feat: 分组管理页面新增专属倍率管理

- 后端新增 GET /admin/groups/:id/rate-multipliers API
- 前端新增 GroupRateMultipliersModal 组件，支持查看/添加/修改/删除用户专属倍率
- 分组列表操作列新增"专属倍率"按钮
- 修复 antigravity_gateway_service_test.go 参数不匹配的预存问题

backend/internal/handler/admin/admin_service_stub_test.go

@@ -175,6 +175,10 @@ func (s *stubAdminService) GetGroupAPIKeys(ctx context.Context, groupID int64, p
 	return s.apiKeys, int64(len(s.apiKeys)), nil
 }
 
+func (s *stubAdminService) GetGroupRateMultipliers(_ context.Context, _ int64) ([]service.UserGroupRateEntry, error) {
+	return nil, nil
+}
+
 func (s *stubAdminService) ListAccounts(ctx context.Context, page, pageSize int, platform, accountType, status, search string, groupID int64) ([]service.Account, int64, error) {
 	return s.accounts, int64(len(s.accounts)), nil
 }

backend/internal/handler/admin/group_handler.go

@@ -339,6 +339,27 @@ func (h *GroupHandler) GetGroupAPIKeys(c *gin.Context) {
 	response.Paginated(c, outKeys, total, page, pageSize)
 }
 
+// GetGroupRateMultipliers handles getting rate multipliers for users in a group
+// GET /api/v1/admin/groups/:id/rate-multipliers
+func (h *GroupHandler) GetGroupRateMultipliers(c *gin.Context) {
+	groupID, err := strconv.ParseInt(c.Param("id"), 10, 64)
+	if err != nil {
+		response.BadRequest(c, "Invalid group ID")
+		return
+	}
+
+	entries, err := h.adminService.GetGroupRateMultipliers(c.Request.Context(), groupID)
+	if err != nil {
+		response.ErrorFrom(c, err)
+		return
+	}
+
+	if entries == nil {
+		entries = []service.UserGroupRateEntry{}
+	}
+	response.Success(c, entries)
+}
+
 // UpdateSortOrderRequest represents the request to update group sort orders
 type UpdateSortOrderRequest struct {
 	Updates []struct {

backend/internal/repository/user_group_rate_repo.go

@@ -95,6 +95,35 @@ func (r *userGroupRateRepository) GetByUserIDs(ctx context.Context, userIDs []in
 	return result, nil
 }
 
+// GetByGroupID 获取指定分组下所有用户的专属倍率
+func (r *userGroupRateRepository) GetByGroupID(ctx context.Context, groupID int64) ([]service.UserGroupRateEntry, error) {
+	query := `
+		SELECT ugr.user_id, u.email, ugr.rate_multiplier
+		FROM user_group_rate_multipliers ugr
+		JOIN users u ON u.id = ugr.user_id
+		WHERE ugr.group_id = $1
+		ORDER BY ugr.user_id
+	`
+	rows, err := r.sql.QueryContext(ctx, query, groupID)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+
+	var result []service.UserGroupRateEntry
+	for rows.Next() {
+		var entry service.UserGroupRateEntry
+		if err := rows.Scan(&entry.UserID, &entry.UserEmail, &entry.RateMultiplier); err != nil {
+			return nil, err
+		}
+		result = append(result, entry)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
 // GetByUserAndGroup 获取用户在特定分组的专属倍率
 func (r *userGroupRateRepository) GetByUserAndGroup(ctx context.Context, userID, groupID int64) (*float64, error) {
 	query := `SELECT rate_multiplier FROM user_group_rate_multipliers WHERE user_id = $1 AND group_id = $2`

backend/internal/server/routes/admin.go

@@ -228,6 +228,7 @@ func registerGroupRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		groups.PUT("/:id", h.Admin.Group.Update)
 		groups.DELETE("/:id", h.Admin.Group.Delete)
 		groups.GET("/:id/stats", h.Admin.Group.GetStats)
+		groups.GET("/:id/rate-multipliers", h.Admin.Group.GetGroupRateMultipliers)
 		groups.GET("/:id/api-keys", h.Admin.Group.GetGroupAPIKeys)
 	}
 }

backend/internal/service/admin_service.go

@@ -42,6 +42,7 @@ type AdminService interface {
 	UpdateGroup(ctx context.Context, id int64, input *UpdateGroupInput) (*Group, error)
 	DeleteGroup(ctx context.Context, id int64) error
 	GetGroupAPIKeys(ctx context.Context, groupID int64, page, pageSize int) ([]APIKey, int64, error)
+	GetGroupRateMultipliers(ctx context.Context, groupID int64) ([]UserGroupRateEntry, error)
 	UpdateGroupSortOrders(ctx context.Context, updates []GroupSortOrderUpdate) error
 
 	// API Key management (admin)
@@ -1263,6 +1264,13 @@ func (s *adminServiceImpl) GetGroupAPIKeys(ctx context.Context, groupID int64, p
 	return keys, result.Total, nil
 }
 
+func (s *adminServiceImpl) GetGroupRateMultipliers(ctx context.Context, groupID int64) ([]UserGroupRateEntry, error) {
+	if s.userGroupRateRepo == nil {
+		return nil, nil
+	}
+	return s.userGroupRateRepo.GetByGroupID(ctx, groupID)
+}
+
 func (s *adminServiceImpl) UpdateGroupSortOrders(ctx context.Context, updates []GroupSortOrderUpdate) error {
 	return s.groupRepo.UpdateSortOrders(ctx, updates)
 }

backend/internal/service/admin_service_list_users_test.go

@@ -68,6 +68,10 @@ func (s *userGroupRateRepoStubForListUsers) SyncUserGroupRates(_ context.Context
 	panic("unexpected SyncUserGroupRates call")
 }
 
+func (s *userGroupRateRepoStubForListUsers) GetByGroupID(_ context.Context, groupID int64) ([]UserGroupRateEntry, error) {
+	panic("unexpected GetByGroupID call")
+}
+
 func (s *userGroupRateRepoStubForListUsers) DeleteByGroupID(_ context.Context, groupID int64) error {
 	panic("unexpected DeleteByGroupID call")
 }

backend/internal/service/antigravity_gateway_service_test.go

@@ -1022,7 +1022,7 @@ func TestHandleClaudeStreamingResponse_EmptyStream(t *testing.T) {
 		fmt.Fprintln(pw, "")
 	}()
 
-	_, err := svc.handleClaudeStreamingResponse(c, resp, time.Now(), "claude-sonnet-4-5")
+	_, err := svc.handleClaudeStreamingResponse(c, resp, time.Now(), "claude-sonnet-4-5", 0)
 	_ = pr.Close()
 
 	// 应当返回 UpstreamFailoverError 而非 nil，以便上层触发 failover

backend/internal/service/user_group_rate.go

@@ -2,6 +2,13 @@ package service
 
 import "context"
 
+// UserGroupRateEntry 分组下用户专属倍率条目
+type UserGroupRateEntry struct {
+	UserID         int64   `json:"user_id"`
+	UserEmail      string  `json:"user_email"`
+	RateMultiplier float64 `json:"rate_multiplier"`
+}
+
 // 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 {
@@ -13,6 +20,9 @@ type UserGroupRateRepository interface {
 	// 如果未设置专属倍率，返回 nil
 	GetByUserAndGroup(ctx context.Context, userID, groupID int64) (*float64, error)
 
+	// GetByGroupID 获取指定分组下所有用户的专属倍率
+	GetByGroupID(ctx context.Context, groupID int64) ([]UserGroupRateEntry, 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