refactor(streaming): extract landblock physics publisher

Move streamed terrain/cell/building and static collision publication behind a focused update-thread owner. Preserve retail publication order while making replacement and retirement exact by logical landblock ownership, including current-cell rebasing and adjacent-seam isolation.

Co-authored-by: Codex <noreply@openai.com>

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

@@ -151,4 +151,36 @@ public class PhysicsEngineResidencyTests
             entry => entry.EntityId == dynamicId);
         Assert.Equal(1, engine.ShadowObjects.RetainedRegistrationCount);
     }
+
+    [Fact]
+    public void RemoveLandblock_RemovesOnlyItsCachedBuildings()
+    {
+        const uint landblockId = 0xA9B4FFFFu;
+        const uint retiredBuildingCell = 0xA9B40001u;
+        const uint adjacentBuildingCell = 0xAAB40001u;
+        var cache = new PhysicsDataCache();
+        var engine = new PhysicsEngine { DataCache = cache };
+        cache.RegisterBuildingForTest(
+            retiredBuildingCell,
+            Building(Matrix4x4.Identity));
+        cache.RegisterBuildingForTest(
+            adjacentBuildingCell,
+            Building(Matrix4x4.CreateTranslation(192f, 0f, 0f)));
+
+        engine.RemoveLandblock(landblockId);
+
+        Assert.Null(cache.GetBuilding(retiredBuildingCell));
+        Assert.NotNull(cache.GetBuilding(adjacentBuildingCell));
+    }
+
+    private static BuildingPhysics Building(Matrix4x4 transform)
+    {
+        Matrix4x4.Invert(transform, out Matrix4x4 inverse);
+        return new BuildingPhysics
+        {
+            WorldTransform = transform,
+            InverseWorldTransform = inverse,
+            Portals = Array.Empty<BldPortalInfo>(),
+        };
+    }
 }

tests/AcDream.Core.Tests/World/Cells/CellGraphTests.cs

@@ -56,6 +56,21 @@ public class CellGraphTests
         Assert.Null(g.GetVisible(0xA9B40014u));
     }
 
+    [Fact]
+    public void RemoveLandblock_ClearsCurrentCellForRetiredPrefixOnly()
+    {
+        var g = new CellGraph();
+        var current = Env(0xA9B40174u);
+        g.Add(current);
+        g.CurrCell = current;
+
+        g.RemoveLandblock(0xAAB40000u);
+        Assert.Same(current, g.CurrCell);
+
+        g.RemoveLandblock(0xA9B40000u);
+        Assert.Null(g.CurrCell);
+    }
+
     [Fact]
     public void RemoveEnvCellsForLandblock_PreservesTerrain()
     {
@@ -69,6 +84,21 @@ public class CellGraphTests
         Assert.IsType<LandCell>(g.GetVisible(0xA9B40014u));
     }
 
+    [Fact]
+    public void RemoveEnvCellsForLandblock_ClearsOnlyMatchingIndoorCurrentCell()
+    {
+        var g = new CellGraph();
+        var current = Env(0xA9B40174u);
+        g.Add(current);
+        g.CurrCell = current;
+
+        g.RemoveEnvCellsForLandblock(0xAAB4FFFFu);
+        Assert.Same(current, g.CurrCell);
+
+        g.RemoveEnvCellsForLandblock(0xA9B4FFFFu);
+        Assert.Null(g.CurrCell);
+    }
+
     [Fact]
     public void Neighbor_ResolvesPortalOtherCellId()
     {