fix(search): fix history overlay flicker and clear/delete behavior

frontend/test/app_search_bar_test.dart

@@ -0,0 +1,164 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:frontend/ui/shared/inputs/app_search_bar.dart';
+import 'package:frontend/ui/providers/search_history_provider.dart';
+
+void main() {
+  setUp(() {
+    SharedPreferences.setMockInitialValues({
+      'app_search_history': '["test item 1", "test item 2"]',
+    });
+  });
+
+  test('SearchHistoryNotifier loads, adds, removes, and clears history', () async {
+    final container = ProviderContainer();
+    addTearDown(container.dispose);
+
+    expect(container.read(searchHistoryProvider), isEmpty);
+
+    await Future<void>.delayed(const Duration(milliseconds: 100));
+    final history = container.read(searchHistoryProvider);
+    expect(history, containsAll(['test item 1', 'test item 2']));
+
+    await container.read(searchHistoryProvider.notifier).addSearch('new item');
+    expect(container.read(searchHistoryProvider).first, equals('new item'));
+
+    await container.read(searchHistoryProvider.notifier).removeSearch('test item 1');
+    expect(container.read(searchHistoryProvider), isNot(contains('test item 1')));
+
+    await container.read(searchHistoryProvider.notifier).clearHistory();
+    expect(container.read(searchHistoryProvider), isEmpty);
+  });
+
+  testWidgets('AppSearchBar displays history overlay on focus and supports clear all', (tester) async {
+    final container = ProviderContainer();
+    addTearDown(container.dispose);
+
+    container.read(searchHistoryProvider);
+    await tester.pump(const Duration(milliseconds: 100));
+
+    await tester.pumpWidget(
+      UncontrolledProviderScope(
+        container: container,
+        child: const MaterialApp(
+          home: Scaffold(
+            body: Center(
+              child: AppSearchBar(
+                hint: 'Search test...',
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+
+    // Tap search bar to focus
+    await tester.tap(find.byType(TextField));
+    await tester.pump(const Duration(milliseconds: 50));
+    await tester.pump(const Duration(milliseconds: 50));
+
+    // Verify history overlay is displayed
+    expect(find.text('Recent Searches'), findsOneWidget);
+    expect(find.text('test item 1'), findsOneWidget);
+    expect(find.text('test item 2'), findsOneWidget);
+    expect(find.text('Clear all'), findsOneWidget);
+
+    // Tap Clear all
+    await tester.tap(find.text('Clear all'));
+    await tester.pump(const Duration(milliseconds: 50));
+
+    // History is now cleared and overlay closes
+    expect(container.read(searchHistoryProvider), isEmpty);
+    expect(find.text('Recent Searches'), findsNothing);
+  });
+
+  testWidgets('AppSearchBar individual item deletion removes item and keeps overlay open', (tester) async {
+    final container = ProviderContainer();
+    addTearDown(container.dispose);
+
+    container.read(searchHistoryProvider);
+    await tester.pump(const Duration(milliseconds: 100));
+
+    await tester.pumpWidget(
+      UncontrolledProviderScope(
+        container: container,
+        child: const MaterialApp(
+          home: Scaffold(
+            body: Center(
+              child: AppSearchBar(
+                hint: 'Search test...',
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+
+    // Open overlay
+    await tester.tap(find.byType(TextField));
+    await tester.pump(const Duration(milliseconds: 50));
+    await tester.pump(const Duration(milliseconds: 50));
+
+    expect(find.text('test item 1'), findsOneWidget);
+    expect(find.text('test item 2'), findsOneWidget);
+
+    // Find the close buttons on history items
+    final closeIcons = find.byIcon(Icons.close_rounded);
+    expect(closeIcons, findsWidgets);
+
+    // Tap the first history item close button
+    await tester.tap(closeIcons.first);
+    await tester.pump(const Duration(milliseconds: 50));
+
+    // Item 1 was removed, Item 2 remains, overlay remains open
+    expect(container.read(searchHistoryProvider), isNot(contains('test item 1')));
+    expect(container.read(searchHistoryProvider), contains('test item 2'));
+    expect(find.text('Recent Searches'), findsOneWidget);
+    expect(find.text('test item 2'), findsOneWidget);
+  });
+
+  testWidgets('AppSearchBar pressing escape closes overlay', (tester) async {
+    final container = ProviderContainer();
+    addTearDown(container.dispose);
+
+    container.read(searchHistoryProvider);
+    await tester.pump(const Duration(milliseconds: 100));
+
+    await tester.pumpWidget(
+      UncontrolledProviderScope(
+        container: container,
+        child: const MaterialApp(
+          home: Scaffold(
+            body: Center(
+              child: AppSearchBar(
+                hint: 'Search test...',
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pump();
+
+    // Focus to open overlay
+    await tester.tap(find.byType(TextField));
+    await tester.pump(const Duration(milliseconds: 50));
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(find.text('Recent Searches'), findsOneWidget);
+
+    // Press Escape
+    await tester.sendKeyEvent(LogicalKeyboardKey.escape);
+    await tester.pump(const Duration(milliseconds: 50));
+
+    // Overlay is dismissed
+    expect(find.text('Recent Searches'), findsNothing);
+  });
+}