feat: 代码片段功能与 Markdown 内嵌片段渲染、文档截图等

backend/handler/chat.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/freefire/jiang13-bbs/middleware"
@@ -240,11 +241,32 @@ func (h *Handlers) JoinChatRoom(c *gin.Context) {
 	if !ok {
 		return
 	}
-	_, _, err := h.Chat.Join(claims.ID, roomID)
+	member, joined, err := h.Chat.Join(claims.ID, roomID)
 	if err != nil {
 		c.JSON(chatErrToStatus(err), gin.H{"error": err.Error()})
 		return
 	}
+	// 首次加入则向房间广播系统提示 + 成员变更
+	if joined && member != nil {
+		displayName := h.Chat.DisplayName(claims.ID)
+		if displayName != "" {
+			sysMsg, _ := h.Chat.SendSystemMessage(roomID, displayName+" 加入了群聊")
+			if sysMsg != nil && sysMsg.ID > 0 {
+				h.Hub.BroadcastRoom(realtime.RoomChat(roomID), realtime.Envelope{
+					Type: realtime.EventChatMessage,
+					Data: sysMsg,
+				})
+			}
+		}
+		h.Hub.BroadcastRoom(realtime.RoomChat(roomID), realtime.Envelope{
+			Type: realtime.EventChatMembership,
+			Data: gin.H{
+				"room_id": roomID,
+				"status":  "joined",
+				"user_id": claims.ID,
+			},
+		})
+	}
 	c.JSON(http.StatusOK, gin.H{"ok": true})
 }
 
@@ -300,6 +322,35 @@ func (h *Handlers) InviteChatMembers(c *gin.Context) {
 			Data: gin.H{"room_id": roomID, "status": "invited"},
 		})
 	}
+	// 被邀请者入群时向房间广播系统提示 + 成员变更
+	if len(added) > 0 {
+		var names []string
+		for _, uid := range added {
+			if n := h.Chat.DisplayName(uid); n != "" {
+				names = append(names, n)
+			}
+		}
+		if len(names) > 0 {
+			content := strings.Join(names, "、") + " 加入了群聊"
+			sysMsg, _ := h.Chat.SendSystemMessage(roomID, content)
+			if sysMsg != nil && sysMsg.ID > 0 {
+				h.Hub.BroadcastRoom(realtime.RoomChat(roomID), realtime.Envelope{
+					Type: realtime.EventChatMessage,
+					Data: sysMsg,
+				})
+			}
+		}
+		for _, uid := range added {
+			h.Hub.BroadcastRoom(realtime.RoomChat(roomID), realtime.Envelope{
+				Type: realtime.EventChatMembership,
+				Data: gin.H{
+					"room_id": roomID,
+					"status":  "joined",
+					"user_id": uid,
+				},
+			})
+		}
+	}
 	c.JSON(http.StatusOK, gin.H{"added": added})
 }
 

backend/handler/handlers.go

@@ -42,6 +42,7 @@ type Handlers struct {
 	Badge          *service.BadgeService
 	LeaderboardSvc *service.LeaderboardService
 	LibrarySvc     *service.LibraryService
+	SnippetSvc     *service.SnippetService
 }
 
 // resolvePublishStatus 决定新帖/新评的初始状态：

backend/handler/snippet.go

@@ -0,0 +1,424 @@
+package handler
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/freefire/jiang13-bbs/middleware"
+	"github.com/freefire/jiang13-bbs/model"
+	"github.com/freefire/jiang13-bbs/service"
+	"github.com/gin-gonic/gin"
+)
+
+// snippetError 统一错误映射
+func snippetError(c *gin.Context, err error) {
+	switch {
+	case errors.Is(err, service.ErrSnippetNotFound):
+		c.JSON(http.StatusNotFound, gin.H{"error": "代码片段不存在"})
+	case errors.Is(err, service.ErrSnippetForbidden):
+		c.JSON(http.StatusForbidden, gin.H{"error": "无权操作该代码片段"})
+	case errors.Is(err, service.ErrSnippetBadInput):
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+	case errors.Is(err, service.ErrCommentNotFound):
+		c.JSON(http.StatusNotFound, gin.H{"error": "评论不存在"})
+	case errors.Is(err, service.ErrCommentForbidden):
+		c.JSON(http.StatusForbidden, gin.H{"error": "无权操作该评论"})
+	default:
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "服务器错误"})
+	}
+}
+
+// SnippetList 公开片段广场
+func (h *Handlers) SnippetList(c *gin.Context) {
+	q := c.Query("q")
+	lang := c.Query("lang")
+	sort := c.Query("sort")
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "12"))
+	items, total, err := h.SnippetSvc.ListPublic(q, lang, sort, page, size)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "获取片段列表失败"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"items": nonNilSlice(items), "total": total})
+}
+
+// SnippetLanguages 语言白名单
+func (h *Handlers) SnippetLanguages(c *gin.Context) {
+	c.JSON(http.StatusOK, gin.H{"languages": service.SnippetLanguages()})
+}
+
+// SnippetStats 广场聚合统计
+func (h *Handlers) SnippetStats(c *gin.Context) {
+	stats, err := h.SnippetSvc.Stats()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "获取统计失败"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"stats": stats})
+}
+
+// SnippetDetail 公开片段详情
+func (h *Handlers) SnippetDetail(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	var viewerID uint
+	if claims := middleware.CurrentUser(c); claims != nil {
+		viewerID = claims.ID
+	}
+	isStaff := h.isStaff(c)
+	detail, err := h.SnippetSvc.GetPublic(uint(id), viewerID, isStaff)
+	if err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"snippet": detail})
+}
+
+// SnippetMine 我的片段列表
+func (h *Handlers) SnippetMine(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	q := c.Query("q")
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "12"))
+	items, total, err := h.SnippetSvc.ListMine(claims.ID, q, page, size)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "获取片段列表失败"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"items": nonNilSlice(items), "total": total})
+}
+
+// SnippetCreate 创建片段
+func (h *Handlers) SnippetCreate(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	var in service.SnippetInput
+	if err := c.ShouldBindJSON(&in); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请求参数无效"})
+		return
+	}
+	snippet, err := h.SnippetSvc.Create(&in, claims.ID)
+	if err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusCreated, gin.H{"snippet": snippet})
+}
+
+// SnippetUpdate 更新片段
+func (h *Handlers) SnippetUpdate(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	var in service.SnippetInput
+	if err := c.ShouldBindJSON(&in); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请求参数无效"})
+		return
+	}
+	snippet, err := h.SnippetSvc.Update(uint(id), &in, claims.ID, h.isStaff(c))
+	if err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"snippet": snippet})
+}
+
+// SnippetDelete 删除片段（owner 或 staff）
+func (h *Handlers) SnippetDelete(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	if err := h.SnippetSvc.Delete(uint(id), claims.ID, h.isStaff(c)); err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true})
+}
+
+// SnippetFork Fork 公开片段
+func (h *Handlers) SnippetFork(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	snippet, err := h.SnippetSvc.Fork(uint(id), claims.ID)
+	if err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusCreated, gin.H{"snippet": snippet})
+}
+
+// SnippetCopy 记录复制（节流由 service 内部处理）
+func (h *Handlers) SnippetCopy(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	key := c.ClientIP()
+	if claims := middleware.CurrentUser(c); claims != nil {
+		key = "user:" + strconv.FormatUint(uint64(claims.ID), 10)
+	}
+	if err := h.SnippetSvc.RecordCopy(uint(id), key); err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true})
+}
+
+// SnippetHistory 片段编辑历史
+func (h *Handlers) SnippetHistory(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "10"))
+	items, total, err := h.SnippetSvc.ListHistory(uint(id), page, size)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "获取历史失败"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"items": nonNilSlice(items), "total": total})
+}
+
+// SnippetForks 公开 fork 列表
+func (h *Handlers) SnippetForks(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "12"))
+	items, total, err := h.SnippetSvc.ListForks(uint(id), page, size)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "获取 Fork 列表失败"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"items": nonNilSlice(items), "total": total})
+}
+
+// SnippetComments 片段评论列表
+func (h *Handlers) SnippetComments(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "20"))
+	items, total, err := h.SnippetSvc.ListComments(uint(id), page, size)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "获取评论失败"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"items": nonNilSlice(items), "total": total})
+}
+
+// SnippetCommentCreate 创建片段评论
+func (h *Handlers) SnippetCommentCreate(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	snippetID, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	var in struct {
+		Content  string `json:"content"`
+		ParentID *uint  `json:"parent_id"`
+	}
+	if err := c.ShouldBindJSON(&in); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请求参数无效"})
+		return
+	}
+	comment, err := h.SnippetSvc.CreateComment(claims.ID, uint(snippetID), in.Content, in.ParentID)
+	if err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusCreated, gin.H{"comment": comment})
+}
+
+// SnippetCommentUpdate 更新片段评论
+func (h *Handlers) SnippetCommentUpdate(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	cid, err := strconv.ParseUint(c.Param("cid"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的评论 ID"})
+		return
+	}
+	var in struct {
+		Content string `json:"content"`
+	}
+	if err := c.ShouldBindJSON(&in); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请求参数无效"})
+		return
+	}
+	comment, err := h.SnippetSvc.UpdateComment(uint(cid), claims.ID, in.Content)
+	if err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"comment": comment})
+}
+
+// SnippetCommentDelete 删除片段评论
+func (h *Handlers) SnippetCommentDelete(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	cid, err := strconv.ParseUint(c.Param("cid"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的评论 ID"})
+		return
+	}
+	if err := h.SnippetSvc.DeleteComment(uint(cid), claims.ID, h.isStaff(c)); err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true})
+}
+
+// SnippetCommentHistory 片段评论编辑历史（登录即可见；分页）
+func (h *Handlers) SnippetCommentHistory(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.SnippetSvc.ListCommentHistory(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,
+	})
+}
+
+// AdminSnippetList 管理端片段列表
+func (h *Handlers) AdminSnippetList(c *gin.Context) {
+	q := c.Query("q")
+	visibility := c.Query("visibility")
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	size, _ := strconv.Atoi(c.DefaultQuery("size", "20"))
+	items, total, err := h.SnippetSvc.AdminList(q, visibility, page, size)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "获取片段列表失败"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"items": nonNilSlice(items), "total": total})
+}
+
+// AdminSnippetDelete 管理端软删片段
+func (h *Handlers) AdminSnippetDelete(c *gin.Context) {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
+		return
+	}
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	if err := h.SnippetSvc.AdminDelete(uint(id), claims.ID); err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true})
+}
+
+// AdminSnippetSetVisibility 管理端强制修改可见性
+func (h *Handlers) AdminSnippetSetVisibility(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "无效的片段 ID"})
+		return
+	}
+	var in struct {
+		Visibility string `json:"visibility"`
+	}
+	if err := c.ShouldBindJSON(&in); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请求参数无效"})
+		return
+	}
+	if err := h.SnippetSvc.AdminSetVisibility(uint(id), in.Visibility); err != nil {
+		snippetError(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"ok": true})
+}
+
+// isStaff 判断当前用户是否为管理角色
+func (h *Handlers) isStaff(c *gin.Context) bool {
+	claims := middleware.CurrentUser(c)
+	if claims == nil {
+		return false
+	}
+	return model.IsStaff(model.Role(claims.Role))
+}

backend/model/db.go

@@ -64,6 +64,7 @@ func InitDB(dsn string) error {
 		&Badge{}, &UserBadge{},
 		&PostPollVote{}, &PostLotteryEntry{}, &Ad{}, &SidebarWidget{}, &FriendLink{},
 		&ImportRecord{}, &LibraryDoc{}, &LibraryFile{}, &LibrarySection{},
+		&CodeSnippet{}, &SnippetVersion{}, &SnippetComment{}, &SnippetCommentEditHistory{},
 	); err != nil {
 		return fmt.Errorf("自动迁移失败: %w", err)
 	}

backend/model/models.go

@@ -576,6 +576,75 @@ type LibrarySection struct {
 	DeletedAt gorm.DeletedAt `gorm:"index" json:"-"`
 }
 
+// CodeSnippet 代码片段：用户所有，公开进广场，私有仅自己可见
+type CodeSnippet struct {
+	ID           uint           `gorm:"primaryKey" json:"id"`
+	Title        string         `gorm:"size:120;not null" json:"title"`
+	Description  string         `gorm:"type:text" json:"description"`
+	Language     string         `gorm:"size:32;not null;index" json:"language"`
+	Code         string         `gorm:"type:text;not null" json:"code"`
+	Visibility   string         `gorm:"size:16;not null;default:private;index" json:"visibility"` // public/private
+	UserID       uint           `gorm:"index;not null" json:"user_id"`
+	ForkedFromID *uint          `gorm:"index" json:"forked_from_id"`
+	CopyCount    int            `gorm:"not null;default:0" json:"copy_count"`
+	ViewCount    int            `gorm:"not null;default:0" json:"view_count"`
+	CommentCount int            `gorm:"not null;default:0" json:"comment_count"`
+	ForkCount    int            `gorm:"not null;default:0" json:"fork_count"`
+	CreatedAt    time.Time      `json:"created_at"`
+	UpdatedAt    time.Time      `json:"updated_at"`
+	DeletedAt    gorm.DeletedAt `gorm:"index" json:"-"`
+}
+
+// SnippetVersion 编辑前旧值快照（同 PostEditHistory 思路）
+type SnippetVersion struct {
+	ID             uint      `gorm:"primaryKey" json:"id"`
+	SnippetID      uint      `gorm:"index;not null" json:"snippet_id"`
+	EditorID       uint      `gorm:"index;not null" json:"editor_id"`
+	OldTitle       string    `gorm:"size:120;not null;default:''" json:"old_title"`
+	OldLanguage    string    `gorm:"size:32;not null;default:''" json:"old_language"`
+	OldDescription string    `gorm:"type:text" json:"old_description"`
+	OldCode        string    `gorm:"type:text;not null" json:"old_code"`
+	CreatedAt      time.Time `gorm:"index" json:"created_at"`
+}
+
+// SnippetComment 片段评论（楼层树：ParentID 空=主评，非空=回复；RootID=所属主楼）
+type SnippetComment struct {
+	ID         uint           `gorm:"primaryKey" json:"id"`
+	SnippetID  uint           `gorm:"index;not null" json:"snippet_id"`
+	UserID     uint           `gorm:"index;not null" json:"user_id,omitempty"`
+	ParentID   *uint          `gorm:"index" json:"parent_id"`
+	RootID     *uint          `gorm:"index" json:"root_id"`
+	Depth      int            `gorm:"not null;default:0" json:"depth"`
+	Content    string         `gorm:"type:text;not null" json:"content"`
+	DeleteType string         `gorm:"size:32;default:''" json:"delete_type,omitempty"`
+	DeletedBy  uint           `gorm:"not null;default:0" json:"deleted_by,omitempty"`
+	CreatedAt  time.Time      `json:"created_at"`
+	UpdatedAt  time.Time      `json:"updated_at"`
+	DeletedAt  gorm.DeletedAt `gorm:"index" json:"-"`
+}
+
+// SnippetCommentEditHistory 片段评论修订快照（每次编辑前的旧正文；登录用户可见）
+type SnippetCommentEditHistory struct {
+	ID         uint      `gorm:"primaryKey" json:"id"`
+	CommentID  uint      `gorm:"index;not null" json:"comment_id"`
+	EditorID   uint      `gorm:"index;not null" json:"editor_id"`
+	OldContent string    `gorm:"type:text;not null" json:"old_content"`
+	CreatedAt  time.Time `gorm:"index" json:"created_at"`
+}
+
+const (
+	SnippetVisibilityPublic  = "public"
+	SnippetVisibilityPrivate = "private"
+)
+
+// NormalizeSnippetVisibility 归一化可见性：空或未知值一律回落 private
+func NormalizeSnippetVisibility(v string) string {
+	if v == SnippetVisibilityPublic {
+		return SnippetVisibilityPublic
+	}
+	return SnippetVisibilityPrivate
+}
+
 // SiteSetting 站点级键值设置（如历史在线峰值 peak_online）
 type SiteSetting struct {
 	Key       string    `gorm:"primaryKey;size:64" json:"key"`

backend/router/router.go

@@ -104,6 +104,7 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 	librarySvc := service.NewLibraryService(model.DB, cfg.DataDir).
 		WithSetting(settingSvc).
 		WithUploadsDir(filepath.Join(cfg.DataDir, "uploads"))
+	snippetSvc := service.NewSnippetService(model.DB)
 	adminUserSvc := service.NewAdminUserService(model.DB)
 	legacyImportSvc := service.NewLegacyImportService(model.DB, filepath.Join(cfg.DataDir, "uploads"))
 	moderationSvc := service.NewModerationService(model.DB, notifSvc)
@@ -165,6 +166,7 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 		Badge:          badgeSvc,
 		LeaderboardSvc: leaderboardSvc,
 		LibrarySvc:     librarySvc,
+		SnippetSvc:     snippetSvc,
 	}
 	// 通知落库后统一推 WS 红点（点赞/评论/审核/@ 等共用）
 	notifSvc.OnNotifyNew = func(userID uint) {
@@ -229,6 +231,13 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 		pubAPI.GET("/library", h.LibraryList)
 		pubAPI.GET("/library/:slug", h.LibraryDetail)
 		pubAPI.GET("/library/files/:fid/download", h.LibraryFileDownload)
+		// 代码片段（公开广场/详情/评论/Fork 列表）
+		pubAPI.GET("/snippets", h.SnippetList)
+		pubAPI.GET("/snippets/languages", h.SnippetLanguages)
+		pubAPI.GET("/snippets/stats", h.SnippetStats)
+		pubAPI.GET("/snippets/:id", h.SnippetDetail)
+		pubAPI.GET("/snippets/:id/comments", h.SnippetComments)
+		pubAPI.GET("/snippets/:id/forks", h.SnippetForks)
 		pubAPI.GET("/site-state", h.SiteState)
 		// 自适应图片变体（?u=<源图URL>&w=<白名单宽度>，公开只读、immutable 缓存）
 		pubAPI.GET("/img", h.ImageVariant)
@@ -308,6 +317,19 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 		// 时间线：从 Git releases 页导入更新日志
 		api.POST("/timeline/from-releases", middleware.StaffExempt(middleware.RateLimitUserMiddleware(limiter, service.RateTimelineGit)), h.TimelineFromReleases)
 
+		// 代码片段（登录区）
+		api.POST("/snippets", middleware.StaffExempt(middleware.RateLimitMiddleware(limiter, service.RateSnippet)), h.SnippetCreate)
+		api.GET("/snippets/mine", h.SnippetMine)
+		api.PUT("/snippets/:id", h.SnippetUpdate)
+		api.DELETE("/snippets/:id", h.SnippetDelete)
+		api.POST("/snippets/:id/fork", middleware.StaffExempt(middleware.RateLimitMiddleware(limiter, service.RateSnippet)), h.SnippetFork)
+		api.POST("/snippets/:id/copy", h.SnippetCopy)
+		api.GET("/snippets/:id/history", h.SnippetHistory)
+		api.POST("/snippets/:id/comments", middleware.StaffExempt(middleware.RateLimitMiddleware(limiter, service.RateComment)), h.SnippetCommentCreate)
+		api.PUT("/snippets/:id/comments/:cid", middleware.StaffExempt(middleware.RateLimitMiddleware(limiter, service.RateComment)), h.SnippetCommentUpdate)
+		api.DELETE("/snippets/:id/comments/:cid", h.SnippetCommentDelete)
+		api.GET("/snippets/:id/comments/:cid/history", h.SnippetCommentHistory)
+
 		// 群聊（二期）：建群/成员/消息/未读；全站关闭消息时前台一律 403
 		chatAPI := api.Group("/chat", h.RequireMessagesOpen)
 		{
@@ -508,6 +530,11 @@ func Setup(cfg *config.Config) (*gin.Engine, error) {
 			usersAPI.GET("/users/:id/messages", h.AdminUserAuditMessages)
 		}
 
+		// 代码片段管理（任意 staff）
+		staffAPI.GET("/snippets", h.AdminSnippetList)
+		staffAPI.DELETE("/snippets/:id", h.AdminSnippetDelete)
+		staffAPI.PUT("/snippets/:id/visibility", h.AdminSnippetSetVisibility)
+
 		// 板块管理（仅站长）：增删改、排序、版主授权
 		boardsAPI := staffAPI.Group("", authMW.RequirePerm(service.PermBoards))
 		{

backend/service/chat.go

@@ -767,6 +767,18 @@ func (s *ChatService) Kick(operatorID, roomID, targetID uint, oversee bool) erro
 	return s.removeMember(roomID, targetID)
 }
 
+// DisplayName 取用户群聊展示名（昵称优先，退回用户名）；用户不存在/封禁时返回空串
+func (s *ChatService) DisplayName(userID uint) string {
+	var u model.User
+	if err := s.db.Select("id", "nickname", "username").First(&u, userID).Error; err != nil {
+		return ""
+	}
+	if u.Nickname != "" {
+		return u.Nickname
+	}
+	return u.Username
+}
+
 // SendSystemMessage 向房间落库一条系统提示消息（sender_id=0，is_system=true）。
 // 只推进房间 updated_at，不推进 last_message_id：系统提示不作为会话预览，
 // 也不参与排序顶置，避免禁言/解禁等管理动作在会话列表伪装成「新消息」。

backend/service/header_nav.go

@@ -24,7 +24,7 @@ const (
 
 // HeaderNavBuiltinKeys 内置菜单 key 白名单（顺序即默认顺序）；
 // 与前端 lib/headerNav.ts 的 HEADER_NAV_BUILTIN_KEYS 保持一致。
-var HeaderNavBuiltinKeys = []string{"home", "leaderboard", "library"}
+var HeaderNavBuiltinKeys = []string{"home", "leaderboard", "library", "snippets"}
 
 // HeaderNavItem 顶部导航菜单项：
 //

backend/service/header_nav_test.go

@@ -25,18 +25,19 @@ func newHeaderNavTestService(t *testing.T) *SettingService {
 func TestHeaderNavDefaultWhenMissing(t *testing.T) {
 	s := newHeaderNavTestService(t)
 	got := s.HeaderNav()
-	if len(got) != 3 ||
+	if len(got) != 4 ||
 		got[0] != (HeaderNavItem{Type: HeaderNavItemBuiltin, Key: "home"}) ||
 		got[1] != (HeaderNavItem{Type: HeaderNavItemBuiltin, Key: "leaderboard"}) ||
-		got[2] != (HeaderNavItem{Type: HeaderNavItemBuiltin, Key: "library"}) {
+		got[2] != (HeaderNavItem{Type: HeaderNavItemBuiltin, Key: "library"}) ||
+		got[3] != (HeaderNavItem{Type: HeaderNavItemBuiltin, Key: "snippets"}) {
 		t.Fatalf("missing row should fall back to builtin defaults, got %+v", got)
 	}
 	pub, err := s.Public()
 	if err != nil {
 		t.Fatal(err)
 	}
-	if len(pub.HeaderNav) != 3 {
-		t.Fatalf("Public().HeaderNav len = %d, want 3", len(pub.HeaderNav))
+	if len(pub.HeaderNav) != 4 {
+		t.Fatalf("Public().HeaderNav len = %d, want 4", len(pub.HeaderNav))
 	}
 }
 
@@ -133,7 +134,7 @@ func TestNormalizeHeaderNavDedupesBuiltins(t *testing.T) {
 
 func TestParseHeaderNavJSONTolerant(t *testing.T) {
 	// 坏 JSON 回落默认
-	if got := parseHeaderNavJSON("{bad"); len(got) != 3 {
+	if got := parseHeaderNavJSON("{bad"); len(got) != 4 {
 		t.Fatalf("bad json should fall back to defaults, got %+v", got)
 	}
 	// 空数组 = 全部隐藏

backend/service/ratelimit.go

@@ -85,6 +85,7 @@ const (
 	RateAdSubmit     = "ad_submit"     // 广告申购 5/分钟（按 IP）
 	RateCaptcha      = "captcha"       // 验证码刷新 30/分钟
 	RateTelemetry    = "telemetry"     // 页面浏览埋点 120/分钟（按 IP）
+	RateSnippet      = "snippet"       // 代码片段创建/Fork 10/分钟
 )
 
 // DefaultRateLimiter 创建默认速率限制器
@@ -102,5 +103,6 @@ func DefaultRateLimiter() *RateLimiter {
 	rl.SetLimit(RateAdSubmit, 5)      // 广告申购 5/分钟
 	rl.SetLimit(RateCaptcha, 30)      // 验证码 30/分钟
 	rl.SetLimit(RateTelemetry, 120)   // 埋点 120/分钟
+	rl.SetLimit(RateSnippet, 10)      // 代码片段 10/分钟
 	return rl
 }