feat(render): Phase A8 — WbDrawDispatcher.EntitySet partition

Adds EntitySet { All, IndoorOnly, OutdoorOnly } and a Draw parameter to
partition the per-entity walk by ParentCellId presence. EntitySet.All
preserves pre-A8 behavior; IndoorOnly drops null-ParentCellId entities;
OutdoorOnly drops ParentCellId.HasValue entities. The visibleCellIds
filter is still applied on top.

Used by Task 7 to split the render frame's single Draw call into two
(indoor stencil-OFF, outdoor stencil-gated).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/AcDream.Core.Tests/Rendering/Wb/WbDrawDispatcherEntitySetTests.cs

@@ -0,0 +1,110 @@
+// Phase A8 — verify the WbDrawDispatcher EntitySet partition.
+//
+// The pure-data WalkEntitiesForTest helper iterates a flat entity list and
+// returns the IDs that survive the EntitySet filter + visibleCellIds gate.
+// EntitySet.IndoorOnly should include only entities with ParentCellId,
+// EntitySet.OutdoorOnly only entities with null ParentCellId, and
+// EntitySet.All (the default) should match the pre-A8 behavior.
+
+using System.Collections.Generic;
+using System.Numerics;
+using AcDream.App.Rendering.Wb;
+using AcDream.Core.World;
+using Xunit;
+
+namespace AcDream.Core.Tests.Rendering.Wb;
+
+public class WbDrawDispatcherEntitySetTests
+{
+    private static WorldEntity Indoor(uint id, uint cellId) => new()
+    {
+        Id = id,
+        SourceGfxObjOrSetupId = 0x01000001u,
+        ParentCellId = cellId,
+        MeshRefs = new List<AcDream.Core.World.MeshRef>
+        {
+            new() { GfxObjId = 0x01000001u },
+        },
+        Position = Vector3.Zero,
+        Rotation = System.Numerics.Quaternion.Identity,
+    };
+
+    private static WorldEntity Outdoor(uint id) => new()
+    {
+        Id = id,
+        SourceGfxObjOrSetupId = 0x01000001u,
+        ParentCellId = null,
+        MeshRefs = new List<AcDream.Core.World.MeshRef>
+        {
+            new() { GfxObjId = 0x01000001u },
+        },
+        Position = Vector3.Zero,
+        Rotation = System.Numerics.Quaternion.Identity,
+    };
+
+    [Fact]
+    public void EntitySet_IndoorOnly_DropsOutdoorEntities()
+    {
+        var entities = new List<WorldEntity>
+        {
+            Indoor(0x10000001, 0xA9B40143),
+            Outdoor(0x10000002),
+            Indoor(0x10000003, 0xA9B40144),
+        };
+
+        var visible = new HashSet<uint> { 0xA9B40143u, 0xA9B40144u };
+        var result = WbDrawDispatcher.WalkEntitiesForTest(
+            entities,
+            visibleCellIds: visible,
+            set: WbDrawDispatcher.EntitySet.IndoorOnly);
+
+        Assert.Equal(2, result.Count);
+        Assert.Contains(0x10000001u, result);
+        Assert.Contains(0x10000003u, result);
+        Assert.DoesNotContain(0x10000002u, result);
+    }
+
+    [Fact]
+    public void EntitySet_OutdoorOnly_KeepsOnlyNullParentCellId()
+    {
+        var entities = new List<WorldEntity>
+        {
+            Indoor(0x10000001, 0xA9B40143),
+            Outdoor(0x10000002),
+            Outdoor(0x10000003),
+        };
+
+        var result = WbDrawDispatcher.WalkEntitiesForTest(
+            entities,
+            visibleCellIds: null,
+            set: WbDrawDispatcher.EntitySet.OutdoorOnly);
+
+        Assert.Equal(2, result.Count);
+        Assert.Contains(0x10000002u, result);
+        Assert.Contains(0x10000003u, result);
+        Assert.DoesNotContain(0x10000001u, result);
+    }
+
+    [Fact]
+    public void EntitySet_All_MatchesPreA8Behavior()
+    {
+        var entities = new List<WorldEntity>
+        {
+            Indoor(0x10000001, 0xA9B40143),
+            Outdoor(0x10000002),
+            Indoor(0x10000003, 0xA9B40999),  // not in visibleCellIds
+        };
+
+        var visible = new HashSet<uint> { 0xA9B40143u };
+        var result = WbDrawDispatcher.WalkEntitiesForTest(
+            entities,
+            visibleCellIds: visible,
+            set: WbDrawDispatcher.EntitySet.All);
+
+        // Pre-A8: visibleCellIds gates indoor entities, outdoor entities pass.
+        Assert.Equal(2, result.Count);
+        Assert.Contains(0x10000001u, result);
+        Assert.Contains(0x10000002u, result);
+        Assert.DoesNotContain(0x10000003u, result);
+    }
+}