feat(mail): 支持自定义邮件文件夹排序

- 后端为 `folders` 增加 `sort_order`，并提供文件夹重排接口。
- 前端邮件侧边栏支持自定义文件夹拖拽排序与乐观更新。
- 补充文件夹排序相关测试，并同步更新 API 类型定义。

apps/api/internal/app/admin_handlers.go

@@ -1149,6 +1149,14 @@ func (a *App) ensureFolder(ctx context.Context, mailboxID, folder string) (strin
 	}
 	role := strings.ToLower(folder)
 	id = newID("fld")
-	_, err := a.db.ExecContext(ctx, `INSERT INTO folders(id,mailbox_id,name,role,uid_validity,uid_next,highest_modseq,created_at) VALUES(?,?,?,?,?,?,?,?)`, id, mailboxID, folder, role, a.newUIDValidity(), 1, 1, a.now().UTC().Format(time.RFC3339Nano))
+	sortOrder := 0
+	if !isSystemFolderName(folder) {
+		var err error
+		sortOrder, err = a.nextCustomFolderSortOrder(ctx, mailboxID)
+		if err != nil {
+			return "", err
+		}
+	}
+	_, err := a.db.ExecContext(ctx, `INSERT INTO folders(id,mailbox_id,name,role,sort_order,uid_validity,uid_next,highest_modseq,created_at) VALUES(?,?,?,?,?,?,?,?,?)`, id, mailboxID, folder, role, sortOrder, a.newUIDValidity(), 1, 1, a.now().UTC().Format(time.RFC3339Nano))
 	return id, err
 }

apps/api/internal/app/app.go

@@ -202,6 +202,7 @@ func (a *App) migrate(ctx context.Context) error {
 			mailbox_id TEXT NOT NULL REFERENCES mailboxes(id) ON DELETE CASCADE,
 			name TEXT NOT NULL,
 			role TEXT NOT NULL,
+			sort_order INTEGER NOT NULL DEFAULT 0,
 			uid_validity INTEGER NOT NULL DEFAULT 0,
 			uid_next INTEGER NOT NULL DEFAULT 1,
 			highest_modseq INTEGER NOT NULL DEFAULT 1,
@@ -448,6 +449,9 @@ func (a *App) migrate(ctx context.Context) error {
 	if err := a.migrateIMAPMetadata(ctx); err != nil {
 		return err
 	}
+	if err := a.migrateFolderSortOrder(ctx); err != nil {
+		return err
+	}
 	if err := a.ensureDefaultPermissionGroups(ctx); err != nil {
 		return err
 	}
@@ -1131,7 +1135,7 @@ func (a *App) createMailboxWithPasswordHash(ctx context.Context, userID, domainI
 		return "", err
 	}
 	for _, f := range defaultFolderDefs() {
-		_, err = tx.ExecContext(ctx, `INSERT INTO folders(id,mailbox_id,name,role,uid_validity,uid_next,highest_modseq,created_at) VALUES(?,?,?,?,?,?,?,?)`, newID("fld"), id, f.name, f.role, a.newUIDValidity(), 1, 1, now)
+		_, err = tx.ExecContext(ctx, `INSERT INTO folders(id,mailbox_id,name,role,sort_order,uid_validity,uid_next,highest_modseq,created_at) VALUES(?,?,?,?,?,?,?,?,?)`, newID("fld"), id, f.name, f.role, 0, a.newUIDValidity(), 1, 1, now)
 		if err != nil {
 			return "", err
 		}

apps/api/internal/app/app_test.go

@@ -1047,6 +1047,80 @@ func TestCustomMailFoldersCreateAndMove(t *testing.T) {
 	}
 }
 
+func TestCustomMailFoldersReorder(t *testing.T) {
+	a := newTestApp(t)
+	ts := httptest.NewServer(a.Router())
+	defer ts.Close()
+	admin := &testClient{t: t, server: ts}
+
+	var login map[string]any
+	if code := admin.do("POST", "/api/auth/login", map[string]string{"email": "admin@lanqin.local", "password": "ChangeMe123!"}, &login); code != http.StatusOK {
+		t.Fatalf("login code=%d body=%v", code, login)
+	}
+
+	createFolder := func(name string) MailFolder {
+		t.Helper()
+		var folder MailFolder
+		if code := admin.do("POST", "/api/mail/folders", map[string]string{"name": name}, &folder); code != http.StatusCreated {
+			t.Fatalf("create folder %s code=%d folder=%+v", name, code, folder)
+		}
+		return folder
+	}
+	customer := createFolder("客户")
+	bills := createFolder("账单")
+	project := createFolder("项目")
+
+	var ok map[string]any
+	if code := admin.do("POST", "/api/mail/folders/reorder", map[string]any{"folderIds": []string{project.ID, customer.ID, bills.ID}}, &ok); code != http.StatusOK {
+		t.Fatalf("reorder code=%d body=%v", code, ok)
+	}
+	if code := admin.do("POST", "/api/mail/folders/reorder", map[string]any{"folders": []map[string]any{
+		{"id": customer.ID, "sortOrder": 500},
+		{"id": project.ID, "sortOrder": 2500},
+		{"id": bills.ID, "sortOrder": 3500},
+	}}, &ok); code != http.StatusOK {
+		t.Fatalf("reorder with explicit sort order code=%d body=%v", code, ok)
+	}
+	var folders struct {
+		Items []MailFolder `json:"items"`
+	}
+	if code := admin.do("GET", "/api/mail/folders", nil, &folders); code != http.StatusOK {
+		t.Fatalf("list folders code=%d items=%+v", code, folders.Items)
+	}
+	got := customFolderNames(folders.Items)
+	want := []string{"客户", "项目", "账单"}
+	if strings.Join(got, ",") != strings.Join(want, ",") {
+		t.Fatalf("custom folder order=%v want=%v", got, want)
+	}
+	if folders.Items[0].ID != customer.ID {
+		t.Fatalf("customer folder should be before inbox after explicit sort order, first=%+v", folders.Items[0])
+	}
+	var inboxID string
+	for _, item := range folders.Items {
+		if item.Name == "Inbox" {
+			inboxID = item.ID
+			break
+		}
+	}
+	if inboxID == "" {
+		t.Fatalf("inbox not found in folders: %+v", folders.Items)
+	}
+	var bad map[string]any
+	if code := admin.do("POST", "/api/mail/folders/reorder", map[string]any{"folderIds": []string{project.ID, inboxID, customer.ID, bills.ID}}, &bad); code != http.StatusBadRequest {
+		t.Fatalf("reorder with system folder should be rejected code=%d body=%v", code, bad)
+	}
+
+	domain := createTestDomain(t, admin, "folders.test")
+	other := createTestMailbox(t, admin, domain.ID, "other", "Other", "Password123!", nil)
+	otherFolderID, err := a.ensureFolder(context.Background(), other.ID, "其他")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if code := admin.do("POST", "/api/mail/folders/reorder", map[string]any{"folderIds": []string{project.ID, customer.ID, otherFolderID}}, &bad); code != http.StatusBadRequest {
+		t.Fatalf("reorder with other mailbox folder should be rejected code=%d body=%v", code, bad)
+	}
+}
+
 func TestCatchAllStoresUnregisteredMailForAdminOnly(t *testing.T) {
 	a := newTestApp(t)
 	ts := httptest.NewServer(a.Router())
@@ -3803,6 +3877,16 @@ func folderListContains(items []MailFolder, name string) bool {
 	return false
 }
 
+func customFolderNames(items []MailFolder) []string {
+	names := []string{}
+	for _, item := range items {
+		if !isSystemFolderName(item.Name) {
+			names = append(names, item.Name)
+		}
+	}
+	return names
+}
+
 func withoutPermissions(items []string, removed ...string) []string {
 	removedSet := map[string]bool{}
 	for _, item := range removed {

apps/api/internal/app/imap_metadata.go

@@ -44,6 +44,38 @@ func (a *App) migrateIMAPMetadata(ctx context.Context) error {
 	return err
 }
 
+func (a *App) migrateFolderSortOrder(ctx context.Context) error {
+	if err := a.ensureTableColumn(ctx, "folders", "sort_order", `ALTER TABLE folders ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0`); err != nil {
+		return err
+	}
+	rows, err := a.db.QueryContext(ctx, `SELECT id FROM folders WHERE lower(name) NOT IN ('inbox','sent','drafts','archive','spam','trash') ORDER BY mailbox_id, created_at, name, id`)
+	if err != nil {
+		return err
+	}
+	var folderIDs []string
+	for rows.Next() {
+		var id string
+		if err := rows.Scan(&id); err != nil {
+			rows.Close()
+			return err
+		}
+		folderIDs = append(folderIDs, id)
+	}
+	if err := rows.Err(); err != nil {
+		rows.Close()
+		return err
+	}
+	rows.Close()
+	order := customFolderDefaultSortOrderBase + 1
+	for _, id := range folderIDs {
+		if _, err := a.db.ExecContext(ctx, `UPDATE folders SET sort_order=? WHERE id=? AND sort_order=0`, order, id); err != nil {
+			return err
+		}
+		order++
+	}
+	return nil
+}
+
 func (a *App) ensureTableColumn(ctx context.Context, table, column, alterSQL string) error {
 	rows, err := a.db.QueryContext(ctx, `PRAGMA table_info(`+table+`)`)
 	if err != nil {

apps/api/internal/app/mail_handlers.go

@@ -22,6 +22,8 @@ import (
 // mailMessagesPageSize is the max number of messages returned per page in mail listing.
 const mailMessagesPageSize = 30
 
+const customFolderDefaultSortOrderBase = 100000
+
 type AttachmentInput struct {
 	Filename      string `json:"filename"`
 	ContentType   string `json:"contentType"`
@@ -87,10 +89,18 @@ func (a *App) handleMailFolders(w http.ResponseWriter, r *http.Request) {
 	rows, err := a.db.QueryContext(r.Context(), `SELECT f.id,f.name,f.role,
 		COALESCE(SUM(CASE WHEN m.is_read=0 THEN 1 ELSE 0 END),0) AS unread,
 		COUNT(m.id) AS total,
-		f.uid_validity,f.uid_next,f.highest_modseq
+		f.sort_order,f.uid_validity,f.uid_next,f.highest_modseq
 		FROM folders f LEFT JOIN messages m ON m.folder_id=f.id
-		WHERE f.mailbox_id=? GROUP BY f.id,f.name,f.role
+		WHERE f.mailbox_id=? GROUP BY f.id,f.name,f.role,f.sort_order,f.uid_validity,f.uid_next,f.highest_modseq
-		ORDER BY CASE f.role WHEN 'inbox' THEN 1 WHEN 'sent' THEN 2 WHEN 'drafts' THEN 3 WHEN 'archive' THEN 4 WHEN 'spam' THEN 5 WHEN 'trash' THEN 6 ELSE 99 END, f.name`, mb.ID)
+		ORDER BY CASE
+			WHEN lower(f.name)='inbox' THEN 1000
+			WHEN lower(f.name)='sent' THEN 5000
+			WHEN lower(f.name)='drafts' THEN 6000
+			WHEN lower(f.name)='archive' THEN 7000
+			WHEN lower(f.name)='spam' THEN 8000
+			WHEN lower(f.name)='trash' THEN 9000
+			ELSE f.sort_order
+		END, f.created_at,f.name`, mb.ID)
 	if err != nil {
 		respondError(w, http.StatusInternalServerError, "failed to load folders")
 		return
@@ -99,7 +109,7 @@ func (a *App) handleMailFolders(w http.ResponseWriter, r *http.Request) {
 	items := []MailFolder{}
 	for rows.Next() {
 		var f MailFolder
-		if err := rows.Scan(&f.ID, &f.Name, &f.Role, &f.UnreadCount, &f.TotalCount, &f.UIDValidity, &f.UIDNext, &f.HighestModSeq); err != nil {
+		if err := rows.Scan(&f.ID, &f.Name, &f.Role, &f.UnreadCount, &f.TotalCount, &f.SortOrder, &f.UIDValidity, &f.UIDNext, &f.HighestModSeq); err != nil {
 			respondError(w, http.StatusInternalServerError, "failed to scan folders")
 			return
 		}
@@ -108,6 +118,102 @@ func (a *App) handleMailFolders(w http.ResponseWriter, r *http.Request) {
 	respondJSON(w, http.StatusOK, map[string]any{"items": items})
 }
 
+func (a *App) handleReorderMailFolders(w http.ResponseWriter, r *http.Request) {
+	mb, err := a.mailboxForCurrentUser(r)
+	if err != nil {
+		respondError(w, http.StatusNotFound, "mailbox not found")
+		return
+	}
+	var req struct {
+		FolderIDs []string `json:"folderIds"`
+		Folders   []struct {
+			ID        string `json:"id"`
+			SortOrder int    `json:"sortOrder"`
+		} `json:"folders"`
+	}
+	if err := decodeJSON(r, &req); err != nil {
+		badRequest(w, err)
+		return
+	}
+	seen := map[string]bool{}
+	if len(req.Folders) == 0 {
+		for i, id := range req.FolderIDs {
+			id = strings.TrimSpace(id)
+			req.Folders = append(req.Folders, struct {
+				ID        string `json:"id"`
+				SortOrder int    `json:"sortOrder"`
+			}{ID: id, SortOrder: customFolderDefaultSortOrderBase + i + 1})
+		}
+	}
+	for i := range req.Folders {
+		req.Folders[i].ID = strings.TrimSpace(req.Folders[i].ID)
+		if req.Folders[i].ID == "" || req.Folders[i].SortOrder <= 0 || seen[req.Folders[i].ID] {
+			badRequest(w, errors.New("invalid folder order"))
+			return
+		}
+		seen[req.Folders[i].ID] = true
+	}
+	if len(req.Folders) == 0 {
+		badRequest(w, errors.New("folderIds is required"))
+		return
+	}
+	rows, err := a.db.QueryContext(r.Context(), `SELECT id,name FROM folders WHERE mailbox_id=?`, mb.ID)
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "failed to load folders")
+		return
+	}
+	customIDs := map[string]bool{}
+	for rows.Next() {
+		var id, name string
+		if err := rows.Scan(&id, &name); err != nil {
+			rows.Close()
+			respondError(w, http.StatusInternalServerError, "failed to scan folders")
+			return
+		}
+		if !isSystemFolderName(name) {
+			customIDs[id] = true
+		}
+	}
+	if err := rows.Err(); err != nil {
+		rows.Close()
+		respondError(w, http.StatusInternalServerError, "failed to scan folders")
+		return
+	}
+	rows.Close()
+	if len(customIDs) != len(req.Folders) {
+		badRequest(w, errors.New("invalid folder order"))
+		return
+	}
+	for _, item := range req.Folders {
+		if !customIDs[item.ID] {
+			badRequest(w, errors.New("invalid folder order"))
+			return
+		}
+	}
+	tx, err := a.db.BeginTx(r.Context(), nil)
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "failed to reorder folders")
+		return
+	}
+	defer tx.Rollback()
+	for _, item := range req.Folders {
+		res, err := tx.ExecContext(r.Context(), `UPDATE folders SET sort_order=? WHERE id=? AND mailbox_id=?`, item.SortOrder, item.ID, mb.ID)
+		if err != nil {
+			respondError(w, http.StatusInternalServerError, "failed to reorder folders")
+			return
+		}
+		if affected, err := res.RowsAffected(); err != nil || affected != 1 {
+			badRequest(w, errors.New("invalid folder order"))
+			return
+		}
+	}
+	if err := tx.Commit(); err != nil {
+		respondError(w, http.StatusInternalServerError, "failed to reorder folders")
+		return
+	}
+	respondJSON(w, http.StatusOK, map[string]any{"ok": true})
+}
+
 func (a *App) handleCreateMailFolder(w http.ResponseWriter, r *http.Request) {
 	mb, err := a.mailboxForCurrentUser(r)
 	if err != nil {
@@ -130,7 +236,7 @@ func (a *App) handleCreateMailFolder(w http.ResponseWriter, r *http.Request) {
 		badRequest(w, errors.New("system folder already exists"))
 		return
 	}
-	folderID, err := a.ensureFolder(r.Context(), mb.ID, name)
+	folderID, err := a.ensureCustomFolder(r.Context(), mb.ID, name)
 	if err != nil {
 		respondError(w, http.StatusInternalServerError, "failed to create folder")
 		return
@@ -143,6 +249,21 @@ func (a *App) handleCreateMailFolder(w http.ResponseWriter, r *http.Request) {
 	respondJSON(w, http.StatusCreated, folder)
 }
 
+func (a *App) ensureCustomFolder(ctx context.Context, mailboxID, name string) (string, error) {
+	return a.ensureFolder(ctx, mailboxID, name)
+}
+
+func (a *App) nextCustomFolderSortOrder(ctx context.Context, mailboxID string) (int, error) {
+	var maxOrder int
+	if err := a.db.QueryRowContext(ctx, `SELECT COALESCE(MAX(sort_order),0) FROM folders WHERE mailbox_id=? AND lower(name) NOT IN ('inbox','sent','drafts','archive','spam','trash')`, mailboxID).Scan(&maxOrder); err != nil {
+		return 0, err
+	}
+	if maxOrder < customFolderDefaultSortOrderBase {
+		maxOrder = customFolderDefaultSortOrderBase
+	}
+	return maxOrder + 1, nil
+}
+
 func (a *App) handleMailMessages(w http.ResponseWriter, r *http.Request) {
 	mb, err := a.mailboxForCurrentUser(r)
 	if err != nil {
@@ -1491,11 +1612,11 @@ func (a *App) folderByID(ctx context.Context, folderID, mailboxID string) (*Mail
 	row := a.db.QueryRowContext(ctx, `SELECT f.id,f.name,f.role,
 		COALESCE(SUM(CASE WHEN m.is_read=0 THEN 1 ELSE 0 END),0) AS unread,
 		COUNT(m.id) AS total,
-		f.uid_validity,f.uid_next,f.highest_modseq
+		f.sort_order,f.uid_validity,f.uid_next,f.highest_modseq
 		FROM folders f LEFT JOIN messages m ON m.folder_id=f.id
-		WHERE f.id=? AND f.mailbox_id=? GROUP BY f.id,f.name,f.role`, folderID, mailboxID)
+		WHERE f.id=? AND f.mailbox_id=? GROUP BY f.id,f.name,f.role,f.sort_order,f.uid_validity,f.uid_next,f.highest_modseq`, folderID, mailboxID)
 	var f MailFolder
-	if err := row.Scan(&f.ID, &f.Name, &f.Role, &f.UnreadCount, &f.TotalCount, &f.UIDValidity, &f.UIDNext, &f.HighestModSeq); err != nil {
+	if err := row.Scan(&f.ID, &f.Name, &f.Role, &f.UnreadCount, &f.TotalCount, &f.SortOrder, &f.UIDValidity, &f.UIDNext, &f.HighestModSeq); err != nil {
 		return nil, err
 	}
 	return &f, nil

apps/api/internal/app/router_auth.go

@@ -66,6 +66,7 @@ func (a *App) Router() http.Handler {
 			r.With(a.requirePermission(PermissionMailAccess)).Get("/mail/mailboxes", a.handleMyMailboxes)
 			r.With(a.requirePermission(PermissionMailRead)).Get("/mail/folders", a.handleMailFolders)
 			r.With(a.requirePermission(PermissionMailOrganize)).Post("/mail/folders", a.handleCreateMailFolder)
+			r.With(a.requirePermission(PermissionMailOrganize)).Post("/mail/folders/reorder", a.handleReorderMailFolders)
 			r.With(a.requireAnyPermission(PermissionMailRead, PermissionMailLabels)).Get("/mail/labels", a.handleMailLabels)
 			r.With(a.requirePermission(PermissionMailLabels)).Post("/mail/labels", a.handleCreateMailLabel)
 			r.With(a.requirePermission(PermissionMailLabels)).Delete("/mail/labels/{id}", a.handleDeleteMailLabel)

apps/api/internal/app/types.go

@@ -60,6 +60,7 @@ type MailFolder struct {
 	ID            string `json:"id"`
 	Name          string `json:"name"`
 	Role          string `json:"role"`
+	SortOrder     int    `json:"sortOrder"`
 	UnreadCount   int    `json:"unreadCount"`
 	TotalCount    int    `json:"totalCount"`
 	UIDValidity   int64  `json:"uidValidity"`

apps/web/src/lib/api-types.ts

@@ -56,7 +56,7 @@ export type AdminOverview = { users: number; activeUsers: number; domains: numbe
 export type Domain = { id: string; name: string; status: string; dkimSelector: string; dkimPublicKey?: string; dnsStatus: string; dnsCheckedAt?: string; createdAt: string }
 export type Mailbox = { id: string; userId: string; userEmail?: string; domainId: string; localPart: string; address: string; displayName: string; quotaMb: number; status: string; createdAt: string }
 export type Alias = { id: string; domainId: string; source: string; destination: string; enabled: boolean; createdAt: string }
-export type MailFolder = { id: string; name: string; role: string; unreadCount: number; totalCount: number; uidValidity: number; uidNext: number; highestModseq: number }
+export type MailFolder = { id: string; name: string; role: string; sortOrder: number; unreadCount: number; totalCount: number; uidValidity: number; uidNext: number; highestModseq: number }
 export type Attachment = { id: string; messageId: string; filename: string; contentType: string; sizeBytes: number; createdAt: string }
 export type MailLabel = { id: string; mailboxId?: string; name: string; color: string; messageCount?: number }
 export type MailMessage = {

apps/web/src/lib/api.ts

@@ -120,6 +120,10 @@ export const api = {
     const query = payload.mailboxId ? `?mailboxId=${encodeURIComponent(payload.mailboxId)}` : ""
     return request<MailFolder>(`/api/mail/folders${query}`, { method: "POST", body: JSON.stringify({ name: payload.name }) })
   },
+  reorderFolders: (payload: { mailboxId?: string; folderIds: string[]; folders?: { id: string; sortOrder: number }[] }) => {
+    const query = payload.mailboxId ? `?mailboxId=${encodeURIComponent(payload.mailboxId)}` : ""
+    return request<{ ok: boolean }>(`/api/mail/folders/reorder${query}`, { method: "POST", body: JSON.stringify(payload.folders ? { folders: payload.folders } : { folderIds: payload.folderIds }) })
+  },
   labels: (mailboxId?: string) => request<ListResponse<MailLabel>>(`/api/mail/labels${mailboxId ? `?mailboxId=${encodeURIComponent(mailboxId)}` : ""}`),
   createLabel: (payload: { mailboxId?: string; name: string; color?: string }) => {
     const query = payload.mailboxId ? `?mailboxId=${encodeURIComponent(payload.mailboxId)}` : ""

apps/web/src/pages/mail.tsx

@@ -67,11 +67,12 @@ type PendingConfirm = { title: string; description?: string; confirmText: string
 type MailNotificationState = { latestId: string; latestReceivedAt: string }
 type ComposeSendIntent = { title: string; description: string; confirmText: string; onConfirm: () => void }
 type MessageContextMenuState = { message: MailMessage; x: number; y: number }
+type FolderDropTarget = { key: string; edge: "before" | "after" | "end" }
 type MailMenuItem =
-  | { type: "starred"; key: string; label: string; icon: React.ReactNode; count: number }
+  | { type: "starred"; key: string; label: string; icon: React.ReactNode; count: number; order: number }
-  | { type: "scheduled"; key: string; label: string; icon: React.ReactNode; count: number }
+  | { type: "scheduled"; key: string; label: string; icon: React.ReactNode; count: number; order: number }
-  | { type: "sendQueue"; key: string; label: string; icon: React.ReactNode; count: number }
+  | { type: "sendQueue"; key: string; label: string; icon: React.ReactNode; count: number; order: number }
-  | { type: "folder"; key: string; folderName: string; label: string; icon: React.ReactNode; count: number }
+  | { type: "folder"; key: string; folderId: string; folderName: string; label: string; icon: React.ReactNode; count: number; custom: boolean; order: number }
 
 const filterLabels: Record<MailFilter, string> = {
   all: "全部邮件",
@@ -113,6 +114,8 @@ export function MailPage() {
   const [newLabelEditing, setNewLabelEditing] = React.useState(false)
   const [messageContextMenu, setMessageContextMenu] = React.useState<MessageContextMenuState | null>(null)
   const [folderDialogOpen, setFolderDialogOpen] = React.useState(false)
+  const [draggingFolderId, setDraggingFolderId] = React.useState("")
+  const [folderDropTarget, setFolderDropTarget] = React.useState<FolderDropTarget | null>(null)
   const sidebarPanelRef = React.useRef<ImperativePanelHandle>(null)
   const themeMountedRef = React.useRef(false)
   const mailNotifyStateRef = React.useRef<Record<string, MailNotificationState>>({})
@@ -296,6 +299,29 @@ export function MailPage() {
     },
     onError: (error) => toast({ title: "创建文件夹失败", description: error instanceof Error ? error.message : "请稍后重试" }),
   })
+  const reorderFolders = useMutation({
+    mutationFn: (items: { id: string; sortOrder: number }[]) => api.reorderFolders({ mailboxId: activeMailboxId, folderIds: items.map((item) => item.id), folders: items }),
+    onMutate: async (items) => {
+      await qc.cancelQueries({ queryKey: ["folders", activeMailboxId] })
+      const previous = qc.getQueryData<ListResponse<MailFolder>>(["folders", activeMailboxId])
+      qc.setQueryData<ListResponse<MailFolder>>(["folders", activeMailboxId], (current) => {
+        if (!current?.items) return current
+        const order = new Map(items.map((item) => [item.id, item.sortOrder]))
+        return {
+          ...current,
+          items: current.items
+            .map((item) => order.has(item.id) ? { ...item, sortOrder: order.get(item.id) || item.sortOrder } : item)
+            .sort(compareMailFolders),
+        }
+      })
+      return { previous }
+    },
+    onError: (error, _items, context) => {
+      if (context?.previous) qc.setQueryData(["folders", activeMailboxId], context.previous)
+      toast({ title: "文件夹排序失败", description: error instanceof Error ? error.message : "请稍后重试" })
+    },
+    onSettled: () => qc.invalidateQueries({ queryKey: ["folders", activeMailboxId] }),
+  })
   const retrySendQueue = useMutation({
     mutationFn: (item: SendQueueItem) => api.retrySendQueue(item.id),
     onMutate: (item) => setSendQueuePendingId(item.id),
@@ -650,6 +676,69 @@ export function MailPage() {
   function closeMessageContextMenu() {
     setMessageContextMenu(null)
   }
+  function reorderCustomFolder(draggedId: string, target: FolderDropTarget) {
+    if (!canOrganizeMail || reorderFolders.isPending) return
+    const foldersByID = new Map((folders.data?.items || []).map((item) => [item.id, item]))
+    const dragged = foldersByID.get(draggedId)
+    if (!dragged || !isCustomMailFolder(dragged)) return
+    const menuWithoutDragged = mailMenuItems.filter((item) => !(item.type === "folder" && item.folderId === draggedId))
+    let insertIndex = menuWithoutDragged.length
+    if (target.edge !== "end") {
+      const targetIndex = menuWithoutDragged.findIndex((item) => item.key === target.key)
+      if (targetIndex < 0) return
+      insertIndex = target.edge === "before" ? targetIndex : targetIndex + 1
+    }
+    const draggedMenuItem: MailMenuItem = {
+      type: "folder",
+      key: dragged.id,
+      folderId: dragged.id,
+      folderName: dragged.name,
+      label: folderLabels[dragged.name] || dragged.name,
+      icon: folderIcons[dragged.role] || <Inbox className="h-4 w-4" />,
+      count: dragged.name === "Drafts" ? dragged.totalCount : dragged.unreadCount,
+      custom: true,
+      order: dragged.sortOrder,
+    }
+    const nextMenu = [...menuWithoutDragged]
+    nextMenu.splice(insertIndex, 0, draggedMenuItem)
+    const nextFolders = assignCustomFolderOrders(nextMenu)
+    reorderFolders.mutate(nextFolders)
+  }
+  function handleFolderDragStart(event: React.DragEvent, item: MailMenuItem) {
+    if (item.type !== "folder" || !item.custom || sidebarCollapsed || !canOrganizeMail) return
+    event.dataTransfer.effectAllowed = "move"
+    event.dataTransfer.setData("text/plain", item.folderId)
+    setDraggingFolderId(item.folderId)
+  }
+  function handleFolderDragOver(event: React.DragEvent, item: MailMenuItem) {
+    if (!draggingFolderId || item.key === draggingFolderId) return
+    event.preventDefault()
+    event.dataTransfer.dropEffect = "move"
+    const rect = event.currentTarget.getBoundingClientRect()
+    setFolderDropTarget({ key: item.key, edge: event.clientY < rect.top + rect.height / 2 ? "before" : "after" })
+  }
+  function handleFolderDrop(event: React.DragEvent, item: MailMenuItem) {
+    if (!draggingFolderId) return
+    event.preventDefault()
+    const draggedId = event.dataTransfer.getData("text/plain") || draggingFolderId
+    const rect = event.currentTarget.getBoundingClientRect()
+    const edge = event.clientY < rect.top + rect.height / 2 ? "before" : "after"
+    setDraggingFolderId("")
+    setFolderDropTarget(null)
+    reorderCustomFolder(draggedId, { key: item.key, edge })
+  }
+  function handleFolderDropEnd(event: React.DragEvent) {
+    if (!draggingFolderId) return
+    event.preventDefault()
+    const draggedId = event.dataTransfer.getData("text/plain") || draggingFolderId
+    setDraggingFolderId("")
+    setFolderDropTarget(null)
+    reorderCustomFolder(draggedId, { key: "__end__", edge: "end" })
+  }
+  function clearFolderDragState() {
+    setDraggingFolderId("")
+    setFolderDropTarget(null)
+  }
   function runMessageContextAction(action: "open" | "reply" | "forward" | "read" | "star" | "archive" | "trash" | "spam" | "delete", message: MailMessage) {
     closeMessageContextMenu()
     if (action === "open") {
@@ -778,10 +867,25 @@ export function MailPage() {
           <SidebarGroupContent>
             <SidebarMenu>
               {mailMenuItems.map((item) => (
-                <SidebarMenuItem key={item.key}>
+                <SidebarMenuItem
+                  key={item.key}
+                  draggable={item.type === "folder" && item.custom && canOrganizeMail && !sidebarCollapsed}
+                  onDragStart={(event) => handleFolderDragStart(event, item)}
+                  onDragOver={(event) => handleFolderDragOver(event, item)}
+                  onDragLeave={() => { if (folderDropTarget?.key === item.key) setFolderDropTarget(null) }}
+                  onDrop={(event) => handleFolderDrop(event, item)}
+                  onDragEnd={clearFolderDragState}
+                >
                   <SidebarMenuButton
                     isActive={item.type === "starred" ? mailView === "starred" : item.type === "scheduled" ? mailView === "scheduled" : item.type === "sendQueue" ? mailView === "sendQueue" : mailView === "folder" && folder === item.folderName}
-                    className={cn(sidebarCollapsed && "justify-center px-0")}
+                    className={cn(
+                      sidebarCollapsed && "justify-center px-0",
+                      item.type === "folder" && item.custom && canOrganizeMail && !sidebarCollapsed && "cursor-grab active:cursor-grabbing",
+                      item.type === "folder" && item.custom && draggingFolderId === item.folderId && "opacity-50",
+                      folderDropTarget?.key === item.key && "bg-accent/60",
+                      folderDropTarget?.key === item.key && folderDropTarget.edge === "before" && "border-t-2 border-t-primary",
+                      folderDropTarget?.key === item.key && folderDropTarget.edge === "after" && "border-b-2 border-b-primary"
+                    )}
                     onClick={() => item.type === "starred" ? openStarred() : item.type === "scheduled" ? openScheduled() : item.type === "sendQueue" ? openSendQueue() : openFolder(item.folderName)}
                   >
                     {item.icon}
@@ -790,6 +894,19 @@ export function MailPage() {
                   </SidebarMenuButton>
                 </SidebarMenuItem>
               ))}
+              {!sidebarCollapsed && canOrganizeMail && (
+                <div
+                  className={cn("mx-2 h-4 rounded-sm border border-dashed border-transparent", folderDropTarget?.edge === "end" && "border-primary bg-accent/60")}
+                  onDragOver={(event) => {
+                    if (!draggingFolderId) return
+                    event.preventDefault()
+                    event.dataTransfer.dropEffect = "move"
+                    setFolderDropTarget({ key: "__end__", edge: "end" })
+                  }}
+                  onDragLeave={() => { if (folderDropTarget?.edge === "end") setFolderDropTarget(null) }}
+                  onDrop={handleFolderDropEnd}
+                />
+              )}
             </SidebarMenu>
             {folders.isLoading && <FolderSkeleton />}
           </SidebarGroupContent>
@@ -1146,27 +1263,84 @@ export function MailPage() {
 
 function buildMailMenuItems(folders: MailFolder[], starredCount: number, scheduledCount: number, includeScheduled: boolean, sendQueueCount: number, includeSendQueue: boolean): MailMenuItem[] {
   const byName = new Map(folders.map((item) => [item.name, item]))
-  const normalizedFolders = ["Inbox", "Drafts", "Sent", "Archive", "Spam", "Trash"].map((name) => byName.get(name) || { id: `virtual-${name}`, name, role: name.toLowerCase(), unreadCount: 0, totalCount: 0 })
+  const normalizedFolders = ["Inbox", "Drafts", "Sent", "Archive", "Spam", "Trash"].map((name) => byName.get(name) || { id: `virtual-${name}`, name, role: name.toLowerCase(), sortOrder: 0, unreadCount: 0, totalCount: 0, uidValidity: 0, uidNext: 1, highestModseq: 1 })
   for (const item of folders) {
     if (!normalizedFolders.some((folder) => folder.name === item.name)) normalizedFolders.push(item)
   }
   const folderItems: MailMenuItem[] = normalizedFolders.map((item) => ({
     type: "folder",
     key: item.id,
+    folderId: item.id,
     folderName: item.name,
     label: folderLabels[item.name] || item.name,
     icon: folderIcons[item.role] || <Inbox className="h-4 w-4" />,
     count: item.name === "Drafts" ? item.totalCount : item.unreadCount,
+    custom: isCustomMailFolder(item),
+    order: isCustomMailFolder(item) ? item.sortOrder || 100000 : menuAnchorOrder(item.name),
   }))
-  const starredItem: MailMenuItem = { type: "starred", key: "starred", label: "星标邮件", icon: <Star className="h-4 w-4" />, count: starredCount }
+  const starredItem: MailMenuItem = { type: "starred", key: "starred", label: "星标邮件", icon: <Star className="h-4 w-4" />, count: starredCount, order: 2000 }
-  const scheduledItem: MailMenuItem = { type: "scheduled", key: "scheduled", label: "待发送", icon: <Clock3 className="h-4 w-4" />, count: scheduledCount }
+  const scheduledItem: MailMenuItem = { type: "scheduled", key: "scheduled", label: "待发送", icon: <Clock3 className="h-4 w-4" />, count: scheduledCount, order: 3000 }
-  const sendQueueItem: MailMenuItem = { type: "sendQueue", key: "send-queue", label: "发送队列", icon: <History className="h-4 w-4" />, count: sendQueueCount }
+  const sendQueueItem: MailMenuItem = { type: "sendQueue", key: "send-queue", label: "发送队列", icon: <History className="h-4 w-4" />, count: sendQueueCount, order: 4000 }
-  const inboxIndex = folderItems.findIndex((item) => item.type === "folder" && item.folderName === "Inbox")
-  const insertAt = inboxIndex >= 0 ? inboxIndex + 1 : 0
   const specialItems: MailMenuItem[] = [starredItem]
   if (includeScheduled) specialItems.push(scheduledItem)
   if (includeSendQueue) specialItems.push(sendQueueItem)
-  return [...folderItems.slice(0, insertAt), ...specialItems, ...folderItems.slice(insertAt)]
+  return [...folderItems, ...specialItems].sort((a, b) => a.order - b.order || a.label.localeCompare(b.label))
+}
+
+function isCustomMailFolder(folder: Pick<MailFolder, "name" | "id">) {
+  return !folder.id.startsWith("virtual-") && !["inbox", "sent", "drafts", "archive", "spam", "trash"].includes(folder.name.trim().toLowerCase())
+}
+
+function compareMailFolders(a: MailFolder, b: MailFolder) {
+  return (isCustomMailFolder(a) ? a.sortOrder || 100000 : menuAnchorOrder(a.name)) - (isCustomMailFolder(b) ? b.sortOrder || 100000 : menuAnchorOrder(b.name)) || a.name.localeCompare(b.name)
+}
+
+function assignCustomFolderOrders(items: MailMenuItem[]) {
+  const out: { id: string; sortOrder: number }[] = []
+  for (let i = 0; i < items.length; i++) {
+    const item = items[i]
+    if (!isCustomMenuFolder(item)) continue
+    let start = 0
+    for (let j = i - 1; j >= 0; j--) {
+      if (!isCustomMenuFolder(items[j])) {
+        start = items[j].order
+        break
+      }
+    }
+    const groupStart = i
+    let groupEnd = i
+    while (groupEnd + 1 < items.length && isCustomMenuFolder(items[groupEnd + 1])) groupEnd++
+    let end = start + (groupEnd - groupStart + 2) * 1000
+    for (let j = groupEnd + 1; j < items.length; j++) {
+      if (!isCustomMenuFolder(items[j])) {
+        end = items[j].order
+        break
+      }
+    }
+    const step = Math.max(1, Math.floor((end - start) / (groupEnd - groupStart + 2)))
+    for (let j = groupStart; j <= groupEnd; j++) {
+      const folder = items[j] as Extract<MailMenuItem, { type: "folder" }>
+      out.push({ id: folder.folderId, sortOrder: start + step * (j - groupStart + 1) })
+    }
+    i = groupEnd
+  }
+  return out
+}
+
+function isCustomMenuFolder(item: MailMenuItem): item is Extract<MailMenuItem, { type: "folder" }> {
+  return item.type === "folder" && item.custom
+}
+
+function menuAnchorOrder(name: string) {
+  switch (name) {
+    case "Inbox": return 1000
+    case "Sent": return 5000
+    case "Drafts": return 6000
+    case "Archive": return 7000
+    case "Spam": return 8000
+    case "Trash": return 9000
+    default: return 100000
+  }
 }
 
 function FolderSkeleton() { return <div className="space-y-2 p-2"><Skeleton className="h-8 w-full" /><Skeleton className="h-8 w-4/5" /><Skeleton className="h-8 w-3/4" /></div> }