新增：community feature 数据层——契约 v1.3.0 十九操作全覆盖 + ToggleSync 乐观更新状态机（T3-12）

- community_models：community/media 域 DTO 逐字段照冻结契约手写 JSON 映射
  （Post/FeedCard/PostComment/AuthorSummary 降级形态/媒体两步上传凭据等），
  未知枚举抛 FormatException 暴露契约漂移；CursorPage 上移 core 复用
- community_repository：13 路径 19 操作全覆盖；createPost/createComment
  必带 Idempotency-Key（每次逻辑提交换新键、刷新重放同键）；点赞/收藏/
  关注走 PUT/DELETE 语义幂等
- community_exceptions：v1.3.0 新增 9 码 + 40902 共码类型化异常映射
- toggle_sync：乐观翻转 + 快照回滚 + 单飞合并最终意图 + 代次守卫，
  点赞/收藏共用一套参数化状态机，权威终态对账收敛
- community_controller：Feed 多页缓存 + 首屏四态 + 尾部加载三态 +
  游标拼接 + 刷新代次丢弃旧尾页；详情副本与卡片互动状态同源；reset 清态
- app.dart 装配：community 服务分端口直连（:8084），共享 TokenRefresher，
  登出同步 reset
- 测试 286 → 347（模型映射 / 19 操作线路 / 错误映射 / 竞态序列全覆盖）

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

lib/features/community/community_controller.dart

@@ -0,0 +1,291 @@
+import 'package:flutter/foundation.dart';
+import 'package:patbond_flutter/core/network/api_exception.dart';
+import 'package:patbond_flutter/features/community/community_models.dart';
+import 'package:patbond_flutter/features/community/community_repository.dart';
+import 'package:patbond_flutter/features/community/toggle_sync.dart';
+
+/// Feed 首屏四态（同 pets 先例）。
+enum FeedPhase { initial, loading, ready, error }
+
+/// 尾部加载更多三态（游标累积流新增，pets 无此并发点）。
+enum LoadMorePhase { idle, loading, error }
+
+/// community feature 状态控制器（03 号评估 §2 分层：
+/// Page/Widget → CommunityController → CommunityRepository → ApiClient）。
+///
+/// Tab 级单例（app.dart 装配注入主壳）：Feed 是游标累积流，且详情页与
+/// 首页共享同一份帖子内存副本（点赞状态跨页一致），不做页面级 state。
+/// 评论列表只属详情页，按「页面级状态按页自建」纪律经 [repository]
+/// 自取，不膨胀本控制器。服务端是唯一事实来源，内存副本仅作展示缓存。
+class CommunityController extends ChangeNotifier {
+  CommunityController({required this._repository}) {
+    _likeSync = ToggleSync(
+      read: (id) {
+        final post = _postCache[id];
+        if (post != null) {
+          return ToggleReading(active: post.likedByMe, count: post.likeCount);
+        }
+        final card = _cardOrNull(id);
+        if (card == null) return null;
+        return ToggleReading(active: card.likedByMe, count: card.likeCount);
+      },
+      write: (id, active, count) =>
+          _writeInteraction(id, likedByMe: active, likeCount: count),
+      send: (id, target) async {
+        final state = target
+            ? await _repository.likePost(id)
+            : await _repository.unlikePost(id);
+        return ToggleOutcome(active: state.liked, count: state.likeCount);
+      },
+      generation: () => _generation,
+      onError: _onToggleError,
+    );
+    _bookmarkSync = ToggleSync(
+      read: (id) {
+        final post = _postCache[id];
+        if (post != null) {
+          return ToggleReading(
+            active: post.bookmarkedByMe,
+            count: post.bookmarkCount,
+          );
+        }
+        final card = _cardOrNull(id);
+        if (card == null) return null;
+        return ToggleReading(
+          active: card.bookmarkedByMe,
+          count: card.bookmarkCount,
+        );
+      },
+      write: (id, active, count) =>
+          _writeInteraction(id, bookmarkedByMe: active, bookmarkCount: count),
+      send: (id, target) async {
+        final state = target
+            ? await _repository.bookmarkPost(id)
+            : await _repository.unbookmarkPost(id);
+        return ToggleOutcome(
+          active: state.bookmarked,
+          count: state.bookmarkCount,
+        );
+      },
+      generation: () => _generation,
+      onError: _onToggleError,
+    );
+  }
+
+  final CommunityRepository _repository;
+
+  /// 页面级状态（评论列表、我的帖子、收藏页等）按页直接经仓库取数。
+  CommunityRepository get repository => _repository;
+
+  late final ToggleSync _likeSync;
+  late final ToggleSync _bookmarkSync;
+
+  FeedPhase _phase = FeedPhase.initial;
+  LoadMorePhase _loadMorePhase = LoadMorePhase.idle;
+  List<FeedCard> _feed = const [];
+  String? _nextCursor;
+  bool _hasMore = false;
+
+  /// 首屏加载失败（error 态时非 null）。
+  ApiException? _lastError;
+
+  /// 刷新失败但旧列表被保留时的错误（页面 SnackBar 轻提示后消费）。
+  ApiException? _refreshError;
+
+  /// 加载更多失败（尾部重试条渲染依据）。
+  ApiException? _loadMoreError;
+
+  /// 最近一次点赞/收藏对账失败（T3-15/16 SnackBar 消费）。
+  ApiException? _toggleError;
+
+  /// 刷新代次：整体替换列表后，在途旧代次响应（尾页 / 互动对账）一律丢弃。
+  int _generation = 0;
+
+  /// 详情内存副本（详情页与 Feed 卡片互动状态同源）。
+  final Map<String, Post> _postCache = {};
+
+  bool _disposed = false;
+
+  FeedPhase get phase => _phase;
+  LoadMorePhase get loadMorePhase => _loadMorePhase;
+
+  /// 累积的多页 Feed 缓存（服务端 published_at DESC, id DESC 原样保留）。
+  List<FeedCard> get feed => _feed;
+  bool get hasMore => _hasMore;
+
+  /// ready 且列表为空 → 空态。
+  bool get isEmpty => _phase == FeedPhase.ready && _feed.isEmpty;
+
+  ApiException? get lastError => _lastError;
+  ApiException? get refreshError => _refreshError;
+  ApiException? get loadMoreError => _loadMoreError;
+  ApiException? get toggleError => _toggleError;
+
+  /// 详情内存副本（进入详情页先渲染缓存，再 [getPost] 拉新）。
+  Post? cachedPost(String postId) => _postCache[postId];
+
+  /// 首屏加载 / 下拉刷新：丢弃游标从头拉第一页，成功后**整体替换**累积列表。
+  /// 刷新失败保留旧列表（不清空不闪空态），错误经 [refreshError] 轻提示；
+  /// 首屏（空列表）失败收敛为 error 态供页面渲染 + retry。
+  Future<void> refresh() async {
+    _generation += 1;
+    final generation = _generation;
+    _lastError = null;
+    _refreshError = null;
+    _loadMorePhase = LoadMorePhase.idle;
+    _loadMoreError = null;
+    if (_feed.isEmpty) _phase = FeedPhase.loading;
+    _notify();
+    try {
+      final page = await _repository.getFeed();
+      if (generation != _generation) return; // 期间又发生过刷新/登出。
+      _feed = page.items;
+      _nextCursor = page.nextCursor;
+      _hasMore = page.hasMore;
+      _phase = FeedPhase.ready;
+    } on ApiException catch (error) {
+      if (generation != _generation) return;
+      if (_feed.isEmpty) {
+        _lastError = error;
+        _phase = FeedPhase.error;
+      } else {
+        _refreshError = error;
+      }
+    }
+    _notify();
+  }
+
+  /// 滚动近底加载下一页：携带上一页 nextCursor（keyset 翻页不丢不重）。
+  /// 失败置 [LoadMorePhase.error] 渲染尾部重试条；期间发生过刷新的
+  /// 旧代次响应直接丢弃（避免「刷新后旧尾页追加」的重复/错位）。
+  Future<void> loadMore() async {
+    if (_phase != FeedPhase.ready ||
+        !_hasMore ||
+        _loadMorePhase == LoadMorePhase.loading) {
+      return;
+    }
+    final generation = _generation;
+    _loadMorePhase = LoadMorePhase.loading;
+    _loadMoreError = null;
+    _notify();
+    try {
+      final page = await _repository.getFeed(cursor: _nextCursor);
+      if (generation != _generation) return; // 旧代次尾页，丢弃。
+      _feed = [..._feed, ...page.items];
+      _nextCursor = page.nextCursor;
+      _hasMore = page.hasMore;
+      _loadMorePhase = LoadMorePhase.idle;
+    } on ApiException catch (error) {
+      if (generation != _generation) return;
+      _loadMoreError = error;
+      _loadMorePhase = LoadMorePhase.error;
+    }
+    _notify();
+  }
+
+  /// 拉取帖子详情并同步内存副本（Feed 卡片互动字段一并回写）。
+  Future<Post> getPost(String postId) async {
+    final post = await _repository.getPost(postId);
+    _postCache[postId] = post;
+    _syncCardFromPost(post);
+    _notify();
+    return post;
+  }
+
+  /// 点赞/取消点赞（乐观翻转，终态由 [ToggleSync] 对账收敛，不外抛）。
+  void toggleLike(String postId) => _likeSync.toggle(postId);
+
+  /// 收藏/取消收藏（与点赞同构）。
+  void toggleBookmark(String postId) => _bookmarkSync.toggle(postId);
+
+  /// 消费一次性 toggle 错误（SnackBar 展示后清除）。
+  void clearToggleError() => _toggleError = null;
+
+  /// 登出清空：回 initial 态、清多页缓存与详情副本、丢弃全部在途链，
+  /// 避免上一账号数据跨会话泄漏；重登后主壳重建，Feed 页重新触发 [refresh]。
+  void reset() {
+    _generation += 1;
+    _phase = FeedPhase.initial;
+    _loadMorePhase = LoadMorePhase.idle;
+    _feed = const [];
+    _nextCursor = null;
+    _hasMore = false;
+    _lastError = null;
+    _refreshError = null;
+    _loadMoreError = null;
+    _toggleError = null;
+    _postCache.clear();
+    _likeSync.reset();
+    _bookmarkSync.reset();
+    _notify();
+  }
+
+  FeedCard? _cardOrNull(String postId) {
+    for (final card in _feed) {
+      if (card.id == postId) return card;
+    }
+    return null;
+  }
+
+  /// 互动字段统一写入口：详情副本与 Feed 卡片同步更新后 notify（同帧反馈）。
+  void _writeInteraction(
+    String postId, {
+    bool? likedByMe,
+    int? likeCount,
+    bool? bookmarkedByMe,
+    int? bookmarkCount,
+  }) {
+    final post = _postCache[postId];
+    if (post != null) {
+      _postCache[postId] = post.copyWithInteraction(
+        likedByMe: likedByMe,
+        likeCount: likeCount,
+        bookmarkedByMe: bookmarkedByMe,
+        bookmarkCount: bookmarkCount,
+      );
+    }
+    final index = _feed.indexWhere((card) => card.id == postId);
+    if (index != -1) {
+      _feed = [..._feed]
+        ..[index] = _feed[index].copyWithInteraction(
+          likedByMe: likedByMe,
+          likeCount: likeCount,
+          bookmarkedByMe: bookmarkedByMe,
+          bookmarkCount: bookmarkCount,
+        );
+    }
+    if (post != null || index != -1) _notify();
+  }
+
+  void _syncCardFromPost(Post post) {
+    final index = _feed.indexWhere((card) => card.id == post.id);
+    if (index == -1) return;
+    _feed = [..._feed]
+      ..[index] = _feed[index].copyWithInteraction(
+        likedByMe: post.likedByMe,
+        likeCount: post.likeCount,
+        commentCount: post.commentCount,
+        bookmarkedByMe: post.bookmarkedByMe,
+        bookmarkCount: post.bookmarkCount,
+      );
+  }
+
+  void _onToggleError(String postId, Object error) {
+    if (error is ApiException) {
+      _toggleError = error;
+    } else {
+      _toggleError = ApiNetworkException('$error');
+    }
+    _notify();
+  }
+
+  void _notify() {
+    if (!_disposed) notifyListeners();
+  }
+
+  @override
+  void dispose() {
+    _disposed = true;
+    super.dispose();
+  }
+}

lib/features/community/community_exceptions.dart

@@ -0,0 +1,102 @@
+import 'package:patbond_flutter/core/network/api_exception.dart';
+
+/// community / media 域类型化业务异常（契约 v1.3.0 定型的 9 个新错误码，
+/// 20 号收口报告 §1；40902 乐观锁与 pets 域共码，本域映射为独立类型）。
+/// 全部继承 [ApiBusinessException]，既有按基类捕获的通用错误处理不受影响。
+
+/// 40301：对可见帖子/评论无相应操作权限（改删他人已发布帖、
+/// 删他人可见评论——含帖主删他人评论，D3-7 首版不做）。
+final class PostAccessDeniedException extends ApiBusinessException {
+  const PostAccessDeniedException({required super.message})
+    : super(code: ApiCodes.postAccessDenied);
+}
+
+/// 40403：帖子不存在 / 已软删 / hidden/archived（含作者）/ 他人 draft
+/// （防枚举，全部情况响应完全一致；互动路径上含作者本人草稿）。
+final class PostNotFoundException extends ApiBusinessException {
+  const PostNotFoundException({required super.message})
+    : super(code: ApiCodes.postNotFound);
+}
+
+/// 40404：评论不存在、已删或所属帖子不可见（防枚举合并）。
+final class CommentNotFoundException extends ApiBusinessException {
+  const CommentNotFoundException({required super.message})
+    : super(code: ApiCodes.commentNotFound);
+}
+
+/// 40405：media asset 不存在、非本人所有或已删（防枚举合并）。
+final class MediaAssetNotFoundException extends ApiBusinessException {
+  const MediaAssetNotFoundException({required super.message})
+    : super(code: ApiCodes.mediaNotFound);
+}
+
+/// 40406：目标用户不存在或已注销（合并不泄露成因）。
+final class CommunityUserNotFoundException extends ApiBusinessException {
+  const CommunityUserNotFoundException({required super.message})
+    : super(code: ApiCodes.communityUserNotFound);
+}
+
+/// 40902：帖子编辑乐观锁版本冲突（version 过期）。
+/// 客户端处理：刷新详情取新 version 后重提。
+final class PostVersionConflictException extends ApiBusinessException {
+  const PostVersionConflictException({required super.message})
+    : super(code: ApiCodes.versionConflict);
+}
+
+/// 40905：同 Idempotency-Key 不同 payload（规范化 request_hash 不符）。
+/// 客户端每次逻辑提交应换新键，重试间保持不变。
+final class IdempotencyMismatchException extends ApiBusinessException {
+  const IdempotencyMismatchException({required super.message})
+    : super(code: ApiCodes.idempotencyKeyMismatch);
+}
+
+/// 42203：引用了本人所有但非 ready（uploading/failed）状态的 asset。
+final class MediaNotReadyException extends ApiBusinessException {
+  const MediaNotReadyException({required super.message})
+    : super(code: ApiCodes.mediaNotReady);
+}
+
+/// 42204：自关注（仅 PUT；自取关走 DELETE 的 200 幂等 no-op）。
+final class SelfFollowException extends ApiBusinessException {
+  const SelfFollowException({required super.message})
+    : super(code: ApiCodes.selfFollow);
+}
+
+/// 42205：上传状态不允许确认——对象未上传（保持 uploading 可重试）、
+/// 大小/类型不符（置 failed 终态）、failed 态再确认（已 ready 幂等 200 除外）。
+final class MediaUploadStateException extends ApiBusinessException {
+  const MediaUploadStateException({required super.message})
+    : super(code: ApiCodes.mediaUploadStateInvalid);
+}
+
+/// 把通用业务异常按 community/media 域错误码升格为类型化异常；
+/// 未覆盖的码（40000 参数错误、40401 宠物防枚举等）原样返回，沿用通用处理。
+ApiBusinessException mapCommunityBusinessException(ApiBusinessException error) {
+  return switch (error.code) {
+    ApiCodes.postAccessDenied => PostAccessDeniedException(
+      message: error.message,
+    ),
+    ApiCodes.postNotFound => PostNotFoundException(message: error.message),
+    ApiCodes.commentNotFound => CommentNotFoundException(
+      message: error.message,
+    ),
+    ApiCodes.mediaNotFound => MediaAssetNotFoundException(
+      message: error.message,
+    ),
+    ApiCodes.communityUserNotFound => CommunityUserNotFoundException(
+      message: error.message,
+    ),
+    ApiCodes.versionConflict => PostVersionConflictException(
+      message: error.message,
+    ),
+    ApiCodes.idempotencyKeyMismatch => IdempotencyMismatchException(
+      message: error.message,
+    ),
+    ApiCodes.mediaNotReady => MediaNotReadyException(message: error.message),
+    ApiCodes.selfFollow => SelfFollowException(message: error.message),
+    ApiCodes.mediaUploadStateInvalid => MediaUploadStateException(
+      message: error.message,
+    ),
+    _ => error,
+  };
+}

lib/features/community/community_models.dart

@@ -0,0 +1,630 @@
+/// community / media 域响应 / 请求模型（接口契约冻结稿 openapi.yaml v1.3.0，
+/// 字段名与后端逐字一致；枚举取值严格校验，未知值抛 [FormatException]
+/// 以便契约漂移在测试期暴露而非静默吞掉）。
+library;
+
+export 'package:patbond_flutter/core/models/cursor_page.dart';
+
+T _enumFromJson<T extends Enum>(List<T> values, String raw, String field) {
+  for (final value in values) {
+    if (value.name == raw) return value;
+  }
+  throw FormatException('未知的 $field 取值：$raw');
+}
+
+DateTime? _dateTimeOrNull(Object? value) =>
+    value == null ? null : DateTime.parse(value as String);
+
+/// 帖子分类。ai_creation 为 M4 预留值，仅读侧出现（M3 提交即 400/40000）。
+enum PostCategory {
+  general('general'),
+  help('help'),
+  aiCreation('ai_creation');
+
+  const PostCategory(this.wire);
+
+  /// 契约线上取值（aiCreation 的枚举名与线上 snake_case 不同，序列化走本值）。
+  final String wire;
+
+  static PostCategory fromJson(String value) {
+    for (final category in values) {
+      if (category.wire == value) return category;
+    }
+    throw FormatException('未知的 category 取值：$value');
+  }
+}
+
+/// 帖子状态。hidden/archived（运营态）永不出现在响应（对作者与他人一律
+/// 404/40403），枚举保持两值。
+enum PostStatus {
+  draft,
+  published;
+
+  static PostStatus fromJson(String value) =>
+      _enumFromJson(values, value, 'status');
+}
+
+/// 帖子可见性。M3 恒 public（followers/private 语义后置，字段保留）。
+enum PostVisibility {
+  public;
+
+  static PostVisibility fromJson(String value) =>
+      _enumFromJson(values, value, 'visibility');
+}
+
+/// media asset 类型。M3 仅 image（视频后置，video/document 为向后新增预留）。
+enum MediaKind {
+  image;
+
+  static MediaKind fromJson(String value) =>
+      _enumFromJson(values, value, 'kind');
+}
+
+/// 上传用途白名单（M3 定型仅 post_image，决定 objectKey 前缀）。
+enum MediaPurpose {
+  postImage('post_image');
+
+  const MediaPurpose(this.wire);
+
+  final String wire;
+}
+
+/// media asset 状态。deleted 态对外恒 404/40405，不出现在响应。
+enum MediaAssetStatus {
+  uploading,
+  ready,
+  failed;
+
+  static MediaAssetStatus fromJson(String value) =>
+      _enumFromJson(values, value, 'status');
+}
+
+/// 作者公开摘要（D3-9 方案 B）。正常路径 nickname 恒非空（空昵称由服务端
+/// 回退为 username，客户端不做回退拼装）；nickname 与 avatarUrl 同为 null
+/// 即「降级/墓碑」形态（作者资料暂不可得或已注销），客户端只需一种占位逻辑。
+class AuthorSummary {
+  const AuthorSummary({
+    required this.userId,
+    required this.nickname,
+    required this.avatarUrl,
+  });
+
+  factory AuthorSummary.fromJson(Map<String, dynamic> json) {
+    return AuthorSummary(
+      userId: json['userId'] as String,
+      nickname: json['nickname'] as String?,
+      // 时效性预签名 GET URL，每次响应现签，不得持久化、过期即重取。
+      avatarUrl: json['avatarUrl'] as String?,
+    );
+  }
+
+  final String userId;
+  final String? nickname;
+  final String? avatarUrl;
+
+  /// 降级/墓碑形态（id-only）：页面渲染统一占位。
+  bool get isDegraded => nickname == null && avatarUrl == null;
+}
+
+/// 帖子挂接的一张图（响应形态）。url 为时效性预签名 GET（TTL 默认 1 小时），
+/// 每次响应现签，客户端不得持久化、过期即重取。
+class PostMediaItem {
+  const PostMediaItem({
+    required this.assetId,
+    required this.position,
+    required this.isCover,
+    required this.url,
+    required this.widthPx,
+    required this.heightPx,
+    required this.caption,
+  });
+
+  factory PostMediaItem.fromJson(Map<String, dynamic> json) {
+    return PostMediaItem(
+      assetId: json['assetId'] as String,
+      position: json['position'] as int,
+      isCover: json['isCover'] as bool,
+      url: json['url'] as String,
+      widthPx: json['widthPx'] as int?,
+      heightPx: json['heightPx'] as int?,
+      caption: json['caption'] as String?,
+    );
+  }
+
+  final String assetId;
+  final int position;
+  final bool isCover;
+  final String url;
+  final int? widthPx;
+  final int? heightPx;
+  final String? caption;
+}
+
+/// 帖子挂接的一张图（请求形态）。position 全给或全不给（全给须恰为 0..n-1
+/// 连续不重复，混合 400/40000）；isCover 至多一个 true；caption trim 后 ≤300。
+class PostMediaAttachRequest {
+  const PostMediaAttachRequest({
+    required this.assetId,
+    this.position,
+    this.isCover,
+    this.caption,
+  });
+
+  final String assetId;
+  final int? position;
+  final bool? isCover;
+  final String? caption;
+
+  Map<String, Object?> toJson() => {
+    'assetId': assetId,
+    if (position != null) 'position': position,
+    if (isCover != null) 'isCover': isCover,
+    if (caption != null) 'caption': caption,
+  };
+}
+
+/// 创建帖子请求。content 必填（纯文字帖合法，media 空数组或缺席）；
+/// status=published 即创建即发布（服务端写 publishedAt）。
+class CreatePostRequest {
+  const CreatePostRequest({
+    required this.content,
+    this.title,
+    this.category,
+    this.status,
+    this.petId,
+    this.media,
+  });
+
+  final String content;
+  final String? title;
+  final PostCategory? category;
+  final PostStatus? status;
+  final String? petId;
+  final List<PostMediaAttachRequest>? media;
+
+  Map<String, Object?> toJson() => {
+    'content': content,
+    if (title != null) 'title': title,
+    if (category != null) 'category': category!.wire,
+    if (status != null) 'status': status!.name,
+    if (petId != null) 'petId': petId,
+    if (media != null) 'media': media!.map((item) => item.toJson()).toList(),
+  };
+}
+
+/// 编辑帖子 / 发布草稿请求（部分更新：缺席字段不变，不支持清空回 null；
+/// version 乐观锁必带）。
+///
+/// - [publish]：`status: published` 状态迁移（draft→published 唯一开放迁移；
+///   对已发布帖重复提交为幂等 no-op，弱网重发不报错）。
+/// - [media] 三态：null = 缺席不动；`[]` = 清空为纯文字帖；非空 = 整组替换。
+class UpdatePostRequest {
+  const UpdatePostRequest({
+    required this.version,
+    this.title,
+    this.content,
+    this.category,
+    this.petId,
+    this.publish = false,
+    this.media,
+  });
+
+  final int version;
+  final String? title;
+  final String? content;
+  final PostCategory? category;
+  final String? petId;
+  final bool publish;
+  final List<PostMediaAttachRequest>? media;
+
+  Map<String, Object?> toJson() => {
+    'version': version,
+    if (title != null) 'title': title,
+    if (content != null) 'content': content,
+    if (category != null) 'category': category!.wire,
+    if (petId != null) 'petId': petId,
+    if (publish) 'status': PostStatus.published.name,
+    if (media != null) 'media': media!.map((item) => item.toJson()).toList(),
+  };
+}
+
+/// 帖子完整形态（详情 / 我的帖子列表 / 写响应共用）。
+/// 「内容是否编辑过」以 version 为准（互动计数维护亦会推动 updatedAt）。
+class Post {
+  const Post({
+    required this.id,
+    required this.author,
+    required this.petId,
+    required this.category,
+    required this.title,
+    required this.content,
+    required this.status,
+    required this.visibility,
+    required this.media,
+    required this.likeCount,
+    required this.commentCount,
+    required this.bookmarkCount,
+    required this.likedByMe,
+    required this.bookmarkedByMe,
+    required this.createdAt,
+    required this.updatedAt,
+    required this.publishedAt,
+    required this.version,
+  });
+
+  factory Post.fromJson(Map<String, dynamic> json) {
+    return Post(
+      id: json['id'] as String,
+      author: AuthorSummary.fromJson(json['author'] as Map<String, dynamic>),
+      petId: json['petId'] as String?,
+      category: PostCategory.fromJson(json['category'] as String),
+      title: json['title'] as String?,
+      content: json['content'] as String,
+      status: PostStatus.fromJson(json['status'] as String),
+      visibility: PostVisibility.fromJson(json['visibility'] as String),
+      media: (json['media'] as List)
+          .map((item) => PostMediaItem.fromJson(item as Map<String, dynamic>))
+          .toList(),
+      likeCount: json['likeCount'] as int,
+      commentCount: json['commentCount'] as int,
+      bookmarkCount: json['bookmarkCount'] as int,
+      likedByMe: json['likedByMe'] as bool,
+      bookmarkedByMe: json['bookmarkedByMe'] as bool,
+      createdAt: DateTime.parse(json['createdAt'] as String),
+      updatedAt: DateTime.parse(json['updatedAt'] as String),
+      // 仅 published 非空（发布时恰写一次）。
+      publishedAt: _dateTimeOrNull(json['publishedAt']),
+      version: json['version'] as int,
+    );
+  }
+
+  final String id;
+  final AuthorSummary author;
+  final String? petId;
+  final PostCategory category;
+  final String? title;
+  final String content;
+  final PostStatus status;
+  final PostVisibility visibility;
+  final List<PostMediaItem> media;
+  final int likeCount;
+  final int commentCount;
+  final int bookmarkCount;
+  final bool likedByMe;
+  final bool bookmarkedByMe;
+  final DateTime createdAt;
+  final DateTime updatedAt;
+  final DateTime? publishedAt;
+  final int version;
+
+  /// 互动字段副本更新（乐观翻转 / 权威终态对账用，其余字段不变）。
+  Post copyWithInteraction({
+    int? likeCount,
+    int? commentCount,
+    int? bookmarkCount,
+    bool? likedByMe,
+    bool? bookmarkedByMe,
+  }) {
+    return Post(
+      id: id,
+      author: author,
+      petId: petId,
+      category: category,
+      title: title,
+      content: content,
+      status: status,
+      visibility: visibility,
+      media: media,
+      likeCount: likeCount ?? this.likeCount,
+      commentCount: commentCount ?? this.commentCount,
+      bookmarkCount: bookmarkCount ?? this.bookmarkCount,
+      likedByMe: likedByMe ?? this.likedByMe,
+      bookmarkedByMe: bookmarkedByMe ?? this.bookmarkedByMe,
+      createdAt: createdAt,
+      updatedAt: updatedAt,
+      publishedAt: publishedAt,
+      version: version,
+    );
+  }
+}
+
+/// Feed / 收藏列表卡片形态（较 Post 裁剪：只带 coverImage + mediaCount，
+/// 全文恒走帖子详情端点）。publishedAt 恒非空（谓词只放行 published）。
+class FeedCard {
+  const FeedCard({
+    required this.id,
+    required this.author,
+    required this.category,
+    required this.title,
+    required this.contentPreview,
+    required this.coverImage,
+    required this.mediaCount,
+    required this.likeCount,
+    required this.commentCount,
+    required this.bookmarkCount,
+    required this.likedByMe,
+    required this.bookmarkedByMe,
+    required this.publishedAt,
+  });
+
+  factory FeedCard.fromJson(Map<String, dynamic> json) {
+    final cover = json['coverImage'];
+    return FeedCard(
+      id: json['id'] as String,
+      author: AuthorSummary.fromJson(json['author'] as Map<String, dynamic>),
+      category: PostCategory.fromJson(json['category'] as String),
+      title: json['title'] as String?,
+      contentPreview: json['contentPreview'] as String,
+      // 封面 = 库中唯一 is_cover 行；纯文字帖为 null。
+      coverImage: cover == null
+          ? null
+          : PostMediaItem.fromJson(cover as Map<String, dynamic>),
+      mediaCount: json['mediaCount'] as int,
+      likeCount: json['likeCount'] as int,
+      commentCount: json['commentCount'] as int,
+      bookmarkCount: json['bookmarkCount'] as int,
+      likedByMe: json['likedByMe'] as bool,
+      bookmarkedByMe: json['bookmarkedByMe'] as bool,
+      publishedAt: DateTime.parse(json['publishedAt'] as String),
+    );
+  }
+
+  final String id;
+  final AuthorSummary author;
+  final PostCategory category;
+  final String? title;
+  final String contentPreview;
+  final PostMediaItem? coverImage;
+  final int mediaCount;
+  final int likeCount;
+  final int commentCount;
+  final int bookmarkCount;
+  final bool likedByMe;
+  final bool bookmarkedByMe;
+  final DateTime publishedAt;
+
+  /// 互动字段副本更新（乐观翻转 / 权威终态对账用，其余字段不变）。
+  FeedCard copyWithInteraction({
+    int? likeCount,
+    int? commentCount,
+    int? bookmarkCount,
+    bool? likedByMe,
+    bool? bookmarkedByMe,
+  }) {
+    return FeedCard(
+      id: id,
+      author: author,
+      category: category,
+      title: title,
+      contentPreview: contentPreview,
+      coverImage: coverImage,
+      mediaCount: mediaCount,
+      likeCount: likeCount ?? this.likeCount,
+      commentCount: commentCount ?? this.commentCount,
+      bookmarkCount: bookmarkCount ?? this.bookmarkCount,
+      likedByMe: likedByMe ?? this.likedByMe,
+      bookmarkedByMe: bookmarkedByMe ?? this.bookmarkedByMe,
+      publishedAt: publishedAt,
+    );
+  }
+}
+
+/// 创建评论请求。content trim 后 1~2000；replyToUserId 可选 @ 回复目标
+/// （单层平铺，无楼中楼）。
+class CreateCommentRequest {
+  const CreateCommentRequest({required this.content, this.replyToUserId});
+
+  final String content;
+  final String? replyToUserId;
+
+  Map<String, Object?> toJson() => {
+    'content': content,
+    if (replyToUserId != null) 'replyToUserId': replyToUserId,
+  };
+}
+
+/// 评论（M3 无评论编辑，不带 updatedAt）。
+class PostComment {
+  const PostComment({
+    required this.id,
+    required this.postId,
+    required this.author,
+    required this.replyToUser,
+    required this.content,
+    required this.createdAt,
+  });
+
+  factory PostComment.fromJson(Map<String, dynamic> json) {
+    final replyTo = json['replyToUser'];
+    return PostComment(
+      id: json['id'] as String,
+      postId: json['postId'] as String,
+      author: AuthorSummary.fromJson(json['author'] as Map<String, dynamic>),
+      // @ 回复目标公开摘要（含降级 id-only 形态）；非回复为 null。
+      replyToUser: replyTo == null
+          ? null
+          : AuthorSummary.fromJson(replyTo as Map<String, dynamic>),
+      content: json['content'] as String,
+      createdAt: DateTime.parse(json['createdAt'] as String),
+    );
+  }
+
+  final String id;
+  final String postId;
+  final AuthorSummary author;
+  final AuthorSummary? replyToUser;
+  final String content;
+  final DateTime createdAt;
+}
+
+/// 创建上传请求（两步上传第一步）。mimeType 白名单
+/// image/jpeg|png|webp，byteSize ≤ 10485760（10 MiB，服务端配置项）；
+/// sha256 可选（64 位小写 hex，M3 照收照存不核验）。
+class CreateMediaUploadRequest {
+  const CreateMediaUploadRequest({
+    required this.kind,
+    required this.purpose,
+    required this.mimeType,
+    required this.byteSize,
+    this.sha256,
+  });
+
+  final MediaKind kind;
+  final MediaPurpose purpose;
+  final String mimeType;
+  final int byteSize;
+  final String? sha256;
+
+  Map<String, Object?> toJson() => {
+    'kind': kind.name,
+    'purpose': purpose.wire,
+    'mimeType': mimeType,
+    'byteSize': byteSize,
+    if (sha256 != null) 'sha256': sha256,
+  };
+}
+
+/// 预签名直传凭据。凭据（uploadUrl 含签名）TTL 默认 10 分钟，过期后
+/// 重新创建上传；直传必须原样携带 requiredHeaders（Content-Type 已签进
+/// 签名，改动即被存储侧拒绝）。凭据会过期，不得持久化。
+class MediaUploadCredentials {
+  const MediaUploadCredentials({
+    required this.assetId,
+    required this.uploadUrl,
+    required this.method,
+    required this.requiredHeaders,
+    required this.expiresAt,
+  });
+
+  factory MediaUploadCredentials.fromJson(Map<String, dynamic> json) {
+    return MediaUploadCredentials(
+      assetId: json['assetId'] as String,
+      uploadUrl: json['uploadUrl'] as String,
+      method: json['method'] as String,
+      requiredHeaders: (json['requiredHeaders'] as Map<String, dynamic>).map(
+        (key, value) => MapEntry(key, value as String),
+      ),
+      expiresAt: DateTime.parse(json['expiresAt'] as String),
+    );
+  }
+
+  final String assetId;
+  final String uploadUrl;
+
+  /// 契约定型恒为 PUT（enum 单值；直传时按本值发起请求）。
+  final String method;
+  final Map<String, String> requiredHeaders;
+  final DateTime expiresAt;
+}
+
+/// media asset（confirm 后的可引用形态）。url 仅 ready 态非空——时效性
+/// 预签名 GET（TTL 默认 1 小时），每次响应现签，不得持久化、过期即重取。
+class MediaAsset {
+  const MediaAsset({
+    required this.id,
+    required this.kind,
+    required this.purpose,
+    required this.mimeType,
+    required this.byteSize,
+    required this.widthPx,
+    required this.heightPx,
+    required this.status,
+    required this.url,
+    required this.readyAt,
+    required this.createdAt,
+  });
+
+  factory MediaAsset.fromJson(Map<String, dynamic> json) {
+    return MediaAsset(
+      id: json['id'] as String,
+      kind: MediaKind.fromJson(json['kind'] as String),
+      purpose: json['purpose'] as String,
+      mimeType: json['mimeType'] as String,
+      byteSize: json['byteSize'] as int?,
+      widthPx: json['widthPx'] as int?,
+      heightPx: json['heightPx'] as int?,
+      status: MediaAssetStatus.fromJson(json['status'] as String),
+      url: json['url'] as String?,
+      readyAt: _dateTimeOrNull(json['readyAt']),
+      createdAt: DateTime.parse(json['createdAt'] as String),
+    );
+  }
+
+  final String id;
+  final MediaKind kind;
+  final String purpose;
+  final String mimeType;
+  final int? byteSize;
+  final int? widthPx;
+  final int? heightPx;
+  final MediaAssetStatus status;
+  final String? url;
+  final DateTime? readyAt;
+  final DateTime createdAt;
+}
+
+/// 点赞权威终态（乐观更新以此对账回滚，回滚基准取响应值）。
+class LikeState {
+  const LikeState({required this.liked, required this.likeCount});
+
+  factory LikeState.fromJson(Map<String, dynamic> json) {
+    return LikeState(
+      liked: json['liked'] as bool,
+      likeCount: json['likeCount'] as int,
+    );
+  }
+
+  final bool liked;
+  final int likeCount;
+}
+
+/// 收藏权威终态（与点赞同构）。
+class BookmarkState {
+  const BookmarkState({required this.bookmarked, required this.bookmarkCount});
+
+  factory BookmarkState.fromJson(Map<String, dynamic> json) {
+    return BookmarkState(
+      bookmarked: json['bookmarked'] as bool,
+      bookmarkCount: json['bookmarkCount'] as int,
+    );
+  }
+
+  final bool bookmarked;
+  final int bookmarkCount;
+}
+
+/// 关注权威终态；followerCount 为目标用户的粉丝数（实时 COUNT）。
+class FollowState {
+  const FollowState({required this.following, required this.followerCount});
+
+  factory FollowState.fromJson(Map<String, dynamic> json) {
+    return FollowState(
+      following: json['following'] as bool,
+      followerCount: json['followerCount'] as int,
+    );
+  }
+
+  final bool following;
+  final int followerCount;
+}
+
+/// 关注计数（关注数 / 粉丝数 / 我是否已关注；查自己 followedByMe 恒 false）。
+class FollowStats {
+  const FollowStats({
+    required this.followerCount,
+    required this.followingCount,
+    required this.followedByMe,
+  });
+
+  factory FollowStats.fromJson(Map<String, dynamic> json) {
+    return FollowStats(
+      followerCount: json['followerCount'] as int,
+      followingCount: json['followingCount'] as int,
+      followedByMe: json['followedByMe'] as bool,
+    );
+  }
+
+  final int followerCount;
+  final int followingCount;
+  final bool followedByMe;
+}

lib/features/community/community_repository.dart

@@ -0,0 +1,281 @@
+import 'package:patbond_flutter/core/network/api_client.dart';
+import 'package:patbond_flutter/core/network/api_exception.dart';
+import 'package:patbond_flutter/features/community/community_exceptions.dart';
+import 'package:patbond_flutter/features/community/community_models.dart';
+import 'package:uuid/uuid.dart';
+
+/// community / media 域仓库接口（契约 v1.3.0 的 13 路径 / 19 操作全覆盖；
+/// 页面依赖此抽象，widget / controller 测试注入假实现）。
+///
+/// media 两步上传本单只到协议层（创建上传 / 确认上传）；预签名 PUT
+/// 直传对象存储不走业务信封与 Bearer 鉴权，属 T3-13 独立客户端。
+abstract class CommunityRepository {
+  // ---- media 两步上传（协议层）----
+  Future<MediaUploadCredentials> createMediaUpload(
+    CreateMediaUploadRequest request,
+  );
+  Future<MediaAsset> completeMediaUpload(String assetId);
+
+  // ---- 帖子 CRUD / 发布 ----
+  Future<Post> createPost(CreatePostRequest request);
+  Future<Post> getPost(String postId);
+  Future<Post> updatePost(String postId, UpdatePostRequest request);
+  Future<void> deletePost(String postId);
+  Future<CursorPage<Post>> listMyPosts({
+    int? limit,
+    String? cursor,
+    PostStatus? status,
+  });
+
+  // ---- Feed（cursor 分页）----
+  Future<CursorPage<FeedCard>> getFeed({int? limit, String? cursor});
+
+  // ---- 评论 ----
+  Future<CursorPage<PostComment>> listComments(
+    String postId, {
+    int? limit,
+    String? cursor,
+  });
+  Future<PostComment> createComment(
+    String postId,
+    CreateCommentRequest request,
+  );
+  Future<void> deleteComment(String commentId);
+
+  // ---- 点赞 / 收藏（PUT/DELETE 语义幂等，响应权威终态）----
+  Future<LikeState> likePost(String postId);
+  Future<LikeState> unlikePost(String postId);
+  Future<BookmarkState> bookmarkPost(String postId);
+  Future<BookmarkState> unbookmarkPost(String postId);
+  Future<CursorPage<FeedCard>> listMyBookmarks({int? limit, String? cursor});
+
+  // ---- 关注 ----
+  Future<FollowState> followUser(String userId);
+  Future<FollowState> unfollowUser(String userId);
+  Future<FollowStats> getFollowStats(String userId);
+}
+
+/// 基于 [ApiClient] 的实现。全部端点走 Bearer 鉴权（复用既有 token
+/// 拦截 + 401/40101 单飞刷新重放）；community 域业务错误码升格为类型化异常。
+///
+/// 幂等：createPost / createComment 两个 POST 按契约**必带**
+/// `Idempotency-Key`（1~128 字符；每次逻辑提交换新键；token 刷新后的
+/// 自动重放沿用同一个键——键在本层每次调用生成一次，重放走同一 headers）。
+/// 点赞/收藏/关注为 PUT/DELETE 语义幂等，无需幂等键。
+class ApiCommunityRepository implements CommunityRepository {
+  ApiCommunityRepository({required this._api, this._uuid = const Uuid()});
+
+  final ApiClient _api;
+  final Uuid _uuid;
+
+  Future<Object?> _request(
+    String path, {
+    String method = 'GET',
+    Object? body,
+    Map<String, Object?>? query,
+    bool idempotent = false,
+  }) async {
+    try {
+      return await _api.request(
+        path,
+        method: method,
+        body: body,
+        query: query,
+        headers: idempotent ? {'Idempotency-Key': _uuid.v4()} : null,
+        requiresAuth: true,
+      );
+    } on ApiBusinessException catch (error) {
+      throw mapCommunityBusinessException(error);
+    }
+  }
+
+  Map<String, dynamic> _asMap(Object? data) => data! as Map<String, dynamic>;
+
+  // ---- media ----
+
+  @override
+  Future<MediaUploadCredentials> createMediaUpload(
+    CreateMediaUploadRequest request,
+  ) async {
+    final data = await _request(
+      '/api/v1/media/uploads',
+      method: 'POST',
+      body: request.toJson(),
+    );
+    return MediaUploadCredentials.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<MediaAsset> completeMediaUpload(String assetId) async {
+    // 幂等由服务端保证：已 ready 重复 confirm 返回 200 同一 asset。
+    final data = await _request(
+      '/api/v1/media/uploads/$assetId/complete',
+      method: 'POST',
+    );
+    return MediaAsset.fromJson(_asMap(data));
+  }
+
+  // ---- posts ----
+
+  @override
+  Future<Post> createPost(CreatePostRequest request) async {
+    final data = await _request(
+      '/api/v1/posts',
+      method: 'POST',
+      body: request.toJson(),
+      idempotent: true,
+    );
+    return Post.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<Post> getPost(String postId) async {
+    final data = await _request('/api/v1/posts/$postId');
+    return Post.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<Post> updatePost(String postId, UpdatePostRequest request) async {
+    final data = await _request(
+      '/api/v1/posts/$postId',
+      method: 'PATCH',
+      body: request.toJson(),
+    );
+    return Post.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<void> deletePost(String postId) async {
+    await _request('/api/v1/posts/$postId', method: 'DELETE');
+  }
+
+  @override
+  Future<CursorPage<Post>> listMyPosts({
+    int? limit,
+    String? cursor,
+    PostStatus? status,
+  }) async {
+    final data = await _request(
+      '/api/v1/me/posts',
+      query: {
+        'limit': ?limit,
+        'cursor': ?cursor,
+        if (status != null) 'status': status.name,
+      },
+    );
+    return CursorPage.fromJson(_asMap(data), Post.fromJson);
+  }
+
+  // ---- feed ----
+
+  @override
+  Future<CursorPage<FeedCard>> getFeed({int? limit, String? cursor}) async {
+    final data = await _request(
+      '/api/v1/feed',
+      query: {'limit': ?limit, 'cursor': ?cursor},
+    );
+    return CursorPage.fromJson(_asMap(data), FeedCard.fromJson);
+  }
+
+  // ---- comments ----
+
+  @override
+  Future<CursorPage<PostComment>> listComments(
+    String postId, {
+    int? limit,
+    String? cursor,
+  }) async {
+    final data = await _request(
+      '/api/v1/posts/$postId/comments',
+      query: {'limit': ?limit, 'cursor': ?cursor},
+    );
+    return CursorPage.fromJson(_asMap(data), PostComment.fromJson);
+  }
+
+  @override
+  Future<PostComment> createComment(
+    String postId,
+    CreateCommentRequest request,
+  ) async {
+    final data = await _request(
+      '/api/v1/posts/$postId/comments',
+      method: 'POST',
+      body: request.toJson(),
+      idempotent: true,
+    );
+    return PostComment.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<void> deleteComment(String commentId) async {
+    // 顶层短路径先例：commentId 全局唯一。
+    await _request('/api/v1/comments/$commentId', method: 'DELETE');
+  }
+
+  // ---- interactions ----
+
+  @override
+  Future<LikeState> likePost(String postId) async {
+    final data = await _request('/api/v1/posts/$postId/like', method: 'PUT');
+    return LikeState.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<LikeState> unlikePost(String postId) async {
+    final data = await _request('/api/v1/posts/$postId/like', method: 'DELETE');
+    return LikeState.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<BookmarkState> bookmarkPost(String postId) async {
+    final data = await _request(
+      '/api/v1/posts/$postId/bookmark',
+      method: 'PUT',
+    );
+    return BookmarkState.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<BookmarkState> unbookmarkPost(String postId) async {
+    final data = await _request(
+      '/api/v1/posts/$postId/bookmark',
+      method: 'DELETE',
+    );
+    return BookmarkState.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<CursorPage<FeedCard>> listMyBookmarks({
+    int? limit,
+    String? cursor,
+  }) async {
+    final data = await _request(
+      '/api/v1/me/bookmarks',
+      query: {'limit': ?limit, 'cursor': ?cursor},
+    );
+    return CursorPage.fromJson(_asMap(data), FeedCard.fromJson);
+  }
+
+  // ---- follows ----
+
+  @override
+  Future<FollowState> followUser(String userId) async {
+    final data = await _request('/api/v1/users/$userId/follow', method: 'PUT');
+    return FollowState.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<FollowState> unfollowUser(String userId) async {
+    final data = await _request(
+      '/api/v1/users/$userId/follow',
+      method: 'DELETE',
+    );
+    return FollowState.fromJson(_asMap(data));
+  }
+
+  @override
+  Future<FollowStats> getFollowStats(String userId) async {
+    final data = await _request('/api/v1/users/$userId/follow-stats');
+    return FollowStats.fromJson(_asMap(data));
+  }
+}

lib/features/community/toggle_sync.dart

@@ -0,0 +1,142 @@
+import 'dart:async';
+
+/// 服务端返回的开关权威终态（LikeState / BookmarkState 的统一投影）。
+class ToggleOutcome {
+  const ToggleOutcome({required this.active, required this.count});
+
+  final bool active;
+  final int count;
+}
+
+/// 内存副本当前读数（乐观翻转与回滚校验的基准）。
+class ToggleReading {
+  const ToggleReading({required this.active, required this.count});
+
+  final bool active;
+  final int count;
+}
+
+/// 点赞 / 收藏共用的乐观更新小状态机（03 号评估 §3 定稿的数据层部分）：
+/// **乐观翻转 + 快照回滚 + 单飞合并意图 + 代次守卫**。字段读写与端点
+/// 全部参数化，like / bookmark 各持一实例，不复制两份逻辑。
+///
+/// 对每个 id 的一轮「操作链」：
+/// 1. 点击立即经 [write] 翻转内存副本（UI 同帧反馈由持有方 notify）；
+/// 2. 非在途则记快照、发请求（PUT/DELETE 语义幂等，重放安全）；
+///    在途则只把新意图并入 pendingTarget，**不发新请求**（单飞）；
+/// 3. 成功：pendingTarget 与已确认态不一致 → 以 pendingTarget 补发一次
+///    （连续快速点击至多两个在途请求，中间抖动全被合并）；一致 → 用服务端
+///    权威计数覆盖乐观计数（吸收他人并发造成的偏差），清状态；
+/// 4. 失败：恢复链起点快照（先校验 id 仍可读且当前态仍是本轮乐观目标，
+///    避免覆盖新数据），经 [onError] 轻提示，**不自动重试**；
+/// 5. 代次守卫：响应到达时 [generation] 与链起点不符（期间发生过刷新，
+///    列表已被服务端数据整体替换）→ 丢弃该响应，不覆盖不回滚。
+class ToggleSync {
+  ToggleSync({
+    required this._read,
+    required this._write,
+    required this._send,
+    required this._generation,
+    this._onError,
+  });
+
+  final ToggleReading? Function(String id) _read;
+  final void Function(String id, bool active, int count) _write;
+  final Future<ToggleOutcome> Function(String id, bool target) _send;
+  final int Function() _generation;
+  final void Function(String id, Object error)? _onError;
+
+  final Map<String, _ToggleChain> _chains = {};
+
+  /// 该 id 是否有请求在途（测试与调试观测口）。
+  bool isInFlight(String id) => _chains.containsKey(id);
+
+  /// 翻转一次。同步完成乐观写入；网络往返在后台收敛，不外抛。
+  void toggle(String id) {
+    final current = _read(id);
+    if (current == null) return; // 已不在列表（刷新剔除），本次点击作废。
+    final target = !current.active;
+    final optimisticCount = target
+        ? current.count + 1
+        : (current.count - 1 < 0 ? 0 : current.count - 1);
+    _write(id, target, optimisticCount);
+
+    final chain = _chains[id];
+    if (chain != null) {
+      chain.pendingTarget = target;
+      return;
+    }
+    final started = _ToggleChain(
+      snapshot: current,
+      generation: _generation(),
+      target: target,
+    );
+    _chains[id] = started;
+    unawaited(_run(id, started));
+  }
+
+  /// 登出 / 整体刷新清态：丢弃全部链（在途响应因代次或链失配被丢弃）。
+  void reset() => _chains.clear();
+
+  Future<void> _run(String id, _ToggleChain chain) async {
+    while (true) {
+      ToggleOutcome outcome;
+      try {
+        outcome = await _send(id, chain.target);
+      } catch (error) {
+        if (_chains[id] == chain && _generation() == chain.generation) {
+          final current = _read(id);
+          final lastTarget = chain.pendingTarget ?? chain.target;
+          // 回滚前校验：id 仍可读且当前态仍是本轮乐观写入的目标态。
+          if (current != null && current.active == lastTarget) {
+            _write(id, chain.snapshot.active, chain.snapshot.count);
+          }
+          _onError?.call(id, error);
+        }
+        _release(id, chain);
+        return;
+      }
+
+      if (_chains[id] != chain || _generation() != chain.generation) {
+        _release(id, chain);
+        return; // 代次不符 / 已被 reset：丢弃响应，不覆盖不回滚。
+      }
+
+      final pending = chain.pendingTarget;
+      if (pending != null && pending != outcome.active) {
+        chain.target = pending;
+        chain.pendingTarget = null;
+        continue; // 以最终意图补发一次。
+      }
+
+      _write(id, outcome.active, outcome.count);
+      _release(id, chain);
+      return;
+    }
+  }
+
+  void _release(String id, _ToggleChain chain) {
+    if (_chains[id] == chain) _chains.remove(id);
+  }
+}
+
+/// 一轮操作链的在途状态。
+class _ToggleChain {
+  _ToggleChain({
+    required this.snapshot,
+    required this.generation,
+    required this.target,
+  });
+
+  /// 链起点快照（回滚基准）。
+  final ToggleReading snapshot;
+
+  /// 链起点的刷新代次。
+  final int generation;
+
+  /// 当前在途请求的目标态。
+  bool target;
+
+  /// 在途期间用户新点出的最终意图（完成后据此决定是否补发）。
+  bool? pendingTarget;
+}