feat: 评论支持回复（两级 + @某人）

不做无限层级——手机屏幕撑不住层层缩进，读到第四层就没法看了。
微信、小红书、B站清一色是两级：一级评论 + 其下的回复列表，回复里
用「回复 @某人」表达指向谁。

数据结构：comments 加 parent_id + reply_to_name。回复的回复会被
压平到同一条一级评论下（parent_id 取爷爷的），同时把被回复人的名字
记进 reply_to_name —— 这样既保住两级，又不丢「在跟谁说话」的信息。

几个容易做错的地方：
- 一次查完这一页所有一级评论的回复，不是每条一次查询（N+1）
- 一级评论默认只带 3 条回复，其余点「展开全部 N 条」再拉，避免热门
  评论一次返回几百条
- 删一级评论要连它下面的回复一起删，否则回复变成挂在空处的孤儿；
  帖子的 comment_count 也要按实际删除条数减，不是减 1
- total 统计含回复，和帖子上显示的数字对得上
- replies 为空时返回 []，不是 null

实测四条评论（含一条回复的回复）：
  ▸ 甲：一级评论   （2 条回复）
      └ 乙：多久了？
      └ 甲 回复 乙：三天了
  ▸ 乙：另一条一级评论   （0 条回复）
删掉第一条一级评论后 total 4→1，comment_count 同步。

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

pets-be/internal/handler/community.go

@@ -115,6 +115,7 @@ func (h *Handler) ListComments(c *gin.Context) {
 type commentReq struct {
 	Content  string   `json:"content"`
 	Images   []string `json:"images"`
+	ParentID string   `json:"parent_id"` // 回复某条评论时传它的 id
 }
 
 // CreateComment POST /api/posts/:id/comments
@@ -128,7 +129,7 @@ func (h *Handler) CreateComment(c *gin.Context) {
 		response.FailParams(c, "评论内容不能为空")
 		return
 	}
-	comment, err := h.svc.CreateComment(middleware.UserID(c), idParam(c, "id"), req.Content, req.Images)
+	comment, err := h.svc.CreateComment(middleware.UserID(c), idParam(c, "id"), req.Content, req.Images, req.ParentID)
 	if err != nil {
 		respondErr(c, err)
 		return
@@ -171,3 +172,13 @@ func (h *Handler) DeleteOwnComment(c *gin.Context) {
 	}
 	response.OK(c, gin.H{"deleted": true})
 }
+
+// ListReplies GET /api/comments/:id/replies 展开某条评论的全部回复
+func (h *Handler) ListReplies(c *gin.Context) {
+	list, err := h.svc.ListReplies(middleware.UserID(c), idParam(c, "id"))
+	if err != nil {
+		respondErr(c, err)
+		return
+	}
+	response.OK(c, list)
+}

pets-be/internal/model/comment.go

@@ -10,7 +10,14 @@ type Comment struct {
 	AuthorName string         `gorm:"size:64" json:"author_name"`
 	Content    string         `gorm:"size:512" json:"content"`
 	Images     datatypes.JSON `json:"images"`
+	// 两级评论：ParentID 为空是一级评论，否则是某条一级评论下的回复。
+	// 不做无限层级——手机上层层缩进读到第四层就没法看了，
+	// 主流产品（微信、小红书、B站）都是两级 + @某人 表达指向。
+	ParentID    string `gorm:"size:24;index" json:"parent_id"`
+	ReplyToName string `gorm:"size:64" json:"reply_to_name"`
 	Status      string `gorm:"size:16;default:published" json:"status"`
 
 	IsSelf  bool      `gorm:"-" json:"is_self"` // 计算字段：是不是我自己发的
+	Replies []Comment `gorm:"-" json:"replies"` // 计算字段：一级评论下挂的回复
+	ReplyN  int       `gorm:"-" json:"reply_n"` // 回复总数（可能多于返回的条数）
 }

pets-be/internal/router/router.go

@@ -100,6 +100,7 @@ func registerUserAPI(api *gin.RouterGroup, h *handler.Handler, jm *appjwt.Manage
 	g.POST("/posts/:id/comments", h.CreateComment)
 	g.DELETE("/posts/:id", h.DeleteOwnPost)
 	g.DELETE("/comments/:id", h.DeleteOwnComment)
+	g.GET("/comments/:id/replies", h.ListReplies)
 
 	g.GET("/articles", h.ListArticles)
 	g.POST("/feedback", h.CreateFeedback)

pets-be/internal/service/community.go

@@ -193,23 +193,67 @@ func (s *Service) postLikeCount(postID string) (int, error) {
 
 // ListComments 评论分页
 func (s *Service) ListComments(userID, postID string, offset, limit int) ([]model.Comment, int64, error) {
-	q := s.db.Model(&model.Comment{}).Where("post_id = ? AND status = ?", postID, "published")
+	base := func() *gorm.DB {
+		return s.db.Model(&model.Comment{}).Where("post_id = ? AND status = ?", postID, "published")
+	}
+	// total 是这条帖子的评论总数（含回复），和帖子上显示的数字对得上
 	var total int64
-	if err := q.Count(&total).Error; err != nil {
+	if err := base().Count(&total).Error; err != nil {
 		return nil, 0, err
 	}
-	var comments []model.Comment
+	// 只分页一级评论，回复跟着它爹一起返回
-	if err := q.Order("id desc").Offset(offset).Limit(limit).Find(&comments).Error; err != nil {
+	var roots []model.Comment
+	if err := base().Where("parent_id = ? OR parent_id IS NULL", "").
+		Order("id desc").Offset(offset).Limit(limit).Find(&roots).Error; err != nil {
 		return nil, 0, err
 	}
-	for i := range comments {
+	if len(roots) == 0 {
-		comments[i].IsSelf = comments[i].UserID == userID
+		return []model.Comment{}, total, nil
 	}
-	return comments, total, nil
+
+	ids := make([]string, 0, len(roots))
+	for i := range roots {
+		roots[i].IsSelf = roots[i].UserID == userID
+		ids = append(ids, roots[i].ID)
+	}
+	// 一次查完这一页所有一级评论的回复，不要每条一次查询
+	var replies []model.Comment
+	s.db.Where("parent_id IN ? AND status = ?", ids, "published").Order("id asc").Find(&replies)
+	byParent := map[string][]model.Comment{}
+	for i := range replies {
+		replies[i].IsSelf = replies[i].UserID == userID
+		byParent[replies[i].ParentID] = append(byParent[replies[i].ParentID], replies[i])
+	}
+	for i := range roots {
+		list := byParent[roots[i].ID]
+		if list == nil {
+			list = []model.Comment{} // 空切片而不是 nil，否则 JSON 出来是 null
+		}
+		roots[i].ReplyN = len(list)
+		// 默认只带前 3 条，其余等前端点「展开」再要，避免热门评论一次拉几百条
+		if len(list) > 3 {
+			list = list[:3]
+		}
+		roots[i].Replies = list
+	}
+	return roots, total, nil
+}
+
+// ListReplies 展开某条一级评论下的全部回复
+func (s *Service) ListReplies(userID, commentID string) ([]model.Comment, error) {
+	var list []model.Comment
+	if err := s.db.Where("parent_id = ? AND status = ?", commentID, "published").
+		Order("id asc").Find(&list).Error; err != nil {
+		return nil, err
+	}
+	for i := range list {
+		list[i].IsSelf = list[i].UserID == userID
+	}
+	return list, nil
 }
 
 // CreateComment 评论
-func (s *Service) CreateComment(userID, postID string, content string, images []string) (*model.Comment, error) {
+func (s *Service) CreateComment(userID, postID string, content string, images []string, parentID string) (*model.Comment, error) {
 	if _, err := s.GetPost(postID); err != nil {
 		return nil, err
 	}
@@ -218,7 +262,23 @@ func (s *Service) CreateComment(userID, postID string, content string, images []
 	if err := s.db.First(&user, userID).Error; err == nil && user.Nickname != "" {
 		name = user.Nickname
 	}
-	comment := model.Comment{PostID: postID, UserID: userID, AuthorName: name, Content: content, Status: "published"}
+	// 回复的回复仍然挂到同一条一级评论下，保持两级不塌成深树
+	replyTo := ""
+	if parentID != "" {
+		var parent model.Comment
+		if err := s.db.Where("id = ? AND post_id = ?", parentID, postID).First(&parent).Error; err != nil {
+			return nil, ErrNotFound
+		}
+		if parent.ParentID != "" {
+			replyTo = parent.AuthorName
+			parentID = parent.ParentID
+		}
+	}
+
+	comment := model.Comment{
+		PostID: postID, UserID: userID, AuthorName: name, Content: content,
+		Status: "published", ParentID: parentID, ReplyToName: replyTo,
+	}
 	// 配图存 JSON 数组。空数组也要显式写，否则前端拿到 null 还要额外判空
 	if b, err := json.Marshal(images); err == nil && len(images) > 0 {
 		comment.Images = b
@@ -265,7 +325,18 @@ func (s *Service) DeleteOwnComment(userID, commentID string) error {
 			Update("status", "deleted").Error; err != nil {
 			return err
 		}
-		return tx.Model(&model.Post{}).Where("id = ? AND comment_count > 0", c.PostID).
+		// 删一级评论要连它下面的回复一起删，否则回复会变成挂在空处的孤儿
-			UpdateColumn("comment_count", gorm.Expr("comment_count - 1")).Error
+		n := int64(1)
+		if c.ParentID == "" {
+			res := tx.Model(&model.Comment{}).
+				Where("parent_id = ? AND status = ?", commentID, "published").
+				Update("status", "deleted")
+			if res.Error != nil {
+				return res.Error
+			}
+			n += res.RowsAffected
+		}
+		return tx.Model(&model.Post{}).Where("id = ? AND comment_count >= ?", c.PostID, n).
+			UpdateColumn("comment_count", gorm.Expr("comment_count - ?", n)).Error
 	})
 }

pets-fe/components/bottom-sheet/bottom-sheet.js

@@ -119,6 +119,7 @@ Component({
     posterSaving: false,
     centered: false,
     commentImages: [],
+    replyTo: {},
   },
   observers: {
     show: function (show) {
@@ -165,6 +166,7 @@ Component({
         patch.addBreed = '';
         patch.commentText = '';
         patch.commentImages = [];
+        patch.replyTo = {};
         patch.riskData = null;
         patch.saving = false;
       }
@@ -417,6 +419,7 @@ Component({
               // 没有头像字段，用昵称首字做个色块，比一律显示同一个 emoji 强
               initial: (c.author_name || '?').slice(0, 1),
               imgs: Array.isArray(c.images) ? c.images : [],
+              replies: (c.replies || []).map((r) => ({ ...r, timeText: fmtAgo(r.created_at) })),
             })),
           }),
         )
@@ -424,8 +427,9 @@ Component({
     },
     // 长按删除自己的评论
     onDeleteComment(e) {
-      const c = this.data.comments[e.currentTarget.dataset.index];
+      const { id, self } = e.currentTarget.dataset;
-      if (!c || !c.is_self) return;
+      if (!id || !self) return;
+      const c = { id };
       wx.showModal({
         title: '删除评论',
         content: '确定删除这条评论？',
@@ -934,8 +938,13 @@ Component({
       if (!text) return wx.showToast({ title: '写点什么再发', icon: 'none' });
       if (!this.data.postId) return this.close();
       try {
-        await api.createComment(this.data.postId, text, this.data.commentImages.map((i) => i.url));
+        await api.createComment(
-        this.setData({ commentText: '', commentImages: [] });
+          this.data.postId,
+          text,
+          this.data.commentImages.map((i) => i.url),
+          this.data.replyTo.id || '',
+        );
+        this.setData({ commentText: '', commentImages: [], replyTo: {} });
         this.loadComments();
         this.triggerEvent('commented');
       } catch (e) {
@@ -955,6 +964,26 @@ Component({
           wx.showToast({ title: (e && e.message) || '上传失败', icon: 'none' });
         });
     },
+    // 回复某条评论：输入区顶部显示「回复 xxx」，发送时带上 parent_id
+    onReplyTo(e) {
+      const { id, name } = e.currentTarget.dataset;
+      this.setData({ replyTo: { id, name } });
+    },
+    onCancelReply() {
+      this.setData({ replyTo: {} });
+    },
+    // 一级评论默认只带 3 条回复，点开拉全量
+    onExpandReplies(e) {
+      const { id, index } = e.currentTarget.dataset;
+      api
+        .listReplies(id)
+        .then((list) =>
+          this.setData({
+            [`comments[${index}].replies`]: (list || []).map((r) => ({ ...r, timeText: fmtAgo(r.created_at) })),
+          }),
+        )
+        .catch((err) => wx.showToast({ title: (err && err.message) || '加载失败', icon: 'none' }));
+    },
     onPreviewCommentImage(e) {
       const { urls, cur } = e.currentTarget.dataset;
       if (urls && urls.length) wx.previewImage({ urls, current: cur });

pets-fe/components/bottom-sheet/bottom-sheet.wxml

@@ -321,7 +321,7 @@ module.exports.sel = function (map, key, index, def) {
     <block wx:elif="{{innerType === 'comments'}}">
       <view class="sheet-h3">评论 {{comments.length ? comments.length : ''}}</view>
 
-      <view wx:for="{{comments}}" wx:key="id" class="cm" bindlongpress="onDeleteComment" data-index="{{index}}">
+      <view wx:for="{{comments}}" wx:key="id" class="cm">
         <view class="cm-av">{{item.initial}}</view>
         <view class="cm-body">
           <view class="cm-head">
@@ -329,12 +329,28 @@ module.exports.sel = function (map, key, index, def) {
             <text wx:if="{{item.is_self}}" class="mine-tag">我</text>
             <text class="cm-time">{{item.timeText}}</text>
           </view>
-          <view class="cm-text">{{item.content}}</view>
+          <view class="cm-text" bindlongpress="onDeleteComment" data-id="{{item.id}}" data-self="{{item.is_self}}">{{item.content}}</view>
           <view wx:if="{{item.imgs.length}}" class="cm-imgs">
             <image wx:for="{{item.imgs}}" wx:for-item="u" wx:key="*this" class="cm-img"
                    src="{{u}}" mode="aspectFill" catchtap="onPreviewCommentImage"
                    data-urls="{{item.imgs}}" data-cur="{{u}}"></image>
           </view>
+
+          <!-- 回复：只缩进一层。再深就没法在手机上读了 -->
+          <view wx:if="{{item.replies.length}}" class="cm-replies">
+            <view wx:for="{{item.replies}}" wx:for-item="r" wx:key="id" class="cm-reply"
+                  bindlongpress="onDeleteComment" data-id="{{r.id}}" data-self="{{r.is_self}}">
+              <text class="cm-name">{{r.author_name}}</text>
+              <text wx:if="{{r.reply_to_name}}" class="cm-at"> 回复 {{r.reply_to_name}}</text>
+              <text class="cm-name">：</text>{{r.content}}
+            </view>
+            <view wx:if="{{item.reply_n > item.replies.length}}" class="cm-more"
+                  bindtap="onExpandReplies" data-id="{{item.id}}" data-index="{{index}}">
+              展开全部 {{item.reply_n}} 条回复
+            </view>
+          </view>
+
+          <view class="cm-act" bindtap="onReplyTo" data-id="{{item.id}}" data-name="{{item.author_name}}">回复</view>
         </view>
       </view>
 
@@ -342,7 +358,11 @@ module.exports.sel = function (map, key, index, def) {
       <view wx:if="{{comments.length}}" class="cm-tip">长按自己的评论可删除</view>
 
       <view class="cm-editor">
-        <textarea class="textarea cm-ta" placeholder="友善交流，分享你的经验…" placeholder-class="placeholder"
+        <view wx:if="{{replyTo.name}}" class="cm-replying">
+          <text>回复 {{replyTo.name}}</text>
+          <view class="cm-cancel" bindtap="onCancelReply"><pt-icon name="close" size="{{24}}"></pt-icon></view>
+        </view>
+        <textarea class="textarea cm-ta" placeholder="{{replyTo.name ? '回复 ' + replyTo.name : '友善交流，分享你的经验…'}}" placeholder-class="placeholder"
                   value="{{commentText}}" bindinput="onCommentInput" maxlength="500"
                   auto-height="{{true}}" show-confirm-bar="{{false}}" cursor-spacing="24"></textarea>
         <view wx:if="{{commentImages.length}}" class="img-picker" style="margin-top:16rpx">

pets-fe/components/bottom-sheet/bottom-sheet.wxss

@@ -127,3 +127,16 @@
 .cm-count{margin-left:auto;color:var(--muted2);font-size:var(--fs-cap)}
 .cm-imgs{display:flex;flex-wrap:wrap;gap:var(--sp-1);margin-top:var(--sp-2)}
 .cm-img{width:150rpx;height:150rpx;border-radius:var(--r-sm)}
+
+/* 回复：只缩进一层，再深手机上就没法读了 */
+.cm-replies{margin-top:var(--sp-2);padding:var(--sp-2) var(--sp-3);background:var(--surface-2);border-radius:var(--r-sm)}
+.cm-reply{font-size:var(--fs-sm);line-height:1.6;color:var(--text);padding:4rpx 0}
+.cm-at{color:var(--muted)}
+.cm-more{margin-top:6rpx;font-size:var(--fs-cap);color:var(--primary-dark)}
+.cm-act{margin-top:var(--sp-2);font-size:var(--fs-cap);color:var(--muted)}
+.cm-replying{
+  display:flex;align-items:center;gap:var(--sp-2);margin-bottom:var(--sp-2);
+  padding:var(--sp-1) var(--sp-3);border-radius:var(--r-full);
+  background:var(--primary-soft);color:var(--primary-ink);font-size:var(--fs-cap);align-self:flex-start;
+}
+.cm-cancel{display:flex;align-items:center}

pets-fe/utils/api.js

@@ -108,8 +108,13 @@ const api = {
   deletePost: (id) => request({ url: `/api/posts/${id}`, method: 'DELETE' }),
   deleteComment: (id) => request({ url: `/api/comments/${id}`, method: 'DELETE' }),
   listComments: (id) => request({ url: `/api/posts/${id}/comments` }),
-  createComment: (id, content, images) =>
+  createComment: (id, content, images, parentId) =>
-    request({ url: `/api/posts/${id}/comments`, method: 'POST', data: { content, images: images || [] } }),
+    request({
+      url: `/api/posts/${id}/comments`,
+      method: 'POST',
+      data: { content, images: images || [], parent_id: parentId || '' },
+    }),
+  listReplies: (commentId) => request({ url: `/api/comments/${commentId}/replies` }),
 
   // 文章
   listArticles: () => request({ url: '/api/articles' }),