feat(rendering): port retail building degrade walk

Add exact retail building degrade selection, shared FPS/degrade ownership, complete-body gating, selected-shell submission, ordinary ladder mesh residency, frame-scoped retry rearm, Config controls, installed-DAT census, and lifecycle/allocation proofs.

Reviews: OpenAI retail pass 3 PASS; OpenAI production pass 5 PASS. Gates: Release 0W/0E; focused 285/285; hermetic 16811/16811; InstalledDat 469 pass, 10 documented fail, 1 documented skip; both manifests 30/30.

tests/AcDream.App.Tests/Streaming/LandblockBuildFactoryTests.cs

@@ -8,6 +8,8 @@ using AcDream.Core.World;
 using DatReaderWriter;
 using DatReaderWriter.DBObjs;
 using DatReaderWriter.Types;
+using DatReaderWriter.Enums;
+using AcDream.App.Rendering.Walk;
 
 namespace AcDream.App.Tests.Streaming;
 
@@ -140,6 +142,52 @@ public sealed class LandblockBuildFactoryTests
         Assert.Equal((LandblockId & 0xFFFF0000u) | 1u, buildingEntry.Building.PositionCellId);
     }
 
+    [Fact]
+    public void WalkBuildingFactory_SetupModelUsesExactlyRestingPartZeroAndDefaultScale()
+    {
+        const uint setupId = 0x0200_0100u;
+        const uint partZeroId = 0x0100_0101u;
+        var dat = CreateDat(out RecordingDatProxy proxy);
+        var resting = new AnimationFrame(1);
+        resting.Frames.Add(new Frame
+        {
+            Origin = new Vector3(1f, 2f, 3f),
+            Orientation = Quaternion.CreateFromAxisAngle(Vector3.UnitZ, 0.25f),
+        });
+        var setup = new Setup();
+        setup.Parts.Add(partZeroId);
+        setup.DefaultScale.Add(new Vector3(2f, 3f, 4f));
+        setup.PlacementFrames[Placement.Resting] = resting;
+        proxy.Add(setupId, setup);
+        proxy.Add(partZeroId, new GfxObj
+        {
+            Id = partZeroId,
+            SortCenter = new Vector3(4f, 5f, 6f),
+        });
+        var info = new BuildingInfo
+        {
+            ModelId = setupId,
+            Frame = new Frame
+            {
+                Origin = new Vector3(12f, 12f, 0f),
+                Orientation = Quaternion.Identity,
+            },
+            Portals = [],
+        };
+
+        WalkBuildingFactory.Entry entry = Assert.Single(
+            WalkBuildingFactory.Build(dat, LandblockId, [info], Vector3.Zero));
+
+        Assert.Equal(partZeroId, entry.Building.GfxObjId);
+        Assert.Equal(new Vector3(4f, 5f, 6f), entry.Building.SortCenter);
+        Assert.Equal(4f, entry.Building.PartZeroScaleZ);
+        Matrix4x4 expected = Matrix4x4.CreateScale(2f, 3f, 4f)
+            * Matrix4x4.CreateFromQuaternion(resting.Frames[0].Orientation)
+            * Matrix4x4.CreateTranslation(1f, 2f, 3f);
+        Assert.Equal(expected, entry.Building.PartZeroTransform);
+        Assert.Equal(expected * entry.WorldTransform, entry.PartZeroWorldTransform);
+    }
+
     [Fact]
     public void BuildFar_NeverPopulatesWalkDataBecauseEnvCellsIsNull()
     {

tests/AcDream.App.Tests/Streaming/StreamingControllerReadinessTests.cs

@@ -1,14 +1,96 @@
 using AcDream.App.Streaming;
 using AcDream.App.Rendering;
 using AcDream.App.Rendering.Wb;
+using AcDream.App.Rendering.Walk;
 using AcDream.Core.World;
 using DatReaderWriter.DBObjs;
 using System.Collections.Immutable;
+using System.Numerics;
 
 namespace AcDream.App.Tests.Streaming;
 
 public sealed class StreamingControllerReadinessTests
 {
+    [Fact]
+    public void NearPublication_OwnsWalkLadderAsOrdinaryReadinessAndReleasesOnRetirement()
+    {
+        const uint landblockId = 0x1236FFFFu;
+        const ulong ladderId = 0x01001234ul;
+        var meshes = new ReadinessMeshAdapter();
+        var state = new GpuWorldState(new LandblockSpawnAdapter(meshes));
+        var outbox = new Queue<LandblockStreamResult>();
+        var building = new WalkBuilding
+        {
+            PositionCellId = 0x12360001u,
+            DegradeLevels =
+            [
+                new WalkBuildingDegradeLevel((uint)ladderId, 1u, 0f, 10f, 20f, null),
+            ],
+        };
+        var envCells = new EnvCellLandblockBuild(
+            landblockId,
+            Array.Empty<LoadedCell>(),
+            Array.Empty<EnvCellShellPlacement>(),
+            [new WalkBuildingFactory.Entry(building, Matrix4x4.Identity, Matrix4x4.Identity)]);
+        var build = new LandblockBuild(
+            new LoadedLandblock(landblockId, new LandBlock(), Array.Empty<WorldEntity>()),
+            envCells);
+        outbox.Enqueue(new LandblockStreamResult.Loaded(
+            landblockId,
+            LandblockStreamTier.Near,
+            build,
+            new AcDream.Core.Terrain.LandblockMeshData([], [])));
+        var controller = new StreamingController(
+            enqueueLoad: (_, _) => { },
+            enqueueUnload: _ => { },
+            drainCompletions: maximum =>
+            {
+                var drained = new List<LandblockStreamResult>();
+                while (drained.Count < maximum && outbox.TryDequeue(out var result))
+                    drained.Add(result);
+                return drained;
+            },
+            applyTerrain: (_, _) => { },
+            state: state,
+            nearRadius: 0,
+            farRadius: 0);
+
+        for (int frame = 0; frame < 32 && !meshes.ReferenceCounts.ContainsKey(ladderId); frame++)
+            controller.Tick(0x12, 0x36);
+
+        Assert.Equal(1, meshes.ReferenceCounts[ladderId]);
+        Assert.False(controller.IsRenderNeighborhoodResident(landblockId, 0, 0));
+        meshes.ReadyIds.Add(ladderId);
+        Assert.True(controller.IsRenderNeighborhoodResident(landblockId, 0, 0));
+
+        state.RemoveEntitiesFromLandblock(landblockId);
+        Assert.Empty(meshes.ReferenceCounts);
+        GpuLandblockSpatialPublication revisit = state.CommitEntitiesToExistingLandblockSpatial(
+            landblockId,
+            Array.Empty<WorldEntity>(),
+            additionalRenderIds: null,
+            additionalOrdinaryRenderIds: envCells.WalkBuildingMeshDependencies);
+        state.ActivateLandblockPresentation(revisit);
+        Assert.Equal(1, meshes.ReferenceCounts[ladderId]);
+        state.RemoveLandblock(landblockId);
+        Assert.Empty(meshes.ReferenceCounts);
+
+        GpuLandblockSpatialPublication resetPublication =
+            state.CommitLandblockSpatial(
+                build.Landblock,
+                additionalRenderIds: null,
+                tier: LandblockStreamTier.Near,
+                additionalOrdinaryRenderIds:
+                    envCells.WalkBuildingMeshDependencies);
+        state.ActivateLandblockPresentation(resetPublication);
+        Assert.Equal(1, meshes.ReferenceCounts[ladderId]);
+
+        GpuWorldRecenterRetirement reset = state.DetachAllForOriginRecenter();
+        Assert.Equal(landblockId, Assert.Single(reset.Landblocks).LandblockId);
+        state.ReleaseLandblockMeshReferences(landblockId);
+        Assert.Empty(meshes.ReferenceCounts);
+    }
+
     [Fact]
     public void RenderNeighborhoodResident_RequiresEveryPublishedLandblockInRing()
     {