frontend/src/features/lists/SharedListsView.tsx

@@ -179,7 +179,7 @@ export const SharedListsView: React.FC<SharedListsViewProps> = ({ onRefreshGloba
       })
     );
 
-    await api.toggleListItem(activeList.id, item.id);
+    await api.toggleListItem(activeList.id, item.id, nextCompleted);
     onRefreshGlobal();
   };
 

frontend/src/lib/api.ts

@@ -487,7 +487,7 @@ export const api = {
     });
   },
 
-  async toggleListItem(listId: string, itemId: string, isCompleted: boolean): Promise<ListItem> {
+  async toggleListItem(listId: string, itemId: string, isCompleted?: boolean): Promise<ListItem> {
     return request<ListItem>(`/api/v1/lists/${listId}/items/${itemId}`, {
       method: 'PATCH',
       body: JSON.stringify({ isCompleted }),