diff --git a/src/AcDream.App/Rendering/Wb/GroupKey.cs b/src/AcDream.App/Rendering/Wb/GroupKey.cs
new file mode 100644
index 0000000..696363c
--- /dev/null
+++ b/src/AcDream.App/Rendering/Wb/GroupKey.cs
@@ -0,0 +1,20 @@
+using AcDream.Core.Meshing;
+
+namespace AcDream.App.Rendering.Wb;
+
+/// <summary>
+/// Bucket identity for <see cref="WbDrawDispatcher"/>'s per-frame group dictionary.
+/// Two (entity, batch) pairs that share the same <see cref="GroupKey"/> render
+/// in a single <c>glMultiDrawElementsIndirect</c> draw command. Promoted to
+/// <c>internal</c> at file scope (was a private nested type) so
+/// <see cref="EntityClassificationCache"/> can store it inside <see cref="CachedBatch"/>
+/// without depending on dispatcher internals.
+/// </summary>
+internal readonly record struct GroupKey(
+    uint Ibo,
+    uint FirstIndex,
+    int BaseVertex,
+    int IndexCount,
+    ulong BindlessTextureHandle,
+    uint TextureLayer,
+    TranslucencyKind Translucency);
diff --git a/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs b/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs
index cb27f87..15d0e6e 100644
--- a/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs
+++ b/src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs
@@ -920,15 +920,6 @@ public sealed unsafe class WbDrawDispatcher : IDisposable
 
     // ────────────────────────────────────────────────────────────────────────
 
-    private readonly record struct GroupKey(
-        uint Ibo,
-        uint FirstIndex,
-        int BaseVertex,
-        int IndexCount,
-        ulong BindlessTextureHandle,
-        uint TextureLayer,
-        TranslucencyKind Translucency);
-
     private sealed class InstanceGroup
     {
         public uint Ibo;