fix(streaming): commit EnvCell landblocks atomically (#214)

Carry one complete cell payload with each streaming completion and publish visibility, physics, and render state on the render thread. Remove the obsolete post-readiness login reload that triggered a duplicate dungeon build.

Co-Authored-By: Codex <noreply@openai.com>

tests/AcDream.Core.Tests/Streaming/LandblockStreamerTests.cs

@@ -1,5 +1,6 @@
 using System.Threading.Tasks;
 using AcDream.App.Streaming;
+using AcDream.App.Rendering.Wb;
 using AcDream.Core.World;
 using DatReaderWriter.DBObjs;
 using Xunit;
@@ -109,6 +110,35 @@ public class LandblockStreamerTests
         Assert.Equal(1, meshBuildCalls);
     }
 
+    [Fact]
+    public async Task Load_CarriesTheExactCompletedCellTransactionToTheConsumer()
+    {
+        var landblock = new LoadedLandblock(
+            0x8C04FFFFu,
+            new LandBlock(),
+            System.Array.Empty<WorldEntity>());
+        var cellBuild = new EnvCellLandblockBuild(
+            landblock.LandblockId,
+            System.Array.Empty<AcDream.App.Rendering.LoadedCell>(),
+            System.Array.Empty<EnvCellShellPlacement>());
+        var build = new LandblockBuild(landblock, cellBuild);
+        var mesh = new AcDream.Core.Terrain.LandblockMeshData(
+            System.Array.Empty<AcDream.Core.Terrain.TerrainVertex>(),
+            System.Array.Empty<uint>());
+
+        using var streamer = new LandblockStreamer(
+            loadLandblock: (_, _) => build,
+            buildMeshOrNull: (_, _) => mesh);
+        streamer.Start();
+        streamer.EnqueueLoad(landblock.LandblockId, LandblockStreamJobKind.LoadNear);
+
+        var loaded = Assert.IsType<LandblockStreamResult.Loaded>(
+            await DrainFirstAsync(streamer));
+
+        Assert.Same(build, loaded.Build);
+        Assert.Same(cellBuild, loaded.Build.EnvCells);
+    }
+
     [Fact]
     public async Task PromoteToNear_OvertakesAndSupersedesQueuedFarLoadForSameLandblock()
     {

tests/AcDream.Core.Tests/Streaming/StreamingControllerDungeonGateTests.cs

@@ -163,6 +163,33 @@ public class StreamingControllerDungeonGateTests
         Assert.DoesNotContain(h.Loads, l => l.Kind == LandblockStreamJobKind.LoadFar);
     }
 
+    [Fact]
+    public void InitializeKnownLoginCenter_DungeonPerformsOneCollapseWithoutReloadChurn()
+    {
+        var h = Make();
+
+        h.Ctrl.InitializeKnownLoginCenter(0, 7, isSealedDungeon: true);
+        h.Ctrl.InitializeKnownLoginCenter(0, 7, isSealedDungeon: true);
+
+        Assert.Single(h.Loads);
+        Assert.Equal(Encode(0, 7), h.Loads[0].Id);
+        Assert.Equal(1, h.ClearCalls());
+    }
+
+    [Fact]
+    public void InitializeKnownLoginCenter_OutdoorWaitsForFirstCorrectlyCenteredTick()
+    {
+        var h = Make();
+
+        h.Ctrl.InitializeKnownLoginCenter(140, 4, isSealedDungeon: false);
+
+        Assert.Empty(h.Loads);
+        Assert.Equal(0, h.ClearCalls());
+
+        h.Ctrl.Tick(140, 4, insideDungeon: false);
+        Assert.Contains(h.Loads, load => load.Id == Encode(140, 4));
+    }
+
     [Fact]
     public void PreCollapse_AfterBootstrapTick_CancelsWindow_UnloadsResidentNeighbors_KeepsDungeon()
     {

tests/AcDream.Core.Tests/Streaming/StreamingControllerTests.cs

@@ -73,7 +73,7 @@ public class StreamingControllerTests
         var applied = new List<LoadedLandblock>();
         var controller = new StreamingController(
             fake.EnqueueLoad, fake.EnqueueUnload, fake.DrainCompletions,
-            (lb, _) => applied.Add(lb), state, nearRadius: 2, farRadius: 2);
+            (build, _) => applied.Add(build.Landblock), state, nearRadius: 2, farRadius: 2);
 
         // Note: LoadedLandblock's actual fields are LandblockId, Heightmap,
         // Entities (positional record). Adjust if the first positional arg

tests/AcDream.Core.Tests/Streaming/StreamingControllerTwoTierTests.cs

@@ -131,7 +131,7 @@ public class StreamingControllerTwoTierTests
             applyTerrain: (appliedLb, appliedMesh) =>
             {
                 applyPromotedCount++;
-                Assert.Same(promotedLb, appliedLb);
+                Assert.Same(promotedLb, appliedLb.Landblock);
                 Assert.Same(promotedMesh, appliedMesh);
             },
             state: state,