feat(antigravity): 增强网关功能和 thinking 块处理

主要改进：
- 优化 thinking blocks 过滤策略，支持 Auto 模式降级
- 将无效 thinking block 内容转为普通 text
- 保留单个空白 text block，不过滤
- 重构配额刷新机制，统一与 Claude 一致
- 支持 cachedContentTokenCount 映射到 cache_read_input_tokens
- Haiku 模型映射到 Sonnet
- 添加 /antigravity/v1/models 端点支持
- countTokens 端点直接返回空值

backend/internal/handler/gateway_handler.go

@@ -1,5 +1,3 @@
-// Package handler provides HTTP request handlers for the API gateway.
-// It handles authentication, request routing, concurrency control, and billing validation.
 package handler
 
 import (
@@ -13,6 +11,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/Wei-Shaw/sub2api/internal/pkg/antigravity"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/claude"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/openai"
 	middleware2 "github.com/Wei-Shaw/sub2api/internal/server/middleware"
@@ -29,7 +28,6 @@ type GatewayHandler struct {
 	userService               *service.UserService
 	billingCacheService       *service.BillingCacheService
 	concurrencyHelper         *ConcurrencyHelper
-	opsService                *service.OpsService
 }
 
 // NewGatewayHandler creates a new GatewayHandler
@@ -40,7 +38,6 @@ func NewGatewayHandler(
 	userService *service.UserService,
 	concurrencyService *service.ConcurrencyService,
 	billingCacheService *service.BillingCacheService,
-	opsService *service.OpsService,
 ) *GatewayHandler {
 	return &GatewayHandler{
 		gatewayService:            gatewayService,
@@ -49,15 +46,14 @@ func NewGatewayHandler(
 		userService:               userService,
 		billingCacheService:       billingCacheService,
 		concurrencyHelper:         NewConcurrencyHelper(concurrencyService, SSEPingFormatClaude),
-		opsService:                opsService,
 	}
 }
 
 // Messages handles Claude API compatible messages endpoint
 // POST /v1/messages
 func (h *GatewayHandler) Messages(c *gin.Context) {
-	// 从context获取apiKey和user（APIKeyAuth中间件已设置）
-	apiKey, ok := middleware2.GetAPIKeyFromContext(c)
+	// 从context获取apiKey和user（ApiKeyAuth中间件已设置）
+	apiKey, ok := middleware2.GetApiKeyFromContext(c)
 	if !ok {
 		h.errorResponse(c, http.StatusUnauthorized, "authentication_error", "Invalid API key")
 		return
@@ -92,7 +88,6 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 	}
 	reqModel := parsedReq.Model
 	reqStream := parsedReq.Stream
-	setOpsRequestContext(c, reqModel, reqStream)
 
 	// 验证 model 必填
 	if reqModel == "" {
@@ -264,7 +259,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 				defer cancel()
 				if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
 					Result:       result,
-					APIKey:       apiKey,
+					ApiKey:       apiKey,
 					User:         apiKey.User,
 					Account:      usedAccount,
 					Subscription: subscription,
@@ -388,7 +383,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 			defer cancel()
 			if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
 				Result:       result,
-				APIKey:       apiKey,
+				ApiKey:       apiKey,
 				User:         apiKey.User,
 				Account:      usedAccount,
 				Subscription: subscription,
@@ -405,7 +400,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 // Returns models based on account configurations (model_mapping whitelist)
 // Falls back to default models if no whitelist is configured
 func (h *GatewayHandler) Models(c *gin.Context) {
-	apiKey, _ := middleware2.GetAPIKeyFromContext(c)
+	apiKey, _ := middleware2.GetApiKeyFromContext(c)
 
 	var groupID *int64
 	var platform string
@@ -451,10 +446,19 @@ func (h *GatewayHandler) Models(c *gin.Context) {
 	})
 }
 
+// AntigravityModels 返回 Antigravity 支持的全部模型
+// GET /antigravity/models
+func (h *GatewayHandler) AntigravityModels(c *gin.Context) {
+	c.JSON(http.StatusOK, gin.H{
+		"object": "list",
+		"data":   antigravity.DefaultModels(),
+	})
+}
+
 // Usage handles getting account balance for CC Switch integration
 // GET /v1/usage
 func (h *GatewayHandler) Usage(c *gin.Context) {
-	apiKey, ok := middleware2.GetAPIKeyFromContext(c)
+	apiKey, ok := middleware2.GetApiKeyFromContext(c)
 	if !ok {
 		h.errorResponse(c, http.StatusUnauthorized, "authentication_error", "Invalid API key")
 		return
@@ -579,7 +583,6 @@ func (h *GatewayHandler) mapUpstreamError(statusCode int) (int, string, string)
 // handleStreamingAwareError handles errors that may occur after streaming has started
 func (h *GatewayHandler) handleStreamingAwareError(c *gin.Context, status int, errType, message string, streamStarted bool) {
 	if streamStarted {
-		recordOpsError(c, h.opsService, status, errType, message, "")
 		// Stream already started, send error as SSE event then close
 		flusher, ok := c.Writer.(http.Flusher)
 		if ok {
@@ -611,7 +614,6 @@ func (h *GatewayHandler) handleStreamingAwareError(c *gin.Context, status int, e
 
 // errorResponse 返回Claude API格式的错误响应
 func (h *GatewayHandler) errorResponse(c *gin.Context, status int, errType, message string) {
-	recordOpsError(c, h.opsService, status, errType, message, "")
 	c.JSON(status, gin.H{
 		"type": "error",
 		"error": gin.H{
@@ -625,8 +627,8 @@ func (h *GatewayHandler) errorResponse(c *gin.Context, status int, errType, mess
 // POST /v1/messages/count_tokens
 // 特点：校验订阅/余额，但不计算并发、不记录使用量
 func (h *GatewayHandler) CountTokens(c *gin.Context) {
-	// 从context获取apiKey和user（APIKeyAuth中间件已设置）
-	apiKey, ok := middleware2.GetAPIKeyFromContext(c)
+	// 从context获取apiKey和user（ApiKeyAuth中间件已设置）
+	apiKey, ok := middleware2.GetApiKeyFromContext(c)
 	if !ok {
 		h.errorResponse(c, http.StatusUnauthorized, "authentication_error", "Invalid API key")
 		return