fix: reset scroll offset when stack collapses

- Add expanded parameter to useListScroll hook
- Reset scroll offset to 0 when stack collapses after hover leave
- Add test for scroll reset behavior

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: zombieJ

src/NotificationList.tsx

@@ -91,7 +91,7 @@ const NotificationList: React.FC<NotificationListProps> = (props) => {
   const [gap, setGap] = React.useState(0);
   const [notificationPosition, setNodeSize] = useListPosition(configList, stackPosition, gap);
   const { contentRef, onTouchEnd, onTouchMove, onTouchStart, onWheel, scrollOffset, viewportRef } =
-    useListScroll(keyList, notificationPosition);
+    useListScroll(keyList, notificationPosition, expanded);
 
   React.useEffect(() => {
     const listNode = contentRef.current;

src/hooks/useListScroll.ts

@@ -27,6 +27,7 @@ function getMaxScroll(viewportNode: HTMLDivElement | null, contentNode: HTMLDivE
 export default function useListScroll(
   keyList: string[],
   notificationPosition: Map<string, NodePosition>,
+  expanded = false,
 ) {
   const viewportRef = React.useRef<HTMLDivElement>(null);
   const contentRef = React.useRef<HTMLDivElement>(null);
@@ -92,6 +93,14 @@ export default function useListScroll(
     };
   }, [syncScrollOffset]);
 
+  React.useEffect(() => {
+    if (!expanded) {
+      touchStartYRef.current = null;
+      touchStartOffsetRef.current = 0;
+      syncScrollOffset(0);
+    }
+  }, [expanded, syncScrollOffset]);
+
   const onWheel = React.useCallback(
     (event: React.WheelEvent<HTMLDivElement>) => {
       const maxScroll = getMaxScroll(viewportRef.current, contentRef.current);

tests/stack.test.tsx

@@ -279,4 +279,53 @@ describe('stack', () => {
     clientHeightSpy.mockRestore();
     scrollHeightSpy.mockRestore();
   });
+
+  it('resets scroll offset when stack collapses after hover leave', () => {
+    const clientHeightSpy = vi
+      .spyOn(HTMLElement.prototype, 'clientHeight', 'get')
+      .mockImplementation(function mockClientHeight() {
+        if (this.classList?.contains('rc-notification-list')) {
+          return 120;
+        }
+
+        return 0;
+      });
+    const scrollHeightSpy = vi
+      .spyOn(HTMLElement.prototype, 'scrollHeight', 'get')
+      .mockImplementation(function mockScrollHeight() {
+        if (this.classList?.contains('rc-notification-list-content')) {
+          return 300;
+        }
+
+        return 0;
+      });
+
+    render(
+      <NotificationList
+        placement="topRight"
+        stack={{ threshold: 3 }}
+        configList={Array.from({ length: 5 }, (_, index) => ({
+          key: index,
+          description: `Notice ${index}`,
+          duration: false,
+        }))}
+      />,
+    );
+
+    const list = document.querySelector<HTMLElement>('.rc-notification-list');
+    const content = document.querySelector<HTMLElement>('.rc-notification-list-content');
+
+    fireEvent.mouseEnter(list!);
+    fireEvent.wheel(list!, { deltaY: 60 });
+
+    expect(content?.style.transform).toBe('translate3d(0, -60px, 0)');
+
+    fireEvent.mouseLeave(list!);
+
+    expect(list).not.toHaveClass('rc-notification-stack-expanded');
+    expect(content?.style.transform).toBe('translate3d(0, 0px, 0)');
+
+    clientHeightSpy.mockRestore();
+    scrollHeightSpy.mockRestore();
+  });
 });