diff --git a/src/app/components/CompositionWireframe.tsx b/src/app/components/CompositionWireframe.tsx
index c8f6cb0..a1c56df 100644
--- a/src/app/components/CompositionWireframe.tsx
+++ b/src/app/components/CompositionWireframe.tsx
@@ -282,6 +282,10 @@ function WireframeTree({ tree }: { tree: ViewNode }) {
     [tree, rectOf],
   );
 
+  // TODO: the drag-math cluster (edgeOf + dropTargetNode + this zone classifier) is pure
+  // decision logic — given pointer, child rects, orientation and paths it returns a commit or
+  // null — but lives in the component, tested only through happy-dom rect stubs. Lift it into a
+  // core function tested without a DOM when a second draggable surface appears (eng-council).
   const resolveDrop = useCallback(
     (x: number, y: number, source: ViewNode, pair: boolean): DropResolution | null => {
       const sourcePath = source.path;