fix(teleport #145): IsLandblockLoaded key mismatch — outdoor gate was permanently NotReady

The Slice 2 outdoor readiness gate queried IsLandblockLoaded(destCell &
0xFFFF0000) = e.g. 0x7D640000, but streaming stores landblocks under the
EncodeLandblockId form (low 16 = 0xFFFF), e.g. 0x7D64FFFF. The raw
ContainsKey never matched, so the outdoor teleport gate could NEVER flip
Ready and every outdoor arrival ran to the 600-frame (~10 s) timeout and
force-placed. The cascade was still prevented (the timeout force-place lands
cleanly), but the gate did no work — the 10 s freeze the apparatus showed
was this bug, NOT the #138 streaming stall I first suspected.

Root cause found via the apparatus re-test (3-agent investigation
wf_8b67a9d1-35c, all high-confidence) + verified against StreamingRegion.cs:99
(EncodeLandblockId | 0xFFFF), PhysicsEngine.cs:79 (stores as-is),
GameWindow.cs:5530 (queries & 0xFFFF0000).

Fix: IsLandblockLoaded normalizes its arg to the canonical 0xFFFF landblock
key, so the prefix form, any contained cell id, and the dat-id form all
resolve. Added the regression test the original Slice 2 test missed (it had
checked the same 0xFFFF form it added; the real caller passes the 0x..0000
form). Red on the prefix/cell forms before the fix, green after. 9/9.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AcDream.Core/Physics/PhysicsEngine.cs

@@ -32,13 +32,23 @@ public sealed class PhysicsEngine
     public int LandblockCount => _landblocks.Count;
 
     /// <summary>
-    /// Returns true iff a landblock with this id has been registered via
-    /// <see cref="AddLandblock"/>. Because <see cref="AddLandblock"/> registers
-    /// terrain + collision cells + portals atomically, ContainsKey implies the
-    /// collision mesh is present and resolvable.
+    /// Returns true iff the landblock CONTAINING the given id has been registered via
+    /// <see cref="AddLandblock"/>. Because <see cref="AddLandblock"/> registers terrain +
+    /// collision cells + portals atomically, a hit implies the collision mesh is present
+    /// and resolvable.
+    /// <para>
+    /// The argument may be any id within the landblock — a full cell id (low 16 = cell
+    /// index), the landblock-prefix form (low 16 = 0x0000, as the teleport gate passes via
+    /// <c>destCell &amp; 0xFFFF0000</c>), or the dat-id storage form. The low 16 bits are
+    /// normalized to the canonical landblock key (<c>0xFFFF</c>) that streaming stores under
+    /// (<see cref="AcDream.App.Streaming.StreamingRegion.EncodeLandblockId"/> ORs in 0xFFFF),
+    /// so all three forms resolve. The earlier raw <c>ContainsKey(id &amp; 0xFFFF0000)</c>
+    /// never matched the 0xFFFF-terminated stored key, leaving the outdoor teleport gate
+    /// permanently NotReady (2026-06-21 #145 apparatus re-test).
+    /// </para>
     /// </summary>
     public bool IsLandblockLoaded(uint landblockId) =>
-        _landblocks.ContainsKey(landblockId);
+        _landblocks.ContainsKey((landblockId & 0xFFFF0000u) | 0xFFFFu);
 
     /// <summary>
     /// Cell-based spatial index for static object collision.

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

@@ -54,4 +54,37 @@ public class PhysicsEngineIsLandblockLoadedTests
 
         Assert.False(engine.IsLandblockLoaded(0xA9B4FFFFu));
     }
+
+    // Regression for the Slice 2 key-mismatch bug (#145 apparatus re-test, 2026-06-21):
+    // landblocks are stored under the EncodeLandblockId form (low 16 = 0xFFFF), but the
+    // teleport gate (TeleportArrivalReadiness) queries with (destCell & 0xFFFF0000) (low
+    // 16 = 0x0000). A raw ContainsKey never matched, so the outdoor gate was permanently
+    // NotReady and every outdoor teleport timed out at 10 s. IsLandblockLoaded must
+    // normalize so ANY id within the landblock resolves to the stored entry.
+    [Theory]
+    [InlineData(0xA9B40000u)] // landblock-prefix form — exactly what the gate passes (destCell & 0xFFFF0000)
+    [InlineData(0xA9B4000Du)] // an outdoor cell id within the landblock
+    [InlineData(0xA9B40143u)] // an indoor cell id within the landblock
+    [InlineData(0xA9B4FFFFu)] // the dat-id storage form
+    public void IsLandblockLoaded_NormalizesLow16_FindsLandblockForAnyContainedId(uint queryId)
+    {
+        var engine = new PhysicsEngine();
+        engine.AddLandblock(0xA9B4FFFFu, MakeFlatTerrain(),
+            Array.Empty<CellSurface>(), Array.Empty<PortalPlane>(),
+            worldOffsetX: 0f, worldOffsetY: 0f);
+
+        Assert.True(engine.IsLandblockLoaded(queryId));
+    }
+
+    [Fact]
+    public void IsLandblockLoaded_DifferentLandblockPrefix_ReturnsFalse()
+    {
+        var engine = new PhysicsEngine();
+        engine.AddLandblock(0xA9B4FFFFu, MakeFlatTerrain(),
+            Array.Empty<CellSurface>(), Array.Empty<PortalPlane>(),
+            worldOffsetX: 0f, worldOffsetY: 0f);
+
+        // A different landblock prefix must NOT match, even in the 0x..0000 query form.
+        Assert.False(engine.IsLandblockLoaded(0xA9B50000u));
+    }
 }