fix(home): 修正首页分类与卡片布局

test/home/home_grid_layout_test.dart

@@ -11,6 +11,7 @@ import 'package:fruitshorts/core/data/repositories/catalog_repository.dart';
 import 'package:fruitshorts/core/data/repositories/favorite_repository.dart';
 import 'package:fruitshorts/core/data/repositories/playback_repository.dart';
 import 'package:fruitshorts/core/data/repositories/watch_history_repository.dart';
+import 'package:fruitshorts/pages/home/widgets/home_feed_card.dart';
 import 'package:fruitshorts/pages/player/player_view.dart';
 import 'package:shared_preferences_platform_interface/in_memory_shared_preferences_async.dart';
 import 'package:shared_preferences_platform_interface/shared_preferences_async_platform_interface.dart';
@@ -88,29 +89,82 @@ void main() {
     expect(find.byKey(const Key('home-tag-uplifting')), findsNothing);
   });
 
-  testWidgets('should_open_existing_pages_from_home_sections', (tester) async {
+  testWidgets('should_switch_home_sections_without_pushing_pages', (
+    tester,
+  ) async {
     final repository = _PagedCatalogRepository();
     await _pumpApp(tester, repository);
 
+    String firstDramaId() {
+      return tester
+          .widget<HomeFeedCard>(find.byType(HomeFeedCard).first)
+          .drama
+          .id;
+    }
+
+    expect(find.byKey(const Key('home-grid')), findsOneWidget);
+    expect(firstDramaId(), 'page1-0');
+
     await tester.tap(find.byKey(const Key('home-section-new')));
     await tester.pumpAndSettle();
-    expect(find.byKey(const Key('new-releases-page')), findsOneWidget);
-    await tester.pageBack();
-    await tester.pumpAndSettle();
+    expect(find.byKey(const Key('new-releases-page')), findsNothing);
+    expect(firstDramaId(), 'page1-9');
 
-    await tester.ensureVisible(find.byKey(const Key('home-section-ranking')));
     await tester.tap(find.byKey(const Key('home-section-ranking')));
     await tester.pumpAndSettle();
-    expect(find.byKey(const Key('ranking-page')), findsOneWidget);
-    await tester.pageBack();
-    await tester.pumpAndSettle();
+    expect(find.byKey(const Key('ranking-page')), findsNothing);
+    expect(firstDramaId(), 'page1-0');
 
-    await tester.ensureVisible(
-      find.byKey(const Key('home-section-categories')),
-    );
     await tester.tap(find.byKey(const Key('home-section-categories')));
     await tester.pumpAndSettle();
-    expect(find.byKey(const Key('filter-page')), findsOneWidget);
+    expect(find.byKey(const Key('filter-page')), findsNothing);
+    expect(find.byKey(const Key('home-grid-cards')), findsOneWidget);
+
+    await tester.tap(find.byKey(const Key('home-section-category-古装')));
+    await tester.pumpAndSettle();
+    expect(firstDramaId(), 'page1-0');
+
+    await tester.tap(find.byKey(const Key('home-section-category-社群')));
+    await tester.pumpAndSettle();
+    expect(find.byKey(const Key('home-grid-empty')), findsOneWidget);
+    expect(find.byKey(const Key('filter-page')), findsNothing);
+  });
+
+  testWidgets('should_keep_scroll_position_when_switching_sections', (
+    tester,
+  ) async {
+    final repository = _PagedCatalogRepository();
+    await _pumpApp(tester, repository);
+
+    await tester.drag(
+      find.byKey(const Key('home-grid-scroll')),
+      const Offset(0, -320),
+    );
+    await tester.pumpAndSettle();
+    final scrollable = find
+        .descendant(
+          of: find.byKey(const Key('home-grid-scroll')),
+          matching: find.byType(Scrollable),
+        )
+        .first;
+    final before = tester.state<ScrollableState>(scrollable).position.pixels;
+    expect(before, greaterThan(0));
+
+    await tester.tap(find.byKey(const Key('home-section-new')));
+    await tester.pumpAndSettle();
+    await tester.tap(find.byKey(const Key('home-section-featured')));
+    await tester.pumpAndSettle();
+
+    final afterScrollable = find
+        .descendant(
+          of: find.byKey(const Key('home-grid-scroll')),
+          matching: find.byType(Scrollable),
+        )
+        .first;
+    expect(
+      tester.state<ScrollableState>(afterScrollable).position.pixels,
+      closeTo(before, 0.1),
+    );
   });
 
   testWidgets('should_load_next_page_without_expanding_page_size', (
@@ -232,14 +286,16 @@ class _PagedCatalogRepository implements CatalogRepository {
 }
 
 Drama _drama(String id) {
+  final index = int.tryParse(id.split('-').last) ?? 0;
   return Drama(
     id: id,
     title: 'Grid Drama $id',
     synopsis: 'synopsis',
     posterUrl: '',
     genre: 'Romance',
-    category: 'Urban',
-    viewCount: 200000,
+    category: index.isEven ? '古装' : 'Urban',
+    viewCount: (10 - index) * 10000,
+    createdAt: DateTime(2026, 10, 1).add(Duration(days: index)),
     detailLoaded: true,
     episodes: [
       Episode(