcEnv.Id, out var pcReg)
-                && pcReg is { SeenOutside: false })
+                && !pcEnv.SeenOutside)
             {
                 insideDungeon = true;
                 // Pin the collapse to the cell's OWN landblock (cell id high 16 bits),