feat: App→网页免登录（一次性换票 SSO）——移动/桌面点链接直达已登录官网

- backend：POST /auth/web-ticket（需登录，签 60s 单次票据，每用户限频）+
  POST /auth/web-ticket/exchange（公开，原子即焚兑换正常登录态，响应同
  /auth/login 另带 shop_code）；web_tickets 新表 + user_sessions.kind 列
  （sso 会话：web 平台、refresh 12h 硬到期、不占设备并发配额、设备管理可见
  可踢）；清理任务顺带清过期票据；schema.sql/AutoMigrate/testutil 同步
- web：/sso 落地页——兑票写入与 Web 版共享的 localStorage 后跳 redirect；
  redirect 白名单只收本站相对路径（防 open redirect），票据即时从地址栏抹除
- client：launchAuthedWebPath(ref, path) 封装（签票→拼 /sso URL→launchUrl，
  失败降级未登录直开；桌面/移动同一套）；授权面板「查看套餐价格」接入

test(backend): web_ticket_test 三用例（兑换+续期/单次即焚/过期拒绝/
sso 不占配额双向验证）

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/internal/service/auth.go

@@ -1,6 +1,8 @@
 package service
 
 import (
+	"crypto/rand"
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"log"
@@ -217,10 +219,12 @@ func (s *AuthService) Login(shopCode, username, password string, dev DeviceInfo)
 		// 统计该 user 全部平台的活跃会话（不分平台类）；已达上限则拒绝。
 		// 仅计未过期会话：refresh 已过期的行等待 cleanup 物理删除，不再占配额
 		// （历史 bug：过期未清理的会话把坑占满，正常用户被锁在门外）。
+		// kind=sso（App→网页免登录的短时会话）不占设备配额。
 		var activeCount int64
 		if err := tx.Model(&model.UserSession{}).
 			Set("gorm:query_option", "FOR UPDATE").
-			Where("shop_id = ? AND user_id = ? AND revoked_at IS NULL AND refresh_exp_at > ?",
+			Where("shop_id = ? AND user_id = ? AND revoked_at IS NULL AND refresh_exp_at > ?"+
+				" AND kind <> 'sso'",
 				shop.ID, user.ID, now).
 			Count(&activeCount).Error; err != nil {
 			return err
@@ -789,3 +793,98 @@ func (s *AuthService) issueTokens(userID, shopID uint64, role, sid, refreshJTI s
 		ShopID:       shopID,
 	}, nil
 }
+
+// ═══════════════ App → 网页免登录（一次性换票，magic-link）═══════════════
+// App 持 JWT 调 IssueWebTicket 签票（TTL 60s、单次可用），浏览器打开 /sso
+// 页后凭票 LoginWithWebTicket 兑换正常 web 会话（kind=sso：不占设备配额、
+// refresh 12 小时硬到期——RefreshTokens 轮换不延长 refresh_exp_at）。
+
+const (
+	webTicketTTL     = 60 * time.Second
+	ssoRefreshExpire = 12 * time.Hour
+)
+
+// ErrTicketInvalid 票据不存在 / 已使用 / 已过期。
+var ErrTicketInvalid = errors.New("票据无效或已过期")
+
+// IssueWebTicket 为已登录用户签发一次性网页登录票据。
+func (s *AuthService) IssueWebTicket(shopID, userID uint64) (string, int, error) {
+	buf := make([]byte, 32)
+	if _, err := rand.Read(buf); err != nil {
+		return "", 0, err
+	}
+	ticket := base64.RawURLEncoding.EncodeToString(buf)
+	wt := model.WebTicket{
+		Ticket:    ticket,
+		ShopID:    shopID,
+		UserID:    userID,
+		ExpiresAt: time.Now().Add(webTicketTTL),
+	}
+	if err := s.db.Create(&wt).Error; err != nil {
+		return "", 0, err
+	}
+	return ticket, int(webTicketTTL.Seconds()), nil
+}
+
+// LoginWithWebTicket 凭一次性票据兑换 web 会话。票据消费为原子置位
+// （UPDATE … WHERE used_at IS NULL），并发重放必失败。
+func (s *AuthService) LoginWithWebTicket(
+	ticket string, dev DeviceInfo,
+) (*TokenPair, *model.User, *model.Shop, error) {
+	now := time.Now()
+	res := s.db.Model(&model.WebTicket{}).
+		Where("ticket = ? AND used_at IS NULL AND expires_at > ?", ticket, now).
+		Update("used_at", now)
+	if res.Error != nil {
+		return nil, nil, nil, res.Error
+	}
+	if res.RowsAffected != 1 {
+		return nil, nil, nil, ErrTicketInvalid
+	}
+	var wt model.WebTicket
+	if err := s.db.Where("ticket = ?", ticket).First(&wt).Error; err != nil {
+		return nil, nil, nil, ErrTicketInvalid
+	}
+
+	var user model.User
+	if err := s.db.Where("id = ? AND shop_id = ?", wt.UserID, wt.ShopID).
+		First(&user).Error; err != nil {
+		return nil, nil, nil, ErrInvalidCredentials
+	}
+	if !user.IsActive {
+		return nil, nil, nil, ErrUserInactive
+	}
+	var shop model.Shop
+	if err := s.db.First(&shop, wt.ShopID).Error; err != nil {
+		return nil, nil, nil, err
+	}
+
+	// sso 会话：web 平台、短时效、不占配额（平台闸门不拦——票据由已登录
+	// 会话签出，权限等同签票用户本人）。
+	sid := uuid.New().String()
+	jti := uuid.New().String()
+	sess := model.UserSession{
+		ShopID:        shop.ID,
+		UserID:        user.ID,
+		SID:           sid,
+		DeviceID:      dev.DeviceID,
+		DeviceName:    "网页免登（App 跳转）",
+		Platform:      "web",
+		PlatformClass: "web",
+		Kind:          "sso",
+		IP:            dev.IP,
+		UserAgent:     dev.UserAgent,
+		RefreshJTI:    jti,
+		LastSeenAt:    now,
+		RefreshExpAt:  now.Add(ssoRefreshExpire),
+	}
+	if err := s.db.Create(&sess).Error; err != nil {
+		return nil, nil, nil, err
+	}
+
+	pair, err := s.issueTokens(user.ID, shop.ID, user.Role, sid, jti)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return pair, &user, &shop, nil
+}

backend/internal/service/session_cleanup.go

@@ -47,6 +47,12 @@ func cleanupOnce(db *gorm.DB, retentionDays int) (sessions, attempts int64) {
 		log.Printf("[cleanup] purge login_attempts failed: %v", r2.Error)
 	}
 
+	// 一次性网页登录票据：过期即无用（TTL 60s），过期一天后物理清除
+	if err := db.Where("expires_at < ?", time.Now().AddDate(0, 0, -1)).
+		Delete(&model.WebTicket{}).Error; err != nil {
+		log.Printf("[cleanup] purge web_tickets failed: %v", err)
+	}
+
 	if r1.RowsAffected > 0 || r2.RowsAffected > 0 {
 		log.Printf("[cleanup] purged %d sessions, %d login_attempts (older than %dd)",
 			r1.RowsAffected, r2.RowsAffected, retentionDays)

backend/internal/service/web_ticket_test.go

@@ -0,0 +1,97 @@
+package service
+
+// App→网页免登录一次性换票的回归测试：签票/兑票/单次即焚/过期/sso 不占配额。
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/wangjia/jiu/backend/config"
+	"github.com/wangjia/jiu/backend/internal/model"
+	"github.com/wangjia/jiu/backend/testutil"
+)
+
+func TestWebTicket_ExchangeOnce(t *testing.T) {
+	db := testutil.SetupTestDB()
+	shop := testutil.CreateTestShop(db, "SSO001")
+	user := testutil.CreateTestUser(db, shop.ID, "admin", "password123", "admin")
+	svc := NewAuthService(db)
+
+	ticket, ttl, err := svc.IssueWebTicket(shop.ID, user.ID)
+	require.NoError(t, err)
+	assert.NotEmpty(t, ticket)
+	assert.Equal(t, 60, ttl)
+
+	dev := DeviceInfo{Platform: "web", IP: "1.2.3.4", UserAgent: "test"}
+	pair, u, sh, err := svc.LoginWithWebTicket(ticket, dev)
+	require.NoError(t, err)
+	assert.NotEmpty(t, pair.AccessToken)
+	assert.Equal(t, user.ID, u.ID)
+	assert.Equal(t, "SSO001", sh.Code)
+
+	// 兑出的 refresh token 可正常续期（会话有效）
+	_, err = svc.RefreshTokens(pair.RefreshToken)
+	assert.NoError(t, err)
+
+	// 单次即焚：二次兑换必失败
+	_, _, _, err = svc.LoginWithWebTicket(ticket, dev)
+	assert.ErrorIs(t, err, ErrTicketInvalid)
+}
+
+func TestWebTicket_Expired(t *testing.T) {
+	db := testutil.SetupTestDB()
+	shop := testutil.CreateTestShop(db, "SSO002")
+	user := testutil.CreateTestUser(db, shop.ID, "admin", "password123", "admin")
+	svc := NewAuthService(db)
+
+	ticket, _, err := svc.IssueWebTicket(shop.ID, user.ID)
+	require.NoError(t, err)
+	// 手动把票据改成已过期
+	require.NoError(t, db.Model(&model.WebTicket{}).
+		Where("ticket = ?", ticket).
+		Update("expires_at", time.Now().Add(-time.Minute)).Error)
+
+	_, _, _, err = svc.LoginWithWebTicket(ticket, DeviceInfo{Platform: "web"})
+	assert.ErrorIs(t, err, ErrTicketInvalid)
+}
+
+func TestWebTicket_SsoSessionNotCountedInQuota(t *testing.T) {
+	db := testutil.SetupTestDB()
+	old := config.C.Session.LimitTotal
+	config.C.Session.LimitTotal = 2
+	defer func() { config.C.Session.LimitTotal = old }()
+
+	shop := testutil.CreateTestShop(db, "SSO003")
+	user := testutil.CreateTestUser(db, shop.ID, "admin", "password123", "admin")
+	svc := NewAuthService(db)
+
+	// 占满 2 个正常配额
+	_, _, err := svc.Login("SSO003", "admin", "password123",
+		DeviceInfo{DeviceID: "d1", Platform: "macos"})
+	require.NoError(t, err)
+	_, _, err = svc.Login("SSO003", "admin", "password123",
+		DeviceInfo{DeviceID: "d2", Platform: "ios"})
+	require.NoError(t, err)
+
+	// 配额已满仍可换票登录（sso 不受配额限制）
+	ticket, _, err := svc.IssueWebTicket(shop.ID, user.ID)
+	require.NoError(t, err)
+	_, _, _, err = svc.LoginWithWebTicket(ticket, DeviceInfo{Platform: "web"})
+	require.NoError(t, err, "sso 会话不受设备配额限制")
+
+	// sso 会话短时效 + 打标记
+	var sess model.UserSession
+	require.NoError(t, db.Where("shop_id = ? AND kind = 'sso'", shop.ID).
+		First(&sess).Error)
+	assert.Equal(t, "web", sess.Platform)
+	assert.WithinDuration(t, time.Now().Add(12*time.Hour), sess.RefreshExpAt,
+		time.Minute)
+
+	// 反向：sso 会话在场时，正常登录的配额统计不把它算进去
+	_, _, err = svc.Login("SSO003", "admin", "password123",
+		DeviceInfo{DeviceID: "d1", Platform: "macos"}) // 同设备重登复用坑位
+	assert.NoError(t, err, "sso 会话不占配额，正常登录不受影响")
+}