fix(ResizeWatcher): address PR review comments

- Add getTrackedElementCount as an optional method on IResizeWatcher
  so TS consumers can call it via the context without casting; keeping
  it optional preserves the freedom for alternate implementations to
  not expose it.
- Wire dependency array on the leak test's tracked-count effect so it
  only re-reads when the watcher or cycle count changes, instead of
  on every render.
- Track the cycle() setTimeout in a ref and clear it on unmount so a
  pending timer cannot setState on an unmounted component if the demo
  is swapped within 200ms.

Author: sankhesh

src/utils/ResizeWatcher.ts

@@ -6,6 +6,7 @@ export type ResizeWatcherStop = () => void;
 export interface IResizeWatcher {
   watch(element: Element, callback: ResizeWatcherCallback): void;
   unwatch(element: Element, callback: ResizeWatcherCallback): void;
+  getTrackedElementCount?(): number;
 }
 
 export const ResizeWatcherContext = createContext<IResizeWatcher | null>(null);

usage/src/Tests/ResizeWatcherLeakTest.jsx

@@ -20,11 +20,11 @@ function ResizeWatcherStats({ cycleCount }) {
   const [trackedCount, setTrackedCount] = useState(0);
 
   useEffect(() => {
-    // Read count after each render triggered by a cycle.
+    // Re-read the count whenever a cycle completes.
     if (resizeWatcher && typeof resizeWatcher.getTrackedElementCount === 'function') {
       setTrackedCount(resizeWatcher.getTrackedElementCount());
     }
-  });
+  }, [resizeWatcher, cycleCount]);
 
   return (
     <div
@@ -83,11 +83,12 @@ function Example() {
   const [showViews, setShowViews] = useState(true);
   const [cycleCount, setCycleCount] = useState(0);
   const intervalRef = useRef(null);
+  const cycleTimeoutRef = useRef(null);
   const [autoCycle, setAutoCycle] = useState(false);
 
   const cycle = () => {
     setShowViews(false);
-    setTimeout(() => {
+    cycleTimeoutRef.current = setTimeout(() => {
       setShowViews(true);
       setCycleCount((c) => c + 1);
     }, 200);
@@ -102,6 +103,13 @@ function Example() {
     return () => clearInterval(intervalRef.current);
   }, [autoCycle]);
 
+  useEffect(
+    () => () => {
+      if (cycleTimeoutRef.current) clearTimeout(cycleTimeoutRef.current);
+    },
+    []
+  );
+
   return (
     <MultiViewRoot style={{ width: '100%' }}>
       <div style={{ padding: '8px', display: 'flex', flexDirection: 'column', gap: '8px' }}>