feat: 评论/帖子编辑历史与编辑标记，内容锁定

- 新增 smartDiff 差异计算与 EditHistoryModal 编辑历史弹窗，替换原 CommentEditHistoryModal - 新增 PostEditedMark 编辑标记展示 - 新增内容锁定机制（content_lock）防止并发编辑冲突 - 审核与通知服务适配
2026-09-25 23:41:45 +08:00
parent cab8230803
commit 5270fee2b7
40 changed files with 2521 additions and 350 deletions
--- a/backend/handler/comment.go
+++ b/backend/handler/comment.go
@@ -2,6 +2,7 @@ package handler

 import (
 	"errors"
+	"fmt"
 	"net/http"
 	"strconv"

@@ -83,7 +84,7 @@ func (h *Handlers) PostComments(c *gin.Context) {

 // CreateCommentRequest 评论请求
 type CreateCommentRequest struct {
-	Content  string `json:"content" binding:"required,min=1"`
+	Content  string `json:"content" binding:"required,min=1,max=5000"`
 	ParentID *uint  `json:"parent_id"` // 非空 = 回复该评论（发为其子评论）
 }

@@ -109,11 +110,24 @@ func (h *Handlers) CreateComment(c *gin.Context) {
 	}
 	// staff 直发；已过审用户在站点开启免审时可直发；其余进待审队列（通过时才发业务通知）
 	status := h.resolvePublishStatus(claims.ID, claims.Role)
-	comment, parent, err := h.Comment.Create(claims.ID, uint(id), req.Content, req.ParentID, status)
+	comment, parent, necroPoints, err := h.Comment.Create(claims.ID, uint(id), req.Content, req.ParentID, status, model.Role(claims.Role))
 	if err != nil {
-		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		switch {
+		case errors.Is(err, service.ErrPostReplyLocked):
+			c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+		case errors.Is(err, service.ErrInsufficientPoints):
+			// 旧帖回复扣分余额不足（文案含具体规则）
+			c.JSON(http.StatusPaymentRequired, gin.H{"error": err.Error()})
+		default:
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		}
 		return
 	}
+	// 旧帖回复扣分：系统提醒本人（ActorID=0，不经过自我通知过滤）
+	if necroPoints > 0 {
+		h.Notification.CreateSystem(claims.ID, model.NotificationTypeNecroReply, uint(id), comment.ID,
+			fmt.Sprintf("您回复了长期没有新回复的旧帖，已扣除 %d 积分", necroPoints))
+	}
 	if comment.Status == model.ContentStatusPublished {
 		if parent == nil {
 			// 主评论：通知帖子作者（排除自己评论自己的帖子）
@@ -146,7 +160,7 @@ func (h *Handlers) UpdateComment(c *gin.Context) {
 		return
 	}
 	var body struct {
-		Content string `json:"content"`
+		Content string `json:"content" binding:"omitempty,min=1,max=5000"`
 	}
 	if err := c.ShouldBindJSON(&body); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
@@ -157,7 +171,9 @@ func (h *Handlers) UpdateComment(c *gin.Context) {
 		switch {
 		case errors.Is(err, service.ErrCommentNotFound):
 			c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
-		case errors.Is(err, service.ErrCommentForbidden):
+		case errors.Is(err, service.ErrCommentForbidden),
+			errors.Is(err, service.ErrCommentPostLocked),
+			errors.Is(err, service.ErrCommentEditLocked):
 			c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
 		case errors.Is(err, service.ErrCommentDeleted),
 			errors.Is(err, service.ErrCommentNotChanged):
@@ -256,3 +272,39 @@ func (h *Handlers) PurgeComment(c *gin.Context) {
 	}
 	c.JSON(http.StatusOK, gin.H{"message": "已彻底删除"})
 }
+
+// CommentEditHistory 评论编辑历史（登录即可见；分页）
+func (h *Handlers) CommentEditHistory(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	cid, err := strconv.ParseUint(c.Param("cid"), 10, 64)
+	if err != nil || cid == 0 {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的评论 ID"})
+		return
+	}
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "10"))
+	items, total, err := h.Comment.ListEditHistory(h.loadActor(claims.ID), uint(cid), page, size)
+	if err != nil {
+		switch {
+		case errors.Is(err, service.ErrCommentNotFound):
+			c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
+		case errors.Is(err, service.ErrCommentForbidden):
+			c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+		default:
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "获取编辑历史失败"})
+		}
+		return
+	}
+	if page < 1 {
+		page = 1
+	}
+	if size < 1 || size > 50 {
+		size = 10
+	}
+	c.JSON(http.StatusOK, gin.H{
+		"items": items,
+		"total": total,
+		"page":  page,
+		"size":  size,
+	})
+}
--- a/backend/handler/moderation.go
+++ b/backend/handler/moderation.go
@@ -193,41 +193,6 @@ func (h *Handlers) AdminPurgeComment(c *gin.Context) {
 	h.execContentAction(c, h.Moderation.PurgeComment)
 }

-// AdminCommentHistory 评论编辑历史（板域 scope；分页）
-func (h *Handlers) AdminCommentHistory(c *gin.Context) {
-	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
-	if err != nil || id == 0 {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的 ID"})
-		return
-	}
-	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
-	size, _ := strconv.Atoi(c.DefaultQuery("size", "10"))
-	items, total, err := h.Comment.ListEditHistory(middleware.CurrentActor(c), uint(id), page, size)
-	if err != nil {
-		switch {
-		case errors.Is(err, service.ErrCommentNotFound):
-			c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
-		case errors.Is(err, service.ErrCommentForbidden):
-			c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
-		default:
-			c.JSON(http.StatusInternalServerError, gin.H{"error": "获取编辑历史失败"})
-		}
-		return
-	}
-	if page < 1 {
-		page = 1
-	}
-	if size < 1 || size > 50 {
-		size = 10
-	}
-	c.JSON(http.StatusOK, gin.H{
-		"items": items,
-		"total": total,
-		"page":  page,
-		"size":  size,
-	})
-}
-
 func (h *Handlers) execContentAction(c *gin.Context, fn func(*service.Actor, uint) error) {
 	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
 	if err != nil || id == 0 {
--- a/backend/handler/post.go
+++ b/backend/handler/post.go
@@ -89,6 +89,7 @@ func (h *Handlers) PostDetail(c *gin.Context) {
 	if claims != nil {
 		post.Liked = h.Like.HasLiked(post.ID, claims.ID)
 	}
+	h.attachNecroReplyHint(claims, post)
 	c.JSON(http.StatusOK, gin.H{"post": post})
 }

@@ -96,7 +97,7 @@ func (h *Handlers) PostDetail(c *gin.Context) {
 type CreatePostRequest struct {
 	BoardID       uint   `json:"board_id" binding:"required"`
 	Title         string `json:"title" binding:"required,min=1,max=256"`
-	Content       string `json:"content" binding:"required,min=1"`
+	Content       string `json:"content" binding:"required,min=1,max=20000"`
 	Tags          string `json:"tags"`
 	PostType      string `json:"post_type"`
 	TypeMeta      string `json:"type_meta"`
@@ -138,7 +139,7 @@ func (h *Handlers) CreatePost(c *gin.Context) {
 // UpdatePostRequest 更新帖子请求
 type UpdatePostRequest struct {
 	Title         string  `json:"title" binding:"omitempty,min=1,max=256"`
-	Content       string  `json:"content" binding:"omitempty,min=1"`
+	Content       string  `json:"content" binding:"omitempty,min=1,max=20000"`
 	Tags          string  `json:"tags"`
 	TypeMeta      *string `json:"type_meta"`
 	AttachmentIDs *[]uint `json:"attachment_ids"`
@@ -172,6 +173,42 @@ func (h *Handlers) UpdatePost(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"post": post})
 }

+// PostEditHistory 帖子编辑历史（登录即可见；分页）
+func (h *Handlers) PostEditHistory(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil || id == 0 {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的帖子 ID"})
+		return
+	}
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "10"))
+	items, total, err := h.Post.ListEditHistory(h.loadActor(claims.ID), uint(id), page, size)
+	if err != nil {
+		switch {
+		case errors.Is(err, service.ErrPostNotFound):
+			c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
+		case errors.Is(err, service.ErrPostForbidden):
+			c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+		default:
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "获取编辑历史失败"})
+		}
+		return
+	}
+	if page < 1 {
+		page = 1
+	}
+	if size < 1 || size > 50 {
+		size = 10
+	}
+	c.JSON(http.StatusOK, gin.H{
+		"items": items,
+		"total": total,
+		"page":  page,
+		"size":  size,
+	})
+}
+
 // UnlockPostContent 积分解锁正文
 func (h *Handlers) UnlockPostContent(c *gin.Context) {
 	claims := middleware.CurrentUser(c)
@@ -239,6 +276,7 @@ func (h *Handlers) UnlockPostPassword(c *gin.Context) {
 	if claims != nil {
 		post.Liked = h.Like.HasLiked(post.ID, claims.ID)
 	}
+	h.attachNecroReplyHint(claims, post)
 	c.JSON(http.StatusOK, gin.H{"post": post})
 }

@@ -539,6 +577,52 @@ func (h *Handlers) ToggleRecommend(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"recommended": rec})
 }

+// TogglePostLock 切换帖子手动锁定（管理员及以上；锁定后普通用户不可编辑/回复，staff 豁免）
+func (h *Handlers) TogglePostLock(c *gin.Context) {
+	if !h.requireAdminOrAbove(c) {
+		return
+	}
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的帖子 ID"})
+		return
+	}
+	locked, err := h.Post.ToggleLock(uint(id))
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"locked": locked})
+}
+
+// attachNecroReplyHint 旧帖回复确认提示：仅当 viewer 已登录、非 staff、规则开启、
+// 帖子判定为旧帖、且其评论将直发（待审不扣分不提醒，不弹窗）时返回
+func (h *Handlers) attachNecroReplyHint(claims *service.UserClaims, detail *service.PostDetail) {
+	if claims == nil || detail == nil || detail.Tombstone || detail.NecroReply != nil {
+		return
+	}
+	if model.IsStaff(model.Role(claims.Role)) {
+		return
+	}
+	afterHours, err1 := h.Setting.NecroReplyAfterHours()
+	penalty, err2 := h.Setting.NecroReplyPenalty()
+	if err1 != nil || err2 != nil || afterHours <= 0 || penalty <= 0 {
+		return
+	}
+	// 旧帖基准：最后回复时间；无回复（null）回落发帖时间
+	baseline := detail.CreatedAt
+	if detail.LastReplyAt != nil {
+		baseline = *detail.LastReplyAt
+	}
+	if !service.IsNecroReply(baseline, afterHours, time.Now()) {
+		return
+	}
+	if h.resolvePublishStatus(claims.ID, claims.Role) != model.ContentStatusPublished {
+		return
+	}
+	detail.NecroReply = &service.NecroReplyHint{AfterHours: afterHours, Penalty: penalty}
+}
+
 // requireAdminOrAbove 置顶/加精仅管理员及以上可用；以 DB Actor 为准
 func (h *Handlers) requireAdminOrAbove(c *gin.Context) bool {
 	claims := middleware.CurrentUser(c)
@@ -556,7 +640,9 @@ func respondPostModError(c *gin.Context, err error) {
 	case errors.Is(err, service.ErrPostNotFound):
 		c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
 	case errors.Is(err, service.ErrPostForbidden),
-		errors.Is(err, service.ErrAuthorProtected):
+		errors.Is(err, service.ErrAuthorProtected),
+		errors.Is(err, service.ErrPostLocked),
+		errors.Is(err, service.ErrPostEditLocked):
 		c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
 	case errors.Is(err, service.ErrPollOptionsLocked),
 		errors.Is(err, service.ErrLotteryPrizesLocked):
--- a/backend/handler/setting.go
+++ b/backend/handler/setting.go
@@ -68,6 +68,11 @@ type updateSettingsRequest struct {
 	PointsReplyDailyCap   *int `json:"points_reply_daily_cap"`
 	PointsRecommendReward *int `json:"points_recommend_reward"`

+	PostEditLockHours    *int `json:"post_edit_lock_hours"`
+	CommentEditLockHours *int `json:"comment_edit_lock_hours"`
+	NecroReplyAfterHours *int `json:"necro_reply_after_hours"`
+	NecroReplyPenalty    *int `json:"necro_reply_penalty"`
+
 	Levels *[]model.LevelDef `json:"levels"`
 	LevelsFx *bool           `json:"levels_fx"`
 }
@@ -120,6 +125,11 @@ func settingsPayload(saved service.PublicSiteSettings) gin.H {
 		"points_reply_daily_cap":   saved.PointsReplyDailyCap,
 		"points_recommend_reward":  saved.PointsRecommendReward,

+		"post_edit_lock_hours":     saved.PostEditLockHours,
+		"comment_edit_lock_hours":  saved.CommentEditLockHours,
+		"necro_reply_after_hours":  saved.NecroReplyAfterHours,
+		"necro_reply_penalty":      saved.NecroReplyPenalty,
+
 		"levels": saved.Levels,
 		"levels_fx": saved.LevelsFx,
 	}
@@ -142,7 +152,9 @@ func (req *updateSettingsRequest) hasAny() bool {
 		req.PointsCheckinBase != nil || req.PointsStreakEveryDays != nil || req.PointsStreakBonus != nil ||
 		req.PointsPostReward != nil || req.PointsPostDailyCap != nil ||
 		req.PointsReplyReward != nil || req.PointsReplyDailyCap != nil ||
-		req.PointsRecommendReward != nil || req.Levels != nil || req.LevelsFx != nil
+		req.PointsRecommendReward != nil || req.Levels != nil || req.LevelsFx != nil ||
+		req.PostEditLockHours != nil || req.CommentEditLockHours != nil ||
+		req.NecroReplyAfterHours != nil || req.NecroReplyPenalty != nil
 }

 // AdminGetSettings 超管读取站点设置（与公开 payload 字段一致）
@@ -247,6 +259,29 @@ func (h *Handlers) UpdateSettings(c *gin.Context) {
 			return
 		}
 	}
+	lockRules := []struct {
+		req  *int
+		set  func(int) error
+		hint string
+	}{
+		{req.PostEditLockHours, h.Setting.SetPostEditLockHours, "帖子可编辑时长须为 0–8760 小时"},
+		{req.CommentEditLockHours, h.Setting.SetCommentEditLockHours, "评论可编辑时长须为 0–8760 小时"},
+		{req.NecroReplyAfterHours, h.Setting.SetNecroReplyAfterHours, "旧帖回复阈值须为 0–8760 小时"},
+		{req.NecroReplyPenalty, h.Setting.SetNecroReplyPenalty, "旧帖回复扣分须为 0–100"},
+	}
+	for _, r := range lockRules {
+		if r.req == nil {
+			continue
+		}
+		if err := r.set(*r.req); err != nil {
+			if errors.Is(err, service.ErrInvalidSiteSetting) {
+				c.JSON(http.StatusBadRequest, gin.H{"error": r.hint})
+				return
+			}
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "保存站点设置失败"})
+			return
+		}
+	}
 	pointsRules := []struct {
 		req  *int
 		set  func(int) error
--- a/backend/model/db.go
+++ b/backend/model/db.go
@@ -57,7 +57,7 @@ func InitDB(dsn string) error {

 	if err := db.AutoMigrate(
 		&TemporaryUpload{}, &ModuleConfig{}, &SettingsAudit{}, &ActionCounter{}, &MailTask{}, &EmailChallenge{}, &StoredObject{},
-		&User{}, &Board{}, &Post{}, &Comment{}, &CommentEditHistory{}, &RefreshToken{}, &Like{}, &Notification{}, &Checkin{},
+		&User{}, &Board{}, &Post{}, &PostEditHistory{}, &Comment{}, &CommentEditHistory{}, &RefreshToken{}, &Like{}, &Notification{}, &Checkin{},
 		&Announcement{}, &SitePage{}, &SiteSetting{}, &SiteDailyStats{}, &SiteDailyVisitor{}, &VisitEvent{}, &Attachment{}, &UserBoard{}, &LoginLog{},
 		&ChatRoom{}, &ChatRoomMember{}, &ChatMessage{},
 		&PointLedger{}, &PostContentUnlock{}, &PostAttachment{}, &PostAttachmentUnlock{},
--- a/backend/model/models.go
+++ b/backend/model/models.go
@@ -220,6 +220,7 @@ type Post struct {
 	TypeMeta      string `gorm:"type:text;default:''" json:"type_meta"`              // 类型扩展 JSON（投票/悬赏/抽奖壳）
 	Pinned        int    `gorm:"default:0" json:"pinned"`
 	Recommended   bool   `gorm:"default:false;index" json:"recommended"`
+	Locked        bool   `gorm:"default:false;index" json:"locked"` // 管理员手动锁定：普通用户不可编辑/回复（staff 豁免）
 	Status        string `gorm:"size:16;default:published;index" json:"status"`
 	LikeCount     int    `gorm:"default:0" json:"like_count"`
 	ViewCount     int    `gorm:"default:0" json:"view_count"`
@@ -327,6 +328,7 @@ const (
 	PointReasonStreakBonus    = "streak_bonus" // 连续签到里程碑加成
 	PointReasonRecommend      = "recommend_reward" // 帖子被推荐奖励（可配置，0=关闭，每帖仅一次）
 	PointReasonAdminAdjust    = "admin_adjust"     // 管理员手动调整（加分计累计可升级；扣分仅扣余额）
+	PointReasonNecroReply     = "necro_reply"      // 旧帖回复扣分（可配置，0=关闭）
 )

 // PostPollVote 投票记录（多选时同一用户多行）
@@ -412,6 +414,16 @@ type CommentEditHistory struct {
 	CreatedAt  time.Time `gorm:"index" json:"created_at"`
 }

+// PostEditHistory 帖子修订快照（每次编辑前的旧标题/旧正文；登录用户可见）
+type PostEditHistory struct {
+	ID         uint      `gorm:"primaryKey" json:"id"`
+	PostID     uint      `gorm:"index;not null" json:"post_id"`
+	EditorID   uint      `gorm:"index;not null" json:"editor_id"`
+	OldTitle   string    `gorm:"size:256;not null;default:''" json:"old_title"`
+	OldContent string    `gorm:"type:text;not null" json:"old_content"`
+	CreatedAt  time.Time `gorm:"index" json:"created_at"`
+}
+
 // Like 点赞记录（联合唯一索引防止重复点赞）
 type Like struct {
 	ID        uint      `gorm:"primaryKey" json:"id"`
@@ -440,6 +452,7 @@ const (
 	NotificationTypePendingReview = "pending_review" // 有新内容待审核（发给可审者）
 	NotificationTypeBadge         = "badge"          // 获得管理员颁发的徽章
 	NotificationTypeDeleted       = "deleted"        // 帖子被管理员删除
+	NotificationTypeNecroReply    = "necro_reply"    // 回复旧帖提醒（系统，ActorID=0）
 )

 // Notification 站内通知
--- a/backend/router/router.go
+++ b/backend/router/router.go
@@ -204,6 +204,9 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 		api.PUT("/profile", h.UpdateProfile)
 		api.POST("/posts", middleware.StaffExempt(middleware.RateLimitMiddleware(limiter, service.RatePost)), h.CreatePost)
 		api.PUT("/posts/:id", h.UpdatePost)
+		api.GET("/posts/:id/history", h.PostEditHistory)
+		// 评论编辑历史（登录即可见；顶层路由：管理后台无 post_id 上下文）
+		api.GET("/comments/:cid/history", h.CommentEditHistory)
 		api.POST("/posts/:id/unlock", middleware.StaffExempt(middleware.RateLimitUserMiddleware(limiter, service.RateInteract)), h.UnlockPostContent)
 		api.POST("/posts/:id/poll/vote", middleware.StaffExempt(middleware.RateLimitUserMiddleware(limiter, service.RateInteract)), h.VotePoll)
 		api.POST("/posts/:id/poll/close", h.ClosePoll)
@@ -215,6 +218,7 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 		api.DELETE("/posts/:id", h.DeletePost)
 		api.PUT("/posts/:id/pin", h.TogglePin)
 		api.PUT("/posts/:id/recommend", h.ToggleRecommend)
+		api.PUT("/posts/:id/lock", h.TogglePostLock)
 		api.POST("/posts/:id/like", h.ToggleLike)
 		api.POST("/posts/:id/comments", middleware.StaffExempt(middleware.RateLimitMiddleware(limiter, service.RateComment)), h.CreateComment)
 		api.PUT("/posts/:id/comments/:cid", middleware.StaffExempt(middleware.RateLimitMiddleware(limiter, service.RateComment)), h.UpdateComment)
@@ -293,7 +297,6 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 		staffAPI.DELETE("/content/comments/:id", h.AdminSoftDeleteComment)
 		staffAPI.PUT("/content/comments/:id/restore", h.AdminRestoreComment)
 		staffAPI.DELETE("/content/comments/:id/purge", h.AdminPurgeComment)
-		staffAPI.GET("/content/comments/:id/history", h.AdminCommentHistory)

 		// 积分与类型帖概览（管理员及以上）
 		staffAPI.GET("/economy", authMW.RequirePerm(service.PermAnnouncements), h.AdminPointsStats)
--- a/backend/service/admin_content.go
+++ b/backend/service/admin_content.go
@@ -81,6 +81,7 @@ type AdminContentComment struct {
 	BoardID   uint       `json:"board_id"`
 	Content   string     `json:"content"`
 	Status    string     `json:"status"`
+	Edited    bool       `json:"edited"` // 相对创建已编辑（同评论侧规则），用于隐藏无修订的历史入口
 	Deleted   bool       `json:"deleted"`
 	DeletedAt *time.Time `json:"deleted_at,omitempty"`
 	CreatedAt time.Time  `json:"created_at"`
@@ -223,13 +224,14 @@ func (s *ModerationService) ListAdminComments(actor *Actor, status, keyword stri
 		Content   string
 		Status    string
 		CreatedAt time.Time
+		UpdatedAt time.Time
 		DeletedAt gorm.DeletedAt
 		BoardID   uint
 		PostTitle string
 		UserID    uint
 	}
 	var rows []row
-	if err := q.Select("comments.id, comments.post_id, comments.content, comments.status, comments.created_at, comments.deleted_at, posts.board_id, posts.title AS post_title, comments.user_id").
+	if err := q.Select("comments.id, comments.post_id, comments.content, comments.status, comments.created_at, comments.updated_at, comments.deleted_at, posts.board_id, posts.title AS post_title, comments.user_id").
 		Order("comments.id DESC").
 		Offset((page - 1) * adminContentPageSize).Limit(adminContentPageSize).
 		Scan(&rows).Error; err != nil {
@@ -276,6 +278,7 @@ func (s *ModerationService) ListAdminComments(actor *Actor, status, keyword stri
 			BoardID:   r.BoardID,
 			Content:   r.Content,
 			Status:    r.Status,
+			Edited:    r.UpdatedAt.Sub(r.CreatedAt) > time.Minute,
 			CreatedAt: r.CreatedAt,
 			Board:     boards[r.BoardID],
 			User:      users[r.UserID],
@@ -354,7 +357,8 @@ func (s *ModerationService) SoftDeletePost(actor *Actor, id uint, deleteType, de
 		"delete_reason": deleteReason,
 		"deleted_by":    actor.ID,
 	}
-	if err := s.db.Model(post).Updates(updates).Error; err != nil {
+	// UpdateColumns：删除元数据非内容编辑，不刷新 updated_at（详情页「更新于」由该字段推导）
+	if err := s.db.Model(post).UpdateColumns(updates).Error; err != nil {
 		return 0, err
 	}
 	if err := s.db.Delete(post).Error; err != nil {
@@ -375,7 +379,8 @@ func (s *ModerationService) RestorePost(actor *Actor, id uint) error {
 	if !post.DeletedAt.Valid {
 		return errors.New("帖子未被删除")
 	}
-	return s.db.Unscoped().Model(&model.Post{}).Where("id = ?", id).Update("deleted_at", nil).Error
+	// UpdateColumn：恢复非内容编辑，不刷新 updated_at
+	return s.db.Unscoped().Model(&model.Post{}).Where("id = ?", id).UpdateColumn("deleted_at", nil).Error
 }

 // PurgePost 彻底删除已软删帖子及其评论（仅站长）
@@ -391,6 +396,9 @@ func (s *ModerationService) PurgePost(actor *Actor, id uint) error {
 		return ErrContentNotDeleted
 	}
 	return s.db.Transaction(func(tx *gorm.DB) error {
+		if err := tx.Unscoped().Where("post_id = ?", id).Delete(&model.PostEditHistory{}).Error; err != nil {
+			return err
+		}
 		if err := tx.Unscoped().Where("post_id = ?", id).Delete(&model.Comment{}).Error; err != nil {
 			return err
 		}
@@ -430,7 +438,8 @@ func (s *ModerationService) SoftDeleteComment(actor *Actor, id uint, deleteType,
 		"delete_reason": deleteReason,
 		"deleted_by":    actor.ID,
 	}
-	if err := s.db.Model(cm).Updates(updates).Error; err != nil {
+	// UpdateColumns：删除元数据非内容编辑，不刷新 updated_at（该字段用于 edited 判定）
+	if err := s.db.Model(cm).UpdateColumns(updates).Error; err != nil {
 		return err
 	}
 	if err := s.db.Delete(cm).Error; err != nil {
@@ -461,7 +470,8 @@ func (s *ModerationService) RestoreComment(actor *Actor, id uint) error {
 		"delete_reason": "",
 		"deleted_by":    0,
 	}
-	if err := s.db.Unscoped().Model(&model.Comment{}).Where("id = ?", id).Updates(updates).Error; err != nil {
+	// UpdateColumns：恢复非内容编辑，不刷新 updated_at（该字段用于 edited 判定）
+	if err := s.db.Unscoped().Model(&model.Comment{}).Where("id = ?", id).UpdateColumns(updates).Error; err != nil {
 		return err
 	}
 	if cm.Status == model.ContentStatusPublished {
--- a/backend/service/announcement.go
+++ b/backend/service/announcement.go
@@ -3,6 +3,7 @@ package service
 import (
 	"errors"
 	"strings"
+	"unicode/utf8"

 	"github.com/freefire/jiang13-bbs/markdown"
 	"github.com/freefire/jiang13-bbs/model"
@@ -49,6 +50,9 @@ func (in *AnnouncementInput) normalize(existing *model.Announcement) error {
 	if in.Content == "" {
 		return errors.New("内容不能为空")
 	}
+	if utf8.RuneCountInString(in.Content) > 20000 {
+		return errors.New("内容不能超过 20000 字")
+	}
 	if err := markdown.ValidateHideContent(in.Content); err != nil {
 		return err
 	}
--- a/backend/service/comment.go
+++ b/backend/service/comment.go
@@ -2,6 +2,7 @@ package service

 import (
 	"errors"
+	"fmt"
 	"strings"
 	"time"

@@ -18,8 +19,29 @@ var (
 	ErrCommentNotDeleted  = errors.New("评论未被删除")
 	ErrCommentNotChanged  = errors.New("评论内容未变更")
 	ErrCommentDeleted     = errors.New("已删除的评论不可编辑")
+	ErrPostReplyLocked    = errors.New("帖子已被锁定，无法回复")
+	ErrCommentPostLocked  = errors.New("帖子已被锁定，评论无法编辑")
+	ErrCommentEditLocked  = errors.New("评论已超过可编辑时限，无法编辑")
 )

+// commentEditLockHours 评论可编辑时长（setting 未注入或读取出错时=0 关闭）
+func commentEditLockHours(setting *SettingService) int {
+	if setting == nil {
+		return 0
+	}
+	hours, err := setting.CommentEditLockHours()
+	if err != nil {
+		return 0
+	}
+	return hours
+}
+
+// IsNecroReply 旧帖判定：lastReplyAt（最后回复时间，无回复回落发帖时间）距 now 超过 afterHours。
+// staff 豁免、规则开关与回落基准由调用方负责。
+func IsNecroReply(lastReplyAt time.Time, afterHours int, now time.Time) bool {
+	return afterHours > 0 && now.Sub(lastReplyAt) > time.Duration(afterHours)*time.Hour
+}
+
 // CommentService 评论服务
 type CommentService struct {
 	db *gorm.DB
@@ -303,17 +325,18 @@ func applyCommentListVisibility(db *gorm.DB, boardID, viewerID uint, actor *Acto
 // Create 创建评论（parentID 为 nil 时发主评论/楼层，否则发为对应评论的子回复）。
 // status 由 handler 按角色计算：管理团队直发 published，普通用户进入 pending；
 // pending 评论不计入 comment_count，审核通过时才 +1。
-// 返回：新评论、父评论（子回复时非 nil，供通知定位被回复人）
-func (s *CommentService) Create(userID, postID uint, content string, parentID *uint, status string) (*model.Comment, *model.Comment, error) {
+// actorRole 用于锁帖与旧帖扣分规则的 staff 豁免判断。
+// 返回：新评论、父评论（子回复时非 nil，供通知定位被回复人）、旧帖扣分值（0=未触发）
+func (s *CommentService) Create(userID, postID uint, content string, parentID *uint, status string, actorRole model.Role) (*model.Comment, *model.Comment, int, error) {
 	if err := NewOperations(s.db, nil).Filter("comment", content, userID); err != nil {
-		return nil, nil, err
+		return nil, nil, 0, err
 	}
 	content = strings.TrimSpace(content)
 	if content == "" {
-		return nil, nil, errors.New("评论内容不能为空")
+		return nil, nil, 0, errors.New("评论内容不能为空")
 	}
 	if err := rejectHideBlocks(content, ErrCommentHideNotAllowed); err != nil {
-		return nil, nil, err
+		return nil, nil, 0, err
 	}
 	if status != model.ContentStatusPending && status != model.ContentStatusPublished {
 		status = model.ContentStatusPending
@@ -322,10 +345,14 @@ func (s *CommentService) Create(userID, postID uint, content string, parentID *u
 	// 检查帖子存在且已发布（待审/被拒帖子不接受评论）
 	var post model.Post
 	if err := s.db.First(&post, postID).Error; err != nil {
-		return nil, nil, errors.New("帖子不存在")
+		return nil, nil, 0, errors.New("帖子不存在")
 	}
 	if post.Status != model.ContentStatusPublished {
-		return nil, nil, errors.New("帖子不存在")
+		return nil, nil, 0, errors.New("帖子不存在")
+	}
+	// 管理员手动锁帖：普通用户禁止回复，staff 豁免
+	if post.Locked && !model.IsStaff(actorRole) {
+		return nil, nil, 0, ErrPostReplyLocked
 	}

 	comment := &model.Comment{
@@ -342,10 +369,10 @@ func (s *CommentService) Create(userID, postID uint, content string, parentID *u
 		if err := s.db.
 			Where("id = ? AND post_id = ? AND status = ?", *parentID, postID, model.ContentStatusPublished).
 			First(parent).Error; err != nil {
-			return nil, nil, errors.New("回复的评论不存在")
+			return nil, nil, 0, errors.New("回复的评论不存在")
 		}
 		if parent.Depth >= maxReplyDepth {
-			return nil, nil, errors.New("回复层级过深")
+			return nil, nil, 0, errors.New("回复层级过深")
 		}
 		rootID := parent.ID
 		if parent.RootID != nil {
@@ -356,26 +383,57 @@ func (s *CommentService) Create(userID, postID uint, content string, parentID *u
 		comment.Depth = parent.Depth + 1
 	}

-	if err := s.db.Create(comment).Error; err != nil {
-		return nil, nil, err
+	// 旧帖回复扣分（staff 豁免）：仅已发布评论生效，待审不发不提醒。
+	// 旧帖判定：最后一条已发布评论时间距现在超过阈值；无回复（MAX 为 NULL）回落发帖时间。
+	necroAfterHours, necroPoints := 0, 0
+	if comment.Status == model.ContentStatusPublished && s.setting != nil && !model.IsStaff(actorRole) {
+		afterHours, afterErr := s.setting.NecroReplyAfterHours()
+		penalty, penaltyErr := s.setting.NecroReplyPenalty()
+		var lastAt *time.Time
+		if err := s.db.Raw(`SELECT MAX(created_at) FROM comments WHERE post_id = ? AND status = 'published' AND deleted_at IS NULL`, postID).Scan(&lastAt).Error; err != nil || lastAt == nil {
+			lastAt = &post.CreatedAt
+		}
+		if afterErr == nil && penaltyErr == nil &&
+			IsNecroReply(*lastAt, afterHours, time.Now()) {
+			necroAfterHours, necroPoints = afterHours, penalty
+		}
 	}
-	// 仅已发布评论立即计入评论数；待审评论通过审核时才 +1
-	if comment.Status == model.ContentStatusPublished {
-		s.db.Model(&post).UpdateColumn("comment_count", gorm.Expr("comment_count + 1"))
+
+	// 原子事务：评论落库 + 计数 + 旧帖扣分 + 回复奖励（扣分余额不足整体回滚，禁止回复）
+	if err := s.db.Transaction(func(tx *gorm.DB) error {
+		if err := tx.Create(comment).Error; err != nil {
+			return err
+		}
+		if comment.Status != model.ContentStatusPublished {
+			return nil
+		}
+		// 仅已发布评论立即计入评论数；待审评论通过审核时才 +1
+		if err := tx.Model(&post).UpdateColumn("comment_count", gorm.Expr("comment_count + 1")).Error; err != nil {
+			return err
+		}
+		if necroPoints > 0 {
+			if _, err := DebitTx(tx, userID, necroPoints, model.PointReasonNecroReply, "post", post.ID,
+				fmt.Sprintf("回复超过 %d 小时无新回复的旧帖", necroAfterHours)); err != nil {
+				return err
+			}
+		}
 		// 回复奖励（可配置；待审不发且过审不补发，防拒审刷分）
 		if s.setting != nil {
 			if rules, err := s.setting.PointsRules(); err == nil {
-				s.db.Transaction(func(tx *gorm.DB) error {
-					RewardIfConfigured(tx, userID, rules.ReplyReward, rules.ReplyDailyCap,
-						model.PointReasonReplyReward, "comment", comment.ID, "回复奖励："+post.Title)
-					return nil
-				})
+				RewardIfConfigured(tx, userID, rules.ReplyReward, rules.ReplyDailyCap,
+					model.PointReasonReplyReward, "comment", comment.ID, "回复奖励："+post.Title)
 			}
 		}
+		return nil
+	}); err != nil {
+		if necroPoints > 0 && errors.Is(err, ErrInsufficientPoints) {
+			return nil, nil, 0, fmt.Errorf("%w：该帖已超过 %d 小时没有新回复，回复需扣除 %d 积分", ErrInsufficientPoints, necroAfterHours, necroPoints)
+		}
+		return nil, nil, 0, err
 	}
 	// 预加载用户
 	s.db.Preload("User").Preload("User.Badges.Badge").First(comment, comment.ID)
-	return comment, parent, nil
+	return comment, parent, necroPoints, nil
 }

 // UserCommentItem 用户评论列表项（含帖子标题便于跳转）
@@ -484,7 +542,8 @@ func (s *CommentService) Delete(actor *Actor, commentID, userID uint, opts Delet
 		"delete_reason": deleteReason,
 		"deleted_by":    userID,
 	}
-	if err := s.db.Model(&comment).Updates(updates).Error; err != nil {
+	// UpdateColumns：删除元数据非内容编辑，不刷新 updated_at（该字段用于 edited 判定）
+	if err := s.db.Model(&comment).UpdateColumns(updates).Error; err != nil {
 		return err
 	}
 	if err := s.db.Delete(&comment).Error; err != nil {
@@ -537,7 +596,8 @@ func (s *CommentService) Restore(actor *Actor, commentID, userID uint) error {
 		"delete_reason": "",
 		"deleted_by":    0,
 	}
-	if err := s.db.Unscoped().Model(&model.Comment{}).Where("id = ?", commentID).Updates(updates).Error; err != nil {
+	// UpdateColumns：恢复非内容编辑，不刷新 updated_at（该字段用于 edited 判定）
+	if err := s.db.Unscoped().Model(&model.Comment{}).Where("id = ?", commentID).UpdateColumns(updates).Error; err != nil {
 		return err
 	}
 	if comment.Status == model.ContentStatusPublished {
@@ -637,14 +697,23 @@ func (s *CommentService) Update(actor *Actor, commentID, userID uint, content st
 	if comment.DeletedAt.Valid {
 		return nil, ErrCommentDeleted
 	}
+	var post model.Post
+	if err := s.db.Select("id", "board_id", "created_at", "locked").First(&post, comment.PostID).Error; err != nil {
+		return nil, ErrCommentNotFound
+	}
 	if comment.UserID != userID {
-		var post model.Post
-		if err := s.db.Select("id", "board_id").First(&post, comment.PostID).Error; err != nil {
-			return nil, ErrCommentNotFound
-		}
+		// 版主编辑他人评论不受锁帖/时限约束（本就为 staff）
 		if actor == nil || !actor.CanModerateBoard(post.BoardID) {
 			return nil, ErrCommentForbidden
 		}
+	} else if !model.IsStaff(actor.Role) {
+		// 作者本人编辑：锁帖禁止、超过可编辑时限禁止，staff 豁免
+		if post.Locked {
+			return nil, ErrCommentPostLocked
+		}
+		if editLocked(comment.CreatedAt, false, commentEditLockHours(s.setting), time.Now()) {
+			return nil, ErrCommentEditLocked
+		}
 	}
 	if comment.Content == content {
 		return nil, ErrCommentNotChanged
@@ -672,7 +741,7 @@ func (s *CommentService) Update(actor *Actor, commentID, userID uint, content st
 	return &node, nil
 }

-// CommentEditHistoryItem 管理可见的评论修订记录
+// CommentEditHistoryItem 登录可见的评论修订记录
 type CommentEditHistoryItem struct {
 	ID         uint              `json:"id"`
 	Editor     CommentActorBrief `json:"editor"`
@@ -680,7 +749,7 @@ type CommentEditHistoryItem struct {
 	CreatedAt  time.Time         `json:"created_at"`
 }

-// ListEditHistory 评论编辑历史（仅版主；含软删评论；按创建时间倒序分页）
+// ListEditHistory 评论编辑历史（登录即可见；含软删评论；按创建时间倒序分页）
 func (s *CommentService) ListEditHistory(actor *Actor, commentID uint, page, size int) ([]CommentEditHistoryItem, int64, error) {
 	if page < 1 {
 		page = 1
@@ -689,14 +758,10 @@ func (s *CommentService) ListEditHistory(actor *Actor, commentID uint, page, siz
 		size = 10
 	}
 	var comment model.Comment
-	if err := s.db.Unscoped().Select("id", "post_id").First(&comment, commentID).Error; err != nil {
+	if err := s.db.Unscoped().Select("id").First(&comment, commentID).Error; err != nil {
 		return nil, 0, ErrCommentNotFound
 	}
-	var post model.Post
-	if err := s.db.Unscoped().Select("id", "board_id").First(&post, comment.PostID).Error; err != nil {
-		return nil, 0, ErrCommentNotFound
-	}
-	if actor == nil || !actor.CanModerateBoard(post.BoardID) {
+	if actor == nil {
 		return nil, 0, ErrCommentForbidden
 	}

--- a/backend/service/content_lock_test.go
+++ b/backend/service/content_lock_test.go
@@ -0,0 +1,74 @@
+package service
+
+import (
+	"testing"
+	"time"
+
+	"github.com/freefire/jiang13-bbs/model"
+)
+
+// TestEditLocked 内容自动编辑锁定规则（帖子与评论共用）：
+// staff 豁免、hours<=0 关闭、以创建时间为基准计时
+func TestEditLocked(t *testing.T) {
+	now := time.Date(2026, 9, 25, 12, 0, 0, 0, time.Local)
+	createdAt := now.Add(-48 * time.Hour) // 两天前创建
+
+	cases := []struct {
+		name      string
+		createdAt time.Time
+		isStaff   bool
+		hours     int
+		now       time.Time
+		want      bool
+	}{
+		{"未启用", createdAt, false, 0, now, false},
+		{"负值视为关闭", createdAt, false, -1, now, false},
+		{"超过时限锁定", createdAt, false, 24, now, true},
+		{"恰好到期未锁（严格大于）", createdAt, false, 48, now, false},
+		{"未到期不锁", createdAt, false, 72, now, false},
+		{"staff 超时也豁免", createdAt, true, 1, now, false},
+		{"staff 管理员角色豁免", createdAt, model.IsStaff(model.RoleAdmin), 1, now, false},
+		{"普通用户非豁免", createdAt, model.IsStaff(model.RoleUser), 1, now, true},
+		{"板块管理员豁免", createdAt, model.IsStaff(model.RoleBoardAdmin), 1, now, false},
+		{"刚创建且时限极短不锁", now, false, 1, now, false},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			if got := editLocked(c.createdAt, c.isStaff, c.hours, c.now); got != c.want {
+				t.Fatalf("editLocked() = %v, want %v", got, c.want)
+			}
+		})
+	}
+}
+
+// TestIsNecroReply 旧帖判定：最后回复时间（无回复回落发帖时间）距 now 超过阈值。
+// staff 豁免、规则开关、回落基准由调用方负责，不在本 helper 内。
+func TestIsNecroReply(t *testing.T) {
+	now := time.Date(2026, 9, 25, 12, 0, 0, 0, time.Local)
+	lastReplyAt := now.Add(-48 * time.Hour) // 最后回复在两天前
+
+	cases := []struct {
+		name        string
+		lastReplyAt time.Time
+		afterHours  int
+		now         time.Time
+		want        bool
+	}{
+		{"阈值关闭", lastReplyAt, 0, now, false},
+		{"阈值负值视为关闭", lastReplyAt, -1, now, false},
+		{"超过阈值触发", lastReplyAt, 24, now, true},
+		{"恰好到期不触发（严格大于）", lastReplyAt, 48, now, false},
+		{"未到期不触发", lastReplyAt, 72, now, false},
+		{"无回复回落发帖时间同理（基准即发帖时间）", now.Add(-72 * time.Hour), 48, now, true},
+		{"刚回复不久不触发", now.Add(-time.Hour), 2, now, false},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			if got := IsNecroReply(c.lastReplyAt, c.afterHours, c.now); got != c.want {
+				t.Fatalf("IsNecroReply() = %v, want %v", got, c.want)
+			}
+		})
+	}
+}
--- a/backend/service/moderation.go
+++ b/backend/service/moderation.go
@@ -180,7 +180,8 @@ func (s *ModerationService) ApprovePost(actor *Actor, id uint) (boardID uint, er
 		if raw, ok := EnsureDeadlineOnPublish(post.TypeMeta, post.PostType, time.Now().UTC()); ok {
 			updates["type_meta"] = raw
 		}
-		if err := tx.Model(&post).Updates(updates).Error; err != nil {
+		// UpdateColumns：审核非内容编辑，不刷新 updated_at（详情页「更新于」由该字段推导）
+		if err := tx.Model(&post).UpdateColumns(updates).Error; err != nil {
 			return err
 		}
 		boardID = post.BoardID
@@ -204,7 +205,8 @@ func (s *ModerationService) RejectPost(actor *Actor, id uint) error {
 		if post.Status != model.ContentStatusPending {
 			return ErrNotPending
 		}
-		if err := tx.Model(&post).Update("status", model.ContentStatusRejected).Error; err != nil {
+		// UpdateColumn：审核非内容编辑，不刷新 updated_at
+		if err := tx.Model(&post).UpdateColumn("status", model.ContentStatusRejected).Error; err != nil {
 			return err
 		}
 		s.notif.Create(post.UserID, actor.ID, model.NotificationTypeRejected, post.ID, 0,
@@ -230,7 +232,8 @@ func (s *ModerationService) ApproveComment(actor *Actor, id uint) (postID, board
 		if cm.Status != model.ContentStatusPending {
 			return ErrNotPending
 		}
-		if err := tx.Model(&cm).Update("status", model.ContentStatusPublished).Error; err != nil {
+		// UpdateColumn：审核非内容编辑，不刷新评论 updated_at（该字段用于 edited 判定）
+		if err := tx.Model(&cm).UpdateColumn("status", model.ContentStatusPublished).Error; err != nil {
 			return err
 		}
 		if err := tx.Model(&model.Post{}).Where("id = ?", cm.PostID).
@@ -273,7 +276,8 @@ func (s *ModerationService) RejectComment(actor *Actor, id uint) error {
 		if cm.Status != model.ContentStatusPending {
 			return ErrNotPending
 		}
-		if err := tx.Model(&cm).Update("status", model.ContentStatusRejected).Error; err != nil {
+		// UpdateColumn：审核非内容编辑，不刷新评论 updated_at（该字段用于 edited 判定）
+		if err := tx.Model(&cm).UpdateColumn("status", model.ContentStatusRejected).Error; err != nil {
 			return err
 		}
 		s.notif.Create(cm.UserID, actor.ID, model.NotificationTypeRejected, cm.PostID, cm.ID,
--- a/backend/service/notification.go
+++ b/backend/service/notification.go
@@ -100,6 +100,31 @@ func (s *NotificationService) Create(userID, actorID uint, notifType string, pos
 	}
 }

+// CreateSystem 系统通知（ActorID=0，提醒对象即本人，绕过自我通知检查；失败静默）
+func (s *NotificationService) CreateSystem(userID uint, notifType string, postID, commentID uint, content string) {
+	if userID == 0 {
+		return
+	}
+	if len(content) > 200 {
+		content = content[:200]
+	}
+	n := &model.Notification{
+		UserID:    userID,
+		ActorID:   0,
+		Type:      notifType,
+		PostID:    postID,
+		CommentID: commentID,
+		Content:   content,
+		IsRead:    false,
+	}
+	if err := s.db.Create(n).Error; err != nil {
+		return
+	}
+	if s.OnNotifyNew != nil {
+		s.OnNotifyNew(userID)
+	}
+}
+
 // CreateMention 创建群聊 @ 提醒（PostID=0，用 RoomID/MessageID 关联）。
 // 返回创建出的通知 ID（0 表示未创建），供 handler 实时推送。
 func (s *NotificationService) CreateMention(userID, actorID, roomID, messageID uint, content string) uint {
--- a/backend/service/post.go
+++ b/backend/service/post.go
@@ -17,8 +17,27 @@ var (
 	ErrPostForbidden   = errors.New("无权限操作此帖子")
 	ErrPostDeleteMeta  = errors.New("选「其他」时须填写删除理由")
 	ErrPostInvalidType = errors.New("无效的删除类型")
+	ErrPostLocked      = errors.New("帖子已被锁定，无法编辑")
+	ErrPostEditLocked  = errors.New("帖子已超过可编辑时限，无法编辑")
 )

+// editLocked 内容是否已被自动编辑锁定；管理团队豁免；hours<=0 表示不启用
+func editLocked(createdAt time.Time, isStaff bool, hours int, now time.Time) bool {
+	return !isStaff && hours > 0 && now.Sub(createdAt) > time.Duration(hours)*time.Hour
+}
+
+// postEditLockHours 帖子可编辑时长（setting 未注入或读取出错时=0 关闭）
+func postEditLockHours(setting *SettingService) int {
+	if setting == nil {
+		return 0
+	}
+	hours, err := setting.PostEditLockHours()
+	if err != nil {
+		return 0
+	}
+	return hours
+}
+
 // PostService 帖子服务
 type PostService struct {
 	db      *gorm.DB
@@ -323,13 +342,30 @@ func (s *PostService) TogglePin(id uint) (int, error) {
 	} else {
 		newPinned = 1
 	}
-	result := s.db.Model(&post).Update("pinned", newPinned)
+	// UpdateColumn：置顶非内容编辑，不刷新 updated_at
+	result := s.db.Model(&post).UpdateColumn("pinned", newPinned)
 	if result.Error != nil {
 		return 0, result.Error
 	}
 	return newPinned, nil
 }

+// ToggleLock 切换帖子手动锁定状态（仅管理员可操作，由 handler 校验权限）。
+// 锁定后普通用户不可编辑帖子、不可回复；staff 豁免。
+func (s *PostService) ToggleLock(id uint) (bool, error) {
+	var post model.Post
+	if err := s.db.First(&post, id).Error; err != nil {
+		return false, err
+	}
+	newVal := !post.Locked
+	// UpdateColumn：锁定非内容编辑，不刷新 updated_at
+	result := s.db.Model(&post).UpdateColumn("locked", newVal)
+	if result.Error != nil {
+		return false, result.Error
+	}
+	return newVal, nil
+}
+
 // ToggleRecommend 切换帖子加精；加精时向作者发放可配置的推荐奖励（每帖仅一次，自荐不发）
 func (s *PostService) ToggleRecommend(id, operatorID uint) (bool, error) {
 	var post model.Post
@@ -337,7 +373,8 @@ func (s *PostService) ToggleRecommend(id, operatorID uint) (bool, error) {
 		return false, err
 	}
 	newVal := !post.Recommended
-	result := s.db.Model(&post).Update("recommended", newVal)
+	// UpdateColumn：加精非内容编辑，不刷新 updated_at
+	result := s.db.Model(&post).UpdateColumn("recommended", newVal)
 	if result.Error != nil {
 		return false, result.Error
 	}
@@ -414,17 +451,23 @@ type PostDetail struct {
 	TypeStatus    string              `json:"type_status,omitempty"`
 	Pinned        int                 `json:"pinned"`
 	Recommended   bool                `json:"recommended"`
+	Locked        bool                `json:"locked"` // 管理员手动锁定：普通用户不可编辑/回复（staff 豁免）
 	Status        string              `json:"status"`
 	LikeCount     int                 `json:"like_count"`
 	ViewCount     int                 `json:"view_count"`
 	CommentCount  int                 `json:"comment_count"`
 	Liked         bool                `json:"liked"`
-	CreatedAt     time.Time           `json:"created_at"`
-	UpdatedAt     time.Time           `json:"updated_at"`
-	Board         model.Board         `json:"board"`
-	User          model.User          `json:"user"`
-	ContentLocked bool                `json:"content_locked"`
-	AccessHint    string              `json:"access_hint,omitempty"`
+	Edited        bool                `json:"edited"` // 是否存在编辑历史快照（决定"更新于/编辑历史"入口展示）
+	// 最后一条已发布评论时间；null=无回复（旧帖判定回落 created_at）
+	LastReplyAt *time.Time `json:"last_reply_at,omitempty"`
+	// 旧帖回复确认提示：按查看者实时计算，命中才返回；前端存在即弹确认框
+	NecroReply    *NecroReplyHint `json:"necro_reply,omitempty"`
+	CreatedAt     time.Time       `json:"created_at"`
+	UpdatedAt     time.Time       `json:"updated_at"`
+	Board         model.Board     `json:"board"`
+	User          model.User      `json:"user"`
+	ContentLocked bool            `json:"content_locked"`
+	AccessHint    string          `json:"access_hint,omitempty"`
 	Attachments   []PostAttachmentDTO `json:"attachments"`
 	Question      *QuestionState      `json:"question,omitempty"`
 	Poll          *PollState          `json:"poll,omitempty"`
@@ -439,6 +482,12 @@ type PostDetail struct {
 	DeletedAt    *time.Time `json:"deleted_at,omitempty"`
 }

+// NecroReplyHint 旧帖回复确认提示（详情接口按查看者实时计算；命中才返回）
+type NecroReplyHint struct {
+	AfterHours int `json:"after_hours"`
+	Penalty    int `json:"penalty"`
+}
+
 // CreatePostInput 发帖入参（content_access / access_points 由正文 [hide] 派生）
 type CreatePostInput struct {
 	UserID        uint
@@ -498,6 +547,12 @@ func (s *PostService) GetByIDForViewer(id, viewerID uint, loadActor func() *Acto
 	post.ViewCount++

 	detail := buildPostDetail(&post)
+	detail.Edited = s.hasEditHistory(post.ID)
+	// 最后一条已发布评论时间（旧帖判定基准；无回复为 nil，调用方回落 created_at）
+	var lastReplyAt *time.Time
+	if err := s.db.Raw(`SELECT MAX(created_at) FROM comments WHERE post_id = ? AND status = 'published' AND deleted_at IS NULL`, post.ID).Scan(&lastReplyAt).Error; err == nil {
+		detail.LastReplyAt = lastReplyAt
+	}
 	sanitized, fullyLocked, hint := s.sanitizePostContent(&post, viewerID, loadActor, pwdUnlocked)
 	detail.Content = sanitized
 	detail.ContentLocked = fullyLocked
@@ -545,7 +600,7 @@ func buildPostDetail(post *model.Post) *PostDetail {
 		ContentAccess: model.NormalizeContentAccess(post.ContentAccess),
 		AccessPoints:  post.AccessPoints, TypeMeta: post.TypeMeta,
 		TypeStatus: ComputeTypeStatus(post.PostType, post.TypeMeta),
-		Pinned:     post.Pinned, Recommended: post.Recommended, Status: post.Status,
+		Pinned: post.Pinned, Recommended: post.Recommended, Locked: post.Locked, Status: post.Status,
 		LikeCount: post.LikeCount, ViewCount: post.ViewCount, CommentCount: post.CommentCount,
 		Liked: post.Liked, CreatedAt: post.CreatedAt, UpdatedAt: post.UpdatedAt,
 		Board: post.Board, User: post.User,
@@ -919,6 +974,15 @@ func (s *PostService) Update(actor *Actor, postID, userID uint, in UpdatePostInp
 	if post.UserID != userID && !actor.CanModerateBoard(post.BoardID) {
 		return nil, ErrPostForbidden
 	}
+	editorIsStaff := model.IsStaff(actor.Role)
+	// 手动锁定：仅管理团队可编辑
+	if post.Locked && !editorIsStaff {
+		return nil, ErrPostLocked
+	}
+	// 自动编辑锁定：非管理团队的作者超时不可编辑；管理成员（版主代编等）豁免
+	if post.UserID == userID && editLocked(post.CreatedAt, editorIsStaff, postEditLockHours(s.setting), time.Now()) {
+		return nil, ErrPostEditLocked
+	}

 	updates := map[string]interface{}{}
 	if in.Title != "" {
@@ -1042,6 +1106,26 @@ func (s *PostService) Update(actor *Actor, postID, userID uint, in UpdatePostInp
 	}

 	err := s.db.Transaction(func(tx *gorm.DB) error {
+		// 仅标题/正文实际变化时留修订快照（tags/type_meta/附件变更不留痕）
+		newTitle, _ := updates["title"].(string)
+		if newTitle == "" {
+			newTitle = post.Title
+		}
+		newContent, _ := updates["content"].(string)
+		if newContent == "" {
+			newContent = post.Content
+		}
+		if newTitle != post.Title || newContent != post.Content {
+			hist := model.PostEditHistory{
+				PostID:     post.ID,
+				EditorID:   userID, // 执行编辑者（可能是版主代编）
+				OldTitle:   post.Title,
+				OldContent: post.Content,
+			}
+			if err := tx.Create(&hist).Error; err != nil {
+				return err
+			}
+		}
 		if err := tx.Model(&post).Updates(updates).Error; err != nil {
 			return err
 		}
@@ -1085,6 +1169,87 @@ func (s *PostService) Update(actor *Actor, postID, userID uint, in UpdatePostInp
 	return detail, nil
 }

+// PostEditHistoryItem 登录可见的帖子修订记录
+type PostEditHistoryItem struct {
+	ID         uint              `json:"id"`
+	Editor     CommentActorBrief `json:"editor"`
+	OldTitle   string            `json:"old_title"`
+	OldContent string            `json:"old_content"`
+	CreatedAt  time.Time         `json:"created_at"`
+}
+
+// hasEditHistory 帖子是否存在修订快照；updated_at 会被置顶/计数等写操作推动，不可作为编辑依据
+func (s *PostService) hasEditHistory(postID uint) bool {
+	var n int64
+	s.db.Model(&model.PostEditHistory{}).Where("post_id = ?", postID).Limit(1).Count(&n)
+	return n > 0
+}
+
+// ListEditHistory 帖子编辑历史（登录即可见；含软删帖子；按创建时间倒序分页）
+func (s *PostService) ListEditHistory(actor *Actor, postID uint, page, size int) ([]PostEditHistoryItem, int64, error) {
+	if page < 1 {
+		page = 1
+	}
+	if size < 1 || size > 50 {
+		size = 10
+	}
+	var post model.Post
+	if err := s.db.Unscoped().Select("id").First(&post, postID).Error; err != nil {
+		return nil, 0, ErrPostNotFound
+	}
+	if actor == nil {
+		return nil, 0, ErrPostForbidden
+	}
+
+	q := s.db.Model(&model.PostEditHistory{}).Where("post_id = ?", postID)
+	var total int64
+	if err := q.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	var rows []model.PostEditHistory
+	if err := s.db.Where("post_id = ?", postID).
+		Order("created_at DESC").
+		Offset((page - 1) * size).Limit(size).
+		Find(&rows).Error; err != nil {
+		return nil, 0, err
+	}
+	editorIDs := make([]uint, 0, len(rows))
+	seen := map[uint]struct{}{}
+	for _, r := range rows {
+		if _, ok := seen[r.EditorID]; ok {
+			continue
+		}
+		seen[r.EditorID] = struct{}{}
+		editorIDs = append(editorIDs, r.EditorID)
+	}
+	editors := map[uint]CommentActorBrief{}
+	if len(editorIDs) > 0 {
+		var users []model.User
+		s.db.Select("id", "username", "nickname", "avatar").Where("id IN ?", editorIDs).Find(&users)
+		for _, u := range users {
+			editors[u.ID] = CommentActorBrief{
+				ID: u.ID, Username: u.Username, Nickname: u.Nickname, Avatar: u.Avatar,
+			}
+		}
+	}
+	items := make([]PostEditHistoryItem, 0, len(rows))
+	for _, r := range rows {
+		ed := editors[r.EditorID]
+		if ed.ID == 0 {
+			ed = CommentActorBrief{ID: r.EditorID, Username: "已注销", Nickname: "已注销"}
+		}
+		items = append(items, PostEditHistoryItem{
+			ID:         r.ID,
+			Editor:     ed,
+			OldTitle:   r.OldTitle,
+			OldContent: r.OldContent,
+			CreatedAt:  r.CreatedAt,
+		})
+	}
+	return items, total, nil
+}
+
 // EnsurePostVisible 校验帖子对当前访问者可见（评论列表等场景复用，不增加浏览量）
 func (s *PostService) EnsurePostVisible(postID, viewerID uint, loadActor func() *Actor) error {
 	var post model.Post
@@ -1184,7 +1349,8 @@ func (s *PostService) Delete(actor *Actor, postID, userID uint, opts DeletePostO
 		"delete_reason": deleteReason,
 		"deleted_by":    userID,
 	}
-	if err := s.db.Model(&post).Updates(updates).Error; err != nil {
+	// UpdateColumns：删除元数据非内容编辑，不刷新 updated_at（详情页「更新于」由该字段推导）
+	if err := s.db.Model(&post).UpdateColumns(updates).Error; err != nil {
 		return false, authorID, err
 	}
 	if err := s.db.Delete(&post).Error; err != nil {
--- a/backend/service/setting.go
+++ b/backend/service/setting.go
@@ -59,6 +59,12 @@ const (
 	// SettingKeyAnalyticsRetentionDays 访问明细保留天数；缺行=90
 	SettingKeyAnalyticsRetentionDays = "analytics_retention_days"

+	// 内容锁定与旧帖回复（全部缺行=0 关闭）
+	SettingKeyPostEditLockHours    = "post_edit_lock_hours"    // 帖子可编辑时长；0=不锁定
+	SettingKeyCommentEditLockHours = "comment_edit_lock_hours" // 评论可编辑时长；0=不锁定
+	SettingKeyNecroReplyAfterHours = "necro_reply_after_hours" // 超过该时长回复视为旧帖回复；0=关闭
+	SettingKeyNecroReplyPenalty    = "necro_reply_penalty"     // 旧帖回复扣除积分；0=仅提醒不扣分
+
 	// 积分增长规则（正整数奖励；0=关闭/不限，缺行=默认值）
 	SettingKeyPointsCheckinBase     = "points_checkin_base"     // 签到基础分；缺行=5
 	SettingKeyPointsStreakEveryDays = "points_streak_every_days" // 每满 N 天连续签到触发加成；0=关闭；缺行=7
@@ -100,6 +106,9 @@ const (
 	MinAnalyticsRetentionDays     = 7
 	MaxAnalyticsRetentionDays     = 365

+	// MaxContentLockHours 内容锁定/旧帖阈值小时数上限（一年）
+	MaxContentLockHours = 8760
+
 	DefaultPointsCheckinBase     = 5
 	DefaultPointsStreakEveryDays = 7
 	MaxPointsRule                = 100 // 各积分规则值/上限的统一上界
@@ -150,6 +159,12 @@ type PublicSiteSettings struct {
 	AttachmentMaxMB      int          `json:"attachment_max_mb"`
 	AttachmentMaxCount   int          `json:"attachment_max_count"`
 	ImageMaxMB           int          `json:"image_max_mb"`
+
+	// 内容锁定与旧帖回复（0=关闭；公开保持规则透明）
+	PostEditLockHours    int `json:"post_edit_lock_hours"`
+	CommentEditLockHours int `json:"comment_edit_lock_hours"`
+	NecroReplyAfterHours int `json:"necro_reply_after_hours"`
+	NecroReplyPenalty    int `json:"necro_reply_penalty"`
 	BgSiteURL            string       `json:"bg_site_url"`
 	BgSiteMode           string       `json:"bg_site_mode"`
 	BgAdminURL           string       `json:"bg_admin_url"`
@@ -438,6 +453,27 @@ func (s *SettingService) Public() (PublicSiteSettings, error) {
 	}
 	out.ImageMaxMB = imgMB

+	postLock, err := s.PostEditLockHours()
+	if err != nil {
+		return out, err
+	}
+	out.PostEditLockHours = postLock
+	commentLock, err := s.CommentEditLockHours()
+	if err != nil {
+		return out, err
+	}
+	out.CommentEditLockHours = commentLock
+	necroAfter, err := s.NecroReplyAfterHours()
+	if err != nil {
+		return out, err
+	}
+	out.NecroReplyAfterHours = necroAfter
+	necroPenalty, err := s.NecroReplyPenalty()
+	if err != nil {
+		return out, err
+	}
+	out.NecroReplyPenalty = necroPenalty
+
 	siteURL, err := s.BgSiteURL()
 	if err != nil {
 		return out, err
@@ -941,6 +977,91 @@ func (s *SettingService) ImageMaxBytes() (int64, error) {
 	return int64(mb) << 20, nil
 }

+// getLockHours 读取小时数配置（缺行/非法=0 关闭，超上限钳制）
+func (s *SettingService) getLockHours(key string) (int, error) {
+	v, found, err := s.getValue(key)
+	if err != nil {
+		return 0, err
+	}
+	if !found {
+		return 0, nil
+	}
+	n, convErr := strconv.Atoi(strings.TrimSpace(v))
+	if convErr != nil || n < 0 {
+		return 0, nil
+	}
+	if n > MaxContentLockHours {
+		return MaxContentLockHours, nil
+	}
+	return n, nil
+}
+
+func (s *SettingService) setLockHours(key string, hours int) error {
+	if hours < 0 || hours > MaxContentLockHours {
+		return ErrInvalidSiteSetting
+	}
+	if hours == 0 {
+		return s.deleteKey(key)
+	}
+	return s.putValue(key, strconv.Itoa(hours))
+}
+
+// PostEditLockHours 帖子可编辑时长（小时）。缺行=0（不锁定）。
+func (s *SettingService) PostEditLockHours() (int, error) {
+	return s.getLockHours(SettingKeyPostEditLockHours)
+}
+
+func (s *SettingService) SetPostEditLockHours(hours int) error {
+	return s.setLockHours(SettingKeyPostEditLockHours, hours)
+}
+
+// CommentEditLockHours 评论可编辑时长（小时）。缺行=0（不锁定）。
+func (s *SettingService) CommentEditLockHours() (int, error) {
+	return s.getLockHours(SettingKeyCommentEditLockHours)
+}
+
+func (s *SettingService) SetCommentEditLockHours(hours int) error {
+	return s.setLockHours(SettingKeyCommentEditLockHours, hours)
+}
+
+// NecroReplyAfterHours 旧帖回复阈值（小时）。缺行=0（关闭）。
+func (s *SettingService) NecroReplyAfterHours() (int, error) {
+	return s.getLockHours(SettingKeyNecroReplyAfterHours)
+}
+
+func (s *SettingService) SetNecroReplyAfterHours(hours int) error {
+	return s.setLockHours(SettingKeyNecroReplyAfterHours, hours)
+}
+
+// NecroReplyPenalty 旧帖回复扣分。缺行=0（仅提醒不扣分）。
+func (s *SettingService) NecroReplyPenalty() (int, error) {
+	v, found, err := s.getValue(SettingKeyNecroReplyPenalty)
+	if err != nil {
+		return 0, err
+	}
+	if !found {
+		return 0, nil
+	}
+	n, convErr := strconv.Atoi(strings.TrimSpace(v))
+	if convErr != nil || n < 0 {
+		return 0, nil
+	}
+	if n > MaxPointsRule {
+		return MaxPointsRule, nil
+	}
+	return n, nil
+}
+
+func (s *SettingService) SetNecroReplyPenalty(n int) error {
+	if n < 0 || n > MaxPointsRule {
+		return ErrInvalidSiteSetting
+	}
+	if n == 0 {
+		return s.deleteKey(SettingKeyNecroReplyPenalty)
+	}
+	return s.putValue(SettingKeyNecroReplyPenalty, strconv.Itoa(n))
+}
+
 // AnalyticsEnabled 访问统计采集开关。缺行视为开启。
 func (s *SettingService) AnalyticsEnabled() (bool, error) {
 	v, found, err := s.getValue(SettingKeyAnalyticsEnabled)
--- a/backend/service/site_page.go
+++ b/backend/service/site_page.go
@@ -82,6 +82,9 @@ func (in *SitePageInput) normalize(existing *model.SitePage) error {
 	if in.Content == "" {
 		return errors.New("内容不能为空")
 	}
+	if utf8.RuneCountInString(in.Content) > 20000 {
+		return errors.New("内容不能超过 20000 字")
+	}
 	if err := rejectHideBlocks(in.Content, ErrSitePageHideNotAllowed); err != nil {
 		return err
 	}
--- a/frontend/app/admin/announcements/AnnouncementComposeClient.tsx
+++ b/frontend/app/admin/announcements/AnnouncementComposeClient.tsx
@@ -21,6 +21,9 @@ import { ANNOUNCEMENT_COLORS, announcementPublicPath } from "./announcementColor
 type PublishKey = "published" | "draft";
 type StatusFilter = "all" | "published" | "draft";

+/** 公告正文字符上限（与后端 service/announcement.go 校验一致） */
+const CONTENT_MAX = 20000;
+
 type FormState = {
  title: string;
  content: string;
@@ -328,8 +331,9 @@ export default function AnnouncementComposeClient({
              value={form.content}
              onChange={(content) => {
                setErrors((prev) => ({ ...prev, content: undefined }));
-                patchForm({ content });
+                patchForm({ content: content.slice(0, CONTENT_MAX) });
              }}
+              maxChars={CONTENT_MAX}
              allowHide
              allowReplyHide={false}
              placeholder="请输入公告正文，支持 Markdown…"
--- a/frontend/app/admin/badges/BadgesClient.tsx
+++ b/frontend/app/admin/badges/BadgesClient.tsx
@@ -200,7 +200,7 @@ export default function BadgesClient() {
            管理员自定义徽章：全站作者处展示前 2 枚，个人主页展示徽章墙；授予后用户会收到站内通知。
          </p>
        </div>
-        <button type="button" className="btn btn-solid btn-sm" onClick={openCreate}>
+        <button type="button" className="btn btn-primary btn-sm" onClick={openCreate}>
          <Plus size={14} /> 新建徽章
        </button>
      </div>
@@ -290,7 +290,7 @@ export default function BadgesClient() {
                  ) : (
                    <button
                      type="button"
-                      className="btn btn-solid btn-sm"
+                      className="btn btn-primary btn-sm"
                      disabled={grantingId === u.id}
                      onClick={() => void grant(u.id)}
                    >
@@ -416,7 +416,7 @@ export default function BadgesClient() {
          </button>
          <button
            type="button"
-            className="btn btn-solid btn-sm"
+            className="btn btn-primary btn-sm"
            disabled={saving || runeCount(form.name.trim()) === 0}
            onClick={() => void saveForm()}
          >
--- a/frontend/app/admin/content/ContentAdmin.tsx
+++ b/frontend/app/admin/content/ContentAdmin.tsx
@@ -25,6 +25,7 @@ import {
  apiAdminContentPosts,
  apiAdminContentComments,
  apiAdminSoftDeletePost,
+  apiCommentHistory,
  apiAdminRestorePost,
  apiAdminPurgePost,
  apiAdminSoftDeleteComment,
@@ -48,7 +49,7 @@ import AutolinkText from "@/components/AutolinkText";
 import ConfirmDialog from "@/components/ConfirmDialog";
 import StaffDeletePostModal from "@/components/StaffDeletePostModal";
 import DeleteCommentModal from "@/components/DeleteCommentModal";
-import CommentEditHistoryModal from "@/components/CommentEditHistoryModal";
+import EditHistoryModal from "@/components/EditHistoryModal";
 import {
  AdminEmpty,
  AdminPageHeader,
@@ -320,6 +321,7 @@ export default function ContentAdmin({
  const [staffDeleteComment, setStaffDeleteComment] = useState<AdminContentComment | null>(null);
  const [staffDeleteCommentBusy, setStaffDeleteCommentBusy] = useState(false);
  const [historyCommentId, setHistoryCommentId] = useState<number | null>(null);
+  const [historyCommentContent, setHistoryCommentContent] = useState("");

  const refreshCounts = useCallback(() => {
    apiAdminContentCounts().then(setCounts).catch(() => {});
@@ -710,11 +712,17 @@ export default function ContentAdmin({
                      onReject={() => askReject("comments", c.id)}
                    />
                  ) : null}
-                  <ContentAction
-                    label="历史"
-                    icon={<History size={13} />}
-                    onClick={() => setHistoryCommentId(c.id)}
-                  />
+                  {/* 未编辑（无修订快照）的评论不展示历史入口，避免打开空记录 */}
+                  {c.edited ? (
+                    <ContentAction
+                      label="历史"
+                      icon={<History size={13} />}
+                      onClick={() => {
+                        setHistoryCommentContent(c.content);
+                        setHistoryCommentId(c.id);
+                      }}
+                    />
+                  ) : null}
                  {c.deleted ? (
                    <>
                      {canModerateAuthor({ role: viewerRole }, c.user?.role) ? (
@@ -930,9 +938,14 @@ export default function ContentAdmin({
        }}
      />

-      <CommentEditHistoryModal
+      <EditHistoryModal
        open={historyCommentId != null}
-        commentId={historyCommentId}
+        title="评论编辑历史"
+        currentContent={historyCommentContent}
+        fetchPage={(p, s) => {
+          if (historyCommentId == null) return Promise.reject(new Error("未选择评论"));
+          return apiCommentHistory(historyCommentId, p, s);
+        }}
        onClose={() => setHistoryCommentId(null)}
      />
    </div>
--- a/frontend/app/admin/pages/PageComposeClient.tsx
+++ b/frontend/app/admin/pages/PageComposeClient.tsx
@@ -20,6 +20,9 @@ import useUnsavedGuard from "@/hooks/useUnsavedGuard";
 type PublishKey = "published" | "draft";
 type StatusFilter = "all" | "published" | "draft";

+/** 单页正文字符上限（与后端 service/site_page.go 校验一致） */
+const CONTENT_MAX = 20000;
+
 type FormState = {
  slug: string;
  title: string;
@@ -365,8 +368,9 @@ export default function PageComposeClient({
              value={form.content}
              onChange={(content) => {
                setErrors((prev) => ({ ...prev, content: undefined }));
-                patchForm({ content });
+                patchForm({ content: content.slice(0, CONTENT_MAX) });
              }}
+              maxChars={CONTENT_MAX}
              allowHide={false}
              placeholder="请输入页面正文，支持 Markdown…"
              rows={16}
--- a/frontend/app/admin/points/PointsTabs.tsx
+++ b/frontend/app/admin/points/PointsTabs.tsx
@@ -56,7 +56,7 @@ export default function PointsTabs({
    : TAB_OPTIONS.filter((o) => o.key === "overview");

  return (
-    <div>
+    <div className={tab === "users" ? "admin-points-users-tab" : undefined}>
      {canManage ? (
        <div className="mb-4">
          <AdminSegmented
--- a/frontend/app/admin/points/UserPointsTab.tsx
+++ b/frontend/app/admin/points/UserPointsTab.tsx
@@ -24,6 +24,15 @@ const fmt = (n?: number) => (Number(n) || 0).toLocaleString("zh-CN");

 type PointsSortKey = "id" | "points" | "total_points";

+/**
+ * 表头吸顶样式：sticky 相对 .admin-canvas 滚动口生效（lg 起外层不再是滚动容器，见下方包装层）。
+ * 分隔线用 inset 阴影而非 border——border-collapse: collapse 下吸顶 th 的边线会丢失。
+ */
+const thStickStyle = {
+  background: "var(--panel)",
+  boxShadow: "inset 0 -1px 0 var(--line)",
+} as const;
+
 /** 表头排序按钮：未激活显示双向箭头，激活显示单向箭头并高亮 */
 function SortHeader({
  label,
@@ -158,24 +167,40 @@ export default function UserPointsTab() {
        />
      </div>

-      <div className="panel p-0 overflow-hidden">
-        <div className="overflow-x-auto">
+      <div className="panel p-0">
+        {/* lg 起放开横向滚动容器：sticky th 才能相对 admin-canvas 吸顶；窄屏保留横向滚动（不吸顶） */}
+        <div className="overflow-x-auto lg:overflow-x-visible">
          <table className="w-full text-[13px]" style={{ borderCollapse: "collapse" }}>
            <thead>
-              <tr style={{ borderBottom: "1px solid var(--line)" }}>
-                <th className="px-4 py-2.5 text-left font-medium" style={{ color: "var(--ink-3)" }}>
+              <tr>
+                <th
+                  className="sticky top-0 z-10 px-4 py-2.5 text-left font-medium"
+                  style={{ color: "var(--ink-3)", ...thStickStyle }}
+                >
                  用户
                </th>
-                <th className="px-4 py-2.5 text-right font-medium" style={{ color: "var(--ink-3)" }}>
+                <th
+                  className="sticky top-0 z-10 px-4 py-2.5 text-right font-medium"
+                  style={{ color: "var(--ink-3)", ...thStickStyle }}
+                >
                  <SortHeader label="余额" active={sort === "points"} dir={dir} onClick={() => toggleSort("points")} />
                </th>
-                <th className="px-4 py-2.5 text-right font-medium" style={{ color: "var(--ink-3)" }}>
+                <th
+                  className="sticky top-0 z-10 px-4 py-2.5 text-right font-medium"
+                  style={{ color: "var(--ink-3)", ...thStickStyle }}
+                >
                  <SortHeader label="累计获得" active={sort === "total_points"} dir={dir} onClick={() => toggleSort("total_points")} />
                </th>
-                <th className="px-4 py-2.5 text-left font-medium" style={{ color: "var(--ink-3)" }}>
+                <th
+                  className="sticky top-0 z-10 px-4 py-2.5 text-left font-medium"
+                  style={{ color: "var(--ink-3)", ...thStickStyle }}
+                >
                  等级
                </th>
-                <th className="px-4 py-2.5 text-right font-medium" style={{ color: "var(--ink-3)" }}>
+                <th
+                  className="sticky top-0 z-10 px-4 py-2.5 text-right font-medium"
+                  style={{ color: "var(--ink-3)", ...thStickStyle }}
+                >
                  操作
                </th>
              </tr>
--- a/frontend/app/admin/settings/AccessSettings.tsx
+++ b/frontend/app/admin/settings/AccessSettings.tsx
@@ -1,6 +1,6 @@
 "use client";

-import { ExternalLink, LogIn, MessageSquare, MessagesSquare, ShieldCheck, ShieldOff, Timer } from "lucide-react";
+import { ExternalLink, LogIn, MessageSquare, MessagesSquare, ShieldCheck, ShieldOff, Timer, Lock, Hourglass, Coins, History } from "lucide-react";
 import { useState } from "react";
 import {
  AdminSettingsGroup,
@@ -18,6 +18,59 @@ function InstantNote({ saving }: { saving?: boolean }) {
  return <span className="admin-settings-instant">{saving ? "正在保存…" : "修改后立即生效"}</span>;
 }

+/** 内容锁定 4 键（小时上限 8760 / 积分上限 100，后端裁剪） */
+type LockKeys = Pick<
+  PublicSettings,
+  "post_edit_lock_hours" | "comment_edit_lock_hours" | "necro_reply_after_hours" | "necro_reply_penalty"
+>;
+type LockKey = keyof LockKeys;
+
+const LOCK_META: { key: LockKey; icon: React.ReactNode; label: string; hint: string; max: number; unit: string; toast: (v: number) => string }[] = [
+  {
+    key: "post_edit_lock_hours",
+    icon: <Lock size={15} />,
+    label: "帖子可编辑时长",
+    hint: "发帖后仅在该时长内可编辑（0=不限制，上限 8760 小时），到期后编辑入口隐藏；管理团队不受限。",
+    max: 8760,
+    unit: "小时",
+    toast: (v) => (v === 0 ? "已关闭帖子编辑时限" : `帖子可编辑时长已设为 ${v} 小时`),
+  },
+  {
+    key: "comment_edit_lock_hours",
+    icon: <Hourglass size={15} />,
+    label: "评论可编辑时长",
+    hint: "评论发布后仅在该时长内可编辑（0=不限制，上限 8760 小时）；管理团队不受限。",
+    max: 8760,
+    unit: "小时",
+    toast: (v) => (v === 0 ? "已关闭评论编辑时限" : `评论可编辑时长已设为 ${v} 小时`),
+  },
+  {
+    key: "necro_reply_after_hours",
+    icon: <History size={15} />,
+    label: "旧帖回复判定时长",
+    hint: "回复超过该时长的帖子将提醒作者并按下方分值扣分（0=关闭，上限 8760 小时）；管理团队不受限。",
+    max: 8760,
+    unit: "小时",
+    toast: (v) => (v === 0 ? "已关闭旧帖回复提醒" : `旧帖判定时长已设为 ${v} 小时`),
+  },
+  {
+    key: "necro_reply_penalty",
+    icon: <Coins size={15} />,
+    label: "旧帖回复扣除积分",
+    hint: "触发旧帖回复时扣除的积分（0=仅提醒不扣分，上限 100）；积分不足将无法回复。",
+    max: 100,
+    unit: "分",
+    toast: (v) => (v === 0 ? "旧帖回复仅提醒不扣分" : `旧帖回复将扣除 ${v} 积分`),
+  },
+];
+
+const pickLock = (s: PublicSettings): LockKeys => ({
+  post_edit_lock_hours: s.post_edit_lock_hours,
+  comment_edit_lock_hours: s.comment_edit_lock_hours,
+  necro_reply_after_hours: s.necro_reply_after_hours,
+  necro_reply_penalty: s.necro_reply_penalty,
+});
+
 /** 内容互动开关 + 访问安全模块 */
 export default function AccessSettings({ initial }: { initial: PublicSettings }) {
  const [allowComments, setAllowComments] = useState(initial.allow_comments !== false);
@@ -37,8 +90,12 @@ export default function AccessSettings({ initial }: { initial: PublicSettings })
  const [togglingTrust, setTogglingTrust] = useState(false);
  const [togglingWithoutReview, setTogglingWithoutReview] = useState(false);
  const [savingCooldown, setSavingCooldown] = useState(false);
+  const [lockForm, setLockForm] = useState<LockKeys>(() => pickLock(initial));
+  const [savedLock, setSavedLock] = useState<LockKeys>(() => pickLock(initial));
+  const [savingLockKey, setSavingLockKey] = useState<LockKey | null>(null);
  const [moduleDirty, setModuleDirty] = useState(false);
-  const leave = useUnsavedGuard(moduleDirty);
+  const lockDirty = (Object.keys(savedLock) as LockKey[]).some((k) => lockForm[k] !== savedLock[k]);
+  const leave = useUnsavedGuard(moduleDirty || lockDirty);

  const toggleComments = async () => {
    if (togglingComments) return;
@@ -164,6 +221,23 @@ export default function AccessSettings({ initial }: { initial: PublicSettings })
    }
  };

+  const saveLock = async (key: LockKey) => {
+    if (savingLockKey) return;
+    const n = Math.max(0, Math.min(8760, Math.round(Number(lockForm[key])) || 0));
+    setSavingLockKey(key);
+    try {
+      const res = await apiUpdateSiteSettings({ [key]: n });
+      const saved = pickLock(res);
+      setLockForm((f) => ({ ...f, [key]: saved[key] }));
+      setSavedLock((f) => ({ ...f, [key]: saved[key] }));
+      toast(LOCK_META.find((m) => m.key === key)?.toast(saved[key]) || "已保存", "ok");
+    } catch (e) {
+      toast(e instanceof Error ? e.message : "保存失败");
+    } finally {
+      setSavingLockKey(null);
+    }
+  };
+
  return (
    <div className="admin-settings-stack">
      <AdminSettingsGroup title="内容与互动">
@@ -308,6 +382,31 @@ export default function AccessSettings({ initial }: { initial: PublicSettings })
          </div>
        </AdminSettingsRow>
      </AdminSettingsGroup>
+      <AdminSettingsGroup title="内容锁定与旧帖回复">
+        {LOCK_META.map((m) => (
+          <AdminSettingsRow key={m.key} label={<span className="inline-flex items-center gap-1.5">{m.icon} {m.label}</span>} hintBelow={m.hint}>
+            <div className="flex items-center gap-2 flex-wrap">
+              <AdminStepper
+                value={lockForm[m.key]}
+                onChange={(v) => setLockForm((f) => ({ ...f, [m.key]: v }))}
+                min={0}
+                max={m.max}
+                unit={m.unit}
+                ariaLabel={`${m.label}${m.unit}`}
+                disabled={savingLockKey !== null}
+              />
+              <button
+                type="button"
+                className="btn btn-line btn-sm"
+                disabled={savingLockKey !== null || lockForm[m.key] === savedLock[m.key]}
+                onClick={() => void saveLock(m.key)}
+              >
+                {savingLockKey === m.key ? "保存中…" : "保存"}
+              </button>
+            </div>
+          </AdminSettingsRow>
+        ))}
+      </AdminSettingsGroup>
      <OperationsPanel name="security" onDirtyChange={setModuleDirty} />
      <ConfirmDialog
        open={leave.leaveOpen}
--- a/frontend/app/admin/settings/EconomySettings.tsx
+++ b/frontend/app/admin/settings/EconomySettings.tsx
@@ -212,7 +212,7 @@ export default function EconomySettings({ initial }: { initial: PublicSettings }
      <div className="flex items-center gap-3">
        <button
          type="button"
-          className="btn btn-solid btn-sm"
+          className="btn btn-primary btn-sm"
          disabled={saving || !dirty}
          onClick={() => void save()}
        >
--- a/frontend/app/globals.css
+++ b/frontend/app/globals.css
@@ -3335,6 +3335,12 @@ body:has([data-admin-viewport]) {
  padding-top: 0;
 }

+/* 用户积分表头吸顶：同 admin-users-stick，画布顶内边距必须归零 sticky 才能贴紧顶栏
+   （内边距挪到 .admin-points-users-tab；标记类仅在用户积分标签激活时挂载，不影响其他标签） */
+.admin-canvas:has(.admin-points-users-tab) {
+  padding-top: 0;
+}
+
 /* 移动端导航抽屉 */
 .admin-drawer {
  position: fixed;
@@ -5692,6 +5698,21 @@ a.j13-mention-token:hover {
    box-shadow: var(--shadow-sm);
  }

+  /* 用户积分标签：画布顶内边距挪到这里（见未分层区 canvas:has 规则），吸顶 th 才能贴齐 admin-topbar */
+  .admin-points-users-tab {
+    padding-top: 1.25rem;
+  }
+  @media (min-width: 640px) {
+    .admin-points-users-tab {
+      padding-top: 1.5rem;
+    }
+  }
+  @media (min-width: 1024px) {
+    .admin-points-users-tab {
+      padding-top: 1.75rem;
+    }
+  }
+
  /* 内容管理页：窄屏可整页滚；桌面高度由上方未分层的 canvas:has 规则锁定 */
  .admin-content-page {
    display: flex;
@@ -8409,6 +8430,78 @@ button.cmt-edited {
  text-decoration: underline;
  text-underline-offset: 2px;
 }
+/* 评论编辑历史：git diff 风格修订视图 */
+.cmt-diff {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+.cmt-diff-stat {
+  display: flex;
+  gap: 8px;
+  font-size: 11.5px;
+  font-weight: 600;
+  line-height: 1;
+  font-variant-numeric: tabular-nums;
+}
+.cmt-diff-stat-add {
+  color: var(--ok);
+}
+.cmt-diff-stat-del {
+  color: var(--danger);
+}
+.cmt-diff-body {
+  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
+  font-size: 12.5px;
+  line-height: 1.55;
+  background: var(--panel);
+  border: 1px solid var(--line);
+  border-radius: 6px;
+  padding: 4px 0;
+}
+.cmt-diff-line {
+  display: flex;
+  gap: 8px;
+  padding: 0 10px;
+  white-space: pre-wrap;
+  word-break: break-word;
+  min-height: 1.55em;
+}
+.cmt-diff-sign {
+  flex-shrink: 0;
+  width: 1ch;
+  user-select: none;
+  opacity: 0.65;
+}
+.cmt-diff-text {
+  min-width: 0;
+  flex: 1;
+}
+.cmt-diff-line.is-del {
+  background: color-mix(in srgb, var(--danger-soft) 60%, transparent);
+}
+.cmt-diff-line.is-add {
+  background: color-mix(in srgb, var(--ok-soft) 60%, transparent);
+}
+.cmt-diff-line.is-ctx {
+  color: var(--ink-2);
+}
+.cmt-diff-chg {
+  border-radius: 3px;
+  padding: 0 1px;
+  background: color-mix(in srgb, var(--danger) 24%, transparent);
+  color: inherit;
+}
+.cmt-diff-line.is-add .cmt-diff-chg {
+  background: color-mix(in srgb, var(--ok) 24%, transparent);
+}
+.cmt-diff-fold {
+  padding: 2px 10px;
+  font-size: 11.5px;
+  text-align: center;
+  color: var(--ink-2);
+  background: color-mix(in srgb, var(--ink) 3%, transparent);
+}
 .cmt-badge {
  display: inline-flex;
  align-items: center;
--- a/frontend/app/notifications/NotificationsClient.tsx
+++ b/frontend/app/notifications/NotificationsClient.tsx
@@ -3,7 +3,7 @@
 import { useState } from "react";
 import { useRouter } from "next/navigation";
 import Link from "next/link";
-import { Heart, MessageCircle, CheckCheck, Bell, CheckCircle2, XCircle, AtSign, ClipboardList, Award } from "lucide-react";
+import { Heart, MessageCircle, CheckCheck, Bell, CheckCircle2, XCircle, AtSign, ClipboardList, Award, AlertTriangle } from "lucide-react";
 import { apiMarkRead, apiMarkAllRead, type NotificationsResponse, type NotificationItem } from "@/lib/api";

 /**
@@ -76,22 +76,26 @@ export default function NotificationsClient({ initialData }: { initialData: Noti
        <div className="panel overflow-hidden p-0">
          {notifications.map((n, i) => {
            const approval = n.type === "approved" || n.type === "rejected";
+            // 系统提醒（ActorID=0）：不渲染操作者链接，仅展示标题与内容
+            const system = n.type === "necro_reply";
            const iconNode = n.type === "approved"
              ? <CheckCircle2 size={16} />
              : n.type === "rejected" || n.type === "deleted"
                ? <XCircle size={16} />
-                : n.type === "like"
-                  ? <Heart size={16} />
-                  : n.type === "mention"
-                    ? <AtSign size={16} />
-                    : n.type === "pending_review"
-                      ? <ClipboardList size={16} />
-                      : n.type === "badge"
-                        ? <Award size={16} />
-                        : <MessageCircle size={16} />;
+                : n.type === "necro_reply"
+                  ? <AlertTriangle size={16} />
+                  : n.type === "like"
+                    ? <Heart size={16} />
+                    : n.type === "mention"
+                      ? <AtSign size={16} />
+                      : n.type === "pending_review"
+                        ? <ClipboardList size={16} />
+                        : n.type === "badge"
+                          ? <Award size={16} />
+                          : <MessageCircle size={16} />;
            const iconColor = n.type === "approved"
              ? "var(--ok)"
-              : n.type === "rejected" || n.type === "deleted"
+              : n.type === "rejected" || n.type === "deleted" || n.type === "necro_reply"
                ? "var(--danger)"
                : n.type === "like"
                  ? "var(--clay)"
@@ -100,7 +104,7 @@ export default function NotificationsClient({ initialData }: { initialData: Noti
                    : "var(--accent)";
            const iconBg = n.type === "approved"
              ? "var(--ok-soft)"
-              : n.type === "rejected" || n.type === "deleted"
+              : n.type === "rejected" || n.type === "deleted" || n.type === "necro_reply"
                ? "var(--danger-soft)"
                : n.type === "like"
                  ? "var(--clay-soft)"
@@ -133,6 +137,10 @@ export default function NotificationsClient({ initialData }: { initialData: Noti
                    >
                      {n.type === "approved" ? "审核通过" : "未通过审核"}
                    </span>
+                  ) : system ? (
+                    <span className="font-bold" style={{ color: "var(--danger)" }}>
+                      旧帖回复提醒
+                    </span>
                  ) : (
                    <>
                      <Link
--- a/frontend/app/post/[id]/page.tsx
+++ b/frontend/app/post/[id]/page.tsx
@@ -37,6 +37,7 @@ import BadgeChip from "@/components/BadgeChip";
 import MarkdownBody from "@/components/MarkdownBody";
 import { publicMarkdownForSeo } from "@/lib/hideBlocks";
 import PostAttachments from "@/components/PostAttachments";
+import PostEditedMark from "@/components/PostEditedMark";
 import PostInteractPanels, { QuestionStatusCard } from "@/components/PostInteractPanels";
 import AcceptedAnswerCard from "@/components/AcceptedAnswerCard";
 import { canModerateBoard } from "@/lib/roles";
@@ -323,8 +324,7 @@ export default async function PostDetailPage({ params, searchParams }: PageProps
  const toc = extractToc(publicBody);
  const headingToc = markdownHeadingToc(toc);
  const readingMinutes = estimateReadingMinutes(publicBody, post.title.length);
-  const edited =
-    new Date(post.updated_at).getTime() - new Date(post.created_at).getTime() > 60_000;
+  const edited = post.edited ?? false;

  // 侧栏布局：post 范围左右两列（toc 需在下方已就绪）
  const sidebarLists = sidebarScopeLists(sidebar.config, "post");
@@ -560,6 +560,9 @@ export default async function PostDetailPage({ params, searchParams }: PageProps
                    pinned={post.pinned}
                    recommended={post.recommended}
                    status={post.status}
+                    createdAt={post.created_at}
+                    locked={post.locked}
+                    postEditLockHours={publicSettings.post_edit_lock_hours}
                    title={post.title}
                  />
                </div>
@@ -586,6 +589,16 @@ export default async function PostDetailPage({ params, searchParams }: PageProps
                      <>
                        {" "}
                        · 更新于 <time dateTime={post.updated_at}>{formatDateTime(post.updated_at)}</time>
+                        {me.user && (
+                          <>
+                            {" "}·{" "}
+                            <PostEditedMark
+                              postId={post.id}
+                              currentTitle={post.title}
+                              currentContent={post.content || ""}
+                            />
+                          </>
+                        )}
                      </>
                    )}
                  </p>
@@ -670,6 +683,9 @@ export default async function PostDetailPage({ params, searchParams }: PageProps
                page={commentsData.page}
                size={commentsData.size}
                user={me.user}
+                postLocked={post.locked}
+                commentEditLockHours={publicSettings.comment_edit_lock_hours}
+                necroReply={post.necro_reply}
                acceptMode={acceptMode}
                acceptedCommentId={
                  post.question?.accepted_comment_id ||
--- a/frontend/components/CommentEditHistoryModal.tsx
+++ b/frontend/components/CommentEditHistoryModal.tsx
@@ -1,173 +0,0 @@
-"use client";
-
-import { useCallback, useEffect, useState } from "react";
-import Link from "next/link";
-import { Loader2 } from "lucide-react";
-import Modal from "@/components/Modal";
-import Avatar from "@/components/Avatar";
-import MarkdownBodyClient from "@/components/MarkdownBodyClient";
-import {
-  apiAdminCommentHistory,
-  type CommentEditHistoryItem,
-} from "@/lib/api";
-
-const PAGE_SIZE = 10;
-
-/**
- * 版主可见：评论历次编辑前的旧正文快照（倒序分页）。
- * 宽度对齐详情页评论主栏（约 800px+），长文可滚动；底部「加载更多」。
- */
-export default function CommentEditHistoryModal({
-  open,
-  commentId,
-  onClose,
-}: {
-  open: boolean;
-  commentId: number | null;
-  onClose: () => void;
-}) {
-  const [loading, setLoading] = useState(false);
-  const [loadingMore, setLoadingMore] = useState(false);
-  const [error, setError] = useState("");
-  const [items, setItems] = useState<CommentEditHistoryItem[]>([]);
-  const [page, setPage] = useState(1);
-  const [total, setTotal] = useState(0);
-
-  const hasMore = items.length < total;
-
-  const loadPage = useCallback(
-    async (nextPage: number, append: boolean) => {
-      if (commentId == null) return;
-      if (append) setLoadingMore(true);
-      else {
-        setLoading(true);
-        setError("");
-      }
-      try {
-        const res = await apiAdminCommentHistory(commentId, nextPage, PAGE_SIZE);
-        const batch = res.items || [];
-        setError("");
-        setTotal(res.total ?? 0);
-        setPage(res.page ?? nextPage);
-        setItems((prev) => (append ? [...prev, ...batch] : batch));
-      } catch (e) {
-        const msg = e instanceof Error ? e.message : "加载失败";
-        if (append) {
-          // 追加失败不清空已有列表
-          setError(msg);
-        } else {
-          setError(msg);
-          setItems([]);
-          setTotal(0);
-        }
-      } finally {
-        setLoading(false);
-        setLoadingMore(false);
-      }
-    },
-    [commentId]
-  );
-
-  useEffect(() => {
-    if (!open || commentId == null) return;
-    setItems([]);
-    setPage(1);
-    setTotal(0);
-    setError("");
-    void loadPage(1, false);
-  }, [open, commentId, loadPage]);
-
-  return (
-    <Modal
-      open={open}
-      title="评论编辑历史"
-      description={total > 0 ? `共 ${total} 条修订记录` : undefined}
-      onClose={onClose}
-      // 对齐详情页中间评论栏可用宽度（1440 三栏布局下约 800px）
-      maxWidthClass="max-w-[min(840px,calc(100vw-2rem))]"
-      panelClassName="p-5 sm:p-6 max-h-[85vh] flex flex-col min-h-0 overflow-hidden"
-      bodyClassName="overflow-y-auto min-h-0 flex-1 -mx-1 px-1"
-      footer={
-        <button type="button" className="btn btn-line btn-sm" onClick={onClose}>
-          关闭
-        </button>
-      }
-    >
-      {loading ? (
-        <div className="flex items-center justify-center gap-2 py-10 meta text-[13px]">
-          <Loader2 size={16} className="animate-spin" />
-          加载中…
-        </div>
-      ) : error && items.length === 0 ? (
-        <p className="text-[13.5px] py-6 text-center" style={{ color: "var(--danger)" }}>
-          {error}
-        </p>
-      ) : items.length === 0 ? (
-        <p className="meta text-[13.5px] py-8 text-center">暂无编辑记录</p>
-      ) : (
-        <div className="flex flex-col gap-4">
-          <ul className="flex flex-col gap-4">
-            {items.map((it) => {
-              const name = it.editor.nickname || it.editor.username || "用户";
-              return (
-                <li
-                  key={it.id}
-                  className="rounded-md p-3 sm:p-4"
-                  style={{ background: "var(--panel-2)", border: "1px solid var(--line)" }}
-                >
-                  <div className="flex items-center gap-2 mb-2.5">
-                    <Link href={`/u/${it.editor.id}`} className="shrink-0">
-                      <Avatar name={name} src={it.editor.avatar || undefined} size={28} />
-                    </Link>
-                    <div className="min-w-0 flex-1">
-                      <Link
-                        href={`/u/${it.editor.id}`}
-                        className="text-[13px] hover:text-[var(--accent)]"
-                        style={{ color: "var(--ink)" }}
-                      >
-                        {name}
-                      </Link>
-                      <p className="meta text-[11.5px] tabular-nums">
-                        {new Date(it.created_at).toLocaleString("zh-CN")} · 编辑前正文
-                      </p>
-                    </div>
-                  </div>
-                  <MarkdownBodyClient
-                    content={it.old_content}
-                    className="prose-content prose-comment"
-                  />
-                </li>
-              );
-            })}
-          </ul>
-
-          {error && items.length > 0 && (
-            <p className="text-[12.5px] text-center" style={{ color: "var(--danger)" }}>
-              {error}
-            </p>
-          )}
-
-          {hasMore && (
-            <div className="flex justify-center pt-1 pb-1">
-              <button
-                type="button"
-                className="btn btn-line btn-sm"
-                disabled={loadingMore}
-                onClick={() => void loadPage(page + 1, true)}
-              >
-                {loadingMore ? (
-                  <span className="inline-flex items-center gap-1.5">
-                    <Loader2 size={14} className="animate-spin" />
-                    加载中…
-                  </span>
-                ) : (
-                  `加载更多（已显示 ${items.length}/${total}）`
-                )}
-              </button>
-            </div>
-          )}
-        </div>
-      )}
-    </Modal>
-  );
-}
--- a/frontend/components/CommentSection.tsx
+++ b/frontend/components/CommentSection.tsx
@@ -1,4 +1,4 @@
-"use client";
+"use client";

 import { useEffect, useRef, useState } from "react";
 import { useRouter } from "next/navigation";
@@ -7,6 +7,7 @@ import {
  MessagesSquare,
  ChevronRight,
  ChevronDown,
+  Lock,
 } from "lucide-react";
 import {
  apiCreateComment,
@@ -16,13 +17,14 @@ import {
  apiUpdateComment,
  apiAcceptBounty,
  apiAcceptQuestion,
+  apiCommentHistory,
  apiAdminApproveComment,
  apiAdminRejectComment,
  postDeleteTypeLabel,
  type CommentNode,
  type User,
 } from "@/lib/api";
-import { canModerateBoard, canStaffSoftDelete, canPurgeContent } from "@/lib/roles";
+import { canModerateBoard, canStaffSoftDelete, canPurgeContent, isStaff } from "@/lib/roles";
 import { toast } from "@/lib/toast";
 import { formatCommentTime, formatDateTime } from "@/lib/format";
 import { useAllowComments, useCommentsRequireLogin } from "@/components/CommentsPolicyProvider";
@@ -36,7 +38,7 @@ import MarkdownBodyClient from "@/components/MarkdownBodyClient";
 import MarkdownEditor from "@/components/MarkdownEditor";
 import ConfirmDialog from "@/components/ConfirmDialog";
 import DeleteCommentModal, { type DeleteCommentPayload } from "@/components/DeleteCommentModal";
-import CommentEditHistoryModal from "@/components/CommentEditHistoryModal";
+import EditHistoryModal from "@/components/EditHistoryModal";

 interface CommentSectionProps {
  postId: string;
@@ -56,6 +58,12 @@ interface CommentSectionProps {
  acceptedCommentId?: number;
  /** 抽奖已开奖：中奖楼层评论 ID（每名中奖者仅其最早主评一条） */
  winnerCommentIds?: number[];
+  /** 帖子是否被管理员手动锁定（普通用户不可回复/编辑评论，staff 豁免） */
+  postLocked: boolean;
+  /** 评论可编辑时长（小时）；0=不锁定；staff 豁免 */
+  commentEditLockHours: number;
+  /** 旧帖回复确认提示（后端按查看者计算；存在时提交回复前需用户确认，确认后发送并扣分） */
+  necroReply?: { after_hours: number; penalty: number } | null;
 }

 // 递归统计子树回复数（彻底删除级联提示用）
@@ -63,6 +71,9 @@ function countReplies(node: CommentNode): number {
  return node.replies?.reduce((acc, r) => acc + 1 + countReplies(r), 0) ?? 0;
 }

+/** 评论正文字符上限（与后端 handler/comment.go 校验一致） */
+const COMMENT_MAX = 5000;
+
 function findComment(nodes: CommentNode[], id: number): CommentNode | null {
  for (const n of nodes) {
    if (n.id === id) return n;
@@ -196,11 +207,22 @@ export default function CommentSection({
  acceptMode = null,
  acceptedCommentId = 0,
  winnerCommentIds = [],
+  postLocked,
+  commentEditLockHours,
+  necroReply = null,
 }: CommentSectionProps) {
  const winnerCommentIdSet = new Set(winnerCommentIds.filter((id) => id > 0));
  const router = useRouter();
  const commentsOpen = useAllowComments();
  const commentsRequireLogin = useCommentsRequireLogin();
+  const staffViewer = !!user && isStaff(user.role);
+  /** 锁帖后普通用户禁止回复与编辑自己的评论，staff 豁免 */
+  const replyBlocked = postLocked && !staffViewer;
+  /** 评论是否已超过可编辑时限（staff 豁免；0=不启用） */
+  const commentTimeLocked = (createdAt: string) =>
+    !staffViewer &&
+    commentEditLockHours > 0 &&
+    Date.now() - new Date(createdAt).getTime() > commentEditLockHours * 3_600_000;
  const [content, setContent] = useState("");
  // 内联回复目标：同一时间只有一个回复框；草稿按目标评论隔离
  const [replyTarget, setReplyTarget] = useState<{
@@ -221,6 +243,8 @@ export default function CommentSection({
  const [replyUploading, setReplyUploading] = useState(false);
  const [editUploading, setEditUploading] = useState(false);
  const [awayHref, setAwayHref] = useState<string | null>(null);
+  // 旧帖回复确认：记录待确认的提交入口（主楼层 / 内联回复）
+  const [necroConfirm, setNecroConfirm] = useState<null | "floor" | "reply">(null);
  const [discardReplyOpen, setDiscardReplyOpen] = useState(false);
  const [discardEditOpen, setDiscardEditOpen] = useState(false);
  const [deleting, setDeleting] = useState(false);
@@ -237,6 +261,7 @@ export default function CommentSection({
  const [editContent, setEditContent] = useState("");
  const [savingEdit, setSavingEdit] = useState(false);
  const [historyCommentId, setHistoryCommentId] = useState<number | null>(null);
+  const [historyCommentContent, setHistoryCommentContent] = useState("");
  // 折叠状态：哪些楼层展开了子回复（默认全部折叠，SSR 初始为收起）
  const [expandedFloors, setExpandedFloors] = useState<Set<number>>(new Set());

@@ -304,6 +329,11 @@ export default function CommentSection({

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
+    // 旧帖回复：确认后才发送并扣分（后端按查看者下发提示，staff/待审用户不会拿到）
+    if (necroReply) {
+      setNecroConfirm("floor");
+      return;
+    }
    void submitFloor();
  };

@@ -347,6 +377,11 @@ export default function CommentSection({

  const handleSubmitReply = (e: React.FormEvent) => {
    e.preventDefault();
+    // 旧帖回复：确认后才发送并扣分
+    if (necroReply) {
+      setNecroConfirm("reply");
+      return;
+    }
    void submitReply();
  };

@@ -472,9 +507,16 @@ export default function CommentSection({
    (user.id === comment.user?.id ||
      canStaffSoftDelete(user, boardId, comment.user?.role));

-  const canEdit = (comment: CommentNode) => canSoftDelete(comment);
+  const canEdit = (comment: CommentNode) => {
+    if (!canSoftDelete(comment)) return false;
+    // 作者本人编辑：锁帖与可编辑时限限制（staff 豁免；版主编辑他人不受此限）
+    if (user?.id === comment.user?.id && (replyBlocked || commentTimeLocked(comment.created_at))) {
+      return false;
+    }
+    return true;
+  };

-  const canViewHistory = !!user && canModerateBoard(user, boardId);
+  const canViewHistory = !!user;

  const canPurge = (comment: CommentNode) =>
    !!user && canPurgeContent(user.role) && canModerateBoard(user, boardId);
@@ -615,9 +657,10 @@ export default function CommentSection({
            density="comment"
            value={editContent}
            onChange={(v) => {
-              setEditContent(v);
+              setEditContent(v.slice(0, COMMENT_MAX));
              if (editError) setEditError("");
            }}
+            maxChars={COMMENT_MAX}
            disabled={savingEdit}
            autoFocus
            allowHide={false}
@@ -671,7 +714,14 @@ export default function CommentSection({
    if (!c.edited) return null;
    if (canViewHistory) {
      return (
-        <button type="button" className="cmt-edited" onClick={() => setHistoryCommentId(c.id)}>
+        <button
+          type="button"
+          className="cmt-edited"
+          onClick={() => {
+            setHistoryCommentContent(c.content);
+            setHistoryCommentId(c.id);
+          }}
+        >
          已编辑
        </button>
      );
@@ -693,11 +743,15 @@ export default function CommentSection({
        onSelect: () => startEdit(c),
      });
    }
-    if (canViewHistory) {
+    // 未编辑（无修订快照）的评论不展示历史入口，避免打开空记录
+    if (canViewHistory && c.edited) {
      items.push({
        key: "history",
        label: "编辑历史",
-        onSelect: () => setHistoryCommentId(c.id),
+        onSelect: () => {
+          setHistoryCommentContent(c.content);
+          setHistoryCommentId(c.id);
+        },
      });
    }
    if (canRestore(c)) {
@@ -758,9 +812,10 @@ export default function CommentSection({
          density="comment"
          value={replyContent}
          onChange={(v) => {
-            setReplyContent(v);
+            setReplyContent(v.slice(0, COMMENT_MAX));
            if (replyError) setReplyError("");
          }}
+          maxChars={COMMENT_MAX}
          disabled={submitting}
          autoFocus
          allowHide={false}
@@ -1015,7 +1070,7 @@ export default function CommentSection({
              </div>
              {renderContentOrEditor(c)}
              <div className="cmt-actions">
-                {commentsOpen && user && editingId !== c.id && (
+                {commentsOpen && user && !replyBlocked && editingId !== c.id && (
                  <button
                    type="button"
                    onClick={() => openReply(c, floor)}
@@ -1117,7 +1172,7 @@ export default function CommentSection({
            </div>
            {renderContentOrEditor(c)}
            <div className="cmt-actions">
-              {commentsOpen && user && editingId !== c.id && (
+              {commentsOpen && user && !replyBlocked && editingId !== c.id && (
                <button
                  type="button"
                  onClick={() => openReply(c, floor)}
@@ -1214,7 +1269,18 @@ export default function CommentSection({
        ) : null}
      </div>

-      {user ? (
+      {replyBlocked ? (
+        <div
+          className="mb-8 px-5 py-4 rounded-2xl flex items-center gap-2.5 border"
+          style={{ borderColor: "var(--line)", background: "transparent" }}
+          role="status"
+        >
+          <Lock size={15} style={{ color: "var(--ink-3)" }} className="shrink-0" />
+          <span className="text-sm" style={{ color: "var(--ink-2)" }}>
+            帖子已被锁定，暂时无法回复
+          </span>
+        </div>
+      ) : user ? (
        <form onSubmit={handleSubmit} className="mb-6">
          <div className="cmt-md-editor cmt-md-editor-floor scroll-mt-28">
            <MarkdownEditor
@@ -1222,9 +1288,10 @@ export default function CommentSection({
              density="comment"
              value={content}
              onChange={(v) => {
-                setContent(v);
+                setContent(v.slice(0, COMMENT_MAX));
                if (floorError) setFloorError("");
              }}
+              maxChars={COMMENT_MAX}
              disabled={submitting}
              allowHide={false}
              ariaLabel="发表评论"
@@ -1355,9 +1422,29 @@ export default function CommentSection({
        onCancel={() => setDiscardEditOpen(false)}
      />

-      <CommentEditHistoryModal
+      {/* 旧帖回复确认：确认后才发送并扣分（提示由后端按查看者下发） */}
+      <ConfirmDialog
+        open={necroConfirm !== null}
+        title="回复旧帖提醒"
+        message={`该帖已超过 ${necroReply?.after_hours ?? 0} 小时没有新回复，回复将扣除 ${necroReply?.penalty ?? 0} 积分。确定继续吗？`}
+        confirmLabel="继续回复"
+        onConfirm={() => {
+          const kind = necroConfirm;
+          setNecroConfirm(null);
+          if (kind === "floor") void submitFloor();
+          else if (kind === "reply") void submitReply();
+        }}
+        onCancel={() => setNecroConfirm(null)}
+      />
+
+      <EditHistoryModal
        open={historyCommentId != null}
-        commentId={historyCommentId}
+        title="评论编辑历史"
+        currentContent={historyCommentContent}
+        fetchPage={(p, s) => {
+          if (historyCommentId == null) return Promise.reject(new Error("未选择评论"));
+          return apiCommentHistory(historyCommentId, p, s);
+        }}
        onClose={() => setHistoryCommentId(null)}
      />
    </section>
--- a/frontend/components/EditHistoryModal.tsx
+++ b/frontend/components/EditHistoryModal.tsx
@@ -0,0 +1,433 @@
+"use client";
+
+import { useCallback, useEffect, useMemo, useState } from "react";
+import Link from "next/link";
+import { Loader2 } from "lucide-react";
+import Modal from "@/components/Modal";
+import Avatar from "@/components/Avatar";
+
+const PAGE_SIZE = 10;
+
+export interface EditHistoryItem {
+  id: number;
+  editor: {
+    id: number;
+    username: string;
+    nickname: string;
+    avatar: string;
+  };
+  old_title?: string; // 帖子场景有；评论场景无
+  old_content: string;
+  created_at: string;
+}
+
+export type FetchHistoryPage = (
+  page: number,
+  size: number
+) => Promise<{
+  items: EditHistoryItem[];
+  total: number;
+  page: number;
+  size: number;
+}>;
+
+/* ---------------- 行级 diff（LCS），git diff 风格渲染 ---------------- */
+
+type DiffOp = "del" | "add" | "ctx";
+
+interface DiffLine {
+  op: DiffOp;
+  text: string;
+}
+
+interface Seg {
+  chg: boolean;
+  text: string;
+}
+
+type Row =
+  | { kind: "line"; op: DiffOp; text: string; pair: string | null }
+  | { kind: "fold"; count: number };
+
+// 超大文本退化为整段替换，避免 O(n·m) 内存膨胀
+const MAX_DIFF_CELLS = 400_000;
+// 单行超过该长度不做行内变更高亮
+const MAX_INLINE_DIFF_LEN = 2000;
+// 相同内容行超过该数量时折叠中段
+const CONTEXT_FOLD_LIMIT = 8;
+
+function splitLines(text: string): string[] {
+  if (!text) return [];
+  return text.replace(/\r\n/g, "\n").split("\n");
+}
+
+function diffLines(oldText: string, newText: string): DiffLine[] {
+  const a = splitLines(oldText);
+  const b = splitLines(newText);
+  const n = a.length;
+  const m = b.length;
+  if (n * m > MAX_DIFF_CELLS) {
+    return [
+      ...a.map((text) => ({ op: "del" as const, text })),
+      ...b.map((text) => ({ op: "add" as const, text })),
+    ];
+  }
+  const width = m + 1;
+  const dp = new Uint32Array((n + 1) * width);
+  for (let i = n - 1; i >= 0; i--) {
+    for (let j = m - 1; j >= 0; j--) {
+      dp[i * width + j] =
+        a[i] === b[j]
+          ? dp[(i + 1) * width + (j + 1)] + 1
+          : Math.max(dp[(i + 1) * width + j], dp[i * width + (j + 1)]);
+    }
+  }
+  const out: DiffLine[] = [];
+  let i = 0;
+  let j = 0;
+  while (i < n && j < m) {
+    if (a[i] === b[j]) {
+      out.push({ op: "ctx", text: a[i] });
+      i += 1;
+      j += 1;
+    } else if (dp[(i + 1) * width + j] >= dp[i * width + (j + 1)]) {
+      out.push({ op: "del", text: a[i] });
+      i += 1;
+    } else {
+      out.push({ op: "add", text: b[j] });
+      j += 1;
+    }
+  }
+  while (i < n) {
+    out.push({ op: "del", text: a[i] });
+    i += 1;
+  }
+  while (j < m) {
+    out.push({ op: "add", text: b[j] });
+    j += 1;
+  }
+  return normalizeBlocks(out);
+}
+
+// 每个连续变更块内统一「先删后增」，与 git diff 呈现一致
+function normalizeBlocks(lines: DiffLine[]): DiffLine[] {
+  const out: DiffLine[] = [];
+  let k = 0;
+  while (k < lines.length) {
+    if (lines[k].op === "ctx") {
+      out.push(lines[k]);
+      k += 1;
+      continue;
+    }
+    let end = k;
+    while (end < lines.length && lines[end].op !== "ctx") end += 1;
+    for (let t = k; t < end; t++) if (lines[t].op === "del") out.push(lines[t]);
+    for (let t = k; t < end; t++) if (lines[t].op === "add") out.push(lines[t]);
+    k = end;
+  }
+  return out;
+}
+
+// 行内变更高亮：取公共前/后缀，中间差异段标记 chg
+function segmentLine(line: string, other: string | null): Seg[] {
+  if (
+    !other ||
+    line === other ||
+    line.length + other.length > MAX_INLINE_DIFF_LEN * 2
+  ) {
+    return [{ chg: false, text: line }];
+  }
+  const min = Math.min(line.length, other.length);
+  let p = 0;
+  while (p < min && line[p] === other[p]) p += 1;
+  let s = 0;
+  while (
+    s < min - p &&
+    line[line.length - 1 - s] === other[other.length - 1 - s]
+  ) {
+    s += 1;
+  }
+  const segs: Seg[] = [];
+  if (p > 0) segs.push({ chg: false, text: line.slice(0, p) });
+  const mid = line.slice(p, line.length - s);
+  if (mid) segs.push({ chg: true, text: mid });
+  if (s > 0) segs.push({ chg: false, text: line.slice(line.length - s) });
+  return segs.length > 0 ? segs : [{ chg: false, text: line }];
+}
+
+// 折叠长段相同内容；同块内删除/新增按序号配对做行内高亮
+function buildRows(lines: DiffLine[]): Row[] {
+  const rows: Row[] = [];
+  let k = 0;
+  while (k < lines.length) {
+    if (lines[k].op === "ctx") {
+      let end = k;
+      while (end < lines.length && lines[end].op === "ctx") end += 1;
+      const run = end - k;
+      if (run > CONTEXT_FOLD_LIMIT) {
+        for (let t = k; t < k + 3; t++) {
+          rows.push({ kind: "line", op: lines[t].op, text: lines[t].text, pair: null });
+        }
+        rows.push({ kind: "fold", count: run - 6 });
+        for (let t = end - 3; t < end; t++) {
+          rows.push({ kind: "line", op: lines[t].op, text: lines[t].text, pair: null });
+        }
+      } else {
+        for (let t = k; t < end; t++) {
+          rows.push({ kind: "line", op: lines[t].op, text: lines[t].text, pair: null });
+        }
+      }
+      k = end;
+    } else {
+      let end = k;
+      while (end < lines.length && lines[end].op !== "ctx") end += 1;
+      const dels = lines.slice(k, end).filter((l) => l.op === "del");
+      const adds = lines.slice(k, end).filter((l) => l.op === "add");
+      const pairFor = new Map<DiffLine, string | null>();
+      const cnt = Math.min(dels.length, adds.length);
+      for (let t = 0; t < cnt; t++) {
+        pairFor.set(dels[t], adds[t].text);
+        pairFor.set(adds[t], dels[t].text);
+      }
+      for (let t = k; t < end; t++) {
+        rows.push({
+          kind: "line",
+          op: lines[t].op,
+          text: lines[t].text,
+          pair: pairFor.get(lines[t]) ?? null,
+        });
+      }
+      k = end;
+    }
+  }
+  return rows;
+}
+
+function DiffBody({ before, after }: { before: string; after: string }) {
+  const rows = useMemo(() => buildRows(diffLines(before, after)), [before, after]);
+  const delCount = rows.filter((r) => r.kind === "line" && r.op === "del").length;
+  const addCount = rows.filter((r) => r.kind === "line" && r.op === "add").length;
+  return (
+    <div className="cmt-diff">
+      <div className="cmt-diff-stat">
+        <span className="cmt-diff-stat-add">+{addCount}</span>
+        <span className="cmt-diff-stat-del">−{delCount}</span>
+      </div>
+      <div className="cmt-diff-body">
+        {rows.map((r, idx) =>
+          r.kind === "fold" ? (
+            <div key={idx} className="cmt-diff-fold">
+              ⋯ 已省略 {r.count} 行相同内容 ⋯
+            </div>
+          ) : (
+            <div key={idx} className={`cmt-diff-line is-${r.op}`}>
+              <span className="cmt-diff-sign" aria-hidden>
+                {r.op === "del" ? "-" : r.op === "add" ? "+" : " "}
+              </span>
+              <span className="cmt-diff-text">
+                {segmentLine(r.text, r.pair).map((s, si) =>
+                  s.chg ? (
+                    <mark key={si} className="cmt-diff-chg">
+                      {s.text}
+                    </mark>
+                  ) : (
+                    <span key={si}>{s.text}</span>
+                  )
+                )}
+              </span>
+            </div>
+          )
+        )}
+      </div>
+    </div>
+  );
+}
+
+/* ---------------- 弹窗 ---------------- */
+
+/**
+ * 登录可见：历次编辑的 git diff 风格修订视图（倒序分页）。
+ * 后端只存每次编辑前的旧快照：第 i 条的「改后内容」= 第 i-1 条（更新的一条）的快照，
+ * 最新一条的「改后内容」= 当前正文（由调用方传入）。帖子场景另传 currentTitle 渲染标题 diff。
+ */
+export default function EditHistoryModal({
+  open,
+  title,
+  currentTitle,
+  currentContent,
+  fetchPage,
+  onClose,
+}: {
+  open: boolean;
+  title: string;
+  currentTitle?: string;
+  currentContent: string;
+  fetchPage: FetchHistoryPage;
+  onClose: () => void;
+}) {
+  const [loading, setLoading] = useState(false);
+  const [loadingMore, setLoadingMore] = useState(false);
+  const [error, setError] = useState("");
+  const [items, setItems] = useState<EditHistoryItem[]>([]);
+  const [page, setPage] = useState(1);
+  const [total, setTotal] = useState(0);
+
+  const hasMore = items.length < total;
+
+  const loadPage = useCallback(
+    async (nextPage: number, append: boolean) => {
+      if (!open) return;
+      if (append) setLoadingMore(true);
+      else {
+        setLoading(true);
+        setError("");
+      }
+      try {
+        const res = await fetchPage(nextPage, PAGE_SIZE);
+        const batch = res.items || [];
+        setError("");
+        setTotal(res.total ?? 0);
+        setPage(res.page ?? nextPage);
+        setItems((prev) => (append ? [...prev, ...batch] : batch));
+      } catch (e) {
+        const msg = e instanceof Error ? e.message : "加载失败";
+        if (append) {
+          // 追加失败不清空已有列表
+          setError(msg);
+        } else {
+          setError(msg);
+          setItems([]);
+          setTotal(0);
+        }
+      } finally {
+        setLoading(false);
+        setLoadingMore(false);
+      }
+    },
+    [open, fetchPage]
+  );
+
+  useEffect(() => {
+    if (!open) return;
+    setItems([]);
+    setPage(1);
+    setTotal(0);
+    setError("");
+    void loadPage(1, false);
+  }, [open, loadPage]);
+
+  const hasTitle = typeof currentTitle === "string";
+
+  return (
+    <Modal
+      open={open}
+      title={title}
+      description={total > 0 ? `共 ${total} 条修订记录 · - 移除内容 / + 新增内容` : undefined}
+      onClose={onClose}
+      // 对齐详情页中间评论栏可用宽度（1440 三栏布局下约 800px）
+      maxWidthClass="max-w-[min(840px,calc(100vw-2rem))]"
+      panelClassName="p-5 sm:p-6 max-h-[85vh] flex flex-col min-h-0 overflow-hidden"
+      bodyClassName="overflow-y-auto min-h-0 flex-1 -mx-1 px-1"
+      footer={
+        <button type="button" className="btn btn-line btn-sm" onClick={onClose}>
+          关闭
+        </button>
+      }
+    >
+      {loading ? (
+        <div className="flex items-center justify-center gap-2 py-10 meta text-[13px]">
+          <Loader2 size={16} className="animate-spin" />
+          加载中…
+        </div>
+      ) : error && items.length === 0 ? (
+        <p className="text-[13.5px] py-6 text-center" style={{ color: "var(--danger)" }}>
+          {error}
+        </p>
+      ) : items.length === 0 ? (
+        <p className="meta text-[13.5px] py-8 text-center">暂无编辑记录</p>
+      ) : (
+        <div className="flex flex-col gap-4">
+          <ul className="flex flex-col gap-4">
+            {items.map((it, idx) => {
+              const name = it.editor.nickname || it.editor.username || "用户";
+              // 本次编辑的改后内容：上一条（更新的）快照；最新一条为当前正文
+              const afterContent = idx === 0 ? currentContent : items[idx - 1].old_content;
+              const afterTitle = hasTitle
+                ? idx === 0
+                  ? (currentTitle ?? "")
+                  : (items[idx - 1].old_title ?? "")
+                : undefined;
+              const titleChanged = hasTitle && it.old_title !== afterTitle;
+              const contentChanged = it.old_content !== afterContent;
+              return (
+                <li
+                  key={it.id}
+                  className="rounded-md p-3 sm:p-4"
+                  style={{ background: "var(--panel-2)", border: "1px solid var(--line)" }}
+                >
+                  <div className="flex items-center gap-2 mb-2.5">
+                    <Link href={`/u/${it.editor.id}`} className="shrink-0">
+                      <Avatar name={name} src={it.editor.avatar || undefined} size={28} />
+                    </Link>
+                    <div className="min-w-0 flex-1">
+                      <Link
+                        href={`/u/${it.editor.id}`}
+                        className="text-[13px] hover:text-[var(--accent)]"
+                        style={{ color: "var(--ink)" }}
+                      >
+                        {name}
+                      </Link>
+                      <p className="meta text-[11.5px] tabular-nums">
+                        {new Date(it.created_at).toLocaleString("zh-CN")} · 第{" "}
+                        {total - idx} 次编辑
+                      </p>
+                    </div>
+                  </div>
+                  {titleChanged && (
+                    <div className="mb-3">
+                      <p className="meta text-[11.5px] mb-1">标题</p>
+                      <DiffBody before={it.old_title ?? ""} after={afterTitle ?? ""} />
+                    </div>
+                  )}
+                  {contentChanged ? (
+                    <DiffBody before={it.old_content} after={afterContent} />
+                  ) : (
+                    !titleChanged && (
+                      <p className="meta text-[12.5px]">本次仅变更了标签或其他元数据，未修改标题/正文。</p>
+                    )
+                  )}
+                </li>
+              );
+            })}
+          </ul>
+
+          {error && items.length > 0 && (
+            <p className="text-[12.5px] text-center" style={{ color: "var(--danger)" }}>
+              {error}
+            </p>
+          )}
+
+          {hasMore && (
+            <div className="flex justify-center pt-1 pb-1">
+              <button
+                type="button"
+                className="btn btn-line btn-sm"
+                disabled={loadingMore}
+                onClick={() => void loadPage(page + 1, true)}
+              >
+                {loadingMore ? (
+                  <span className="inline-flex items-center gap-1.5">
+                    <Loader2 size={14} className="animate-spin" />
+                    加载中…
+                  </span>
+                ) : (
+                  `加载更多（已显示 ${items.length}/${total}）`
+                )}
+              </button>
+            </div>
+          )}
+        </div>
+      )}
+    </Modal>
+  );
+}
--- a/frontend/components/MarkdownEditor.tsx
+++ b/frontend/components/MarkdownEditor.tsx
@@ -71,6 +71,8 @@ type MarkdownEditorProps = {
  shortcutName?: string;
  /** 底栏右侧操作（发表 / 保存），纳入编辑器边框内 */
  footer?: ReactNode;
+  /** 正文字符数上限；设置后计数器显示「已输入 / 上限」并限制输入 */
+  maxChars?: number;
  /** 提交失败等原因，显示在编辑器内 */
  error?: string;
  onUploadingChange?: (uploading: boolean) => void;
@@ -143,6 +145,7 @@ export default function MarkdownEditor({
  hint,
  shortcutName,
  footer,
+  maxChars,
  error,
  onUploadingChange,
 }: MarkdownEditorProps) {
@@ -1247,6 +1250,7 @@ export default function MarkdownEditor({
            value={value}
            disabled={disabled}
            rows={isComment ? 3 : rows}
+            maxLength={maxChars}
            placeholder={placeholder}
            aria-label={ariaLabel || placeholder || "正文"}
            className="j13-md-textarea"
@@ -1278,7 +1282,9 @@ export default function MarkdownEditor({
              : "支持粘贴/拖拽图片 · Markdown · Ctrl/⌘ + Enter 提交")}
        </span>
        <span className="j13-md-foot-actions">
-          <span className="j13-md-count tabular-nums">{value.length} 字</span>
+          <span className="j13-md-count tabular-nums">
+            {maxChars != null ? `${value.length} / ${maxChars}` : `${value.length} 字`}
+          </span>
          {footer}
        </span>
      </div>
--- a/frontend/components/Modal.tsx
+++ b/frontend/components/Modal.tsx
@@ -1,6 +1,7 @@
 "use client";

 import { useEffect, useRef, type PointerEvent, type ReactNode } from "react";
+import { createPortal } from "react-dom";
 import { X } from "lucide-react";

 export type ModalProps = {
@@ -102,7 +103,7 @@ export default function Modal({
    overlayPressedRef.current = false;
  };

-  return (
+  return createPortal(
    <div
      className={`fixed inset-0 ${zIndexClass} flex items-center justify-center p-4`}
      style={{ background: "rgba(0,0,0,0.55)" }}
@@ -150,7 +151,8 @@ export default function Modal({
          <div className="flex items-center justify-end gap-2 mt-5">{footer}</div>
        ) : null}
      </div>
-    </div>
+    </div>,
+    document.body
  );
 }

--- a/frontend/components/NotificationBell.tsx
+++ b/frontend/components/NotificationBell.tsx
@@ -3,7 +3,7 @@
 import { useState, useEffect, useRef } from "react";
 import { useRouter } from "next/navigation";
 import Link from "next/link";
-import { Bell, CheckCheck, Heart, MessageCircle, CheckCircle2, XCircle, AtSign, ClipboardList, Award } from "lucide-react";
+import { Bell, CheckCheck, Heart, MessageCircle, CheckCircle2, XCircle, AtSign, ClipboardList, Award, AlertTriangle } from "lucide-react";
 import {
  apiFetchNotifications,
  apiUnreadCount,
@@ -137,17 +137,22 @@ export default function NotificationBell({ initialUnread = 0 }: { initialUnread?
    if (n.type === "pending_review") return "有新内容待审核";
    if (n.type === "deleted") return "删除了你的帖子";
    if (n.type === "badge") return "向你颁布了徽章";
+    if (n.type === "necro_reply") return "旧帖回复提醒";
    return "点赞了你的帖子";
  };

  // 审核结果类通知：无互动对象语义，使用专用图标与语义色
  const isApproval = (n: NotificationItem) =>
    n.type === "approved" || n.type === "rejected" || n.type === "deleted";
+  // 系统提醒（ActorID=0）：同样不渲染操作者链接
+  const isSystemNotice = (n: NotificationItem) => n.type === "necro_reply";
  const iconStyle = (n: NotificationItem): { color: string; bg: string; node: React.ReactNode } => {
    if (n.type === "approved")
      return { color: "var(--ok)", bg: "var(--ok-soft)", node: <CheckCircle2 size={15} /> };
    if (n.type === "rejected" || n.type === "deleted")
      return { color: "var(--danger)", bg: "var(--danger-soft)", node: <XCircle size={15} /> };
+    if (n.type === "necro_reply")
+      return { color: "var(--danger)", bg: "var(--danger-soft)", node: <AlertTriangle size={15} /> };
    if (n.type === "like")
      return { color: "var(--clay)", bg: "var(--clay-soft)", node: <Heart size={15} /> };
    if (n.type === "mention")
@@ -223,7 +228,7 @@ export default function NotificationBell({ initialUnread = 0 }: { initialUnread?
            ) : (
              notifications.map((n) => {
                const ic = iconStyle(n);
-                const approval = isApproval(n);
+                const approval = isApproval(n) || isSystemNotice(n);
                return (
                <button
                  key={n.id}
--- a/frontend/components/PostActions.tsx
+++ b/frontend/components/PostActions.tsx
@@ -3,9 +3,9 @@
 import { useState, useEffect, useRef } from "react";
 import { useRouter } from "next/navigation";
 import Link from "next/link";
-import { Pencil, Trash2, Pin, Star, SlidersHorizontal, ChevronDown, Check, BadgeCheck } from "lucide-react";
-import { apiMe, apiDeletePost, apiTogglePin, apiToggleRecommend, apiAdminApprovePost, type User } from "@/lib/api";
-import { canStaffSoftDelete, canModerateBoard, isAdminOrAbove } from "@/lib/roles";
+import { Pencil, Trash2, Pin, Star, SlidersHorizontal, ChevronDown, Check, BadgeCheck, Lock, LockOpen } from "lucide-react";
+import { apiMe, apiDeletePost, apiTogglePin, apiToggleRecommend, apiTogglePostLock, apiAdminApprovePost, type User } from "@/lib/api";
+import { canStaffSoftDelete, canModerateBoard, isAdminOrAbove, isStaff } from "@/lib/roles";
 import { toast } from "@/lib/toast";
 import ConfirmDialog from "@/components/ConfirmDialog";
 import StaffDeletePostModal from "@/components/StaffDeletePostModal";
@@ -19,6 +19,12 @@ interface PostActionsProps {
  recommended: boolean;
  /** 帖子审核状态：pending 时对可审者显示「通过评审」 */
  status: string;
+  /** 帖子创建时间：自动编辑锁计时基准（staff 豁免） */
+  createdAt: string;
+  /** 帖子是否被管理员手动锁定（staff 豁免） */
+  locked: boolean;
+  /** 帖子可编辑时长（小时）；0=不锁定；staff 豁免 */
+  postEditLockHours: number;
  /** 供删除确认展示 */
  title?: string;
 }
@@ -31,6 +37,9 @@ export default function PostActions({
  pinned,
  recommended,
  status,
+  createdAt,
+  locked,
+  postEditLockHours,
  title,
 }: PostActionsProps) {
  const router = useRouter();
@@ -39,6 +48,7 @@ export default function PostActions({
  const [deleting, setDeleting] = useState(false);
  const [isPinned, setIsPinned] = useState(pinned > 0);
  const [isRecommended, setIsRecommended] = useState(recommended);
+  const [isLocked, setIsLocked] = useState(locked);
  const [acting, setActing] = useState(false);
  const [confirmDelete, setConfirmDelete] = useState(false);
  const [staffDeleteOpen, setStaffDeleteOpen] = useState(false);
@@ -70,6 +80,13 @@ export default function PostActions({
    !!user &&
    (user.id === authorId || canStaffSoftDelete(user, boardId, authorRole));
  const isAdmin = !!user && isAdminOrAbove(user.role);
+  const staffUser = !!user && isStaff(user.role);
+  // 编辑入口：手动锁帖或超过可编辑时限时对普通用户隐藏，staff 豁免
+  const editTimeLocked =
+    !staffUser &&
+    postEditLockHours > 0 &&
+    Date.now() - new Date(createdAt).getTime() > postEditLockHours * 3_600_000;
+  const showEdit = canManage && !(isLocked && !staffUser) && !editTimeLocked;
  const canApprove =
    !!user && status === "pending" && canModerateBoard(user, boardId);
  // staff 删他人帖：走类型+理由；作者自删：简单确认
@@ -139,6 +156,21 @@ export default function PostActions({
    }
  };

+  const handleLock = async () => {
+    setActing(true);
+    setOpen(false);
+    try {
+      const res = await apiTogglePostLock(postId);
+      setIsLocked(res.locked);
+      toast(res.locked ? "已锁定，普通用户不可编辑与回复" : "已解除锁定", "ok");
+      router.refresh();
+    } catch {
+      toast("操作失败，请稍后重试");
+    } finally {
+      setActing(false);
+    }
+  };
+
  if (!canManage) return null;

  const itemCls =
@@ -212,18 +244,35 @@ export default function PostActions({
                <span className="flex-1 text-left">{isRecommended ? "取消推荐" : "推荐"}</span>
                {isRecommended && <Check size={14} className="shrink-0" />}
              </button>
+              <button
+                type="button"
+                role="menuitem"
+                onClick={handleLock}
+                className={itemCls}
+                style={isLocked ? { color: "var(--danger)" } : { color: "var(--ink)" }}
+              >
+                {isLocked ? (
+                  <LockOpen size={14} className="shrink-0" />
+                ) : (
+                  <Lock size={14} className="shrink-0" />
+                )}
+                <span className="flex-1 text-left">{isLocked ? "解除锁定" : "锁定"}</span>
+                {isLocked && <Check size={14} className="shrink-0" />}
+              </button>
              <div style={{ height: 1, background: "var(--line)" }} />
            </>
          )}
-          <Link
-            href={`/post/${postId}/edit`}
-            role="menuitem"
-            className={`${itemCls} items-center`}
-            style={{ color: "var(--ink)" }}
-          >
-            <Pencil size={14} className="shrink-0" />
-            <span className="flex-1 text-left">编辑帖子</span>
-          </Link>
+          {showEdit && (
+            <Link
+              href={`/post/${postId}/edit`}
+              role="menuitem"
+              className={`${itemCls} items-center`}
+              style={{ color: "var(--ink)" }}
+            >
+              <Pencil size={14} className="shrink-0" />
+              <span className="flex-1 text-left">编辑帖子</span>
+            </Link>
+          )}
          <button
            type="button"
            role="menuitem"
--- a/frontend/components/PostComposer.tsx
+++ b/frontend/components/PostComposer.tsx
@@ -37,6 +37,8 @@ import Modal from "@/components/Modal";
 import { realtime, RT_SETTINGS_CHANGED, type RtSettingsData } from "@/lib/realtime";

 const TITLE_MAX = 256;
+/** 帖子正文字符上限（与后端 handler/post.go 校验一致） */
+const CONTENT_MAX = 20000;
 const DRAFT_KEY = "j13-compose-draft";
 const DRAFT_DEBOUNCE_MS = 600;
 /** 与 globals.css 工作台分栏断点一致 */
@@ -1640,7 +1642,8 @@ export default function PostComposer(props: PostComposerProps) {
            <MarkdownEditor
              id="compose-content"
              value={content}
-              onChange={setContent}
+              onChange={(v) => setContent(v.slice(0, CONTENT_MAX))}
+              maxChars={CONTENT_MAX}
              allowHide
              disabled={loading}
              rows={18}
--- a/frontend/components/PostEditedMark.tsx
+++ b/frontend/components/PostEditedMark.tsx
@@ -0,0 +1,37 @@
+"use client";
+
+import { useState } from "react";
+import EditHistoryModal from "@/components/EditHistoryModal";
+import { apiPostHistory } from "@/lib/api";
+
+/** 帖子详情「更新于」旁的编辑历史入口（登录用户可见） */
+export default function PostEditedMark({
+  postId,
+  currentTitle,
+  currentContent,
+}: {
+  postId: number;
+  currentTitle: string;
+  currentContent: string;
+}) {
+  const [open, setOpen] = useState(false);
+  return (
+    <>
+      <button
+        type="button"
+        className="cmt-edited"
+        onClick={() => setOpen(true)}
+      >
+        编辑历史
+      </button>
+      <EditHistoryModal
+        open={open}
+        title="帖子编辑历史"
+        currentTitle={currentTitle}
+        currentContent={currentContent}
+        fetchPage={(p, s) => apiPostHistory(postId, p, s)}
+        onClose={() => setOpen(false)}
+      />
+    </>
+  );
+}
--- a/frontend/lib/api.ts
+++ b/frontend/lib/api.ts
@@ -381,11 +381,19 @@ export interface Post {
  type_status?: string;
  pinned: number;
  recommended: boolean;
+  /** 管理员手动锁定：普通用户不可编辑/回复（staff 豁免） */
+  locked: boolean;
+  /** 最后一条已发布评论时间；null=无回复（旧帖判定回落 created_at） */
+  last_reply_at?: string | null;
+  /** 旧帖回复确认提示（详情接口按查看者计算；存在时提交回复前需用户确认） */
+  necro_reply?: { after_hours: number; penalty: number } | null;
  status: string;
  like_count: number;
  view_count: number;
  comment_count: number;
  liked: boolean;
+  /** 详情接口返回：是否存在编辑历史快照（列表接口无此字段） */
+  edited?: boolean;
  created_at: string;
  updated_at: string;
  board: Board;
@@ -608,7 +616,7 @@ export interface NotificationItem {
  id: number;
  user_id: number;
  actor_id: number;
-  type: "comment" | "reply" | "like" | "approved" | "rejected" | "mention" | "pending_review" | "deleted" | "badge";
+  type: "comment" | "reply" | "like" | "approved" | "rejected" | "mention" | "pending_review" | "deleted" | "badge" | "necro_reply";
  post_id: number;
  comment_id: number;
  room_id?: number;
@@ -918,6 +926,14 @@ export interface PublicSettings {
  points_reply_daily_cap: number;
  /** 帖子被推荐奖励（每帖仅一次）；0=关闭；缺省 0 */
  points_recommend_reward: number;
+  /** 帖子可编辑时长（小时）；0=不锁定；缺省 0；上限 8760 */
+  post_edit_lock_hours: number;
+  /** 评论可编辑时长（小时）；0=不锁定；缺省 0；上限 8760 */
+  comment_edit_lock_hours: number;
+  /** 旧帖回复判定时长（小时）；0=关闭；缺省 0 */
+  necro_reply_after_hours: number;
+  /** 旧帖回复扣除积分；0=仅提醒不扣分；缺省 0；上限 100 */
+  necro_reply_penalty: number;
  /** 用户等级体系（数量/每级阈值/每级色板 key）；等级数值由后端计算 */
  levels: LevelDef[];
  /** 等级特效动画总开关（流光动画）；缺省开 */
@@ -980,6 +996,10 @@ const DEFAULT_PUBLIC_SETTINGS: PublicSettings = {
  points_reply_reward: 0,
  points_reply_daily_cap: 0,
  points_recommend_reward: 0,
+  post_edit_lock_hours: 0,
+  comment_edit_lock_hours: 0,
+  necro_reply_after_hours: 0,
+  necro_reply_penalty: 0,
  levels: [...DEFAULT_LEVEL_DEFS],
  levels_fx: true,
 };
@@ -1068,11 +1088,40 @@ function normalizePublicSettings(data: Partial<PublicSettings> | null | undefine
    bg_admin_url: typeof data?.bg_admin_url === "string" ? data.bg_admin_url : "",
    bg_admin_mode: typeof data?.bg_admin_mode === "string" ? data.bg_admin_mode : "cover",
    ...normalizePointsSettings(data),
+    ...normalizeLockSettings(data),
    levels: normalizeLevels(data?.levels),
    levels_fx: data?.levels_fx !== false,
  };
 }

+/** 内容锁定 4 键：小时 0–8760 / 积分 0–100 有效整数，越界/异常回落默认值 */
+function normalizeLockSettings(
+  data: Partial<PublicSettings> | null | undefined,
+): Pick<
+  PublicSettings,
+  | "post_edit_lock_hours"
+  | "comment_edit_lock_hours"
+  | "necro_reply_after_hours"
+  | "necro_reply_penalty"
+> {
+  const hours = (key: keyof PublicSettings): number | undefined => {
+    const v = data?.[key];
+    return typeof v === "number" && v >= 0 && v <= 8760 ? Math.round(v) : undefined;
+  };
+  const points = (key: keyof PublicSettings): number | undefined => {
+    const v = data?.[key];
+    return typeof v === "number" && v >= 0 && v <= 100 ? Math.round(v) : undefined;
+  };
+  return {
+    post_edit_lock_hours: hours("post_edit_lock_hours") ?? DEFAULT_PUBLIC_SETTINGS.post_edit_lock_hours,
+    comment_edit_lock_hours:
+      hours("comment_edit_lock_hours") ?? DEFAULT_PUBLIC_SETTINGS.comment_edit_lock_hours,
+    necro_reply_after_hours:
+      hours("necro_reply_after_hours") ?? DEFAULT_PUBLIC_SETTINGS.necro_reply_after_hours,
+    necro_reply_penalty: points("necro_reply_penalty") ?? DEFAULT_PUBLIC_SETTINGS.necro_reply_penalty,
+  };
+}
+
 /** 积分规则 8 键：0–100 有效整数，越界/异常回落默认值 */
 function normalizePointsSettings(
  data: Partial<PublicSettings> | null | undefined,
@@ -1977,6 +2026,15 @@ export async function apiToggleRecommend(postId: string): Promise<{ recommended:
  return res.json();
 }

+/** 切换帖子手动锁定（管理员及以上）；锁定后普通用户不可编辑/回复 */
+export async function apiTogglePostLock(postId: string): Promise<{ locked: boolean }> {
+  const res = await fetchWithRefresh(`/api/posts/${postId}/lock`, {
+    method: "PUT",
+    headers: clientHeaders(),
+  });
+  return res.json();
+}
+
 export async function apiChangePassword(oldPassword: string, newPassword: string) {
  const res = await fetchWithRefresh("/api/change-password", {
    method: "POST",
@@ -3092,6 +3150,10 @@ export type UpdateSiteSettingsBody = {
  points_reply_reward?: number;
  points_reply_daily_cap?: number;
  points_recommend_reward?: number;
+  post_edit_lock_hours?: number;
+  comment_edit_lock_hours?: number;
+  necro_reply_after_hours?: number;
+  necro_reply_penalty?: number;
  /** 用户等级体系（数量/每级阈值/每级色板 key）；整体替换保存 */
  levels?: LevelDef[];
  levels_fx?: boolean;
@@ -3264,6 +3326,8 @@ export interface AdminContentComment {
  board_id: number;
  content: string;
  status: string;
+  /** 相对创建已编辑（服务端判定）；无编辑时隐藏历史入口 */
+  edited: boolean;
  deleted: boolean;
  deleted_at?: string;
  created_at: string;
@@ -3352,15 +3416,44 @@ export interface CommentEditHistoryItem {
  created_at: string;
 }

-/** 管理：评论编辑历史（分页；默认每页 10 条） */
-export async function apiAdminCommentHistory(
+/** 评论编辑历史（登录可见；分页；默认每页 10 条） */
+export async function apiCommentHistory(
  commentId: number,
  page = 1,
  size = 10
 ): Promise<{ items: CommentEditHistoryItem[]; total: number; page: number; size: number }> {
  const params = new URLSearchParams({ page: String(page), size: String(size) });
  const res = await fetchWithRefresh(
-    `/api/admin/content/comments/${commentId}/history?${params}`,
+    `/api/comments/${commentId}/history?${params}`,
+    { headers: clientHeaders() }
+  );
+  const data = await res.json().catch(() => ({}));
+  if (!res.ok) throw new Error(data.error || "获取编辑历史失败");
+  return data;
+}
+
+export interface PostEditHistoryItem {
+  id: number;
+  editor: {
+    id: number;
+    username: string;
+    nickname: string;
+    avatar: string;
+  };
+  old_title: string;
+  old_content: string;
+  created_at: string;
+}
+
+/** 帖子编辑历史（登录可见；分页；默认每页 10 条） */
+export async function apiPostHistory(
+  postId: number,
+  page = 1,
+  size = 10
+): Promise<{ items: PostEditHistoryItem[]; total: number; page: number; size: number }> {
+  const params = new URLSearchParams({ page: String(page), size: String(size) });
+  const res = await fetchWithRefresh(
+    `/api/posts/${postId}/history?${params}`,
    { headers: clientHeaders() }
  );
  const data = await res.json().catch(() => ({}));
--- a/frontend/lib/smartDiff.test.ts
+++ b/frontend/lib/smartDiff.test.ts
@@ -0,0 +1,214 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+import { smartDiff, toFoldedRows } from "./smartDiff.ts";
+
+/** 把结果压成便于断言的短格式：每行 "op:text" */
+function flat(text: string, other: string): string[] {
+  const r = smartDiff(text, other);
+  return r.blocks.flatMap((b) => b.lines.map((l) => `${l.op}:${l.text}`));
+}
+
+describe("smartDiff", () => {
+  it("场景1：整段中文说明 → 整段 R 代码，判定 block-replace 而非碎片对齐", () => {
+    // 两段各留一个空行作为「诱饵公共行」——朴素 LCS 会围绕它做对齐
+    const oldText = [
+      "本函数用于处理用户上传的数据。",
+      "",
+      "首先校验输入的合法性，",
+      "然后将数据逐行写入临时表，",
+      "最后清理缓存并返回结果。",
+    ].join("\n");
+    const newText = [
+      "process_data <- function(df) {",
+      "",
+      "  stopifnot(!is.null(df))",
+      "  out <- transform(df, total = sum(x))",
+      '  write.csv(out, "out.csv")',
+      "  invisible(out)",
+      "}",
+    ].join("\n");
+
+    const r = smartDiff(oldText, newText);
+    assert.equal(r.blocks.length, 1);
+    assert.equal(r.blocks[0].type, "block-replace");
+    // 大删除块在前、大新增块在后，不出现 -/+ 交替碎片
+    const ops = r.blocks[0].lines.map((l) => l.op);
+    assert.ok(ops.slice(0, 5).every((o) => o === "del"));
+    assert.ok(ops.slice(5).every((o) => o === "ins"));
+    assert.equal(r.stats.dels, 5);
+    assert.equal(r.stats.adds, 7);
+    // 整段替换不做行内细分
+    assert.ok(r.blocks[0].lines.every((l) => l.segments === undefined));
+  });
+
+  it("场景2：单行内改一个词，输出词级 segments 而非整行标红标绿", () => {
+    const oldText = "const total = countItems(list);";
+    const newText = "const total = countUsers(list);";
+    const r = smartDiff(oldText, newText);
+    assert.equal(r.blocks.length, 1);
+    assert.equal(r.blocks[0].type, "replace");
+    const del = r.blocks[0].lines[0];
+    const ins = r.blocks[0].lines[1];
+    assert.ok(del.segments && del.segments.length > 0, "del 行应有 segments");
+    assert.ok(ins.segments && ins.segments.length > 0, "ins 行应有 segments");
+    // 删除行上被标记的正是 countItems，新增行上是 countUsers
+    const delMarked = del.segments!.map((s) => del.text.slice(s.start, s.end)).join("");
+    const insMarked = ins.segments!.map((s) => ins.text.slice(s.start, s.end)).join("");
+    assert.equal(delMarked, "countItems");
+    assert.equal(insMarked, "countUsers");
+    // 片段不应包含未变化的部分
+    for (const s of del.segments!) {
+      assert.ok(!del.text.slice(s.start, s.end).includes("const"));
+    }
+  });
+
+  it("场景3：仅行尾空白变化，不产生假改动", () => {
+    const oldText = "第一行   \n第二行\t";
+    const newText = "第一行\n第二行";
+    const r = smartDiff(oldText, newText);
+    assert.equal(r.blocks.length, 1);
+    assert.equal(r.blocks[0].type, "equal");
+    assert.deepEqual(r.stats, { adds: 0, dels: 0 });
+    // 展示保留原文（含行尾空白），但比较视为相同
+    assert.equal(r.blocks[0].lines[0].text, "第一行   ");
+  });
+
+  it("场景4：大量重复空行/花括号的代码，对齐不错位、变更块不碎", () => {
+    const oldText = [
+      "function a() {",
+      "",
+      "  if (x) {",
+      "",
+      "    return 1;",
+      "",
+      "  }",
+      "",
+      "}",
+    ].join("\n");
+    const newText = [
+      "function a() {",
+      "",
+      "  if (y) {",
+      "",
+      "    return 2;",
+      "",
+      "  }",
+      "",
+      "}",
+    ].join("\n");
+
+    const r = smartDiff(oldText, newText);
+    // 期望：equal → replace(if 行) → equal → replace(return 行) → equal
+    assert.deepEqual(
+      r.blocks.map((b) => b.type),
+      ["equal", "replace", "equal", "replace", "equal"]
+    );
+    // 两个 replace 块均有行内细分，且只标记真正变化的字符
+    const [b1, b2] = [r.blocks[1], r.blocks[3]];
+    assert.equal(b1.lines[0].text, "  if (x) {");
+    assert.equal(
+      b1.lines[0].segments!.map((s) => b1.lines[0].text.slice(s.start, s.end)).join(""),
+      "x"
+    );
+    assert.equal(
+      b1.lines[1].segments!.map((s) => b1.lines[1].text.slice(s.start, s.end)).join(""),
+      "y"
+    );
+    assert.equal(
+      b2.lines[0].segments!.map((s) => b2.lines[0].text.slice(s.start, s.end)).join(""),
+      "1"
+    );
+    // 空行不进入任何变更块
+    assert.ok(r.blocks.every((b) => b.type === "equal" || !b.lines.some((l) => l.text === "")));
+  });
+
+  it("场景5：完全相同的文本，只有一个 equal 块", () => {
+    const text = "第一行\n第二行\n第三行";
+    const r = smartDiff(text, text);
+    assert.equal(r.blocks.length, 1);
+    assert.equal(r.blocks[0].type, "equal");
+    assert.equal(r.blocks[0].lines.length, 3);
+    assert.deepEqual(r.stats, { adds: 0, dels: 0 });
+  });
+
+  it("CRLF / CR 行尾符差异不影响比较", () => {
+    const r = smartDiff("a\r\nb\rc", "a\nb\nc");
+    assert.equal(r.blocks.length, 1);
+    assert.equal(r.blocks[0].type, "equal");
+    assert.deepEqual(r.stats, { adds: 0, dels: 0 });
+  });
+
+  it("单侧为空：整体删除 / 整体新增", () => {
+    const ins = smartDiff("", "新的一行\n再来一行");
+    assert.deepEqual(ins.blocks.map((b) => b.type), ["insert"]);
+    assert.equal(ins.stats.adds, 2);
+
+    const del = smartDiff("旧行一\n旧行二", "");
+    assert.deepEqual(del.blocks.map((b) => b.type), ["delete"]);
+    assert.equal(del.stats.dels, 2);
+
+    assert.deepEqual(smartDiff("", "").blocks, []);
+  });
+
+  it("后处理不变式：相邻同向块必合并，replace 块内 del 全部在 ins 之前", () => {
+    const oldText = Array.from({ length: 30 }, (_, i) => `common ${i}`).join("\n");
+    const newText = oldText
+      .replace("common 5", "changed 5")
+      .replace("common 6", "changed 6")
+      .replace("common 20", "changed 20");
+    const r = smartDiff(oldText, newText);
+    // 相邻块不允许同为变更块（equal 必然隔开两个变更区域）
+    for (let i = 1; i < r.blocks.length; i++) {
+      const prev = r.blocks[i - 1];
+      const cur = r.blocks[i];
+      assert.ok(
+        !(prev.type !== "equal" && cur.type !== "equal"),
+        "相邻变更块未被合并"
+      );
+    }
+    for (const b of r.blocks) {
+      if (b.type !== "replace") continue;
+      const firstIns = b.lines.findIndex((l) => l.op === "ins");
+      const lastDel = b.lines.map((l) => l.op).lastIndexOf("del");
+      assert.ok(lastDel < firstIns, "replace 块内应先删后增");
+    }
+  });
+
+  it("上下文折叠：长 equal 块折叠为上下文 + 省略标记，头/尾单侧保留", () => {
+    const lines = Array.from({ length: 40 }, (_, i) => `L${i}`);
+    const oldText = lines.join("\n");
+    const newText = [...lines.slice(0, 20), "changed", ...lines.slice(21)].join("\n");
+    const rows = toFoldedRows(smartDiff(oldText, newText).blocks);
+    // 头部 equal 块（L0..L19，isHead）只保留尾部 3 行上下文 L17/L18/L19 + 折叠 17 行；
+    // 尾部 equal 块（L21..L39，isTail）只保留头部 3 行上下文 L21/L22/L23 + 折叠 16 行
+    const folds = rows.filter((r) => r.kind === "fold") as Array<{ kind: "fold"; count: number }>;
+    assert.deepEqual(
+      folds.map((f) => f.count),
+      [17, 16]
+    );
+    // 头部 equal 块（L0..L19，isHead）：省略前 17 行 → 保留尾部上下文 L17/L18/L19；
+    // 尾部 equal 块（L21..L39，isTail）：保留头部上下文 L21/L22/L23 → 省略后 16 行
+    assert.deepEqual(rows.slice(0, 4).map((r) => (r.kind === "fold" ? "fold" : r.text)), [
+      "fold",
+      "L17",
+      "L18",
+      "L19",
+    ]);
+  });
+
+  it("10 万行大文件在 2 秒内完成", () => {
+    const n = 100_000;
+    const oldLines = Array.from({ length: n }, (_, i) => `line-${i}`);
+    const newLines = [...oldLines];
+    const changes = 20;
+    for (let k = 0; k < changes; k++) {
+      newLines[k * 4_000 + 7] = `line-${k * 4_000 + 7}-changed`;
+    }
+    const start = performance.now();
+    const r = smartDiff(oldLines.join("\n"), newLines.join("\n"));
+    const elapsed = performance.now() - start;
+    assert.equal(r.stats.dels, changes);
+    assert.equal(r.stats.adds, changes);
+    assert.ok(elapsed < 2_000, `应在 2 秒内完成，实际 ${elapsed.toFixed(0)}ms`);
+  });
+});
--- a/frontend/lib/smartDiff.ts
+++ b/frontend/lib/smartDiff.ts
@@ -0,0 +1,527 @@
+/**
+ * smartDiff —— 面向可读性的结构化行级 diff（自研，无第三方依赖）。
+ *
+ * 四层处理：
+ * 1. 预处理：CRLF/CR → LF（仅用于比较与展示），行尾空白在比较时忽略（展示保留原文）。
+ * 2. 算法选择：行级相似度（difflib ratio 思路：2M/(a+b)，M 为多重集交集）低于阈值时
+ *    判定「整段替换」，输出一个 block-replace，跳过逐行对齐——避免把毫无对应关系的
+ *    两段文本切成几十对 -/+ 碎片；否则用 Patience diff（锚定双方唯一行，LIS 选链），
+ *    无锚点/超大规模/超深递归的子区间回退为 LCS 或整块替换。
+ * 3. 后处理：相邻同向变更合并为一个块（del 在前 ins 在后），消除 LCS 的交叉配对；
+ *    上下文折叠（默认 3 行，头/尾块只保留单侧上下文）。
+ * 4. 行内细分：replace 块内按下标配对的行对，先分词（CJK 单字、西文单词、空白、符号），
+ *    词级 LCS 相似度 > 阈值时输出变更片段的字符偏移（segments），否则整行视为变更。
+ *
+ * 输出为结构化块数组，供 diff 视图组件渲染；segments 直接挂在对应行上
+ * （start/end 为该行文本的 UTF-16 偏移），UI 只高亮变更部分。
+ */
+
+export type LineOp = "equal" | "del" | "ins";
+export type BlockType = "equal" | "insert" | "delete" | "replace" | "block-replace";
+
+/** 行内变更片段：start/end 为行文本的 UTF-16 偏移，type 为该行视角下的变更方向 */
+export interface InlineSegment {
+  start: number;
+  end: number;
+  type: "del" | "ins";
+}
+
+export interface DiffLine {
+  op: LineOp;
+  /** 原始行文本（保留行尾空白，供展示） */
+  text: string;
+  /** 仅 replace 块中被判定为「修改」的行对附带；缺省表示整行变更 */
+  segments?: InlineSegment[];
+}
+
+export interface DiffBlock {
+  type: BlockType;
+  lines: DiffLine[];
+}
+
+export interface DiffStats {
+  adds: number;
+  dels: number;
+}
+
+export interface DiffResult {
+  blocks: DiffBlock[];
+  stats: DiffStats;
+}
+
+export interface SmartDiffOptions {
+  /** 行级相似度低于该值判定整段替换（默认 0.2；仅任一侧 ≥2 行时生效） */
+  replaceThreshold?: number;
+  /** 行对词级相似度高于该值才做行内细分（默认 0.6） */
+  inlineThreshold?: number;
+}
+
+// 行级 LCS 回退的规模上限（超出则该区间整块替换，避免 O(n·m) 爆炸）
+const MAX_REGION_CELLS = 400_000;
+// 行内词级 LCS 的 token 数上限
+const MAX_INLINE_CELLS = 20_000;
+// 行对合计字符数超过则跳过行内细分
+const MAX_INLINE_CHARS = 4_000;
+// Patience 递归深度上限（超过直接整块替换，防御构造性深递归）
+const MAX_PATIENCE_DEPTH = 32;
+
+/* ---------------- 第一层：预处理 ---------------- */
+
+interface SplitText {
+  raw: string[];
+  /** 归一化后的行（比较用）：行尾空白已去除 */
+  cmp: string[];
+}
+
+function splitLines(text: string): SplitText {
+  const norm = text.replace(/\r\n?/g, "\n");
+  const raw = norm === "" ? [] : norm.split("\n");
+  return { raw, cmp: raw.map((l) => l.replace(/\s+$/, "")) };
+}
+
+/* ---------------- 第二层：相似度与算法选择 ---------------- */
+
+/** 行级相似度：difflib ratio 思路，2M/(a+b)，M 为行多重集交集大小 */
+function lineSimilarity(a: string[], b: string[]): number {
+  if (a.length === 0 && b.length === 0) return 1;
+  const freq = new Map<string, number>();
+  for (const l of a) freq.set(l, (freq.get(l) ?? 0) + 1);
+  let m = 0;
+  for (const l of b) {
+    const c = freq.get(l) ?? 0;
+    if (c > 0) {
+      m += 1;
+      freq.set(l, c - 1);
+    }
+  }
+  return (2 * m) / (a.length + b.length);
+}
+
+type RawOp = { op: LineOp; ai: number; bi: number };
+
+/**
+ * Patience diff：在区间内找到「双方都恰好出现一次」的公共行作锚点，
+ * 对锚点按 i 升序求 j 的最长递增子序列（patience sorting，O(k log k)）作骨架，
+ * 骨架之间的间隙递归；无锚点/超深的区间回退 fallbackRegion。
+ */
+function patienceDiff(
+  cmpA: string[],
+  cmpB: string[],
+  loA: number,
+  hiA: number,
+  loB: number,
+  hiB: number,
+  out: RawOp[],
+  depth: number
+): void {
+  if (loA >= hiA && loB >= hiB) return;
+
+  const countA = new Map<string, number>();
+  for (let i = loA; i < hiA; i++) countA.set(cmpA[i], (countA.get(cmpA[i]) ?? 0) + 1);
+  const countB = new Map<string, number>();
+  for (let j = loB; j < hiB; j++) countB.set(cmpB[j], (countB.get(cmpB[j]) ?? 0) + 1);
+
+  const posA = new Map<string, number>();
+  for (let i = loA; i < hiA; i++) {
+    if (countA.get(cmpA[i]) === 1) posA.set(cmpA[i], i);
+  }
+  const anchors: Array<{ i: number; j: number }> = [];
+  for (let j = loB; j < hiB; j++) {
+    if (countB.get(cmpB[j]) === 1) {
+      const i = posA.get(cmpB[j]);
+      if (i !== undefined) anchors.push({ i, j });
+    }
+  }
+  if (anchors.length === 0 || depth >= MAX_PATIENCE_DEPTH) {
+    fallbackRegion(cmpA, cmpB, loA, hiA, loB, hiB, out);
+    return;
+  }
+
+  anchors.sort((x, y) => x.i - y.i);
+  const tails: number[] = [];
+  const prev = new Array<number>(anchors.length).fill(-1);
+  for (let k = 0; k < anchors.length; k++) {
+    const j = anchors[k].j;
+    let lo = 0;
+    let hi = tails.length;
+    while (lo < hi) {
+      const mid = (lo + hi) >> 1;
+      if (anchors[tails[mid]].j < j) lo = mid + 1;
+      else hi = mid;
+    }
+    if (lo > 0) prev[k] = tails[lo - 1];
+    if (lo === tails.length) tails.push(k);
+    else tails[lo] = k;
+  }
+  const chain: number[] = [];
+  for (let k = tails[tails.length - 1]; k !== -1; k = prev[k]) chain.push(k);
+  chain.reverse();
+
+  let ai = loA;
+  let bi = loB;
+  for (const k of chain) {
+    const { i, j } = anchors[k];
+    patienceDiff(cmpA, cmpB, ai, i, bi, j, out, depth + 1);
+    out.push({ op: "equal", ai: i, bi: j });
+    ai = i + 1;
+    bi = j + 1;
+  }
+  patienceDiff(cmpA, cmpB, ai, hiA, bi, hiB, out, depth + 1);
+}
+
+/** 无锚点区间：无公共行或规模超限时整块替换；否则 LCS 细对齐 */
+function fallbackRegion(
+  cmpA: string[],
+  cmpB: string[],
+  loA: number,
+  hiA: number,
+  loB: number,
+  hiB: number,
+  out: RawOp[]
+): void {
+  const n = hiA - loA;
+  const m = hiB - loB;
+  if (n === 0 && m === 0) return;
+  if (n === 0) {
+    for (let j = loB; j < hiB; j++) out.push({ op: "ins", ai: loA, bi: j });
+    return;
+  }
+  if (m === 0) {
+    for (let i = loA; i < hiA; i++) out.push({ op: "del", ai: i, bi: loB });
+    return;
+  }
+  if (n * m > MAX_REGION_CELLS || !hasCommonLine(cmpA, cmpB, loA, hiA, loB, hiB)) {
+    for (let i = loA; i < hiA; i++) out.push({ op: "del", ai: i, bi: loB });
+    for (let j = loB; j < hiB; j++) out.push({ op: "ins", ai: hiA, bi: j });
+    return;
+  }
+  lcsRegion(cmpA, cmpB, loA, hiA, loB, hiB, out);
+}
+
+function hasCommonLine(
+  cmpA: string[],
+  cmpB: string[],
+  loA: number,
+  hiA: number,
+  loB: number,
+  hiB: number
+): boolean {
+  const set = new Set<string>();
+  for (let i = loA; i < hiA; i++) set.add(cmpA[i]);
+  for (let j = loB; j < hiB; j++) {
+    if (set.has(cmpB[j])) return true;
+  }
+  return false;
+}
+
+/** 行级 LCS（规模已由调用方限制），供无锚点但有公共行的区间使用 */
+function lcsRegion(
+  cmpA: string[],
+  cmpB: string[],
+  loA: number,
+  hiA: number,
+  loB: number,
+  hiB: number,
+  out: RawOp[]
+): void {
+  const n = hiA - loA;
+  const m = hiB - loB;
+  const width = m + 1;
+  const dp = new Uint32Array((n + 1) * width);
+  for (let i = n - 1; i >= 0; i--) {
+    const aLine = cmpA[loA + i];
+    for (let j = m - 1; j >= 0; j--) {
+      dp[i * width + j] =
+        aLine === cmpB[loB + j]
+          ? dp[(i + 1) * width + (j + 1)] + 1
+          : Math.max(dp[(i + 1) * width + j], dp[i * width + (j + 1)]);
+    }
+  }
+  let i = 0;
+  let j = 0;
+  while (i < n && j < m) {
+    if (cmpA[loA + i] === cmpB[loB + j]) {
+      out.push({ op: "equal", ai: loA + i, bi: loB + j });
+      i += 1;
+      j += 1;
+    } else if (dp[(i + 1) * width + j] >= dp[i * width + (j + 1)]) {
+      out.push({ op: "del", ai: loA + i, bi: loB + j });
+      i += 1;
+    } else {
+      out.push({ op: "ins", ai: loA + i, bi: loB + j });
+      j += 1;
+    }
+  }
+  while (i < n) {
+    out.push({ op: "del", ai: loA + i, bi: loB + j });
+    i += 1;
+  }
+  while (j < m) {
+    out.push({ op: "ins", ai: loA + i, bi: loB + j });
+    j += 1;
+  }
+}
+
+/* ---------------- 第三层：后处理（块构建 + 上下文折叠） ---------------- */
+
+/**
+ * 把扁平 op 序列整理成块：
+ * - 连续 equal → equal 块（展示用旧文本原文）
+ * - 连续非 equal 合并为一个变更区域：del 按原顺序在前、ins 按新顺序在后，
+ *   两侧都有 → replace（后续做行内细分），单侧 → delete / insert。
+ * 这一步消除了 LCS 可能出现的 -/+ 交叉碎片（del,ins,del,ins → 一个 replace 块）。
+ */
+function buildBlocks(ops: RawOp[], rawA: string[], rawB: string[]): DiffBlock[] {
+  const blocks: DiffBlock[] = [];
+  let k = 0;
+  while (k < ops.length) {
+    if (ops[k].op === "equal") {
+      const lines: DiffLine[] = [];
+      while (k < ops.length && ops[k].op === "equal") {
+        lines.push({ op: "equal", text: rawA[ops[k].ai] });
+        k += 1;
+      }
+      blocks.push({ type: "equal", lines });
+      continue;
+    }
+    const dels: DiffLine[] = [];
+    const inss: DiffLine[] = [];
+    while (k < ops.length && ops[k].op !== "equal") {
+      const o = ops[k];
+      if (o.op === "del") dels.push({ op: "del", text: rawA[o.ai] });
+      else inss.push({ op: "ins", text: rawB[o.bi] });
+      k += 1;
+    }
+    const type: BlockType =
+      dels.length > 0 && inss.length > 0 ? "replace" : dels.length > 0 ? "delete" : "insert";
+    blocks.push({ type, lines: [...dels, ...inss] });
+  }
+  return blocks;
+}
+
+export type FoldedRow =
+  | { kind: "line"; op: LineOp; text: string; segments?: InlineSegment[] }
+  | { kind: "fold"; count: number };
+
+/**
+ * 上下文折叠：超过 context*2+2 行的 equal 块只保留变更两侧各 context 行，
+ * 头/尾 equal 块只保留单侧；返回渲染用的行序列（fold 为折叠标记）。
+ */
+export function toFoldedRows(blocks: DiffBlock[], context = 3): FoldedRow[] {
+  const rows: FoldedRow[] = [];
+  const pushLine = (l: DiffLine) =>
+    rows.push({ kind: "line", op: l.op, text: l.text, segments: l.segments });
+  blocks.forEach((b, bi) => {
+    if (!(b.type === "equal" && b.lines.length > context * 2 + 2)) {
+      b.lines.forEach(pushLine);
+      return;
+    }
+    const isHead = bi === 0;
+    const isTail = bi === blocks.length - 1;
+    if (isHead && isTail) {
+      // 整个 diff 都是相同内容：不折叠
+      b.lines.forEach(pushLine);
+      return;
+    }
+    const head = isHead ? 0 : context;
+    const tail = isTail ? 0 : context;
+    for (let i = 0; i < head; i++) pushLine(b.lines[i]);
+    rows.push({ kind: "fold", count: b.lines.length - head - tail });
+    for (let i = b.lines.length - tail; i < b.lines.length; i++) pushLine(b.lines[i]);
+  });
+  return rows;
+}
+
+/* ---------------- 第四层：行内细分（词级 diff） ---------------- */
+
+// CJK 逐字成 token（中文无词边界），西文按单词，空白连续，其余单字符
+const TOKEN_RE = /[\p{Script=Han}\p{Script=Hiragana}\p{Script=Katakana}\p{Script=Hangul}]|[A-Za-z0-9_]+|\s+|[^\s]/gu;
+
+interface Tokens {
+  tokens: string[];
+  starts: number[];
+  ends: number[];
+}
+
+function tokenize(line: string): Tokens {
+  const tokens: string[] = [];
+  const starts: number[] = [];
+  const ends: number[] = [];
+  for (const m of line.matchAll(TOKEN_RE)) {
+    const start = m.index;
+    if (start === undefined) continue;
+    tokens.push(m[0]);
+    starts.push(start);
+    ends.push(start + m[0].length);
+  }
+  return { tokens, starts, ends };
+}
+
+function lcsTokenLen(a: string[], b: string[]): number {
+  const n = a.length;
+  const m = b.length;
+  const width = m + 1;
+  const dp = new Uint32Array((n + 1) * width);
+  for (let i = n - 1; i >= 0; i--) {
+    for (let j = m - 1; j >= 0; j--) {
+      dp[i * width + j] =
+        a[i] === b[j]
+          ? dp[(i + 1) * width + (j + 1)] + 1
+          : Math.max(dp[(i + 1) * width + j], dp[i * width + (j + 1)]);
+    }
+  }
+  return dp[0];
+}
+
+/** X 视角下的变更片段：词级 LCS 中未被匹配的连续 token 合并为一个字符区间 */
+function changedSegments(
+  t: Tokens,
+  ops: Array<{ op: "equal" | "chg"; idx: number }>,
+  type: "del" | "ins"
+): InlineSegment[] {
+  const segs: InlineSegment[] = [];
+  let cur: InlineSegment | null = null;
+  for (const o of ops) {
+    if (o.op === "equal") {
+      cur = null;
+      continue;
+    }
+    const start = t.starts[o.idx];
+    const end = t.ends[o.idx];
+    if (cur && cur.end === start) {
+      cur.end = end;
+    } else {
+      cur = { start, end, type };
+      segs.push(cur);
+    }
+  }
+  return segs;
+}
+
+/** 词级 LCS 回溯，产出 X/Y 各自的 equal/chg 序列（idx 为各自 token 下标） */
+function tokenOps(x: Tokens, y: Tokens): {
+  xOps: Array<{ op: "equal" | "chg"; idx: number }>;
+  yOps: Array<{ op: "equal" | "chg"; idx: number }>;
+} {
+  const n = x.tokens.length;
+  const m = y.tokens.length;
+  const width = m + 1;
+  const dp = new Uint32Array((n + 1) * width);
+  for (let i = n - 1; i >= 0; i--) {
+    for (let j = m - 1; j >= 0; j--) {
+      dp[i * width + j] =
+        x.tokens[i] === y.tokens[j]
+          ? dp[(i + 1) * width + (j + 1)] + 1
+          : Math.max(dp[(i + 1) * width + j], dp[i * width + (j + 1)]);
+    }
+  }
+  const xOps: Array<{ op: "equal" | "chg"; idx: number }> = [];
+  const yOps: Array<{ op: "equal" | "chg"; idx: number }> = [];
+  let i = 0;
+  let j = 0;
+  while (i < n && j < m) {
+    if (x.tokens[i] === y.tokens[j]) {
+      xOps.push({ op: "equal", idx: i });
+      yOps.push({ op: "equal", idx: j });
+      i += 1;
+      j += 1;
+    } else if (dp[(i + 1) * width + j] >= dp[i * width + (j + 1)]) {
+      xOps.push({ op: "chg", idx: i });
+      i += 1;
+    } else {
+      yOps.push({ op: "chg", idx: j });
+      j += 1;
+    }
+  }
+  while (i < n) {
+    xOps.push({ op: "chg", idx: i });
+    i += 1;
+  }
+  while (j < m) {
+    yOps.push({ op: "chg", idx: j });
+    j += 1;
+  }
+  return { xOps, yOps };
+}
+
+/** 对 replace 块内按下标配对的行对做词级细分；相似度不足则整行变更、不产出 segments */
+function annotateInline(blocks: DiffBlock[], inlineThreshold: number): void {
+  for (const b of blocks) {
+    if (b.type !== "replace") continue;
+    const dels = b.lines.filter((l) => l.op === "del");
+    const inss = b.lines.filter((l) => l.op === "ins");
+    const n = Math.min(dels.length, inss.length);
+    for (let i = 0; i < n; i++) {
+      const delLine = dels[i];
+      const insLine = inss[i];
+      if (delLine.text.length + insLine.text.length > MAX_INLINE_CHARS) continue;
+      const x = tokenize(delLine.text);
+      const y = tokenize(insLine.text);
+      if (x.tokens.length === 0 || y.tokens.length === 0) continue;
+      if (x.tokens.length * y.tokens.length > MAX_INLINE_CELLS) continue;
+      const ratio = (2 * lcsTokenLen(x.tokens, y.tokens)) / (x.tokens.length + y.tokens.length);
+      if (!(ratio > inlineThreshold)) continue;
+      const { xOps, yOps } = tokenOps(x, y);
+      const delSegs = changedSegments(x, xOps, "del");
+      const insSegs = changedSegments(y, yOps, "ins");
+      if (delSegs.length > 0) delLine.segments = delSegs;
+      if (insSegs.length > 0) insLine.segments = insSegs;
+    }
+  }
+}
+
+/* ---------------- 入口 ---------------- */
+
+export function smartDiff(
+  oldText: string,
+  newText: string,
+  options: SmartDiffOptions = {}
+): DiffResult {
+  const replaceThreshold = options.replaceThreshold ?? 0.2;
+  const inlineThreshold = options.inlineThreshold ?? 0.6;
+  const a = splitLines(oldText);
+  const b = splitLines(newText);
+
+  const ops: RawOp[] = [];
+  let wholeReplace = false;
+  if (a.cmp.length === 0 && b.cmp.length === 0) {
+    // 两侧皆空：无块
+  } else if (a.cmp.length === 0 || b.cmp.length === 0) {
+    // 单侧为空：整体删除/新增
+    if (a.cmp.length > 0) {
+      for (let i = 0; i < a.cmp.length; i++) ops.push({ op: "del", ai: i, bi: 0 });
+    } else {
+      for (let j = 0; j < b.cmp.length; j++) ops.push({ op: "ins", ai: 0, bi: j });
+    }
+  } else if (
+    a.cmp.length >= 2 &&
+    b.cmp.length >= 2 &&
+    lineSimilarity(a.cmp, b.cmp) < replaceThreshold
+  ) {
+    // 整段替换：跳过逐行对齐，输出一个大删除块 + 一个大新增块
+    wholeReplace = true;
+    for (let i = 0; i < a.cmp.length; i++) ops.push({ op: "del", ai: i, bi: 0 });
+    for (let j = 0; j < b.cmp.length; j++) ops.push({ op: "ins", ai: 0, bi: j });
+  } else {
+    patienceDiff(a.cmp, b.cmp, 0, a.cmp.length, 0, b.cmp.length, ops, 0);
+  }
+
+  const blocks = buildBlocks(ops, a.raw, b.raw);
+  if (wholeReplace) {
+    // 相似度低于阈值判定为整段替换：唯一变更块标记为 block-replace，
+    // 不做行内细分（两侧内容无对应关系，细对齐只会产出噪音）
+    const blk = blocks.find((x) => x.type === "replace");
+    if (blk) blk.type = "block-replace";
+  }
+  annotateInline(blocks, inlineThreshold);
+
+  let dels = 0;
+  let adds = 0;
+  for (const blk of blocks) {
+    for (const l of blk.lines) {
+      if (l.op === "del") dels += 1;
+      else if (l.op === "ins") adds += 1;
+    }
+  }
+  return { blocks, stats: { adds, dels } };
+}
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -7,7 +7,7 @@
    "build": "next build",
    "start": "next start -p 3000",
    "lint": "next lint",
-    "test": "node --experimental-strip-types --test lib/siteUrl.test.ts lib/jsonLd.test.ts lib/widgetCode.test.ts"
+    "test": "node --experimental-strip-types --test lib/siteUrl.test.ts lib/jsonLd.test.ts lib/widgetCode.test.ts lib/smartDiff.test.ts"
  },
  "dependencies": {
    "hast-util-to-jsx-runtime": "^2.3.6",