perf(bake): stream catalog and bound validation residency

tests/AcDream.Bake.Tests/BakeDeterminismTests.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using AcDream.Bake;
+using AcDream.Content.Pak;
 
 namespace AcDream.Bake.Tests;
 
@@ -76,4 +77,59 @@ public sealed class BakeDeterminismTests : IDisposable {
         Assert.True(bytesA.AsSpan().SequenceEqual(bytesB),
             "two bakes of the same id set produced different bytes — the sorted-batching determinism guarantee is broken");
     }
+
+    [Fact]
+    public void Bake_RealDuplicateCells_ShareOneBlobAcrossLandblocksAndThreads() {
+        var datDir = ResolveDatDir();
+        if (datDir is null) return;
+
+        // Full-bake discovery fixture: these eight cells span multiple
+        // landblocks but have the same complete environment/structure/surface
+        // tuple. They must remain eight addressable keys backed by one blob.
+        var ids = new HashSet<uint> {
+            0x00A90230u, 0x00B901A8u, 0x00E50602u, 0x00E50610u,
+            0x00E5061Fu, 0x00F90784u, 0x00F9078Eu, 0x00FA073Eu,
+        };
+        var pathA = NewTempPakPath();
+        var pathB = NewTempPakPath();
+
+        var reportA = BakeRunner.RunDetailed(
+            new BakeOptions {
+                DatDir = datDir,
+                OutPath = pathA,
+                IdFilter = ids,
+                Threads = 1,
+            });
+        var reportB = BakeRunner.RunDetailed(
+            new BakeOptions {
+                DatDir = datDir,
+                OutPath = pathB,
+                IdFilter = ids,
+                Threads = 8,
+            });
+
+        Assert.Equal(8, reportA.EnvCellKeys);
+        Assert.Equal(1, reportA.UniqueEnvCellGeometries);
+        Assert.Equal(7, reportA.EnvCellAliases);
+        Assert.Equal(1, reportA.PhysicalBlobs);
+        Assert.Equal(reportA.TotalKeys, reportB.TotalKeys);
+        Assert.True(File.ReadAllBytes(pathA).AsSpan().SequenceEqual(File.ReadAllBytes(pathB)));
+
+        using var reader = new PakReader(pathA);
+        var receipts = ids
+            .Select(id => reader.GetTocEntryForTest(
+                PakKey.Compose(PakAssetType.EnvCellMesh, id)))
+            .ToArray();
+        Assert.All(receipts, receipt => Assert.Equal(receipts[0].Offset, receipt.Offset));
+        Assert.All(receipts, receipt => Assert.Equal(receipts[0].Length, receipt.Length));
+        Assert.All(receipts, receipt => Assert.Equal(receipts[0].Crc32, receipt.Crc32));
+
+        Assert.True(
+            reader.TryReadObjectMeshData(
+                PakKey.Compose(PakAssetType.EnvCellMesh, ids.Min()),
+                out var geometry));
+        Assert.NotNull(geometry);
+        Assert.Equal(0xE000_0000_0000_0000UL,
+            geometry.ObjectId & 0xF000_0000_0000_0000UL);
+    }
 }