feat(home): 支持滑动切换首页分类

docs/plans/PROGRESS.md

@@ -1112,6 +1112,7 @@ $ flutter test
 ## 2026-10-22 首页布局对齐修正
 
 - 一级分类未选 18/w400、选中 20/w700；二级 chips 间距 10、左右 8、15/w600，并以稳定 AnimatedContainer 切换。
+- 首页内容区改为横向 PageView：点击与滑动共用 PageController，各 tab 保留纵向滚动位置。
 - 四类卡片去底板/描边，封面统一 3:4、8 圆角、行距 10、封底标题间距 6；状态角标为右上角紧凑异形丝带。
 - 标题下方恢复左对齐题材文字，使用 `|` 分隔、灰色小字，与封面状态角标保持独立。
 - 首页搜索栏到一级、一级到二级、二级到网格间距为 8/8/10；非精选 tab 直接以 10 衔接网格。

lib/pages/home/widgets/home_feed_grid.dart

@@ -43,6 +43,7 @@ class HomeFeedGrid extends StatefulWidget {
 
 class _HomeFeedGridState extends State<HomeFeedGrid> {
   HomePrimaryTab _selectedPrimary = HomePrimaryTab.featured;
+  late final PageController _pageController;
   late final Map<HomePrimaryTab, ScrollController> _scrollControllers;
   final Map<HomePrimaryTab, String?> _selectedTags = {
     for (final tab in HomePrimaryTab.values) tab: null,
@@ -51,6 +52,7 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
   @override
   void initState() {
     super.initState();
+    _pageController = PageController(initialPage: _selectedPrimary.index);
     _scrollControllers = {
       for (final tab in HomePrimaryTab.values) tab: ScrollController(),
     };
@@ -58,6 +60,7 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
 
   @override
   void dispose() {
+    _pageController.dispose();
     for (final controller in _scrollControllers.values) {
       controller.dispose();
     }
@@ -93,19 +96,30 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
               tags: tags,
               selectedPrimary: _selectedPrimary,
               selectedTag: activeTag,
-              onPrimarySelected: (tab) =>
+              onPrimarySelected: _selectPrimary,
-                  setState(() => _selectedPrimary = tab),
               onTagSelected: (tag) =>
                   setState(() => _selectedTags[_selectedPrimary] = tag),
               walletBadge: walletBadge,
             ),
             Expanded(
-              child: IndexedStack(
+              child: PageView.builder(
-                index: _selectedPrimary.index,
+                key: const Key('home-primary-page-view'),
-                children: [
+                controller: _pageController,
-                  for (final tab in HomePrimaryTab.values)
+                itemCount: HomePrimaryTab.values.length,
-                    _tabGrid(context, l10n, tab: tab, shortcuts: shortcuts),
+                onPageChanged: (index) => setState(
-                ],
+                  () => _selectedPrimary = HomePrimaryTab.values[index],
+                ),
+                itemBuilder: (context, index) => _KeepAlivePage(
+                  key: PageStorageKey(
+                    'home-primary-page-${HomePrimaryTab.values[index].name}',
+                  ),
+                  child: _tabGrid(
+                    context,
+                    l10n,
+                    tab: HomePrimaryTab.values[index],
+                    shortcuts: shortcuts,
+                  ),
+                ),
               ),
             ),
           ],
@@ -114,6 +128,21 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
     );
   }
 
+  void _selectPrimary(HomePrimaryTab tab) {
+    if (tab == _selectedPrimary) return;
+    if (!_pageController.hasClients) {
+      setState(() => _selectedPrimary = tab);
+      return;
+    }
+    unawaited(
+      _pageController.animateToPage(
+        tab.index,
+        duration: AppDimens.homePrimaryTabAnimationDuration,
+        curve: Curves.easeOut,
+      ),
+    );
+  }
+
   Widget _tabGrid(
     BuildContext context,
     AppLocalizations l10n, {
@@ -329,3 +358,24 @@ class _HomeFeedGridState extends State<HomeFeedGrid> {
     );
   }
 }
+
+class _KeepAlivePage extends StatefulWidget {
+  const _KeepAlivePage({super.key, required this.child});
+
+  final Widget child;
+
+  @override
+  State<_KeepAlivePage> createState() => _KeepAlivePageState();
+}
+
+class _KeepAlivePageState extends State<_KeepAlivePage>
+    with AutomaticKeepAliveClientMixin {
+  @override
+  bool get wantKeepAlive => true;
+
+  @override
+  Widget build(BuildContext context) {
+    super.build(context);
+    return widget.child;
+  }
+}

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/core/theme/app_dimens.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';
@@ -170,6 +171,32 @@ void main() {
     );
   });
 
+  testWidgets('should_swipe_between_primary_sections', (tester) async {
+    final repository = _PagedCatalogRepository();
+    await _pumpApp(tester, repository);
+
+    expect(find.byKey(const Key('home-secondary-tags')), findsOneWidget);
+    await tester.drag(
+      find.byKey(const Key('home-primary-page-view')),
+      const Offset(-320, 0),
+    );
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const Key('home-secondary-tags')), findsNothing);
+    final selected = tester.widget<AnimatedDefaultTextStyle>(
+      find.byKey(const Key('home-primary-label-newReleases')),
+    );
+    expect(selected.style.fontSize, AppDimens.homePrimaryTabSelectedFont);
+    expect(selected.style.fontWeight, FontWeight.w700);
+
+    await tester.drag(
+      find.byKey(const Key('home-primary-page-view')),
+      const Offset(320, 0),
+    );
+    await tester.pumpAndSettle();
+    expect(find.byKey(const Key('home-secondary-tags')), findsOneWidget);
+  });
+
   testWidgets('should_load_next_page_without_expanding_page_size', (
     tester,
   ) async {