fix: allow login during sqlite write pressure

internal/service/auth.go

@@ -159,7 +159,7 @@ func (s *AuthService) Login(ctx context.Context, username, password string) (*Lo
 		return nil, ErrInvalidCredentials
 	}
 	// 签发令牌对
-	tokens, err := s.tokenSvc.IssuePair(ctx, u.ID, u.Role, u.Tier)
+	tokens, err := s.tokenSvc.IssuePairBestEffort(ctx, u.ID, u.Role, u.Tier)
 	if err != nil {
 		return nil, err
 	}

internal/service/auth_user_limits_test.go

@@ -291,6 +291,79 @@ func TestLoginRetriesTransientSQLiteBusy(t *testing.T) {
 	}
 }
 
+func TestLoginReturnsTokensWhenSQLiteWriteLockPersists(t *testing.T) {
+	ctx := context.Background()
+	cfg := &config.Config{}
+	cfg.App.DataDir = t.TempDir()
+	cfg.Database.DBPath = filepath.Join(cfg.App.DataDir, "busy-login-degraded.db")
+	cfg.Database.WALMode = true
+	cfg.Database.BusyTimeout = 20
+	cfg.Database.MaxOpenConns = 4
+	cfg.Database.MaxIdleConns = 2
+	cfg.Secrets.JWTSecret = "test-secret"
+	log := zap.NewNop()
+	db, err := database.Open(cfg, log)
+	if err != nil {
+		t.Fatal(err)
+	}
+	sqlDB, err := db.DB()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = sqlDB.Close() }()
+	if err := database.AutoMigrate(db); err != nil {
+		t.Fatal(err)
+	}
+	repos := repository.New(db)
+	permissions := NewPermissionService(log, repos)
+	auth := NewAuthService(cfg, log, repos, NewTokenService(cfg, log, repos), permissions)
+	hash, err := bcrypt.GenerateFromPassword([]byte("password"), bcrypt.MinCost)
+	if err != nil {
+		t.Fatal(err)
+	}
+	user := &model.User{
+		Username:     "viewer",
+		PasswordHash: string(hash),
+		Role:         "user",
+		Tier:         "free",
+		IsActive:     true,
+	}
+	if err := repos.User.Create(ctx, user); err != nil {
+		t.Fatal(err)
+	}
+
+	tx := repos.DB.Begin()
+	if err := tx.Exec("UPDATE users SET updated_at = updated_at WHERE username = ?", "viewer").Error; err != nil {
+		t.Fatal(err)
+	}
+	resp, err := auth.Login(ctx, "viewer", "password")
+	if err != nil {
+		t.Fatalf("login should return tokens while refresh token store is delayed: %v", err)
+	}
+	if resp == nil || resp.Tokens == nil || resp.Tokens.AccessToken == "" || resp.Tokens.RefreshToken == "" {
+		t.Fatalf("login returned incomplete token pair: %#v", resp)
+	}
+
+	if err := tx.Rollback().Error; err != nil {
+		t.Fatal(err)
+	}
+	wantHash := repository.HashToken(resp.Tokens.RefreshToken)
+	deadline := time.Now().Add(5 * time.Second)
+	for {
+		var count int64
+		if err := repos.DB.Model(&model.RefreshToken{}).Where("token_hash = ?", wantHash).Count(&count).Error; err != nil {
+			t.Fatal(err)
+		}
+		if count == 1 {
+			return
+		}
+		if time.Now().After(deadline) {
+			t.Fatal("delayed refresh token store did not complete")
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
 func TestDefaultPermissionsAreViewerOnly(t *testing.T) {
 	perms := DefaultPermissions("user-1")
 	if !perms.CanViewDashboard || !perms.CanPlayMedia || !perms.CanExternalPlayer {

internal/service/db_errors.go

@@ -0,0 +1,7 @@
+package service
+
+import "github.com/ShukeBta/MediaStationGo/internal/repository"
+
+func IsTransientDatabaseLock(err error) bool {
+	return repository.IsSQLiteBusyError(err)
+}

internal/service/permission.go

@@ -78,6 +78,13 @@ func adminGrant(userID string) *model.UserPermission {
 	}
 }
 
+func FallbackPermissions(userID, role string) *model.UserPermission {
+	if role == "admin" {
+		return adminGrant(userID)
+	}
+	return DefaultPermissions(userID)
+}
+
 // Effective returns the permission set the React UI should consume.
 // Admins skip the table entirely and get a synthetic all-grant row.
 func (s *PermissionService) Effective(ctx context.Context, userID string) (*model.UserPermission, error) {

internal/service/token_svc.go

@@ -25,6 +25,8 @@ const (
 	RefreshTokenLength = 32
 )
 
+const loginRefreshTokenStoreTimeout = 750 * time.Millisecond
+
 // Claims 是 JWT 载荷（复制自 middleware 以避免循环导入）。
 type Claims struct {
 	UserID string `json:"uid"`
@@ -62,6 +64,17 @@ var (
 
 // IssuePair 为用户签发新的令牌对。
 func (s *TokenService) IssuePair(ctx context.Context, userID, role, tier string) (*TokenPair, error) {
+	return s.issuePair(ctx, userID, role, tier, false)
+}
+
+// IssuePairBestEffort 为登录签发令牌。SQLite 被后台扫描长期写锁占用时，
+// 登录不能因为 refresh token 暂时无法落库而失败：先返回可用 access token，
+// 再在后台把 refresh token 补写进库。
+func (s *TokenService) IssuePairBestEffort(ctx context.Context, userID, role, tier string) (*TokenPair, error) {
+	return s.issuePair(ctx, userID, role, tier, true)
+}
+
+func (s *TokenService) issuePair(ctx context.Context, userID, role, tier string, bestEffort bool) (*TokenPair, error) {
 	// 生成 Access Token
 	accessToken, err := s.issueAccessToken(userID, role, tier)
 	if err != nil {
@@ -81,11 +94,23 @@ func (s *TokenService) IssuePair(ctx context.Context, userID, role, tier string)
 		TokenHash: tokenHash,
 		ExpiresAt: time.Now().Add(RefreshTokenDuration),
 	}
-	if err := s.repo.RefreshToken.Create(ctx, rt); err != nil {
-		return nil, err
+	storeCtx := ctx
+	cancel := func() {}
+	if bestEffort {
+		storeCtx, cancel = context.WithTimeout(context.Background(), loginRefreshTokenStoreTimeout)
 	}
-	if err := s.repo.RefreshToken.RevokeOldestActiveByUserID(ctx, userID, s.maxActiveRefreshTokens(ctx)); err != nil {
-		s.log.Warn("failed to enforce refresh token session limit", zap.String("user_id", userID), zap.Error(err))
+	err = s.storeRefreshToken(storeCtx, rt)
+	cancel()
+	if err != nil {
+		if !bestEffort {
+			return nil, err
+		}
+		if s.log != nil {
+			s.log.Warn("refresh token store delayed; login will continue",
+				zap.String("user_id", userID),
+				zap.Error(err))
+		}
+		go s.storeRefreshTokenEventually(userID, tokenHash, rt.ExpiresAt)
 	}
 
 	return &TokenPair{
@@ -96,6 +121,52 @@ func (s *TokenService) IssuePair(ctx context.Context, userID, role, tier string)
 	}, nil
 }
 
+func (s *TokenService) storeRefreshToken(ctx context.Context, rt *model.RefreshToken) error {
+	if err := s.repo.RefreshToken.Create(ctx, rt); err != nil {
+		return err
+	}
+	if err := s.repo.RefreshToken.RevokeOldestActiveByUserID(ctx, rt.UserID, s.maxActiveRefreshTokens(ctx)); err != nil && s.log != nil {
+		s.log.Warn("failed to enforce refresh token session limit", zap.String("user_id", rt.UserID), zap.Error(err))
+	}
+	return nil
+}
+
+func (s *TokenService) storeRefreshTokenEventually(userID, tokenHash string, expiresAt time.Time) {
+	delay := 500 * time.Millisecond
+	for attempt := 1; attempt <= 30; attempt++ {
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		err := s.storeRefreshToken(ctx, &model.RefreshToken{
+			UserID:    userID,
+			TokenHash: tokenHash,
+			ExpiresAt: expiresAt,
+		})
+		cancel()
+		if err == nil {
+			return
+		}
+		if !repository.IsSQLiteBusyError(err) && !errors.Is(err, context.DeadlineExceeded) && !errors.Is(err, context.Canceled) {
+			if s.log != nil {
+				s.log.Warn("refresh token delayed store failed permanently", zap.String("user_id", userID), zap.Error(err))
+			}
+			return
+		}
+		if s.log != nil && (attempt == 1 || attempt%10 == 0) {
+			s.log.Warn("refresh token delayed store still waiting",
+				zap.String("user_id", userID),
+				zap.Int("attempt", attempt),
+				zap.Error(err))
+		}
+		timer := time.NewTimer(delay)
+		<-timer.C
+		if delay < 10*time.Second {
+			delay *= 2
+		}
+	}
+	if s.log != nil {
+		s.log.Warn("refresh token delayed store gave up", zap.String("user_id", userID))
+	}
+}
+
 func (s *TokenService) maxActiveRefreshTokens(ctx context.Context) int {
 	cfg := loadBotConfig(ctx, s.repo)
 	if cfg.MaxLoggedClients < 1 {