feat: add git pull to update cached repositories from remote

- Replace dead FetchRemote with PullRepo (fetch + merge) in services/git.go
- Add POST /api/repos/:id/pull endpoint with DB size/last_used update
- Add '更新' button next to each cached repo in the index page

handlers/repos.go

@@ -140,6 +140,41 @@ func (h *ReposHandler) CleanupRepos(c *gin.Context) {
 	c.JSON(http.StatusOK, result)
 }
 
+// PullRepo handles POST /api/repos/:id/pull — fetches and merges latest changes.
+func (h *ReposHandler) PullRepo(c *gin.Context) {
+	user := GetCurrentUser(c)
+	if user == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthenticated"})
+		return
+	}
+
+	id := c.Param("id")
+	var localPath string
+	err := h.db.QueryRow(`SELECT local_path FROM repositories WHERE id = ? AND user_id = ?`, id, user.ID).Scan(&localPath)
+	if err == sql.ErrNoRows {
+		c.JSON(http.StatusNotFound, gin.H{"error": "repository not found"})
+		return
+	}
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	result, err := services.PullRepo(localPath)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	h.db.Exec(`UPDATE repositories SET size_bytes = ?, last_used = NOW() WHERE id = ?`, result.SizeBytes, id)
+
+	c.JSON(http.StatusOK, gin.H{
+		"ok":       true,
+		"repo_id":  id,
+		"size_bytes": result.SizeBytes,
+	})
+}
+
 // CloneRepo handles POST /api/repos with SSE progress events.
 func (h *ReposHandler) CloneRepo(c *gin.Context) {
 	user := GetCurrentUser(c)

main.go

@@ -114,6 +114,7 @@ func main() {
 	r.POST("/api/repos", authMw, repos.CloneRepo)
 	r.DELETE("/api/repos/:id", authMw, repos.DeleteRepo)
 	r.POST("/api/repos/:id/cleanup", authMw, repos.CleanupRepos)
+	r.POST("/api/repos/:id/pull", authMw, repos.PullRepo)
 	r.GET("/api/repos/:id/graph", authMw, repos.GetGraph)
 	r.GET("/api/repos/:id/refs", authMw, repos.GetRefs)
 	r.GET("/api/repos/:id/commits", authMw, repos.GetCommits)

services/git.go

@@ -441,21 +441,53 @@ func GetBranchCommits(repoPath, branchName string, maxCommits int) ([]CommitInfo
 	return GetCommitLog(repo, branchName, maxCommits)
 }
 
-// FetchRemote fetches latest changes for a repo.
-func FetchRemote(repoPath string) error {
+// PullRepo fetches and merges latest changes from origin into the current branch.
+func PullRepo(repoPath string) (*CloneResult, error) {
 	repo, err := OpenRepo(repoPath)
 	if err != nil {
-		return err
+		return nil, err
 	}
-remote, err := repo.Remote("origin")
+
+	w, err := repo.Worktree()
 	if err != nil {
-		return err
+		return nil, fmt.Errorf("worktree: %w", err)
 	}
-	return remote.Fetch(&git.FetchOptions{
-		Force: true,
+
+	err = w.Pull(&git.PullOptions{})
+	if err != nil && err != git.NoErrAlreadyUpToDate {
+		return nil, fmt.Errorf("git pull: %w", err)
+	}
+
+	result := &CloneResult{RepoPath: repoPath}
+
+	iter, err := repo.CommitObjects()
+	if err == nil {
+		_ = iter.ForEach(func(c *object.Commit) error {
+			result.CommitNum++
+			return nil
 		})
 	}
 
+	branches, err := repo.Branches()
+	if err == nil {
+		_ = branches.ForEach(func(ref *plumbing.Reference) error {
+			result.Branches = append(result.Branches, ref.Name().Short())
+			return nil
+		})
+	}
+
+	tags, err := repo.Tags()
+	if err == nil {
+		_ = tags.ForEach(func(ref *plumbing.Reference) error {
+			result.Tags = append(result.Tags, ref.Name().Short())
+			return nil
+		})
+	}
+
+	result.SizeBytes = dirSize(repoPath)
+	return result, nil
+}
+
 // dirSize returns the total size of files in a directory.
 func dirSize(path string) int64 {
 	var size int64

templates/pages/index.html

@@ -52,10 +52,16 @@
                                 <a href="/repo/{{.ID}}" class="text-sm font-medium text-indigo-600 hover:text-indigo-800">{{.URL}}</a>
                                 <p class="text-xs text-gray-400 mt-1">最后使用: {{.LastUsed}}</p>
                             </div>
+                            <div class="flex gap-2">
+                                <button hx-post="/api/repos/{{.ID}}/pull" hx-swap="none"
+                                        hx-on::before-request="this.disabled=true;this.textContent='更新中...'"
+                                        hx-on::after-request="window.location.reload()"
+                                        class="text-xs text-indigo-500 hover:text-indigo-700">更新</button>
                                 <button hx-delete="/api/repos/{{.ID}}" hx-confirm="确定删除此仓库缓存？"
                                         hx-swap="none" hx-on::after-request="window.location.reload()"
                                         class="text-xs text-red-500 hover:text-red-700">删除</button>
                             </div>
+                        </div>
                         {{end}}
                     </div>
                     {{else}}