merge: 合并 K34-H 吸顶闪动修复

lib/pages/discover/discover_view.dart

@@ -37,7 +37,7 @@ const double _categoryTabGap = 20;
 const double _categorySelectedFontSize = 16;
 const double _categoryFontSize = 15;
 const double _stickyHeaderHeight = 44;
-const Duration _stickyHeaderTransition = Duration(milliseconds: 200);
+const Duration _stickyHeaderTransition = Duration(milliseconds: 160);
 
 /// K28-A2 剧场页：搜索、分类/语言 chips 与双列剧库。
 class DiscoverPage extends StatefulWidget {
@@ -113,19 +113,23 @@ class _DiscoverPageState extends State<DiscoverPage> {
   Widget _page(BuildContext context) {
     final l10n = AppLocalizations.of(context)!;
     final categories = context.watch<CategoryController>();
-    final content = SafeArea(
-      bottom: !embedded,
-      child: Column(
-        children: [
-          DiscoverHeader(
-            controller: logic.search,
-            focusNode: logic.searchFocus,
-            onChanged: (_) => logic.onSearchChanged(),
-            loading: logic.searchLoading,
-          ),
-          Expanded(child: _feed(l10n, categories)),
-          if (!embedded) _bottomNav(l10n),
-        ],
+    final content = ColoredBox(
+      key: const Key('theater-page-surface'),
+      color: AppColors.ink,
+      child: SafeArea(
+        bottom: !embedded,
+        child: Column(
+          children: [
+            DiscoverHeader(
+              controller: logic.search,
+              focusNode: logic.searchFocus,
+              onChanged: (_) => logic.onSearchChanged(),
+              loading: logic.searchLoading,
+            ),
+            Expanded(child: _feed(l10n, categories)),
+            if (!embedded) _bottomNav(l10n),
+          ],
+        ),
       ),
     );
     return AnnotatedRegion<SystemUiOverlayStyle>(
@@ -183,7 +187,7 @@ class _DiscoverPageState extends State<DiscoverPage> {
   }
 
   Widget _stickyHeader(AppLocalizations l10n, CategoryController categories) {
-    // 只有背景随吸顶状态变化，分类行内容（child）不参与重建，避免上滑闪烁。
+    // 背景常驻 ink，只有分隔线/阴影随吸顶状态过渡，避免透明→实色的闪动。
     return ValueListenableBuilder<bool>(
       valueListenable: _headerPinned,
       builder: (context, pinned, child) => AnimatedContainer(
@@ -191,7 +195,7 @@ class _DiscoverPageState extends State<DiscoverPage> {
         duration: _stickyHeaderTransition,
         curve: Curves.easeOut,
         decoration: BoxDecoration(
-          color: pinned ? AppColors.ink : Colors.transparent,
+          color: AppColors.ink,
           border: Border(
             bottom: BorderSide(
               color: pinned ? AppColors.border : Colors.transparent,

test/discover/home_all_dramas_grid_test.dart

@@ -215,7 +215,7 @@ void main() {
     final before = tester.getRect(
       find.byKey(const Key('theater-sticky-header')),
     );
-    expect(header().color, Colors.transparent);
+    expect(header().color, AppColors.ink);
 
     await tester.drag(_verticalFeed, const Offset(0, -220));
     await tester.pumpAndSettle();
@@ -227,6 +227,15 @@ void main() {
     expect(header().color, AppColors.ink);
   });
 
+  testWidgets('should_paint_theater_surface_with_ink', (tester) async {
+    await _pumpTheater(tester, categoryRepository: _GridCategoryRepository());
+    final surface = tester.widget<ColoredBox>(
+      find.byKey(const Key('theater-page-surface')),
+    );
+
+    expect(surface.color, AppColors.ink);
+  });
+
   testWidgets('should_keep_category_row_stable_across_scrolls', (tester) async {
     await _pumpTheater(
       tester,