fix(world): remove non-retail portal exit fade

src/AcDream.App/Streaming/TeleportLandblockTransition.cs

@@ -1,9 +1,11 @@
 namespace AcDream.App.Streaming;
 
 /// <summary>
-/// Classifies whether a local-player teleport crosses an AC landblock boundary.
-/// Cell identity comes from the complete retail <c>Position</c>, never from its
-/// frame coordinates: dungeon EnvCells may have valid negative local origins.
+/// Classifies both whether the player crosses an AC landblock boundary and
+/// whether acdream's asynchronous streaming origin must recenter. These are
+/// distinct while a teleport destination is aimed but not yet placed. Cell
+/// identity comes from the complete retail <c>Position</c>, never from its frame
+/// coordinates: dungeon EnvCells may have valid negative local origins.
 /// </summary>
 /// <remarks>
 /// Retail carries <c>Position::objcell_id</c> through
@@ -14,9 +16,12 @@ namespace AcDream.App.Streaming;
 /// </remarks>
 internal readonly record struct TeleportLandblockTransition(
     uint SourceLandblockId,
-    uint DestinationLandblockId)
+    uint DestinationLandblockId,
+    uint StreamingCenterLandblockId)
 {
     public bool CrossesLandblock => SourceLandblockId != DestinationLandblockId;
+    public bool ChangesStreamingCenter =>
+        StreamingCenterLandblockId != DestinationLandblockId;
 
     /// <summary>
     /// Build the transition from the player's current cell and the received
@@ -34,7 +39,8 @@ internal readonly record struct TeleportLandblockTransition(
 
         return new TeleportLandblockTransition(
             sourceLandblockId,
-            NormalizeLandblockId(destinationCellId));
+            NormalizeLandblockId(destinationCellId),
+            NormalizeLandblockId(currentStreamingCenterLandblockId));
     }
 
     private static uint NormalizeLandblockId(uint cellOrLandblockId)