feat: 分类系统 + 标签系统 — Phase 4 完成

分类：Model/Repo/Service/Controller + 管理后台树形页面 + 首页导航栏
标签：Model/Repo/Service/Controller + /tags/{slug} 落地页 + 写文章页输入
Post 加 CategoryID，Create/Update 支持分类和标签
SQL 迁移含 categories/tags/post_tags 表及预设未分类

internal/controller/admin/category_controller.go

@@ -0,0 +1,100 @@
+package admin
+
+import (
+	"net/http"
+	"strconv"
+
+	"metazone.cc/mce/internal/common"
+	"metazone.cc/mce/internal/model"
+
+	"github.com/gin-gonic/gin"
+)
+
+// CategoryController 分类管理控制器
+type CategoryController struct {
+	svc categoryUseCase
+}
+
+type categoryUseCase interface {
+	Create(c *model.Category) error
+	Update(c *model.Category) error
+	Delete(id uint) error
+	Tree() ([]model.Category, error)
+}
+
+// NewCategoryController 构造函数
+func NewCategoryController(svc categoryUseCase) *CategoryController {
+	return &CategoryController{svc: svc}
+}
+
+// Page 分类管理页面
+func (cc *CategoryController) Page(c *gin.Context) {
+	tree, _ := cc.svc.Tree()
+	c.HTML(http.StatusOK, "admin/categories/index.html", common.BuildAdminPageData(c, gin.H{
+		"Title":    "分类管理",
+		"ExtraCSS": "/admin/static/css/categories.css",
+		"ExtraJS":  "/admin/static/js/categories.js",
+		"Tree":     tree,
+	}))
+}
+
+// List 分类列表 API
+func (cc *CategoryController) List(c *gin.Context) {
+	tree, err := cc.svc.Tree()
+	if err != nil {
+		common.Error(c, http.StatusInternalServerError, "查询失败")
+		return
+	}
+	if tree == nil {
+		tree = []model.Category{}
+	}
+	common.Ok(c, tree)
+}
+
+// Create 创建分类
+func (cc *CategoryController) Create(c *gin.Context) {
+	var req model.Category
+	if err := c.ShouldBindJSON(&req); err != nil {
+		common.Error(c, http.StatusBadRequest, "参数错误")
+		return
+	}
+	if err := cc.svc.Create(&req); err != nil {
+		common.Error(c, http.StatusInternalServerError, "创建失败")
+		return
+	}
+	common.OkMessage(c, "分类已创建")
+}
+
+// Update 更新分类
+func (cc *CategoryController) Update(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		common.Error(c, http.StatusBadRequest, "无效的 ID")
+		return
+	}
+	var req model.Category
+	if err := c.ShouldBindJSON(&req); err != nil {
+		common.Error(c, http.StatusBadRequest, "参数错误")
+		return
+	}
+	req.ID = uint(id)
+	if err := cc.svc.Update(&req); err != nil {
+		common.Error(c, http.StatusInternalServerError, "更新失败")
+		return
+	}
+	common.OkMessage(c, "分类已更新")
+}
+
+// Delete 删除分类
+func (cc *CategoryController) Delete(c *gin.Context) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil {
+		common.Error(c, http.StatusBadRequest, "无效的 ID")
+		return
+	}
+	if err := cc.svc.Delete(uint(id)); err != nil {
+		common.Error(c, http.StatusInternalServerError, "删除失败")
+		return
+	}
+	common.OkMessage(c, "分类已删除")
+}

internal/controller/interfaces.go

@@ -42,9 +42,9 @@ type postUseCase interface {
 
 // studioUseCase StudioController 对 PostService 的最小依赖（ISP：9 个方法）
 type studioUseCase interface {
-	Create(userID uint, title, body, visibility, postType, reprintSource, declaration string, reprintProhibited bool) (*model.Post, error)
+	Create(userID uint, title, body, visibility, postType, reprintSource, declaration string, reprintProhibited bool, categoryID string) (*model.Post, error)
 	GetByID(id uint) (*model.Post, error)
-	Update(postID uint, title, body, visibility, postType, reprintSource, declaration string, reprintProhibited bool) error
+	Update(postID uint, title, body, visibility, postType, reprintSource, declaration string, reprintProhibited bool, categoryID string) error
 	Delete(postID uint) error
 	SubmitForAudit(postID uint) error
 	ListByUser(userID uint, status string, page, pageSize int) ([]model.Post, int64, error)

internal/controller/studio_controller.go

@@ -1,6 +1,7 @@
 package controller
 
 import (
+	"metazone.cc/mce/internal/model"
 	"metazone.cc/mce/internal/service"
 )
 
@@ -9,11 +10,24 @@ type trendsUseCase interface {
 	GetTrends(userID uint, since string) (*service.TrendResult, error)
 }
 
+// tagParser ISP：标签解析
+type tagParser interface {
+	ParseAndSave(tagStr string) ([]uint, error)
+	SetPostTags(postID uint, tagStr string) error
+}
+
 // StudioController 创作中心控制器（SSR 页面 + API）
 type StudioController struct {
 	postService studioUseCase
 	energySvc   energyDeducter
 	trendsSvc   trendsUseCase
+	tagSvc      tagParser
+	categorySvc categoryLoader
+}
+
+// categoryLoader ISP：分类叶子节点查询
+type categoryLoader interface {
+	GetLeaves() ([]model.Category, error)
 }
 
 // NewStudioController 构造函数
@@ -32,3 +46,15 @@ func (ctrl *StudioController) WithTrendsService(svc trendsUseCase) *StudioContro
 	ctrl.trendsSvc = svc
 	return ctrl
 }
+
+// WithTagService 链式注入标签服务
+func (ctrl *StudioController) WithTagService(svc tagParser) *StudioController {
+	ctrl.tagSvc = svc
+	return ctrl
+}
+
+// WithCategoryService 链式注入分类服务
+func (ctrl *StudioController) WithCategoryService(svc categoryLoader) *StudioController {
+	ctrl.categorySvc = svc
+	return ctrl
+}

internal/controller/studio_post_api_controller.go

@@ -30,12 +30,17 @@ func (ctrl *StudioController) Create(c *gin.Context) {
 		return
 	}
 
-	post, err := ctrl.postService.Create(uid, req.Title, req.Body, req.Visibility, req.PostType, req.ReprintSource, req.Declaration, req.ReprintProhibited)
+	post, err := ctrl.postService.Create(uid, req.Title, req.Body, req.Visibility, req.PostType, req.ReprintSource, req.Declaration, req.ReprintProhibited, req.CategoryID)
 	if err != nil {
 		common.Error(c, http.StatusInternalServerError, "发布失败")
 		return
 	}
 
+	// 关联标签
+	if ctrl.tagSvc != nil && req.Tags != "" {
+		_ = ctrl.tagSvc.SetPostTags(post.ID, req.Tags)
+	}
+
 	common.OkWithMessage(c, post, "发布成功")
 }
 
@@ -69,10 +74,15 @@ func (ctrl *StudioController) Update(c *gin.Context) {
 		return
 	}
 
-	if err := ctrl.postService.Update(uint(id), req.Title, req.Body, req.Visibility, req.PostType, req.ReprintSource, req.Declaration, req.ReprintProhibited); err != nil {
+	if err := ctrl.postService.Update(uint(id), req.Title, req.Body, req.Visibility, req.PostType, req.ReprintSource, req.Declaration, req.ReprintProhibited, req.CategoryID); err != nil {
 		common.Error(c, http.StatusInternalServerError, "编辑失败")
 		return
 	}
 
+	// 更新标签
+	if ctrl.tagSvc != nil {
+		_ = ctrl.tagSvc.SetPostTags(uint(id), req.Tags)
+	}
+
 	common.OkMessage(c, "编辑成功")
 }

internal/controller/studio_write_controller.go

@@ -17,6 +17,16 @@ func (ctrl *StudioController) WritePage(c *gin.Context) {
 		return
 	}
 
+	// 加载分类列表（叶子节点）
+	var categories []interface{}
+	if ctrl.categorySvc != nil {
+		if leaves, err := ctrl.categorySvc.GetLeaves(); err == nil {
+			for _, cat := range leaves {
+				categories = append(categories, cat)
+			}
+		}
+	}
+
 	// 支持编辑模式：传入 post_id 参数
 	postIDStr := c.Query("id")
 	if postIDStr != "" {
@@ -32,10 +42,11 @@ func (ctrl *StudioController) WritePage(c *gin.Context) {
 					return
 				}
 				c.HTML(http.StatusOK, "studio/write.html", common.BuildPageData(c, gin.H{
-					"Title":     "编辑文章 - 创作中心",
-					"Post":      post,
-					"ActiveTab": "write",
-					"ExtraCSS":  "/static/css/studio.css",
+					"Title":      "编辑文章 - 创作中心",
+					"Post":       post,
+					"ActiveTab":  "write",
+					"ExtraCSS":   "/static/css/studio.css",
+					"Categories": categories,
 				}))
 				return
 			}
@@ -43,9 +54,10 @@ func (ctrl *StudioController) WritePage(c *gin.Context) {
 	}
 
 	c.HTML(http.StatusOK, "studio/write.html", common.BuildPageData(c, gin.H{
-		"Title":     "写文章 - 创作中心",
-		"ActiveTab": "write",
-		"ExtraCSS":  "/static/css/studio.css",
+		"Title":      "写文章 - 创作中心",
+		"ActiveTab":  "write",
+		"ExtraCSS":   "/static/css/studio.css",
+		"Categories": categories,
 	}))
 }
 

internal/controller/tag_controller.go

@@ -0,0 +1,54 @@
+package controller
+
+import (
+	"net/http"
+	"strconv"
+
+	"metazone.cc/mce/internal/common"
+	"metazone.cc/mce/internal/model"
+
+	"github.com/gin-gonic/gin"
+)
+
+// TagController 标签控制器（标签落地页）
+type TagController struct {
+	svc tagUseCase
+}
+
+type tagUseCase interface {
+	GetPostsByTag(slug string, page, pageSize int) ([]model.Post, int64, *model.Tag, error)
+}
+
+// NewTagController 构造函数
+func NewTagController(svc tagUseCase) *TagController {
+	return &TagController{svc: svc}
+}
+
+// TagPage 标签落地页
+func (tc *TagController) TagPage(c *gin.Context) {
+	slug := c.Param("slug")
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	pageSize := 20
+
+	posts, total, tag, err := tc.svc.GetPostsByTag(slug, page, pageSize)
+	if err != nil {
+		c.HTML(http.StatusNotFound, "posts/404.html", common.BuildPageData(c, gin.H{
+			"Title":    "未找到",
+			"ErrorMsg": "该标签不存在",
+		}))
+		return
+	}
+
+	totalPages := common.PageCount(total, pageSize)
+	c.HTML(http.StatusOK, "tags/detail.html", common.BuildPageData(c, gin.H{
+		"Title":      "标签：" + tag.Name,
+		"ExtraCSS":   "/static/css/posts.css",
+		"Posts":      posts,
+		"Total":      total,
+		"Page":       page,
+		"TotalPages": totalPages,
+		"PrevPage":   max(1, page-1),
+		"NextPage":   min(totalPages, page+1),
+		"Tag":        tag,
+	}))
+}

internal/model/category.go

@@ -0,0 +1,18 @@
+package model
+
+import "time"
+
+// Category 文章分类（两级树形结构）
+type Category struct {
+	ID          uint       `gorm:"primarykey" json:"id"`
+	Name        string     `gorm:"type:varchar(50);not null" json:"name"`
+	Slug        string     `gorm:"type:varchar(50);not null;uniqueIndex" json:"slug"`
+	Description string     `gorm:"type:varchar(200);default:''" json:"description,omitempty"`
+	ParentID    *uint      `gorm:"index" json:"parent_id,omitempty"`
+	Sort        int        `gorm:"default:0" json:"sort"`
+	CreatedAt   time.Time  `json:"created_at"`
+	UpdatedAt   time.Time  `json:"updated_at"`
+
+	// 非 DB 字段（树形填充）
+	Children []Category `gorm:"-" json:"children,omitempty"`
+}

internal/model/dto.go

@@ -39,6 +39,8 @@ type PostCreateRequest struct {
 	ReprintSource     string `json:"reprint_source"`
 	Declaration       string `json:"declaration"`
 	ReprintProhibited bool   `json:"reprint_prohibited"`
+	CategoryID        string `json:"category_id"`
+	Tags              string `json:"tags"`
 }
 
 // PostUpdateRequest 编辑请求
@@ -50,6 +52,8 @@ type PostUpdateRequest struct {
 	ReprintSource     string `json:"reprint_source"`
 	Declaration       string `json:"declaration"`
 	ReprintProhibited bool   `json:"reprint_prohibited"`
+	CategoryID        string `json:"category_id"`
+	Tags              string `json:"tags"`
 }
 
 // PostRejectRequest 退回请求

internal/model/post.go

@@ -21,6 +21,7 @@ type Post struct {
 	RejectReason string         `gorm:"type:varchar(500);default:''" json:"reject_reason,omitempty"`
 
 	// 文章属性
+	CategoryID        *uint   `gorm:"index" json:"category_id,omitempty"`                                   // 二级分类 ID
 	Visibility        string  `gorm:"type:varchar(10);default:public" json:"visibility"`                    // public / private
 	PostType          string  `gorm:"type:varchar(10);default:original" json:"post_type"`                    // original / reprint
 	ReprintSource     string  `gorm:"type:varchar(500);default:''" json:"reprint_source,omitempty"`          // 转载来源

internal/model/tag.go

@@ -0,0 +1,17 @@
+package model
+
+import "time"
+
+// Tag 标签
+type Tag struct {
+	ID        uint      `gorm:"primarykey" json:"id"`
+	Name      string    `gorm:"type:varchar(50);not null" json:"name"`
+	Slug      string    `gorm:"type:varchar(50);not null;uniqueIndex" json:"slug"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+// PostTag 文章-标签关联
+type PostTag struct {
+	PostID uint `gorm:"primarykey" json:"post_id"`
+	TagID  uint `gorm:"primarykey" json:"tag_id"`
+}

internal/repository/category_repo.go

@@ -0,0 +1,63 @@
+package repository
+
+import (
+	"metazone.cc/mce/internal/model"
+	"metazone.cc/mce/internal/service"
+
+	"gorm.io/gorm"
+)
+
+// CategoryRepo 分类数据访问
+type CategoryRepo struct {
+	db *gorm.DB
+}
+
+// NewCategoryRepo 构造函数
+func NewCategoryRepo(db *gorm.DB) *CategoryRepo {
+	return &CategoryRepo{db: db}
+}
+
+// WithTx 基于事务创建新实例
+func (r *CategoryRepo) WithTx(tx *gorm.DB) service.CategoryStore {
+	return &CategoryRepo{db: tx}
+}
+
+// Create 创建分类
+func (r *CategoryRepo) Create(c *model.Category) error {
+	return r.db.Create(c).Error
+}
+
+// Update 更新分类
+func (r *CategoryRepo) Update(c *model.Category) error {
+	return r.db.Save(c).Error
+}
+
+// Delete 删除分类
+func (r *CategoryRepo) Delete(id uint) error {
+	return r.db.Delete(&model.Category{}, id).Error
+}
+
+// FindByID 按 ID 查询
+func (r *CategoryRepo) FindByID(id uint) (*model.Category, error) {
+	var c model.Category
+	err := r.db.First(&c, id).Error
+	if err != nil {
+		return nil, err
+	}
+	return &c, nil
+}
+
+// ListAll 查询全部分类（按 sort 排序）
+func (r *CategoryRepo) ListAll() ([]model.Category, error) {
+	var list []model.Category
+	err := r.db.Order("sort ASC, id ASC").Find(&list).Error
+	return list, err
+}
+
+// GetLeaves 查询所有叶子分类（有子分类的父节点不返回）
+func (r *CategoryRepo) GetLeaves() ([]model.Category, error) {
+	var leaves []model.Category
+	err := r.db.Where("id NOT IN (SELECT DISTINCT parent_id FROM categories WHERE parent_id IS NOT NULL)").
+		Order("sort ASC, id ASC").Find(&leaves).Error
+	return leaves, err
+}

internal/repository/tag_repo.go

@@ -0,0 +1,97 @@
+package repository
+
+import (
+	"metazone.cc/mce/internal/model"
+	"metazone.cc/mce/internal/service"
+
+	"gorm.io/gorm"
+)
+
+// TagRepo 标签数据访问
+type TagRepo struct {
+	db *gorm.DB
+}
+
+// NewTagRepo 构造函数
+func NewTagRepo(db *gorm.DB) *TagRepo {
+	return &TagRepo{db: db}
+}
+
+// WithTx 基于事务创建新实例
+func (r *TagRepo) WithTx(tx *gorm.DB) service.TagStore {
+	return &TagRepo{db: tx}
+}
+
+// FindOrCreate 查找或创建标签（按名字）
+func (r *TagRepo) FindOrCreate(name, slug string) (*model.Tag, error) {
+	var tag model.Tag
+	err := r.db.Where("slug = ?", slug).First(&tag).Error
+	if err == nil {
+		return &tag, nil
+	}
+	if err != gorm.ErrRecordNotFound {
+		return nil, err
+	}
+	tag = model.Tag{Name: name, Slug: slug}
+	if err := r.db.Create(&tag).Error; err != nil {
+		return nil, err
+	}
+	return &tag, nil
+}
+
+// FindBySlug 按 slug 查询
+func (r *TagRepo) FindBySlug(slug string) (*model.Tag, error) {
+	var tag model.Tag
+	err := r.db.Where("slug = ?", slug).First(&tag).Error
+	if err != nil {
+		return nil, err
+	}
+	return &tag, nil
+}
+
+// SetPostTags 设置文章的标签（删除旧的，插入新的）
+func (r *TagRepo) SetPostTags(postID uint, tagIDs []uint) error {
+	return r.db.Transaction(func(tx *gorm.DB) error {
+		if err := tx.Where("post_id = ?", postID).Delete(&model.PostTag{}).Error; err != nil {
+			return err
+		}
+		for _, tagID := range tagIDs {
+			if err := tx.Create(&model.PostTag{PostID: postID, TagID: tagID}).Error; err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+}
+
+// GetPostTags 获取文章关联的标签
+func (r *TagRepo) GetPostTags(postID uint) ([]model.Tag, error) {
+	var tags []model.Tag
+	err := r.db.Table("tags").
+		Joins("JOIN post_tags ON post_tags.tag_id = tags.id").
+		Where("post_tags.post_id = ?", postID).
+		Find(&tags).Error
+	return tags, err
+}
+
+// GetPostsByTag 按标签查询文章（公开+已发布）
+func (r *TagRepo) GetPostsByTag(tagID uint, offset, limit int) ([]model.Post, int64, error) {
+	var total int64
+	query := r.db.Table("posts").
+		Joins("JOIN post_tags ON post_tags.post_id = posts.id").
+		Joins("LEFT JOIN users ON users.id = posts.user_id").
+		Where("post_tags.tag_id = ?", tagID).
+		Where("posts.status = ?", model.PostStatusApproved).
+		Where("posts.visibility = ?", model.VisibilityPublic).
+		Where("posts.deleted_at IS NULL").
+		Select("posts.*, users.username as author_name")
+
+	if err := query.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	var posts []model.Post
+	err := query.Order("CASE WHEN posts.pin_type = 'global' THEN 0 ELSE 1 END ASC, posts.pinned_at DESC NULLS LAST, posts.created_at DESC").
+		Offset(offset).Limit(limit).Find(&posts).Error
+	return posts, total, err
+}

internal/router/admin.go

@@ -33,6 +33,7 @@ func setupAdminRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		adminPages.GET("/energy/fund-logs", d.adminEnergyCtrl.FundLogPage)
 		adminPages.GET("/comments", d.adminCommentCtrl.CommentsPage)
 		adminPages.GET("/announcements", d.announcementCtrl.Page)
+		adminPages.GET("/categories", d.categoryCtrl.Page)
 	}
 
 	// --- 管理后台 API ---
@@ -115,4 +116,17 @@ func setupAdminRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		announcementAPI.PUT("/:id", d.announcementCtrl.Update)
 		announcementAPI.DELETE("/:id", d.announcementCtrl.Delete)
 	}
+
+	// --- 分类管理 API（moderator+） ---
+	categoryAPI := r.Group("/api/admin/categories")
+	categoryAPI.Use(d.authMdw.Required())
+	categoryAPI.Use(middleware.RequireMinRole(model.RoleModerator))
+	categoryAPI.Use(d.authMdw.BannedWriteGuard())
+	categoryAPI.Use(middleware.CSRF(cfg))
+	{
+		categoryAPI.GET("", d.categoryCtrl.List)
+		categoryAPI.POST("", d.categoryCtrl.Create)
+		categoryAPI.PUT("/:id", d.categoryCtrl.Update)
+		categoryAPI.DELETE("/:id", d.categoryCtrl.Delete)
+	}
 }

internal/router/deps_core.go

@@ -47,6 +47,10 @@ type dependencies struct {
 	homeCache         *cache.HomePageCache
 	announcementService *service.AnnouncementService
 	announcementCtrl    *adminCtrl.AnnouncementController
+	categoryCtrl        *adminCtrl.CategoryController
+	categoryService     *service.CategoryService
+	tagCtrl             *controller.TagController
+	tagService          *service.TagService
 }
 
 func buildDepsCore(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSettings, redisClient *redis.Client) (

internal/router/deps_extra.go

@@ -103,6 +103,18 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 
 	maintenanceMdw := middleware.NewMaintenanceMiddleware(cfg, siteSettings, sessionMgr)
 
+	// 分类系统
+	categoryRepo := repository.NewCategoryRepo(db)
+	categoryService := service.NewCategoryService(categoryRepo)
+	categoryCtrl := adminCtrl.NewCategoryController(categoryService)
+	studioCtrl.WithCategoryService(categoryService)
+
+	// 标签系统
+	tagRepo := repository.NewTagRepo(db)
+	tagService := service.NewTagService(tagRepo)
+	tagCtrl := controller.NewTagController(tagService)
+	studioCtrl.WithTagService(tagService)
+
 	// 公告系统
 	announcementRepo := repository.NewAnnouncementRepo(db)
 	announcementService := service.NewAnnouncementService(announcementRepo)
@@ -135,5 +147,9 @@ func buildDeps(db *gorm.DB, cfg *config.Config, siteSettings *config.SiteSetting
 		homeCache:          homeCache,
 		announcementService: announcementService,
 		announcementCtrl:   announcementCtrl,
+		categoryCtrl:       categoryCtrl,
+		categoryService:    categoryService,
+		tagCtrl:            tagCtrl,
+		tagService:         tagService,
 	}
 }

internal/router/frontend.go

@@ -34,12 +34,14 @@ func setupFrontendRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 				}
 			}
 			announcements, _ := d.announcementService.ListActive()
+			categoryNav, _ := d.categoryService.GetLeaves()
 			c.HTML(http.StatusOK, "home/index.html", common.BuildPageData(c, gin.H{
 				"Title":         "首页",
 				"ExtraCSS":      "/static/css/home.css",
 				"Posts":         posts,
 				"PostCount":     total,
 				"Announcements": announcements,
+				"CategoryNav":   categoryNav,
 			}))
 		})
 
@@ -56,6 +58,9 @@ func setupFrontendRoutes(r *gin.Engine, cfg *config.Config, d *dependencies) {
 		// 帖子页面
 		pages.GET("/posts", d.postCtrl.ListPage)
 		pages.GET("/posts/:id", d.postCtrl.ShowPage)
+
+		// 标签落地页
+		pages.GET("/tags/:slug", d.tagCtrl.TagPage)
 		pages.GET("/posts/:id/edit", d.authMdw.Required(), func(c *gin.Context) {
 			c.Redirect(http.StatusMovedPermanently, "/studio/write?id="+c.Param("id"))
 		})

internal/service/category_service.go

@@ -0,0 +1,75 @@
+package service
+
+import "metazone.cc/mce/internal/model"
+
+// CategoryStore 分类仓库接口（ISP）
+type CategoryStore interface {
+	Create(c *model.Category) error
+	Update(c *model.Category) error
+	Delete(id uint) error
+	FindByID(id uint) (*model.Category, error)
+	ListAll() ([]model.Category, error)
+	GetLeaves() ([]model.Category, error)
+}
+
+// CategoryService 分类业务逻辑
+type CategoryService struct {
+	repo CategoryStore
+}
+
+// NewCategoryService 构造函数
+func NewCategoryService(repo CategoryStore) *CategoryService {
+	return &CategoryService{repo: repo}
+}
+
+// Create 创建分类
+func (s *CategoryService) Create(c *model.Category) error {
+	return s.repo.Create(c)
+}
+
+// Update 更新分类
+func (s *CategoryService) Update(c *model.Category) error {
+	return s.repo.Update(c)
+}
+
+// Delete 删除分类
+func (s *CategoryService) Delete(id uint) error {
+	return s.repo.Delete(id)
+}
+
+// Tree 获取两级分类树
+func (s *CategoryService) Tree() ([]model.Category, error) {
+	all, err := s.repo.ListAll()
+	if err != nil {
+		return nil, err
+	}
+	// 构建树：parent_id=nil 的为根节点
+	parentMap := make(map[uint]*model.Category)
+	var roots []*model.Category
+	for i := range all {
+		c := &all[i]
+		c.Children = []model.Category{}
+		parentMap[c.ID] = c
+		if c.ParentID == nil {
+			roots = append(roots, c)
+		}
+	}
+	for i := range all {
+		c := &all[i]
+		if c.ParentID != nil {
+			if parent, ok := parentMap[*c.ParentID]; ok {
+				parent.Children = append(parent.Children, *c)
+			}
+		}
+	}
+	result := make([]model.Category, len(roots))
+	for i, r := range roots {
+		result[i] = *r
+	}
+	return result, nil
+}
+
+// GetLeaves 获取所有叶子分类（用于写文章页下拉选择）
+func (s *CategoryService) GetLeaves() ([]model.Category, error) {
+	return s.repo.GetLeaves()
+}

internal/service/post_audit_service.go

@@ -1,12 +1,14 @@
 package service
 
 import (
+	"strconv"
+
 	"metazone.cc/mce/internal/common"
 	"metazone.cc/mce/internal/model"
 )
 
 // Update 编辑帖子（权限在 controller 层检查）
-func (s *PostService) Update(postID uint, title, body string, visibility, postType, reprintSource, declaration string, reprintProhibited bool) error {
+func (s *PostService) Update(postID uint, title, body string, visibility, postType, reprintSource, declaration string, reprintProhibited bool, categoryID string) error {
 	post, err := s.findPost(postID)
 	if err != nil {
 		return err
@@ -22,6 +24,13 @@ func (s *PostService) Update(postID uint, title, body string, visibility, postTy
 	post.ReprintSource = reprintSource
 	post.Declaration = declaration
 	post.ReprintProhibited = reprintProhibited
+	// 分类
+	if cid, err := strconv.ParseUint(categoryID, 10, 64); err == nil && cid > 0 {
+		id := uint(cid)
+		post.CategoryID = &id
+	} else {
+		post.CategoryID = nil
+	}
 
 	// 已通过帖子：编辑内容保存为待审修订，不影响当前展示
 	if post.Status == model.PostStatusApproved {

internal/service/post_service.go

@@ -3,6 +3,7 @@ package service
 import (
 	"errors"
 	"fmt"
+	"strconv"
 	"time"
 
 	"metazone.cc/mce/internal/common"
@@ -68,7 +69,7 @@ func (s *PostService) findPostWithAuthor(id uint) (*model.Post, error) {
 // Create 创建帖子
 // body 为 Vditor 输出的 Markdown，后端直接存储不做 HTML 消毒
 // MD 是纯文本，无 XSS 注入风险；前端渲染时由 Vditor 转 HTML
-func (s *PostService) Create(userID uint, title, body string, visibility, postType, reprintSource, declaration string, reprintProhibited bool) (*model.Post, error) {
+func (s *PostService) Create(userID uint, title, body string, visibility, postType, reprintSource, declaration string, reprintProhibited bool, categoryID string) (*model.Post, error) {
 	status := model.PostStatusApproved
 	if s.auditEnabled() {
 		status = model.PostStatusDraft
@@ -87,6 +88,11 @@ func (s *PostService) Create(userID uint, title, body string, visibility, postTy
 		Declaration:       declaration,
 		ReprintProhibited: reprintProhibited,
 	}
+	// 解析分类 ID
+	if cid, err := strconv.ParseUint(categoryID, 10, 64); err == nil && cid > 0 {
+		id := uint(cid)
+		post.CategoryID = &id
+	}
 	if err := s.repo.Create(post); err != nil {
 		return nil, err
 	}

internal/service/tag_service.go

@@ -0,0 +1,82 @@
+package service
+
+import (
+	"regexp"
+	"strings"
+
+	"metazone.cc/mce/internal/model"
+)
+
+// TagStore 标签仓库接口（ISP）
+type TagStore interface {
+	FindOrCreate(name, slug string) (*model.Tag, error)
+	FindBySlug(slug string) (*model.Tag, error)
+	SetPostTags(postID uint, tagIDs []uint) error
+	GetPostTags(postID uint) ([]model.Tag, error)
+	GetPostsByTag(tagID uint, offset, limit int) ([]model.Post, int64, error)
+}
+
+var slugRegex = regexp.MustCompile(`[^a-z0-9\-]`)
+
+// TagService 标签业务逻辑
+type TagService struct {
+	repo TagStore
+}
+
+// NewTagService 构造函数
+func NewTagService(repo TagStore) *TagService {
+	return &TagService{repo: repo}
+}
+
+// ParseAndSave 解析标签名列表（逗号分隔），查找或创建，返回 tagID 列表
+func (s *TagService) ParseAndSave(tagStr string) ([]uint, error) {
+	if strings.TrimSpace(tagStr) == "" {
+		return nil, nil
+	}
+	names := strings.Split(tagStr, ",")
+	var tagIDs []uint
+	seen := make(map[string]bool)
+	for _, name := range names {
+		name = strings.TrimSpace(name)
+		if name == "" || len(name) > 50 {
+			continue
+		}
+		slug := slugify(name)
+		if seen[slug] {
+			continue
+		}
+		seen[slug] = true
+		tag, err := s.repo.FindOrCreate(name, slug)
+		if err != nil {
+			return nil, err
+		}
+		tagIDs = append(tagIDs, tag.ID)
+	}
+	return tagIDs, nil
+}
+
+// SetPostTags 解析标签字符串并关联到文章
+func (s *TagService) SetPostTags(postID uint, tagStr string) error {
+	tagIDs, err := s.ParseAndSave(tagStr)
+	if err != nil {
+		return err
+	}
+	return s.repo.SetPostTags(postID, tagIDs)
+}
+
+// GetPostsByTag 按标签分页查询文章
+func (s *TagService) GetPostsByTag(slug string, page, pageSize int) ([]model.Post, int64, *model.Tag, error) {
+	tag, err := s.repo.FindBySlug(slug)
+	if err != nil {
+		return nil, 0, nil, err
+	}
+	offset := (page - 1) * pageSize
+	posts, total, err := s.repo.GetPostsByTag(tag.ID, offset, pageSize)
+	return posts, total, tag, err
+}
+
+func slugify(name string) string {
+	s := strings.ToLower(strings.TrimSpace(name))
+	s = strings.ReplaceAll(s, " ", "-")
+	return slugRegex.ReplaceAllString(s, "")
+}