fix(groups): 用户分组不下发内部路由信息

- 普通用户 Group DTO 移除 model_routing/account_count/account_groups，避免泄露内部路由与账号信息\n- 新增 AdminGroup DTO，并仅在管理员分组接口返回完整字段\n- 前端拆分 Group/AdminGroup，管理端页面与 API 使用 AdminGroup\n- 增加 /api/v1/groups/available 契约测试，防止回归

backend/internal/handler/admin/group_handler.go

@@ -94,9 +94,9 @@ func (h *GroupHandler) List(c *gin.Context) {
 		return
 	}
 
-	outGroups := make([]dto.Group, 0, len(groups))
+	outGroups := make([]dto.AdminGroup, 0, len(groups))
 	for i := range groups {
-		outGroups = append(outGroups, *dto.GroupFromService(&groups[i]))
+		outGroups = append(outGroups, *dto.GroupFromServiceAdmin(&groups[i]))
 	}
 	response.Paginated(c, outGroups, total, page, pageSize)
 }
@@ -120,9 +120,9 @@ func (h *GroupHandler) GetAll(c *gin.Context) {
 		return
 	}
 
-	outGroups := make([]dto.Group, 0, len(groups))
+	outGroups := make([]dto.AdminGroup, 0, len(groups))
 	for i := range groups {
-		outGroups = append(outGroups, *dto.GroupFromService(&groups[i]))
+		outGroups = append(outGroups, *dto.GroupFromServiceAdmin(&groups[i]))
 	}
 	response.Success(c, outGroups)
 }
@@ -142,7 +142,7 @@ func (h *GroupHandler) GetByID(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, dto.GroupFromService(group))
+	response.Success(c, dto.GroupFromServiceAdmin(group))
 }
 
 // Create handles creating a new group
@@ -177,7 +177,7 @@ func (h *GroupHandler) Create(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, dto.GroupFromService(group))
+	response.Success(c, dto.GroupFromServiceAdmin(group))
 }
 
 // Update handles updating a group
@@ -219,7 +219,7 @@ func (h *GroupHandler) Update(c *gin.Context) {
 		return
 	}
 
-	response.Success(c, dto.GroupFromService(group))
+	response.Success(c, dto.GroupFromServiceAdmin(group))
 }
 
 // Delete handles deleting a group

backend/internal/handler/dto/mappers.go

@@ -72,36 +72,29 @@ func GroupFromServiceShallow(g *service.Group) *Group {
 	if g == nil {
 		return nil
 	}
-	return &Group{
-		ID:                  g.ID,
-		Name:                g.Name,
-		Description:         g.Description,
-		Platform:            g.Platform,
-		RateMultiplier:      g.RateMultiplier,
-		IsExclusive:         g.IsExclusive,
-		Status:              g.Status,
-		SubscriptionType:    g.SubscriptionType,
-		DailyLimitUSD:       g.DailyLimitUSD,
-		WeeklyLimitUSD:      g.WeeklyLimitUSD,
-		MonthlyLimitUSD:     g.MonthlyLimitUSD,
-		ImagePrice1K:        g.ImagePrice1K,
-		ImagePrice2K:        g.ImagePrice2K,
-		ImagePrice4K:        g.ImagePrice4K,
-		ClaudeCodeOnly:      g.ClaudeCodeOnly,
-		FallbackGroupID:     g.FallbackGroupID,
-		ModelRouting:        g.ModelRouting,
-		ModelRoutingEnabled: g.ModelRoutingEnabled,
-		CreatedAt:           g.CreatedAt,
-		UpdatedAt:           g.UpdatedAt,
-		AccountCount:        g.AccountCount,
-	}
+	out := groupFromServiceBase(g)
+	return &out
 }
 
 func GroupFromService(g *service.Group) *Group {
 	if g == nil {
 		return nil
 	}
-	out := GroupFromServiceShallow(g)
+	return GroupFromServiceShallow(g)
+}
+
+// GroupFromServiceAdmin converts a service Group to DTO for admin users.
+// It includes internal fields like model_routing and account_count.
+func GroupFromServiceAdmin(g *service.Group) *AdminGroup {
+	if g == nil {
+		return nil
+	}
+	out := &AdminGroup{
+		Group:               groupFromServiceBase(g),
+		ModelRouting:        g.ModelRouting,
+		ModelRoutingEnabled: g.ModelRoutingEnabled,
+		AccountCount:        g.AccountCount,
+	}
 	if len(g.AccountGroups) > 0 {
 		out.AccountGroups = make([]AccountGroup, 0, len(g.AccountGroups))
 		for i := range g.AccountGroups {
@@ -112,6 +105,29 @@ func GroupFromService(g *service.Group) *Group {
 	return out
 }
 
+func groupFromServiceBase(g *service.Group) Group {
+	return Group{
+		ID:               g.ID,
+		Name:             g.Name,
+		Description:      g.Description,
+		Platform:         g.Platform,
+		RateMultiplier:   g.RateMultiplier,
+		IsExclusive:      g.IsExclusive,
+		Status:           g.Status,
+		SubscriptionType: g.SubscriptionType,
+		DailyLimitUSD:    g.DailyLimitUSD,
+		WeeklyLimitUSD:   g.WeeklyLimitUSD,
+		MonthlyLimitUSD:  g.MonthlyLimitUSD,
+		ImagePrice1K:     g.ImagePrice1K,
+		ImagePrice2K:     g.ImagePrice2K,
+		ImagePrice4K:     g.ImagePrice4K,
+		ClaudeCodeOnly:   g.ClaudeCodeOnly,
+		FallbackGroupID:  g.FallbackGroupID,
+		CreatedAt:        g.CreatedAt,
+		UpdatedAt:        g.UpdatedAt,
+	}
+}
+
 func AccountFromServiceShallow(a *service.Account) *Account {
 	if a == nil {
 		return nil

backend/internal/handler/dto/types.go

@@ -58,13 +58,19 @@ type Group struct {
 	ClaudeCodeOnly  bool   `json:"claude_code_only"`
 	FallbackGroupID *int64 `json:"fallback_group_id"`
 
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}
+
+// AdminGroup 是管理员接口使用的 group DTO（包含敏感/内部字段）。
+// 注意：普通用户接口不得返回 model_routing/account_count/account_groups 等内部信息。
+type AdminGroup struct {
+	Group
+
 	// 模型路由配置（仅 anthropic 平台使用）
 	ModelRouting        map[string][]int64 `json:"model_routing"`
 	ModelRoutingEnabled bool               `json:"model_routing_enabled"`
 
-	CreatedAt time.Time `json:"created_at"`
-	UpdatedAt time.Time `json:"updated_at"`
-
 	AccountGroups []AccountGroup `json:"account_groups,omitempty"`
 	AccountCount  int64          `json:"account_count,omitempty"`
 }