refactor: centralize selection key helper

packages/editor/src/editor/Canvas.tsx

@@ -5,6 +5,7 @@ import { Button, Space } from 'antd';
 import type { ResizeHandle } from './types';
 import { rectFromPoints } from './geometry';
 import type { ContextMenuState } from './ContextMenu';
+import { selectionKeyOf } from './selection';
 
 export interface CanvasProps {
   screen: Screen;
@@ -40,12 +41,6 @@ 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);

packages/editor/src/editor/ContextMenu.tsx

@@ -1,11 +1,7 @@
 import { useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
 import { Typography } from 'antd';
 
-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('|');
-}
+import { selectionKeyOf } from './selection';
 
 export type ContextMenuState =
   | {

packages/editor/src/editor/selection.ts

@@ -0,0 +1,5 @@
+export 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('|');
+}