perf(discover): 剧场与新片页网格改为按行懒加载

双列网格原来是两个 Column 一次性建出所有卡片，翻几页后上百张卡连同封面都留在树上；
现在改成按行的 SliverList，只构建可见行，剧场页/新片页/搜索结果的滚动容器一并换成 sliver。
搜索结果、加载失败等状态同步改成 sliver，滚动位置与下拉刷新行为保持不变。

lib/pages/discover/discover_view.dart

@@ -153,14 +153,19 @@ class _DiscoverPageState extends State<DiscoverPage> {
               edgeOffset: _stickyHeaderHeight + 8,
               onRefresh: () =>
                   Future.wait([categories.load(), theater.refreshCurrent()]),
-              child: ListView(
+              child: CustomScrollView(
                 controller: logic.scroll,
                 physics: AppPullToRefresh.physics,
-                padding: EdgeInsets.only(
+                slivers: [
-                  top: showHeader ? _stickyHeaderHeight : 0,
+                  if (showHeader)
-                  bottom: AppDimens.spaceXl,
+                    const SliverToBoxAdapter(
-                ),
+                      child: SizedBox(height: _stickyHeaderHeight),
-                children: _content(l10n, categories),
+                    ),
+                  ..._content(l10n, categories),
+                  const SliverToBoxAdapter(
+                    child: SizedBox(height: AppDimens.spaceXl),
+                  ),
+                ],
               ),
             ),
           ),
@@ -228,12 +233,12 @@ class _DiscoverPageState extends State<DiscoverPage> {
       ];
     }
     if (categories.loading && categories.categories.isEmpty) {
-      return [_block(const CircularProgressIndicator(strokeWidth: 2))];
+      return [_sliverBlock(const CircularProgressIndicator(strokeWidth: 2))];
     }
     final error = categories.error;
     if (error != null) {
       return [
-        _block(
+        _sliverBlock(
           EmptyState(
             key: const Key('home-categories-error'),
             icon: Icons.cloud_off_rounded,
@@ -253,12 +258,12 @@ class _DiscoverPageState extends State<DiscoverPage> {
       ];
     }
     if (theater.loadingFirstPage) {
-      return [_block(const CircularProgressIndicator(strokeWidth: 2))];
+      return [_sliverBlock(const CircularProgressIndicator(strokeWidth: 2))];
     }
     final theaterError = theater.lastError;
     if (theaterError != null && theater.dramas.isEmpty) {
       return [
-        _block(
+        _sliverBlock(
           EmptyState(
             key: const Key('home-categories-error'),
             icon: Icons.cloud_off_rounded,
@@ -282,38 +287,49 @@ class _DiscoverPageState extends State<DiscoverPage> {
   List<Widget> _theaterBlocks(AppLocalizations l10n) {
     final dramas = theater.dramas;
     return [
-      _toolbar(),
+      SliverToBoxAdapter(child: _toolbar()),
       if (dramas.isEmpty)
-        Padding(
+        SliverToBoxAdapter(
-          padding: const EdgeInsets.symmetric(vertical: 40),
+          child: Padding(
-          child: EmptyState(
+            padding: const EdgeInsets.symmetric(vertical: 40),
-            key: const Key('discover-empty'),
+            child: EmptyState(
-            icon: Icons.movie_filter_outlined,
+              key: const Key('discover-empty'),
-            title: l10n.noStories,
+              icon: Icons.movie_filter_outlined,
-            subtitle: l10n.emptyHint,
+              title: l10n.noStories,
+              subtitle: l10n.emptyHint,
+            ),
           ),
         )
       else
-        DramaGrid(l10n: l10n, dramas: dramas, onOpen: _openDrama),
+        SliverDramaGrid(
+          key: const Key('home-all-dramas-grid'),
+          l10n: l10n,
+          dramas: dramas,
+          onOpen: _openDrama,
+        ),
       if (theater.loadingMore)
-        const Padding(
+        const SliverToBoxAdapter(
-          padding: EdgeInsets.symmetric(vertical: 20),
+          child: Padding(
-          child: Center(
+            padding: EdgeInsets.symmetric(vertical: 20),
-            child: SizedBox.square(
+            child: Center(
-              key: Key('theater-load-more'),
+              child: SizedBox.square(
-              dimension: 22,
+                key: Key('theater-load-more'),
-              child: CircularProgressIndicator(strokeWidth: 2),
+                dimension: 22,
+                child: CircularProgressIndicator(strokeWidth: 2),
+              ),
             ),
           ),
         )
       else if (dramas.isNotEmpty && !theater.hasMore)
-        Padding(
+        SliverToBoxAdapter(
-          key: const Key('paged-list-no-more'),
+          child: Padding(
-          padding: const EdgeInsets.symmetric(vertical: 16),
+            key: const Key('paged-list-no-more'),
-          child: Text(
+            padding: const EdgeInsets.symmetric(vertical: 16),
-            l10n.noMoreItems,
+            child: Text(
-            textAlign: TextAlign.center,
+              l10n.noMoreItems,
-            style: const TextStyle(color: AppColors.textHint, fontSize: 12),
+              textAlign: TextAlign.center,
+              style: const TextStyle(color: AppColors.textHint, fontSize: 12),
+            ),
           ),
         ),
     ];
@@ -401,6 +417,8 @@ class _DiscoverPageState extends State<DiscoverPage> {
     Navigator.of(context).push<void>(MaterialPageRoute(builder: (_) => page));
   }
 
+  Widget _sliverBlock(Widget child) => SliverToBoxAdapter(child: _block(child));
+
   Widget _block(Widget child) => ConstrainedBox(
     constraints: const BoxConstraints(minHeight: 280),
     child: Center(child: child),

lib/pages/discover/widgets/discover_search_results.dart

@@ -10,6 +10,8 @@ import '../../../l10n/app_localizations.dart';
 import 'drama_grid.dart';
 
 /// 剧场搜索结果：加载、失败与空结果都留在同一页内。
+///
+/// 自身是 sliver，好让结果网格跟着剧场页一起懒加载。
 class DiscoverSearchResults extends StatelessWidget {
   const DiscoverSearchResults({
     super.key,
@@ -26,16 +28,24 @@ class DiscoverSearchResults extends StatelessWidget {
   final VoidCallback onRetry;
   final ValueChanged<Drama> onOpen;
 
+  static const EdgeInsets _topPadding = EdgeInsets.only(top: 12);
+
   @override
   Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context)!;
-    return Padding(
+    if (!loading && error == null && results.isNotEmpty) {
-      padding: const EdgeInsets.only(top: 12),
+      return SliverPadding(
-      child: _content(l10n),
+        padding: _topPadding,
+        sliver: SliverDramaGrid(l10n: l10n, dramas: results, onOpen: onOpen),
+      );
+    }
+    return SliverPadding(
+      padding: _topPadding,
+      sliver: SliverToBoxAdapter(child: _state(l10n)),
     );
   }
 
-  Widget _content(AppLocalizations l10n) {
+  Widget _state(AppLocalizations l10n) {
     if (loading) {
       return const Padding(
         padding: EdgeInsets.symmetric(vertical: 80),
@@ -61,14 +71,11 @@ class DiscoverSearchResults extends StatelessWidget {
         onAction: onRetry,
       );
     }
-    if (results.isEmpty) {
+    return EmptyState(
-      return EmptyState(
+      key: const Key('discover-search-empty'),
-        key: const Key('discover-search-empty'),
+      icon: Icons.search_off_rounded,
-        icon: Icons.search_off_rounded,
+      title: l10n.noSearchResults,
-        title: l10n.noSearchResults,
+      subtitle: l10n.emptyHint,
-        subtitle: l10n.emptyHint,
+    );
-      );
-    }
-    return DramaGrid(l10n: l10n, dramas: results, onOpen: onOpen);
   }
 }

lib/pages/discover/widgets/drama_grid.dart

@@ -10,7 +10,6 @@ import '../../../core/theme/app_dimens.dart';
 import '../../../core/widgets/remote_image.dart';
 import '../../../l10n/app_localizations.dart';
 
-const int _columns = 2;
 const double _columnGap = 8;
 const double _cardGap = 14;
 const double _gridHorizontalPadding = 12;
@@ -29,8 +28,10 @@ const Color _tagChipBackground = AppColors.raised;
 final RegExp _tagSplitter = RegExp(r'[,/、·]');
 
 /// 剧场/分类页共用的双列剧目网格。
-class DramaGrid extends StatelessWidget {
+///
-  const DramaGrid({
+/// 按行懒加载：翻到第 N 页时只构建当前可见的几张卡，长列表不会把整本目录都留在树上。
+class SliverDramaGrid extends StatelessWidget {
+  const SliverDramaGrid({
     super.key,
     required this.l10n,
     required this.dramas,
@@ -43,33 +44,41 @@ class DramaGrid extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return Padding(
+    final rowCount = (dramas.length + 1) ~/ 2;
-      key: const Key('home-all-dramas-section'),
+    return SliverPadding(
       padding: const EdgeInsets.symmetric(horizontal: _gridHorizontalPadding),
-      child: Row(
+      sliver: SliverList(
-        key: const Key('home-all-dramas-grid'),
+        delegate: SliverChildBuilderDelegate((context, row) {
-        crossAxisAlignment: CrossAxisAlignment.start,
+          final left = dramas[row * 2];
-        children: [
+          final rightIndex = row * 2 + 1;
-          Expanded(child: _column(0)),
+          final right = rightIndex < dramas.length ? dramas[rightIndex] : null;
-          const SizedBox(width: _columnGap),
+          return Padding(
-          Expanded(child: _column(1)),
+            // 行间距沿用卡片间距，首行不需要。
-        ],
+            padding: EdgeInsets.only(top: row == 0 ? 0 : _cardGap),
+            child: Row(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Expanded(child: _card(left)),
+                const SizedBox(width: _columnGap),
+                Expanded(
+                  child: right == null
+                      ? const SizedBox.shrink()
+                      : _card(right),
+                ),
+              ],
+            ),
+          );
+        }, childCount: rowCount),
       ),
     );
   }
 
-  Widget _column(int start) {
+  Widget _card(Drama drama) {
-    final children = <Widget>[];
+    return DramaGridCard(
-    for (var index = start; index < dramas.length; index += _columns) {
+      l10n: l10n,
-      final drama = dramas[index];
+      drama: drama,
-      children.add(
+      onTap: () => onOpen(drama),
-        DramaGridCard(l10n: l10n, drama: drama, onTap: () => onOpen(drama)),
+    );
-      );
-      if (index + _columns < dramas.length) {
-        children.add(const SizedBox(height: _cardGap));
-      }
-    }
-    return Column(children: children);
   }
 }
 

lib/pages/new_releases/new_releases_page.dart

@@ -135,64 +135,81 @@ class _NewReleasesPageState extends State<NewReleasesPage> {
                     child: AppPullToRefresh(
                       key: const Key('new-releases-refresh'),
                       onRefresh: _refresh,
-                      child: ListView(
+                      child: CustomScrollView(
                         key: const Key('new-releases-list'),
                         controller: _scroll,
                         physics: AppPullToRefresh.physics,
-                        padding: const EdgeInsets.only(bottom: 24),
+                        slivers: hero == null
-                        children: hero == null
                             ? [
-                                SizedBox(
+                                SliverToBoxAdapter(
-                                  height: 420,
+                                  child: SizedBox(
-                                  child: Center(
+                                    height: 420,
-                                    child: Text(
+                                    child: Center(
-                                      l10n.noStories,
+                                      child: Text(
-                                      key: const Key('new-releases-empty'),
+                                        l10n.noStories,
-                                      style: const TextStyle(
+                                        key: const Key('new-releases-empty'),
-                                        color: AppColors.muted,
+                                        style: const TextStyle(
+                                          color: AppColors.muted,
+                                        ),
                                       ),
                                     ),
                                   ),
                                 ),
                               ]
                             : [
-                                Padding(
+                                SliverToBoxAdapter(
-                                  padding: const EdgeInsets.symmetric(
+                                  child: Padding(
-                                    horizontal: 16,
+                                    padding: const EdgeInsets.symmetric(
+                                      horizontal: 16,
+                                    ),
+                                    child: _heroCard(context, l10n, hero),
                                   ),
-                                  child: _heroCard(context, l10n, hero),
                                 ),
-                                const SizedBox(height: 14),
+                                const SliverToBoxAdapter(
-                                const _FilmStrip(),
+                                  child: SizedBox(height: 14),
-                                const SizedBox(height: 14),
+                                ),
+                                const SliverToBoxAdapter(child: _FilmStrip()),
+                                const SliverToBoxAdapter(
+                                  child: SizedBox(height: 14),
+                                ),
                                 if (more.isNotEmpty) ...[
-                                  _moreHeader(l10n),
+                                  SliverToBoxAdapter(
-                                  const SizedBox(height: 10),
+                                    child: _moreHeader(l10n),
-                                  SizedBox(
+                                  ),
-                                    height: _rowHeight,
+                                  const SliverToBoxAdapter(
-                                    child: ListView.separated(
+                                    child: SizedBox(height: 10),
-                                      key: const Key('new-releases-row'),
+                                  ),
-                                      scrollDirection: Axis.horizontal,
+                                  SliverToBoxAdapter(
-                                      padding: const EdgeInsets.symmetric(
+                                    child: SizedBox(
-                                        horizontal: 16,
+                                      height: _rowHeight,
+                                      child: ListView.separated(
+                                        key: const Key('new-releases-row'),
+                                        scrollDirection: Axis.horizontal,
+                                        padding: const EdgeInsets.symmetric(
+                                          horizontal: 16,
+                                        ),
+                                        itemCount: more.length,
+                                        separatorBuilder: (_, _) =>
+                                            const SizedBox(width: 10),
+                                        itemBuilder: (context, index) =>
+                                            _moreCard(
+                                              context,
+                                              l10n,
+                                              more[index],
+                                              index,
+                                            ),
                                       ),
-                                      itemCount: more.length,
-                                      separatorBuilder: (_, _) =>
-                                          const SizedBox(width: 10),
-                                      itemBuilder: (context, index) =>
-                                          _moreCard(
-                                            context,
-                                            l10n,
-                                            more[index],
-                                            index,
-                                          ),
                                     ),
                                   ),
                                 ],
-                                const SizedBox(height: 20),
+                                const SliverToBoxAdapter(
-                                _allHeader(l10n),
+                                  child: SizedBox(height: 20),
-                                const SizedBox(height: 10),
+                                ),
-                                DramaGrid(
+                                SliverToBoxAdapter(child: _allHeader(l10n)),
+                                const SliverToBoxAdapter(
+                                  child: SizedBox(height: 10),
+                                ),
+                                SliverDramaGrid(
                                   key: const Key('new-releases-all-grid'),
                                   l10n: l10n,
                                   dramas: visible,
@@ -200,12 +217,17 @@ class _NewReleasesPageState extends State<NewReleasesPage> {
                                     playDramaFromCatalog(context, drama),
                                   ),
                                 ),
-                                PagedLoadFooter(
+                                SliverToBoxAdapter(
-                                  loading: pager.loading,
+                                  child: Padding(
-                                  hasMore: pager.hasMore,
+                                    padding: const EdgeInsets.only(bottom: 24),
-                                  hasItems: visible.isNotEmpty,
+                                    child: PagedLoadFooter(
-                                  loadMoreKey: const Key(
+                                      loading: pager.loading,
-                                    'new-releases-load-more',
+                                      hasMore: pager.hasMore,
+                                      hasItems: visible.isNotEmpty,
+                                      loadMoreKey: const Key(
+                                        'new-releases-load-more',
+                                      ),
+                                    ),
                                   ),
                                 ),
                               ],

test/discover/home_all_dramas_grid_test.dart

@@ -384,7 +384,7 @@ void main() {
 
     expect(refresh.edgeOffset, 52);
     expect(
-      tester.widget<ListView>(_verticalFeed).physics,
+      tester.widget<CustomScrollView>(_verticalFeed).physics,
       AppPullToRefresh.physics,
     );
     await tester.drag(_verticalFeed, const Offset(0, 240));
@@ -396,7 +396,8 @@ void main() {
 }
 
 final Finder _verticalFeed = find.byWidgetPredicate(
-  (widget) => widget is ListView && widget.scrollDirection == Axis.vertical,
+  (widget) =>
+      widget is CustomScrollView && widget.scrollDirection == Axis.vertical,
 );
 
 Future<void> _pumpTheater(

test/discover/theater_pages_test.dart

@@ -8,6 +8,7 @@ import 'package:fruitshorts/core/data/models/home_feed.dart';
 import 'package:fruitshorts/core/theme/app_colors.dart';
 import 'package:fruitshorts/core/widgets/app_pull_to_refresh.dart';
 import 'package:fruitshorts/pages/discover/discover_view.dart';
+import 'package:fruitshorts/pages/discover/widgets/drama_grid.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';
@@ -234,25 +235,26 @@ void main() {
     await tester.pumpAndSettle();
 
     final list = find.byKey(const Key('new-releases-list'));
-    expect(tester.widget<ListView>(list).physics, AppPullToRefresh.physics);
+    expect(
-    await tester.drag(list, const Offset(0, -400));
+      tester.widget<CustomScrollView>(list).physics,
-    await tester.pump();
+      AppPullToRefresh.physics,
-    expect(_countKeys('home-drama-card-'), 20);
+    );
 
+    // 网格懒加载后只保留可见行，页数直接看传给网格的剧目数。
+    List<Drama> gridDramas() => tester
+        .widget<SliverDramaGrid>(find.byKey(const Key('new-releases-all-grid')))
+        .dramas;
+    expect(gridDramas(), hasLength(20));
+
+    // jumpTo 不发滚动通知，滑到底后再拖一下才会触发加载。
     final position = _scrollPosition(tester, const Key('new-releases-list'));
     position.jumpTo(position.maxScrollExtent);
     await tester.pump();
-    expect(find.byKey(const Key('new-releases-load-more')), findsOneWidget);
+    await tester.drag(list, const Offset(0, -60));
-    await tester.pump(const Duration(milliseconds: 299));
-    expect(_countKeys('home-drama-card-'), 20);
-    await tester.pump(const Duration(milliseconds: 1));
     await tester.pump();
-    expect(_countKeys('home-drama-card-'), 40);
+    expect(find.byKey(const Key('new-releases-load-more')), findsOneWidget);
-
     await tester.pumpAndSettle();
-    position.jumpTo(position.maxScrollExtent);
+    expect(gridDramas(), hasLength(40));
-    await tester.pumpAndSettle();
-    expect(find.byKey(const Key('new-releases-no-more')), findsNothing);
 
     position.jumpTo(0);
     await tester.pump();
@@ -262,10 +264,7 @@ void main() {
     await tester.pumpAndSettle();
     expect(repository.fetchCalls, beforeRefresh + 1);
     expect(position.pixels, 0);
-
+    expect(gridDramas(), hasLength(20));
-    await tester.drag(list, const Offset(0, -400));
-    await tester.pump();
-    expect(_countKeys('home-drama-card-'), 20);
   });
 
   testWidgets('should_refresh_reserve_without_load_more', (tester) async {
@@ -327,14 +326,6 @@ ScrollPosition _scrollPosition(WidgetTester tester, Key listKey) {
   return tester.state<ScrollableState>(scrollable.first).position;
 }
 
-int _countKeys(String prefix) => find
-    .byWidgetPredicate((widget) {
-      final key = widget.key;
-      return key is ValueKey<String> && key.value.startsWith(prefix);
-    })
-    .evaluate()
-    .length;
-
 class _CountingCatalogRepository extends FakeCatalogRepository {
   _CountingCatalogRepository({super.dramas});