Keep Android header backdrop composited beneath search

Co-authored-by: Terp <5856f6900e8e0a4e0ea1f4f8d2ee33e4753d2119bc122f94ecafc660b46c0511@buzz.block.builderlab.xyz>
Signed-off-by: kenny lopez <klopez4212@gmail.com>

mobile/lib/features/home/home_page.dart

@@ -104,6 +104,9 @@ class HomePage extends HookConsumerWidget {
         settingsPageBuilder: settingsPageBuilder,
         onSearch: () => Navigator.of(context).push(
           PageRouteBuilder<void>(
+            // Keep Android backdrop filters composited while search is open.
+            // UIKit controls must instead be hidden beneath the iOS route.
+            opaque: defaultTargetPlatform == TargetPlatform.iOS,
             allowSnapshotting: false,
             transitionDuration: reducedMotion
                 ? Duration.zero

mobile/test/features/channels/channels_page_test.dart

@@ -3,6 +3,7 @@ import 'package:buzz/shared/widgets/app_route_observer.dart';
 import 'package:buzz/features/pairing/pairing_provider.dart';
 import 'package:buzz/shared/community/paired_community_landing.dart';
 import 'dart:async';
+import 'package:shared_preferences/shared_preferences.dart';
 
 import '../profile/presence_snapshot_test.dart'
     show PresenceTestRelay, presenceEvent;
@@ -677,6 +678,56 @@ void main() {
     expect(appBar.frostedBlurSigma, 23.12);
   });
 
+  testWidgets('Home keeps header blur after returning from search', (
+    tester,
+  ) async {
+    SharedPreferences.setMockInitialValues({});
+    final prefs = await SharedPreferences.getInstance();
+    tester.view.physicalSize = const Size(320, 320);
+    tester.view.devicePixelRatio = 1;
+    addTearDown(tester.view.reset);
+    await tester.pumpWidget(
+      buildTestable(
+        realHome: true,
+        topSectionGradient: const LinearGradient(
+          colors: [Colors.yellow, Colors.blue],
+        ),
+        overrides: [
+          savedPrefsProvider.overrideWithValue(prefs),
+          channelsProvider.overrideWith(() => _FakeNotifier(testChannels)),
+        ],
+      ),
+    );
+    await tester.pumpAndSettle();
+    final position = tester
+        .state<ScrollableState>(
+          find
+              .descendant(
+                of: find.byType(CustomScrollView),
+                matching: find.byType(Scrollable),
+              )
+              .first,
+        )
+        .position;
+    position.jumpTo(position.maxScrollExtent);
+    await tester.pumpAndSettle();
+    final header = find.byType(FrostedAppBar).first;
+    expect(
+      find.descendant(of: header, matching: find.byType(BackdropFilter)),
+      findsOneWidget,
+    );
+    final offset = position.pixels;
+    await tester.tap(find.byTooltip('Search'));
+    await tester.pumpAndSettle();
+    tester.state<NavigatorState>(find.byType(Navigator).first).pop();
+    await tester.pumpAndSettle();
+    expect(position.pixels, offset);
+    expect(
+      find.descendant(of: header, matching: find.byType(BackdropFilter)),
+      findsOneWidget,
+    );
+  });
+
   for (final customRoute in [false, true]) {
     testWidgets(
       'Home replays native scroll state on return: custom=$customRoute',

mobile/test/features/home/home_page_test.dart

@@ -147,6 +147,7 @@ void main() {
     expect(find.byType(SearchPage), findsOneWidget);
     final searchRoute = ModalRoute.of(tester.element(find.byType(SearchPage)))!;
     expect(searchRoute.allowSnapshotting, isFalse);
+    expect(searchRoute.opaque, isTrue);
     expect(searchRoute.transitionDuration, const Duration(milliseconds: 260));
     expect(
       searchRoute.reverseTransitionDuration,
@@ -177,6 +178,7 @@ void main() {
       expect(tester.getTopLeft(search).dy, reducedMotion ? 0 : greaterThan(0));
       await tester.pumpAndSettle();
       expect(tester.getTopLeft(search).dy, 0);
+      expect(ModalRoute.of(tester.element(search))!.opaque, isFalse);
       Navigator.of(tester.element(search)).pop();
       await tester.pump();
       await tester.pump(const Duration(milliseconds: 100));