[material_ui] Port flutter/flutter #190206 "Prevent stale async suggestions in SearchAnchor"

packages/material_ui/lib/src/search_anchor.dart

@@ -972,6 +972,8 @@ class _ViewContentState extends State<_ViewContent> {
   Iterable<Widget> result = <Widget>[];
   String? searchValue;
   Timer? _timer;
+  // Identifies the latest call so that older async results cannot replace newer ones.
+  int _suggestionsCallId = 0;
 
   @override
   void initState() {
@@ -1008,14 +1010,9 @@ class _ViewContentState extends State<_ViewContent> {
       _timer?.cancel();
       _timer = Timer(Duration.zero, () async {
         searchValue = _controller.text;
-        final Iterable<Widget> suggestions = await widget.suggestionsBuilder(context, _controller);
+        await _buildSuggestions();
         _timer?.cancel();
         _timer = null;
-        if (mounted) {
-          setState(() {
-            result = suggestions;
-          });
-        }
       });
     }
   }
@@ -1056,15 +1053,21 @@ class _ViewContentState extends State<_ViewContent> {
   Future<void> updateSuggestions() async {
     if (searchValue != _controller.text) {
       searchValue = _controller.text;
-      final Iterable<Widget> suggestions = await widget.suggestionsBuilder(context, _controller);
-      if (mounted) {
-        setState(() {
-          result = suggestions;
-        });
-      }
+      await _buildSuggestions();
     }
   }
 
+  Future<void> _buildSuggestions() async {
+    final int callId = ++_suggestionsCallId;
+    final Iterable<Widget> suggestions = await widget.suggestionsBuilder(context, _controller);
+    if (!mounted || callId != _suggestionsCallId) {
+      return;
+    }
+    setState(() {
+      result = suggestions;
+    });
+  }
+
   @override
   Widget build(BuildContext context) {
     final Widget defaultLeading = BackButton(

packages/material_ui/pending_changelogs/change_2026_08_16_search_anchor.yaml

@@ -0,0 +1,3 @@
+changelog: |
+  - Prevents stale asynchronous suggestions from replacing newer `SearchAnchor` results.
+version: patch

packages/material_ui/test/search_anchor_test.dart

@@ -2261,6 +2261,46 @@ void main() {
     expect(controller.value.text, suggestion);
   });
 
+  testWidgets('SearchAnchor ignores out-of-order async suggestions', (WidgetTester tester) async {
+    final requests = <String, Completer<Iterable<Widget>>>{};
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: SearchAnchor(
+          builder: (BuildContext context, SearchController controller) {
+            return const Icon(Icons.search);
+          },
+          suggestionsBuilder: (BuildContext context, SearchController controller) {
+            final String query = controller.text;
+            if (query.isEmpty) {
+              return <Widget>[];
+            }
+            final request = Completer<Iterable<Widget>>();
+            requests[query] = request;
+            return request.future;
+          },
+        ),
+      ),
+    );
+
+    await tester.tap(find.byIcon(Icons.search));
+    await tester.pumpAndSettle();
+
+    await tester.enterText(findTextField(), 'a');
+    await tester.pump();
+    await tester.enterText(findTextField(), 'ab');
+    await tester.pump();
+
+    requests['ab']!.complete(<Widget>[const Text('ab-result')]);
+    await tester.pumpAndSettle();
+    expect(find.text('ab-result'), findsOneWidget);
+
+    requests['a']!.complete(<Widget>[const Text('a-result')]);
+    await tester.pumpAndSettle();
+    expect(find.text('ab-result'), findsOneWidget);
+    expect(find.text('a-result'), findsNothing);
+  });
+
   testWidgets('SearchAnchor.bar has a default search bar as the anchor', (
     WidgetTester tester,
   ) async {