feat(rendering): prove packed dispatcher output parity

Build a compare-only dispatcher classifier from RenderFrameView and compare complete opaque, alpha, selection, clip, light, texture, transform, and draw payloads against the accepted path. Preserve retail's stable equal-CYpt ordering with explicit draw-local submission ordinals so material-group history cannot affect alpha ties.

src/AcDream.App/Rendering/Selection/IRetailSelectionRenderSink.cs

@@ -1,4 +1,5 @@
 using System.Numerics;
+using AcDream.Core.Selection;
 namespace AcDream.App.Rendering.Selection;
 
 /// <summary>
@@ -14,3 +15,19 @@ internal interface IRetailSelectionRenderSink
         uint gfxObjId,
         Matrix4x4 partWorld);
 }
+
+/// <summary>
+/// Read-only mirror of the exact geometry and drawing-sphere acceptance used
+/// by the retained selection scene. G2's packed dispatcher referee uses it
+/// without publishing a second picking frame.
+/// </summary>
+internal interface IRetailSelectionRenderOracle
+{
+    bool TryCreateVisiblePart(
+        uint serverGuid,
+        uint localEntityId,
+        int partIndex,
+        uint gfxObjId,
+        Matrix4x4 partWorld,
+        out RetailSelectionPart part);
+}

src/AcDream.App/Rendering/Selection/RetailSelectionScene.cs

@@ -21,6 +21,7 @@ internal interface IWorldSceneSelectionFrame
 
 internal sealed class RetailSelectionScene :
     IRetailSelectionRenderSink,
+    IRetailSelectionRenderOracle,
     IRetailSelectionLightingSource,
     IWorldSceneSelectionFrame
 {
@@ -128,32 +129,65 @@ internal sealed class RetailSelectionScene :
             return;
         if (serverGuid == 0u)
             return;
-
         if (!_buildingKeys.Add(new PartKey(
                 localEntityId,
                 partIndex,
                 gfxObjId)))
             return;
-        RetailSelectionMesh? mesh = _geometry.Resolve(gfxObjId);
-        if (mesh is null)
-            return;
-        if (_viewFrustum is not { } frustum
-            || !DrawingSphereIntersectsFrustum(mesh, partWorld, frustum))
+        if (!TryCreateVisiblePart(
+                serverGuid,
+                localEntityId,
+                partIndex,
+                gfxObjId,
+                partWorld,
+                out RetailSelectionPart part))
+        {
             return;
+        }
 
-        _building.Add(new RetailSelectionPart(
-            serverGuid,
-            localEntityId,
-            partIndex,
-            partWorld,
-            mesh));
+        _building.Add(part);
         _currentRenderSceneObserver?.ObserveSelectionPart(
             serverGuid,
             localEntityId,
             partIndex,
             gfxObjId,
             partWorld,
+            part.Mesh);
+    }
+
+    public bool TryCreateVisiblePart(
+        uint serverGuid,
+        uint localEntityId,
+        int partIndex,
+        uint gfxObjId,
+        Matrix4x4 partWorld,
+        out RetailSelectionPart part)
+    {
+        if (serverGuid == 0u)
+        {
+            part = default;
+            return false;
+        }
+
+        RetailSelectionMesh? mesh = _geometry.Resolve(gfxObjId);
+        if (mesh is null
+            || _viewFrustum is not { } frustum
+            || !DrawingSphereIntersectsFrustum(
+                mesh,
+                partWorld,
+                frustum))
+        {
+            part = default;
+            return false;
+        }
+
+        part = new RetailSelectionPart(
+            serverGuid,
+            localEntityId,
+            partIndex,
+            partWorld,
             mesh);
+        return true;
     }
 
     public void CompleteFrame()