feat(group): 添加 MCP XML 注入开关

- Group 新增 mcp_xml_inject 字段，控制 Antigravity 平台的 MCP XML 协议注入
- 默认启用，可在分组设置中关闭
- 修复 GetByKeyForAuth 遗漏查询 mcp_xml_inject 字段导致认证缓存值始终为 false 的问题

backend/internal/service/admin_service.go

@@ -113,6 +113,7 @@ type CreateGroupInput struct {
 	// 模型路由配置（仅 anthropic 平台使用）
 	ModelRouting        map[string][]int64
 	ModelRoutingEnabled bool // 是否启用模型路由
+	MCPXMLInject        *bool
 }
 
 type UpdateGroupInput struct {
@@ -137,6 +138,7 @@ type UpdateGroupInput struct {
 	// 模型路由配置（仅 anthropic 平台使用）
 	ModelRouting        map[string][]int64
 	ModelRoutingEnabled *bool // 是否启用模型路由
+	MCPXMLInject        *bool
 }
 
 type CreateAccountInput struct {
@@ -587,6 +589,12 @@ func (s *adminServiceImpl) CreateGroup(ctx context.Context, input *CreateGroupIn
 		}
 	}
 
+	// MCPXMLInject：默认为 true，仅当显式传入 false 时关闭
+	mcpXMLInject := true
+	if input.MCPXMLInject != nil {
+		mcpXMLInject = *input.MCPXMLInject
+	}
+
 	group := &Group{
 		Name:                            input.Name,
 		Description:                     input.Description,
@@ -605,6 +613,7 @@ func (s *adminServiceImpl) CreateGroup(ctx context.Context, input *CreateGroupIn
 		FallbackGroupID:                 input.FallbackGroupID,
 		FallbackGroupIDOnInvalidRequest: fallbackOnInvalidRequest,
 		ModelRouting:                    input.ModelRouting,
+		MCPXMLInject:                    mcpXMLInject,
 	}
 	if err := s.groupRepo.Create(ctx, group); err != nil {
 		return nil, err
@@ -785,6 +794,9 @@ func (s *adminServiceImpl) UpdateGroup(ctx context.Context, id int64, input *Upd
 	if input.ModelRoutingEnabled != nil {
 		group.ModelRoutingEnabled = *input.ModelRoutingEnabled
 	}
+	if input.MCPXMLInject != nil {
+		group.MCPXMLInject = *input.MCPXMLInject
+	}
 
 	if err := s.groupRepo.Update(ctx, group); err != nil {
 		return nil, err

backend/internal/service/antigravity_gateway_service.go

@@ -19,6 +19,7 @@ import (
 	"time"
 
 	"github.com/Wei-Shaw/sub2api/internal/pkg/antigravity"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/ctxkey"
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
 )
@@ -552,6 +553,10 @@ func (s *AntigravityGatewayService) getClaudeTransformOptions(ctx context.Contex
 	}
 	opts.EnableIdentityPatch = s.settingService.IsIdentityPatchEnabled(ctx)
 	opts.IdentityPatch = s.settingService.GetIdentityPatchPrompt(ctx)
+
+	if group, ok := ctx.Value(ctxkey.Group).(*Group); ok && group != nil {
+		opts.EnableMCPXML = group.MCPXMLInject
+	}
 	return opts
 }
 

backend/internal/service/api_key_auth_cache.go

@@ -43,6 +43,7 @@ type APIKeyAuthGroupSnapshot struct {
 	// Only anthropic groups use these fields; others may leave them empty.
 	ModelRouting        map[string][]int64 `json:"model_routing,omitempty"`
 	ModelRoutingEnabled bool               `json:"model_routing_enabled"`
+	MCPXMLInject        bool               `json:"mcp_xml_inject"`
 }
 
 // APIKeyAuthCacheEntry 缓存条目，支持负缓存

backend/internal/service/api_key_auth_cache_impl.go

@@ -224,6 +224,7 @@ func (s *APIKeyService) snapshotFromAPIKey(apiKey *APIKey) *APIKeyAuthSnapshot {
 			FallbackGroupIDOnInvalidRequest: apiKey.Group.FallbackGroupIDOnInvalidRequest,
 			ModelRouting:                    apiKey.Group.ModelRouting,
 			ModelRoutingEnabled:             apiKey.Group.ModelRoutingEnabled,
+			MCPXMLInject:                    apiKey.Group.MCPXMLInject,
 		}
 	}
 	return snapshot
@@ -269,6 +270,7 @@ func (s *APIKeyService) snapshotToAPIKey(key string, snapshot *APIKeyAuthSnapsho
 			FallbackGroupIDOnInvalidRequest: snapshot.Group.FallbackGroupIDOnInvalidRequest,
 			ModelRouting:                    snapshot.Group.ModelRouting,
 			ModelRoutingEnabled:             snapshot.Group.ModelRoutingEnabled,
+			MCPXMLInject:                    snapshot.Group.MCPXMLInject,
 		}
 	}
 	return apiKey

backend/internal/service/group.go

@@ -38,6 +38,9 @@ type Group struct {
 	ModelRouting        map[string][]int64
 	ModelRoutingEnabled bool
 
+	// MCP XML 协议注入开关（仅 antigravity 平台使用）
+	MCPXMLInject bool
+
 	CreatedAt time.Time
 	UpdatedAt time.Time