feat: 支持用户专属分组倍率配置

backend/internal/service/admin_service.go

@@ -93,6 +93,9 @@ type UpdateUserInput struct {
 	Concurrency   *int     // 使用指针区分"未提供"和"设置为0"
 	Status        string
 	AllowedGroups *[]int64 // 使用指针区分"未提供"和"设置为空数组"
+	// GroupRates 用户专属分组倍率配置
+	// map[groupID]*rate，nil 表示删除该分组的专属倍率
+	GroupRates map[int64]*float64
 }
 
 type CreateGroupInput struct {
@@ -293,6 +296,7 @@ type adminServiceImpl struct {
 	proxyRepo            ProxyRepository
 	apiKeyRepo           APIKeyRepository
 	redeemCodeRepo       RedeemCodeRepository
+	userGroupRateRepo    UserGroupRateRepository
 	billingCacheService  *BillingCacheService
 	proxyProber          ProxyExitInfoProber
 	proxyLatencyCache    ProxyLatencyCache
@@ -307,6 +311,7 @@ func NewAdminService(
 	proxyRepo ProxyRepository,
 	apiKeyRepo APIKeyRepository,
 	redeemCodeRepo RedeemCodeRepository,
+	userGroupRateRepo UserGroupRateRepository,
 	billingCacheService *BillingCacheService,
 	proxyProber ProxyExitInfoProber,
 	proxyLatencyCache ProxyLatencyCache,
@@ -319,6 +324,7 @@ func NewAdminService(
 		proxyRepo:            proxyRepo,
 		apiKeyRepo:           apiKeyRepo,
 		redeemCodeRepo:       redeemCodeRepo,
+		userGroupRateRepo:    userGroupRateRepo,
 		billingCacheService:  billingCacheService,
 		proxyProber:          proxyProber,
 		proxyLatencyCache:    proxyLatencyCache,
@@ -333,11 +339,35 @@ func (s *adminServiceImpl) ListUsers(ctx context.Context, page, pageSize int, fi
 	if err != nil {
 		return nil, 0, err
 	}
+	// 批量加载用户专属分组倍率
+	if s.userGroupRateRepo != nil && len(users) > 0 {
+		for i := range users {
+			rates, err := s.userGroupRateRepo.GetByUserID(ctx, users[i].ID)
+			if err != nil {
+				log.Printf("failed to load user group rates: user_id=%d err=%v", users[i].ID, err)
+				continue
+			}
+			users[i].GroupRates = rates
+		}
+	}
 	return users, result.Total, nil
 }
 
 func (s *adminServiceImpl) GetUser(ctx context.Context, id int64) (*User, error) {
-	return s.userRepo.GetByID(ctx, id)
+	user, err := s.userRepo.GetByID(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	// 加载用户专属分组倍率
+	if s.userGroupRateRepo != nil {
+		rates, err := s.userGroupRateRepo.GetByUserID(ctx, id)
+		if err != nil {
+			log.Printf("failed to load user group rates: user_id=%d err=%v", id, err)
+		} else {
+			user.GroupRates = rates
+		}
+	}
+	return user, nil
 }
 
 func (s *adminServiceImpl) CreateUser(ctx context.Context, input *CreateUserInput) (*User, error) {
@@ -406,6 +436,14 @@ func (s *adminServiceImpl) UpdateUser(ctx context.Context, id int64, input *Upda
 	if err := s.userRepo.Update(ctx, user); err != nil {
 		return nil, err
 	}
+
+	// 同步用户专属分组倍率
+	if input.GroupRates != nil && s.userGroupRateRepo != nil {
+		if err := s.userGroupRateRepo.SyncUserGroupRates(ctx, user.ID, input.GroupRates); err != nil {
+			log.Printf("failed to sync user group rates: user_id=%d err=%v", user.ID, err)
+		}
+	}
+
 	if s.authCacheInvalidator != nil {
 		if user.Concurrency != oldConcurrency || user.Status != oldStatus || user.Role != oldRole {
 			s.authCacheInvalidator.InvalidateAuthCacheByUserID(ctx, user.ID)
@@ -941,6 +979,7 @@ func (s *adminServiceImpl) DeleteGroup(ctx context.Context, id int64) error {
 	if err != nil {
 		return err
 	}
+	// 注意：user_group_rate_multipliers 表通过外键 ON DELETE CASCADE 自动清理
 
 	// 事务成功后，异步失效受影响用户的订阅缓存
 	if len(affectedUserIDs) > 0 && s.billingCacheService != nil {

backend/internal/service/api_key_service.go

@@ -115,15 +115,16 @@ type UpdateAPIKeyRequest struct {
 
 // APIKeyService API Key服务
 type APIKeyService struct {
-	apiKeyRepo  APIKeyRepository
-	userRepo    UserRepository
-	groupRepo   GroupRepository
-	userSubRepo UserSubscriptionRepository
-	cache       APIKeyCache
-	cfg         *config.Config
-	authCacheL1 *ristretto.Cache
-	authCfg     apiKeyAuthCacheConfig
-	authGroup   singleflight.Group
+	apiKeyRepo        APIKeyRepository
+	userRepo          UserRepository
+	groupRepo         GroupRepository
+	userSubRepo       UserSubscriptionRepository
+	userGroupRateRepo UserGroupRateRepository
+	cache             APIKeyCache
+	cfg               *config.Config
+	authCacheL1       *ristretto.Cache
+	authCfg           apiKeyAuthCacheConfig
+	authGroup         singleflight.Group
 }
 
 // NewAPIKeyService 创建API Key服务实例
@@ -132,16 +133,18 @@ func NewAPIKeyService(
 	userRepo UserRepository,
 	groupRepo GroupRepository,
 	userSubRepo UserSubscriptionRepository,
+	userGroupRateRepo UserGroupRateRepository,
 	cache APIKeyCache,
 	cfg *config.Config,
 ) *APIKeyService {
 	svc := &APIKeyService{
-		apiKeyRepo:  apiKeyRepo,
-		userRepo:    userRepo,
-		groupRepo:   groupRepo,
-		userSubRepo: userSubRepo,
-		cache:       cache,
-		cfg:         cfg,
+		apiKeyRepo:        apiKeyRepo,
+		userRepo:          userRepo,
+		groupRepo:         groupRepo,
+		userSubRepo:       userSubRepo,
+		userGroupRateRepo: userGroupRateRepo,
+		cache:             cache,
+		cfg:               cfg,
 	}
 	svc.initAuthCache(cfg)
 	return svc
@@ -627,6 +630,19 @@ func (s *APIKeyService) SearchAPIKeys(ctx context.Context, userID int64, keyword
 	return keys, nil
 }
 
+// GetUserGroupRates 获取用户的专属分组倍率配置
+// 返回 map[groupID]rateMultiplier
+func (s *APIKeyService) GetUserGroupRates(ctx context.Context, userID int64) (map[int64]float64, error) {
+	if s.userGroupRateRepo == nil {
+		return nil, nil
+	}
+	rates, err := s.userGroupRateRepo.GetByUserID(ctx, userID)
+	if err != nil {
+		return nil, fmt.Errorf("get user group rates: %w", err)
+	}
+	return rates, nil
+}
+
 // CheckAPIKeyQuotaAndExpiry checks if the API key is valid for use (not expired, quota not exhausted)
 // Returns nil if valid, error if invalid
 func (s *APIKeyService) CheckAPIKeyQuotaAndExpiry(apiKey *APIKey) error {

backend/internal/service/api_key_service_cache_test.go

@@ -167,7 +167,7 @@ func TestAPIKeyService_GetByKey_UsesL2Cache(t *testing.T) {
 			NegativeTTLSeconds: 30,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 
 	groupID := int64(9)
 	cacheEntry := &APIKeyAuthCacheEntry{
@@ -223,7 +223,7 @@ func TestAPIKeyService_GetByKey_NegativeCache(t *testing.T) {
 			NegativeTTLSeconds: 30,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 	cache.getAuthCache = func(ctx context.Context, key string) (*APIKeyAuthCacheEntry, error) {
 		return &APIKeyAuthCacheEntry{NotFound: true}, nil
 	}
@@ -256,7 +256,7 @@ func TestAPIKeyService_GetByKey_CacheMissStoresL2(t *testing.T) {
 			NegativeTTLSeconds: 30,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 	cache.getAuthCache = func(ctx context.Context, key string) (*APIKeyAuthCacheEntry, error) {
 		return nil, redis.Nil
 	}
@@ -293,7 +293,7 @@ func TestAPIKeyService_GetByKey_UsesL1Cache(t *testing.T) {
 			L1TTLSeconds: 60,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 	require.NotNil(t, svc.authCacheL1)
 
 	_, err := svc.GetByKey(context.Background(), "k-l1")
@@ -320,7 +320,7 @@ func TestAPIKeyService_InvalidateAuthCacheByUserID(t *testing.T) {
 			NegativeTTLSeconds: 30,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 
 	svc.InvalidateAuthCacheByUserID(context.Background(), 7)
 	require.Len(t, cache.deleteAuthKeys, 2)
@@ -338,7 +338,7 @@ func TestAPIKeyService_InvalidateAuthCacheByGroupID(t *testing.T) {
 			L2TTLSeconds: 60,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 
 	svc.InvalidateAuthCacheByGroupID(context.Background(), 9)
 	require.Len(t, cache.deleteAuthKeys, 2)
@@ -356,7 +356,7 @@ func TestAPIKeyService_InvalidateAuthCacheByKey(t *testing.T) {
 			L2TTLSeconds: 60,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 
 	svc.InvalidateAuthCacheByKey(context.Background(), "k1")
 	require.Len(t, cache.deleteAuthKeys, 1)
@@ -375,7 +375,7 @@ func TestAPIKeyService_GetByKey_CachesNegativeOnRepoMiss(t *testing.T) {
 			NegativeTTLSeconds: 30,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 	cache.getAuthCache = func(ctx context.Context, key string) (*APIKeyAuthCacheEntry, error) {
 		return nil, redis.Nil
 	}
@@ -411,7 +411,7 @@ func TestAPIKeyService_GetByKey_SingleflightCollapses(t *testing.T) {
 			Singleflight: true,
 		},
 	}
-	svc := NewAPIKeyService(repo, nil, nil, nil, cache, cfg)
+	svc := NewAPIKeyService(repo, nil, nil, nil, nil, cache, cfg)
 
 	start := make(chan struct{})
 	wg := sync.WaitGroup{}

backend/internal/service/gateway_service.go

@@ -384,6 +384,7 @@ type GatewayService struct {
 	usageLogRepo        UsageLogRepository
 	userRepo            UserRepository
 	userSubRepo         UserSubscriptionRepository
+	userGroupRateRepo   UserGroupRateRepository
 	cache               GatewayCache
 	cfg                 *config.Config
 	schedulerSnapshot   *SchedulerSnapshotService
@@ -405,6 +406,7 @@ func NewGatewayService(
 	usageLogRepo UsageLogRepository,
 	userRepo UserRepository,
 	userSubRepo UserSubscriptionRepository,
+	userGroupRateRepo UserGroupRateRepository,
 	cache GatewayCache,
 	cfg *config.Config,
 	schedulerSnapshot *SchedulerSnapshotService,
@@ -424,6 +426,7 @@ func NewGatewayService(
 		usageLogRepo:        usageLogRepo,
 		userRepo:            userRepo,
 		userSubRepo:         userSubRepo,
+		userGroupRateRepo:   userGroupRateRepo,
 		cache:               cache,
 		cfg:                 cfg,
 		schedulerSnapshot:   schedulerSnapshot,
@@ -4609,10 +4612,17 @@ func (s *GatewayService) RecordUsage(ctx context.Context, input *RecordUsageInpu
 	account := input.Account
 	subscription := input.Subscription
 
-	// 获取费率倍数
+	// 获取费率倍数（优先级：用户专属 > 分组默认 > 系统默认）
 	multiplier := s.cfg.Default.RateMultiplier
 	if apiKey.GroupID != nil && apiKey.Group != nil {
 		multiplier = apiKey.Group.RateMultiplier
+
+		// 检查用户专属倍率
+		if s.userGroupRateRepo != nil {
+			if userRate, err := s.userGroupRateRepo.GetByUserAndGroup(ctx, user.ID, *apiKey.GroupID); err == nil && userRate != nil {
+				multiplier = *userRate
+			}
+		}
 	}
 
 	var cost *CostBreakdown
@@ -4773,10 +4783,17 @@ func (s *GatewayService) RecordUsageWithLongContext(ctx context.Context, input *
 	account := input.Account
 	subscription := input.Subscription
 
-	// 获取费率倍数
+	// 获取费率倍数（优先级：用户专属 > 分组默认 > 系统默认）
 	multiplier := s.cfg.Default.RateMultiplier
 	if apiKey.GroupID != nil && apiKey.Group != nil {
 		multiplier = apiKey.Group.RateMultiplier
+
+		// 检查用户专属倍率
+		if s.userGroupRateRepo != nil {
+			if userRate, err := s.userGroupRateRepo.GetByUserAndGroup(ctx, user.ID, *apiKey.GroupID); err == nil && userRate != nil {
+				multiplier = *userRate
+			}
+		}
 	}
 
 	var cost *CostBreakdown

backend/internal/service/user.go

@@ -21,6 +21,10 @@ type User struct {
 	CreatedAt     time.Time
 	UpdatedAt     time.Time
 
+	// GroupRates 用户专属分组倍率配置
+	// map[groupID]rateMultiplier
+	GroupRates map[int64]float64
+
 	// TOTP 双因素认证字段
 	TotpSecretEncrypted *string    // AES-256-GCM 加密的 TOTP 密钥
 	TotpEnabled         bool       // 是否启用 TOTP
@@ -40,18 +44,20 @@ func (u *User) IsActive() bool {
 
 // CanBindGroup checks whether a user can bind to a given group.
 // For standard groups:
-// - If AllowedGroups is non-empty, only allow binding to IDs in that list.
-// - If AllowedGroups is empty (nil or length 0), allow binding to any non-exclusive group.
+// - Public groups (non-exclusive): all users can bind
+// - Exclusive groups: only users with the group in AllowedGroups can bind
 func (u *User) CanBindGroup(groupID int64, isExclusive bool) bool {
-	if len(u.AllowedGroups) > 0 {
-		for _, id := range u.AllowedGroups {
-			if id == groupID {
-				return true
-			}
-		}
-		return false
+	// 公开分组（非专属）：所有用户都可以绑定
+	if !isExclusive {
+		return true
 	}
-	return !isExclusive
+	// 专属分组：需要在 AllowedGroups 中
+	for _, id := range u.AllowedGroups {
+		if id == groupID {
+			return true
+		}
+	}
+	return false
 }
 
 func (u *User) SetPassword(password string) error {

backend/internal/service/user_group_rate.go

@@ -0,0 +1,25 @@
+package service
+
+import "context"
+
+// UserGroupRateRepository 用户专属分组倍率仓储接口
+// 允许管理员为特定用户设置分组的专属计费倍率，覆盖分组默认倍率
+type UserGroupRateRepository interface {
+	// GetByUserID 获取用户的所有专属分组倍率
+	// 返回 map[groupID]rateMultiplier
+	GetByUserID(ctx context.Context, userID int64) (map[int64]float64, error)
+
+	// GetByUserAndGroup 获取用户在特定分组的专属倍率
+	// 如果未设置专属倍率，返回 nil
+	GetByUserAndGroup(ctx context.Context, userID, groupID int64) (*float64, error)
+
+	// SyncUserGroupRates 同步用户的分组专属倍率
+	// rates: map[groupID]*rateMultiplier，nil 表示删除该分组的专属倍率
+	SyncUserGroupRates(ctx context.Context, userID int64, rates map[int64]*float64) error
+
+	// DeleteByGroupID 删除指定分组的所有用户专属倍率（分组删除时调用）
+	DeleteByGroupID(ctx context.Context, groupID int64) error
+
+	// DeleteByUserID 删除指定用户的所有专属倍率（用户删除时调用）
+	DeleteByUserID(ctx context.Context, userID int64) error
+}