diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index b0dacd3..b323bed 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -1870,7 +1870,7 @@ public sealed class GameWindow : IDisposable
                 _terrain?.RemoveLandblock(id);
                 _physicsEngine.RemoveLandblock(id);
                 _cellVisibility.RemoveLandblock((id >> 16) & 0xFFFFu);
-                _buildingRegistries.Remove(id);  // Phase A8
+                _buildingRegistries.Remove(id & 0xFFFF0000u);  // Phase A8 (key normalization fix 2026-05-28)
                 _envCellRenderer?.RemoveLandblock(id);  // Phase A8
             });
         // A.5 T22.5: apply max-completions from resolved quality.
@@ -5907,7 +5907,18 @@ public sealed class GameWindow : IDisposable
                     if (!lbStampCells.ContainsKey(c.CellId))
                         lbStampCells[c.CellId] = c;
                 }
-                _buildingRegistries[lb.LandblockId] =
+                // FIX 2026-05-28: normalize storage key to the cell-prefix
+                // convention (`landblockId & 0xFFFF0000u`). The lb.LandblockId
+                // field encodes 0xXXYY_FFFF (low 16 bits = 0xFFFF for the
+                // landblock's own LandBlockInfo dat id), but the runtime
+                // lookup at line ~7110 derives the key from a cell id via
+                // `cellId & 0xFFFF0000u` which yields 0xXXYY_0000. Storage
+                // and lookup must agree. Mask both sides to the upper-16
+                // form so the registry resolves correctly. This is the same
+                // bug the RR7.2 commit (`efe3520`, reverted by `9aaae02`)
+                // tried to fix; landing it here in the data-flow layer.
+                uint regKey = lb.LandblockId & 0xFFFF0000u;
+                _buildingRegistries[regKey] =
                     AcDream.App.Rendering.Wb.BuildingLoader.Build(
                         lbInfo, lb.LandblockId, lbStampCells);
             }
@@ -9036,7 +9047,7 @@ public sealed class GameWindow : IDisposable
                     _terrain?.RemoveLandblock(id);
                     _physicsEngine.RemoveLandblock(id);
                     _cellVisibility.RemoveLandblock((id >> 16) & 0xFFFFu);
-                    _buildingRegistries.Remove(id);  // Phase A8
+                    _buildingRegistries.Remove(id & 0xFFFF0000u);  // Phase A8 (key normalization fix 2026-05-28)
                     _envCellRenderer?.RemoveLandblock(id);  // Phase A8
                 });
             _streamingController.MaxCompletionsPerFrame = newResolved.MaxCompletionsPerFrame;