新增：帖子详情页真实数据整页替换——四态/真九宫格大图/评论区/关注双态，Feed 导航与互动全接线，demo 详情退役（T3-15/16）

- post_detail_page 整页重写：内存副本先渲染 + getPost 拉新、四态
 （loading/error+重试/ready/40403 提示后返回 Feed 并刷新）；媒体全量
  ——单图原比例（高度钳制 [0.75w,1.33w]）、多图真九宫格（D11 轮播
  弃用，本单裁定）+ InteractiveViewer 全屏大图（03 号拍板 E）
- 评论区：游标列表触底补页 + 底部输入条创建（幂等键在数据层）+
  仅本人评论渲染删除入口（40301/40404 服务端兜底）；成败埋点对
 （durationMs 取输入会话起点、attemptSeq 会话内递增）；CommentTile
  升共享组件（@ 回复前缀呈现、降级作者「宠友」占位）
- 关注双态钮（tonal ＋关注 / Outlined 已关注 + 取关确认）乐观翻转、
  回滚零动画 + SnackBar，user_followed/unfollowed(post_detail) 挂接；
  本人帖不渲染
- Feed 接通：整卡与评论钮导航详情（T3-14 占位提示移除）、点赞/收藏
  接共享 ToggleSync（详情与卡片同一实例跨页一致）、toggleError
  一次性 SnackBar 消费
- 主壳/装配：openPost 按 postId push；create demo 流不再导航已退役的
  demo 详情（发布页真实化留 T3-17）；AppState 在 post_detail/Feed 面
  消费清零
- compose 冒烟（env 门控默认跳过）：真链路发帖/点赞幂等/收藏/评论/
  删评一轮 + 断网点赞回滚（生产 ApiClient 异常链）

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/features/home/home_page_test.dart

@@ -8,6 +8,7 @@ import 'package:patbond_flutter/core/widgets/feed_skeleton.dart';
 import 'package:patbond_flutter/core/widgets/inline_error_banner.dart';
 import 'package:patbond_flutter/core/widgets/post_card.dart';
 import 'package:patbond_flutter/features/community/community_controller.dart';
+import 'package:patbond_flutter/features/community/community_interaction_analytics.dart';
 import 'package:patbond_flutter/features/community/community_models.dart';
 import 'package:patbond_flutter/features/community/feed_analytics.dart';
 import 'package:patbond_flutter/features/home/home_page.dart';
@@ -39,15 +40,22 @@ void main() {
   late List<(String, Map<String, dynamic>?)> events;
   late FeedAnalytics analytics;
   late int createTaps;
+  late List<String> openedPosts;
 
   setUp(() {
     repository = FakeCommunityRepository();
-    controller = CommunityController(repository: repository);
     events = [];
+    controller = CommunityController(
+      repository: repository,
+      interactionAnalytics: CommunityInteractionAnalytics(
+        (name, [props]) async => events.add((name, props)),
+      ),
+    );
     analytics = FeedAnalytics(
       (name, [props]) async => events.add((name, props)),
     );
     createTaps = 0;
+    openedPosts = [];
   });
 
   List<Map<String, dynamic>?> eventsNamed(String name) =>
@@ -65,6 +73,7 @@ void main() {
             isActive: isActive,
             onOpenServices: (_) {},
             onOpenCreate: () => createTaps++,
+            onOpenPost: openedPosts.add,
           ),
         ),
       ),
@@ -361,7 +370,7 @@ void main() {
     expect(eventsNamed('feed_viewed'), hasLength(2));
   });
 
-  testWidgets('T3-14 取舍：整卡点按提示详情接入中（不导航 demo 详情）', (tester) async {
+  testWidgets('T3-15 导航接通：整卡与评论钮点按回调 onOpenPost（占位提示移除）', (tester) async {
     repository.onFeed = (_, _) async => feedPage([textCard('p-1')]);
 
     await pumpHome(tester);
@@ -371,7 +380,72 @@ void main() {
 
     await tester.tap(find.text('动态内容 p-1'));
     await tester.pump();
-    expect(find.text('帖子详情正在接入真实数据，敬请期待'), findsOneWidget);
+    expect(find.text('帖子详情正在接入真实数据，敬请期待'), findsNothing);
+    expect(openedPosts, ['p-1']);
+
+    await tester.tap(find.byIcon(Icons.chat_bubble_outline));
+    await tester.pump();
+    expect(openedPosts, ['p-1', 'p-1']);
+  });
+
+  testWidgets('T3-16 互动接线：点赞乐观翻转即时显示，成功报 post_liked(source=feed)', (
+    tester,
+  ) async {
+    repository.onFeed = (_, _) async => feedPage([
+      FeedCard.fromJson({
+        ...sampleFeedCardJson(likeCount: 6),
+        'coverImage': null,
+        'mediaCount': 0,
+      }),
+    ]);
+    final like = Completer<LikeState>();
+    repository.onLikeToggle = (_, _) => like.future;
+
+    await pumpHome(tester);
+    await tester.pumpAndSettle();
+    await tester.drag(list(), const Offset(0, -800));
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byIcon(Icons.favorite_border));
+    await tester.pump();
+    // 乐观翻转：请求未回已 +1（同帧反馈）。
+    expect(find.text('7'), findsOneWidget);
+    expect(repository.calls, contains('like:p-1'));
+
+    like.complete(const LikeState(liked: true, likeCount: 7));
+    await tester.pumpAndSettle();
+    expect(eventsNamed('post_liked'), [
+      {'source': 'feed'},
+    ]);
+    expect(find.text('7'), findsOneWidget);
+  });
+
+  testWidgets('T3-16 互动接线：点赞失败回滚 + SnackBar「操作失败，请重试」', (tester) async {
+    repository.onFeed = (_, _) async => feedPage([
+      FeedCard.fromJson({
+        ...sampleFeedCardJson(likeCount: 6),
+        'coverImage': null,
+        'mediaCount': 0,
+      }),
+    ]);
+    final like = Completer<LikeState>();
+    repository.onLikeToggle = (_, _) => like.future;
+
+    await pumpHome(tester);
+    await tester.pumpAndSettle();
+    await tester.drag(list(), const Offset(0, -800));
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.byIcon(Icons.favorite_border));
+    await tester.pump();
+    expect(find.text('7'), findsOneWidget);
+
+    like.completeError(const ApiNetworkException());
+    await tester.pumpAndSettle();
+    // 回滚成对恢复 + SnackBar；不报 post_liked。
+    expect(find.text('6'), findsOneWidget);
+    expect(find.text('操作失败，请重试'), findsOneWidget);
+    expect(eventsNamed('post_liked'), isEmpty);
   });
 
   testWidgets('搜索词过滤已加载卡片；无命中显搜索空态', (tester) async {

test/features/post/post_detail_page_test.dart

@@ -0,0 +1,551 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:patbond_flutter/core/network/api_exception.dart';
+import 'package:patbond_flutter/core/theme/app_theme.dart';
+import 'package:patbond_flutter/core/widgets/comment_tile.dart';
+import 'package:patbond_flutter/core/widgets/inline_error_banner.dart';
+import 'package:patbond_flutter/core/widgets/post_media_grid.dart';
+import 'package:patbond_flutter/features/community/community_controller.dart';
+import 'package:patbond_flutter/features/community/community_exceptions.dart';
+import 'package:patbond_flutter/features/community/community_interaction_analytics.dart';
+import 'package:patbond_flutter/features/community/community_models.dart';
+import 'package:patbond_flutter/features/post/post_detail_page.dart';
+
+import '../../helpers/community_test_helpers.dart';
+
+void main() {
+  late FakeCommunityRepository repository;
+  late CommunityController controller;
+  late List<(String, Map<String, dynamic>?)> events;
+  late CommunityInteractionAnalytics analytics;
+
+  /// 无媒体帖（避免测试环境网络图噪音；媒体形态单测另立）。
+  Post textPost({
+    String id = 'p-1',
+    bool likedByMe = false,
+    int likeCount = 6,
+    int commentCount = 3,
+  }) => Post.fromJson({
+    ...samplePostJson(id: id, likedByMe: likedByMe, likeCount: likeCount),
+    'media': <Object>[],
+    'commentCount': commentCount,
+  });
+
+  setUp(() {
+    repository = FakeCommunityRepository();
+    events = [];
+    analytics = CommunityInteractionAnalytics(
+      (name, [props]) async => events.add((name, props)),
+    );
+    controller = CommunityController(
+      repository: repository,
+      interactionAnalytics: analytics,
+    );
+    // 缺省行为：正常帖 + 空评论 + 未关注（各测试按需覆盖）。
+    repository.onGetPost = (_) async => textPost();
+    repository.onListComments = (_, _) async => commentPage(const []);
+    repository.onGetFollowStats = (_) async => const FollowStats(
+      followerCount: 1,
+      followingCount: 2,
+      followedByMe: false,
+    );
+  });
+
+  List<Map<String, dynamic>?> eventsNamed(String name) =>
+      events.where((e) => e.$1 == name).map((e) => e.$2).toList();
+
+  Widget detailApp({String? currentUserId = 'me'}) => MaterialApp(
+    theme: buildAppTheme(),
+    home: PostDetailPage(
+      controller: controller,
+      postId: 'p-1',
+      currentUserId: currentUserId,
+      analytics: analytics,
+    ),
+  );
+
+  /// 经启动页 push 详情（40403 返回 Feed 的 pop 断言用）。
+  Widget launcherApp({String? currentUserId = 'me'}) => MaterialApp(
+    theme: buildAppTheme(),
+    home: Builder(
+      builder: (context) => Scaffold(
+        body: Center(
+          child: TextButton(
+            onPressed: () => Navigator.of(context).push(
+              MaterialPageRoute<void>(
+                builder: (_) => PostDetailPage(
+                  controller: controller,
+                  postId: 'p-1',
+                  currentUserId: currentUserId,
+                  analytics: analytics,
+                ),
+              ),
+            ),
+            child: const Text('打开详情'),
+          ),
+        ),
+      ),
+    ),
+  );
+
+  group('详情四态', () {
+    testWidgets('loading：请求未回渲染转圈', (tester) async {
+      final post = Completer<Post>();
+      repository.onGetPost = (_) => post.future;
+
+      await tester.pumpWidget(detailApp());
+      await tester.pump();
+      expect(find.byType(CircularProgressIndicator), findsOneWidget);
+
+      post.complete(textPost());
+      await tester.pumpAndSettle();
+      expect(find.text('晒了一下午太阳。'), findsOneWidget);
+    });
+
+    testWidgets('ready：正文/作者/求助标/评论标题齐全', (tester) async {
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+
+      expect(find.text('今天的豆豆'), findsOneWidget);
+      expect(find.text('晒了一下午太阳。'), findsOneWidget);
+      expect(find.text('毛毛的铲屎官'), findsOneWidget);
+      expect(find.text('评论 (3)'), findsOneWidget);
+      expect(find.text('还没有评论，来抢沙发'), findsOneWidget);
+    });
+
+    testWidgets('error：横幅 + 重试恢复 ready', (tester) async {
+      var attempts = 0;
+      repository.onGetPost = (_) async {
+        attempts += 1;
+        if (attempts == 1) throw const ApiNetworkException();
+        return textPost();
+      };
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      expect(find.byType(InlineErrorBanner), findsOneWidget);
+      expect(find.text('网络异常，请检查网络后重试'), findsOneWidget);
+
+      await tester.tap(find.text('重试'));
+      await tester.pumpAndSettle();
+      expect(find.byType(InlineErrorBanner), findsNothing);
+      expect(find.text('晒了一下午太阳。'), findsOneWidget);
+    });
+
+    testWidgets('40403 不存在态：SnackBar + 返回 Feed 并触发刷新', (tester) async {
+      repository.onGetPost = (_) async =>
+          throw const PostNotFoundException(message: 'gone');
+      repository.onFeed = (_, _) async => feedPage(const []);
+
+      await tester.pumpWidget(launcherApp());
+      await tester.tap(find.text('打开详情'));
+      await tester.pumpAndSettle();
+
+      // 已弹回启动页 + 提示 + Feed 整体刷新（失效帖剔除）。
+      expect(find.text('打开详情'), findsOneWidget);
+      expect(find.text('帖子不存在或已被删除'), findsOneWidget);
+      expect(repository.calls, contains('feed:cursor=null'));
+    });
+
+    testWidgets('内存副本先渲染：进入即展示缓存，后台拉新不阻塞', (tester) async {
+      await controller.getPost('p-1'); // 预热详情副本。
+      final refresh = Completer<Post>();
+      repository.onGetPost = (_) => refresh.future;
+
+      await tester.pumpWidget(detailApp());
+      await tester.pump();
+      // 拉新未回已渲染缓存内容，无全页转圈。
+      expect(find.text('晒了一下午太阳。'), findsOneWidget);
+
+      refresh.complete(textPost(likeCount: 9));
+      await tester.pumpAndSettle();
+      expect(find.text('9'), findsOneWidget);
+    });
+  });
+
+  group('媒体', () {
+    testWidgets('多图渲染真九宫格，点格进全屏大图（页码 + 关闭）', (tester) async {
+      repository.onGetPost = (_) async => Post.fromJson({
+        ...samplePostJson(),
+        'media': [
+          for (var i = 0; i < 5; i++)
+            samplePostMediaItemJson(
+              assetId: 'a-$i',
+              position: i,
+              isCover: i == 0,
+            ),
+        ],
+      });
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      expect(find.byType(PostMediaGrid), findsOneWidget);
+
+      await tester.tap(
+        find
+            .descendant(
+              of: find.byType(PostMediaGrid),
+              matching: find.byType(InkWell),
+            )
+            .first,
+      );
+      await tester.pumpAndSettle();
+      expect(find.text('1/5'), findsOneWidget);
+
+      await tester.tap(find.byIcon(Icons.close));
+      await tester.pumpAndSettle();
+      expect(find.byType(PostMediaGrid), findsOneWidget);
+    });
+  });
+
+  group('评论区', () {
+    testWidgets('游标列表：首页渲染 + 触底携游标补页', (tester) async {
+      repository.onListComments = (_, cursor) async {
+        if (cursor == null) {
+          return commentPage(
+            [
+              sampleComment(id: 'c-1', content: '第一条'),
+              sampleComment(id: 'c-2', content: '第二条'),
+            ],
+            nextCursor: 'cc1',
+            hasMore: true,
+          );
+        }
+        return commentPage([sampleComment(id: 'c-3', content: '第三条')]);
+      };
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      expect(find.text('第一条'), findsOneWidget);
+
+      await tester.drag(find.byType(ListView), const Offset(0, -800));
+      await tester.pumpAndSettle();
+      expect(
+        repository.calls.where((c) => c.startsWith('comments:')).toList(),
+        ['comments:p-1:cursor=null', 'comments:p-1:cursor=cc1'],
+      );
+      expect(find.text('第三条'), findsOneWidget);
+    });
+
+    testWidgets('列表失败：话术 + 点按重试恢复', (tester) async {
+      var attempts = 0;
+      repository.onListComments = (_, _) async {
+        attempts += 1;
+        if (attempts == 1) throw const ApiNetworkException();
+        return commentPage([sampleComment(content: '恢复后的评论')]);
+      };
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      expect(find.text('加载失败，点此重试'), findsOneWidget);
+
+      await tester.tap(find.text('加载失败，点此重试'));
+      await tester.pumpAndSettle();
+      expect(find.text('恢复后的评论'), findsOneWidget);
+    });
+
+    testWidgets('创建成功：插入列表头 + 计数 +1 + comment_create_succeeded + 清空输入', (
+      tester,
+    ) async {
+      repository.onCreateComment = (_, request) async =>
+          sampleComment(id: 'c-new', content: request.content);
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+
+      await tester.enterText(find.byType(TextField), '沙发！');
+      await tester.pump();
+      await tester.tap(find.byIcon(Icons.send_rounded));
+      await tester.pumpAndSettle();
+
+      expect(repository.calls, contains('createComment:p-1:沙发！'));
+      expect(find.text('沙发！'), findsOneWidget); // 列表中的新评论。
+      expect(find.text('评论 (4)'), findsOneWidget);
+      expect(
+        tester.widget<TextField>(find.byType(TextField)).controller?.text,
+        '',
+      );
+      final succeeded = eventsNamed('comment_create_succeeded').single!;
+      expect(succeeded['isReply'], false);
+      expect(succeeded['textLengthBucket'], 'short');
+      expect(succeeded['durationMs'], greaterThanOrEqualTo(0));
+      // Feed 卡片同源计数（跨页一致的另一半在 like 测试）。
+      expect(controller.cachedPost('p-1')!.commentCount, 4);
+    });
+
+    testWidgets('创建失败：SnackBar + comment_create_failed，attemptSeq 递增', (
+      tester,
+    ) async {
+      repository.onCreateComment = (_, _) async =>
+          throw const ApiBusinessException(code: 40000, message: 'bad');
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+
+      await tester.enterText(find.byType(TextField), '不合规内容');
+      await tester.pump();
+      await tester.tap(find.byIcon(Icons.send_rounded));
+      await tester.pumpAndSettle();
+      expect(find.text('评论内容不合规，请修改后重试'), findsOneWidget);
+
+      // 等 SnackBar 退场（遮挡底部发送钮）后重试第二次。
+      await tester.pump(const Duration(seconds: 5));
+      await tester.pumpAndSettle();
+      await tester.tap(find.byIcon(Icons.send_rounded));
+      await tester.pumpAndSettle();
+      expect(eventsNamed('comment_create_failed'), [
+        {
+          'failureReason': 'validation_error',
+          'attemptSeq': 1,
+          'errorCode': 40000,
+          'httpStatus': 400,
+        },
+        {
+          'failureReason': 'validation_error',
+          'attemptSeq': 2,
+          'errorCode': 40000,
+          'httpStatus': 400,
+        },
+      ]);
+      // 失败不清空输入、不入列表、不动计数。
+      expect(find.text('评论 (3)'), findsOneWidget);
+    });
+
+    testWidgets('删除权限呈现：仅本人评论有「删除」；确认后删除 + 计数 -1', (tester) async {
+      repository.onListComments = (_, _) async => commentPage([
+        sampleComment(
+          id: 'c-mine',
+          author: sampleAuthorJson(userId: 'me', nickname: '我自己'),
+          content: '我的评论',
+        ),
+        sampleComment(id: 'c-other', content: '别人的评论'),
+      ]);
+      repository.onDeleteComment = (_) async {};
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      await tester.drag(find.byType(ListView), const Offset(0, -400));
+      await tester.pump();
+
+      // 两条评论，删除入口恰一个（本人条目）。
+      expect(find.byType(CommentTile), findsNWidgets(2));
+      expect(find.text('删除'), findsOneWidget);
+
+      await tester.tap(find.text('删除'));
+      await tester.pumpAndSettle();
+      expect(find.text('删除这条评论？'), findsOneWidget);
+      await tester.tap(find.widgetWithText(FilledButton, '删除'));
+      await tester.pumpAndSettle();
+
+      expect(repository.calls, contains('deleteComment:c-mine'));
+      expect(find.text('我的评论'), findsNothing);
+      expect(find.text('别人的评论'), findsOneWidget);
+      expect(find.text('评论 (2)'), findsOneWidget);
+    });
+
+    testWidgets('删除失败：40301 提示无权限，条目保留', (tester) async {
+      repository.onListComments = (_, _) async => commentPage([
+        sampleComment(
+          id: 'c-mine',
+          author: sampleAuthorJson(userId: 'me', nickname: '我自己'),
+          content: '我的评论',
+        ),
+      ]);
+      repository.onDeleteComment = (_) async =>
+          throw const PostAccessDeniedException(message: 'denied');
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      await tester.drag(find.byType(ListView), const Offset(0, -400));
+      await tester.pump();
+
+      await tester.tap(find.text('删除'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, '删除'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('没有权限删除这条评论'), findsOneWidget);
+      expect(find.text('我的评论'), findsOneWidget);
+      expect(find.text('评论 (3)'), findsOneWidget);
+    });
+  });
+
+  group('互动（ToggleSync UI 层）', () {
+    testWidgets('点赞乐观翻转即时 +1，成功报 post_liked(source=post_detail)', (
+      tester,
+    ) async {
+      final like = Completer<LikeState>();
+      repository.onLikeToggle = (_, _) => like.future;
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byIcon(Icons.favorite_border));
+      await tester.pump();
+      expect(find.text('7'), findsOneWidget);
+      expect(find.byIcon(Icons.favorite), findsOneWidget);
+
+      like.complete(const LikeState(liked: true, likeCount: 7));
+      await tester.pumpAndSettle();
+      expect(eventsNamed('post_liked'), [
+        {'source': 'post_detail'},
+      ]);
+    });
+
+    testWidgets('点赞失败：零动画回滚成对恢复 + SnackBar，不报事件', (tester) async {
+      final like = Completer<LikeState>();
+      repository.onLikeToggle = (_, _) => like.future;
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byIcon(Icons.favorite_border));
+      await tester.pump();
+      expect(find.text('7'), findsOneWidget);
+
+      like.completeError(const ApiNetworkException());
+      await tester.pumpAndSettle();
+      expect(find.text('6'), findsOneWidget);
+      expect(find.byIcon(Icons.favorite_border), findsOneWidget);
+      expect(find.text('操作失败，请重试'), findsOneWidget);
+      expect(eventsNamed('post_liked'), isEmpty);
+    });
+
+    testWidgets('收藏接线：成功报 post_favorited(source=post_detail)', (tester) async {
+      repository.onBookmarkToggle = (_, target) async =>
+          BookmarkState(bookmarked: target, bookmarkCount: target ? 3 : 2);
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byIcon(Icons.bookmark_border));
+      await tester.pumpAndSettle();
+      expect(find.byIcon(Icons.bookmark), findsOneWidget);
+      expect(eventsNamed('post_favorited'), [
+        {'source': 'post_detail'},
+      ]);
+    });
+
+    testWidgets('跨页一致：详情页点赞，Feed 卡片同帖同帧更新（共享同一实例）', (tester) async {
+      repository.onFeed = (_, _) async =>
+          feedPage([sampleFeedCard(likeCount: 6)]);
+      await controller.refresh();
+      repository.onLikeToggle = (_, target) async =>
+          LikeState(liked: target, likeCount: target ? 7 : 6);
+
+      await tester.pumpWidget(
+        MaterialApp(
+          theme: buildAppTheme(),
+          home: Column(
+            children: [
+              // 模拟 Feed 侧对同一 controller 的消费。
+              ListenableBuilder(
+                listenable: controller,
+                builder: (context, _) {
+                  final card = controller.feed.single;
+                  return Text('card:${card.likedByMe}:${card.likeCount}');
+                },
+              ),
+              Expanded(
+                child: PostDetailPage(
+                  controller: controller,
+                  postId: 'p-1',
+                  currentUserId: 'me',
+                  analytics: analytics,
+                ),
+              ),
+            ],
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+      expect(find.text('card:false:6'), findsOneWidget);
+
+      await tester.tap(find.byIcon(Icons.favorite_border));
+      await tester.pump();
+      // 乐观写入即同源：卡片副本同帧翻转。
+      expect(find.text('card:true:7'), findsOneWidget);
+      await tester.pumpAndSettle();
+      expect(find.text('card:true:7'), findsOneWidget);
+    });
+  });
+
+  group('关注', () {
+    testWidgets('未关注 → 关注：乐观翻转 + user_followed(post_detail)', (tester) async {
+      repository.onFollowToggle = (_, target) async =>
+          FollowState(following: target, followerCount: target ? 2 : 1);
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      expect(find.text('＋ 关注'), findsOneWidget);
+
+      await tester.tap(find.text('＋ 关注'));
+      await tester.pump();
+      expect(find.text('已关注'), findsOneWidget);
+
+      await tester.pumpAndSettle();
+      expect(repository.calls, contains('follow:u-1'));
+      expect(eventsNamed('user_followed'), [
+        {'source': 'post_detail'},
+      ]);
+    });
+
+    testWidgets('已关注 → 取关：确认弹窗 + user_unfollowed', (tester) async {
+      repository.onGetFollowStats = (_) async => const FollowStats(
+        followerCount: 2,
+        followingCount: 2,
+        followedByMe: true,
+      );
+      repository.onFollowToggle = (_, target) async =>
+          FollowState(following: target, followerCount: target ? 2 : 1);
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+      expect(find.text('已关注'), findsOneWidget);
+
+      await tester.tap(find.text('已关注'));
+      await tester.pumpAndSettle();
+      expect(find.text('不再关注 TA？'), findsOneWidget);
+      await tester.tap(find.widgetWithText(FilledButton, '不再关注'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('＋ 关注'), findsOneWidget);
+      expect(repository.calls, contains('unfollow:u-1'));
+      expect(eventsNamed('user_unfollowed'), [
+        {'source': 'post_detail'},
+      ]);
+    });
+
+    testWidgets('关注失败：回滚直接跳变 + SnackBar', (tester) async {
+      final follow = Completer<FollowState>();
+      repository.onFollowToggle = (_, _) => follow.future;
+
+      await tester.pumpWidget(detailApp());
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.text('＋ 关注'));
+      await tester.pump();
+      expect(find.text('已关注'), findsOneWidget);
+
+      follow.completeError(const ApiNetworkException());
+      await tester.pumpAndSettle();
+      expect(find.text('＋ 关注'), findsOneWidget);
+      expect(find.text('操作失败，请重试'), findsOneWidget);
+      expect(eventsNamed('user_followed'), isEmpty);
+    });
+
+    testWidgets('本人帖：不渲染关注钮、不拉 follow-stats', (tester) async {
+      await tester.pumpWidget(detailApp(currentUserId: 'u-1'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('＋ 关注'), findsNothing);
+      expect(find.text('已关注'), findsNothing);
+      expect(
+        repository.calls.where((c) => c.startsWith('followStats:')),
+        isEmpty,
+      );
+    });
+  });
+}