diff --git a/packages/editor/src/editor/Canvas.tsx b/packages/editor/src/editor/Canvas.tsx
index ea3de9f..2cb55bc 100644
--- a/packages/editor/src/editor/Canvas.tsx
+++ b/packages/editor/src/editor/Canvas.tsx
@@ -40,6 +40,12 @@ function isPrimaryButton(e: React.PointerEvent | PointerEvent): boolean {
   return (e as PointerEvent).buttons === 1 || (e as PointerEvent).button === 0;
 }
 
+function selectionKeyOf(ids: string[]): string {
+  // Keep stable regardless of selection order.
+  // This avoids false mismatches between context-menu state and reducer state.
+  return [...ids].sort().join('|');
+}
+
 export function Canvas(props: CanvasProps) {
   const ref = useRef<HTMLDivElement | null>(null);
   const [box, setBox] = useState<{ x1: number; y1: number; x2: number; y2: number } | null>(null);
@@ -148,7 +154,7 @@ export function Canvas(props: CanvasProps) {
           ? [...props.selectionIds, targetId]
           : [targetId]
       : props.selectionIds;
-    const selectionKey = nextSelectionIds.join('|');
+    const selectionKey = selectionKeyOf(nextSelectionIds);
 
     if (targetId) {
       if (!props.selectionIds.includes(targetId)) {
diff --git a/packages/editor/src/editor/EditorApp.tsx b/packages/editor/src/editor/EditorApp.tsx
index dfe4226..45ca9c9 100644
--- a/packages/editor/src/editor/EditorApp.tsx
+++ b/packages/editor/src/editor/EditorApp.tsx
@@ -86,6 +86,11 @@ export function EditorApp() {
 
   const closeContextMenu = useCallback(() => setCtxMenu(null), []);
 
+  const selectionKeyOf = useCallback((ids: string[]) => {
+    // Keep stable regardless of ordering.
+    return [...ids].sort().join('|');
+  }, []);
+
   const ctxMenuSyncedRef = useRef(false);
 
   useEffect(() => {
@@ -99,7 +104,7 @@ export function EditorApp() {
   useEffect(() => {
     if (!ctxMenu) return;
 
-    const currentKey = state.selection.ids.join('|');
+    const currentKey = selectionKeyOf(state.selection.ids);
 
     // Wait until reducer state has caught up with the context menu's intended selection.
     if (!ctxMenuSyncedRef.current) {