fix: 收敛 Claude Code 探测拦截并补齐回归测试

backend/internal/handler/gateway_handler.go

@@ -2,6 +2,7 @@ package handler
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -111,9 +112,6 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 		return
 	}
 
-	// 检查是否为 Claude Code 客户端，设置到 context 中
-	SetClaudeCodeClientContext(c, body)
-
 	setOpsRequestContext(c, "", false, body)
 
 	parsedReq, err := service.ParseGatewayRequest(body)
@@ -121,11 +119,23 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 		h.errorResponse(c, http.StatusBadRequest, "invalid_request_error", "Failed to parse request body")
 		return
 	}
-	// 在请求上下文中记录 thinking 状态，供 Antigravity 最终模型 key 推导/模型维度限流使用
-	c.Request = c.Request.WithContext(context.WithValue(c.Request.Context(), ctxkey.ThinkingEnabled, parsedReq.ThinkingEnabled))
 	reqModel := parsedReq.Model
 	reqStream := parsedReq.Stream
 
+	// 设置 max_tokens=1 + haiku 探测请求标识到 context 中
+	// 必须在 SetClaudeCodeClientContext 之前设置，因为 ClaudeCodeValidator 需要读取此标识进行绕过判断
+	if isMaxTokensOneHaikuRequest(reqModel, parsedReq.MaxTokens, reqStream) {
+		ctx := context.WithValue(c.Request.Context(), ctxkey.IsMaxTokensOneHaikuRequest, true)
+		c.Request = c.Request.WithContext(ctx)
+	}
+
+	// 检查是否为 Claude Code 客户端，设置到 context 中
+	SetClaudeCodeClientContext(c, body)
+	isClaudeCodeClient := service.IsClaudeCodeClient(c.Request.Context())
+
+	// 在请求上下文中记录 thinking 状态，供 Antigravity 最终模型 key 推导/模型维度限流使用
+	c.Request = c.Request.WithContext(context.WithValue(c.Request.Context(), ctxkey.ThinkingEnabled, parsedReq.ThinkingEnabled))
+
 	setOpsRequestContext(c, reqModel, reqStream, body)
 
 	// 验证 model 必填
@@ -241,7 +251,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 
 			// 检查请求拦截（预热请求、SUGGESTION MODE等）
 			if account.IsInterceptWarmupEnabled() {
-				interceptType := detectInterceptType(body)
+				interceptType := detectInterceptType(body, reqModel, parsedReq.MaxTokens, reqStream, isClaudeCodeClient)
 				if interceptType != InterceptTypeNone {
 					if selection.Acquired && selection.ReleaseFunc != nil {
 						selection.ReleaseFunc()
@@ -403,7 +413,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 
 			// 检查请求拦截（预热请求、SUGGESTION MODE等）
 			if account.IsInterceptWarmupEnabled() {
-				interceptType := detectInterceptType(body)
+				interceptType := detectInterceptType(body, reqModel, parsedReq.MaxTokens, reqStream, isClaudeCodeClient)
 				if interceptType != InterceptTypeNone {
 					if selection.Acquired && selection.ReleaseFunc != nil {
 						selection.ReleaseFunc()
@@ -974,13 +984,37 @@ func (h *GatewayHandler) CountTokens(c *gin.Context) {
 type InterceptType int
 
 const (
-	InterceptTypeNone           InterceptType = iota
-	InterceptTypeWarmup                       // 预热请求（返回 "New Conversation"）
-	InterceptTypeSuggestionMode               // SUGGESTION MODE（返回空字符串）
+	InterceptTypeNone              InterceptType = iota
+	InterceptTypeWarmup                          // 预热请求（返回 "New Conversation"）
+	InterceptTypeSuggestionMode                  // SUGGESTION MODE（返回空字符串）
+	InterceptTypeMaxTokensOneHaiku               // max_tokens=1 + haiku 探测请求（返回 "#"）
 )
 
+// isHaikuModel 检查模型名称是否包含 "haiku"（大小写不敏感）
+func isHaikuModel(model string) bool {
+	return strings.Contains(strings.ToLower(model), "haiku")
+}
+
+// isMaxTokensOneHaikuRequest 检查是否为 max_tokens=1 + haiku 模型的探测请求
+// 这类请求用于 Claude Code 验证 API 连通性
+// 条件：max_tokens == 1 且 model 包含 "haiku" 且非流式请求
+func isMaxTokensOneHaikuRequest(model string, maxTokens int, isStream bool) bool {
+	return maxTokens == 1 && isHaikuModel(model) && !isStream
+}
+
 // detectInterceptType 检测请求是否需要拦截，返回拦截类型
-func detectInterceptType(body []byte) InterceptType {
+// 参数说明：
+//   - body: 请求体字节
+//   - model: 请求的模型名称
+//   - maxTokens: max_tokens 值
+//   - isStream: 是否为流式请求
+//   - isClaudeCodeClient: 是否已通过 Claude Code 客户端校验
+func detectInterceptType(body []byte, model string, maxTokens int, isStream bool, isClaudeCodeClient bool) InterceptType {
+	// 优先检查 max_tokens=1 + haiku 探测请求（仅非流式）
+	if isClaudeCodeClient && isMaxTokensOneHaikuRequest(model, maxTokens, isStream) {
+		return InterceptTypeMaxTokensOneHaiku
+	}
+
 	// 快速检查：如果不包含任何关键字，直接返回
 	bodyStr := string(body)
 	hasSuggestionMode := strings.Contains(bodyStr, "[SUGGESTION MODE:")
@@ -1130,9 +1164,25 @@ func sendMockInterceptStream(c *gin.Context, model string, interceptType Interce
 	}
 }
 
+// generateRealisticMsgID 生成仿真的消息 ID（msg_bdrk_XXXXXXX 格式）
+// 格式与 Claude API 真实响应一致，24 位随机字母数字
+func generateRealisticMsgID() string {
+	const charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+	const idLen = 24
+	randomBytes := make([]byte, idLen)
+	if _, err := rand.Read(randomBytes); err != nil {
+		return fmt.Sprintf("msg_bdrk_%d", time.Now().UnixNano())
+	}
+	b := make([]byte, idLen)
+	for i := range b {
+		b[i] = charset[int(randomBytes[i])%len(charset)]
+	}
+	return "msg_bdrk_" + string(b)
+}
+
 // sendMockInterceptResponse 发送非流式 mock 响应（用于请求拦截）
 func sendMockInterceptResponse(c *gin.Context, model string, interceptType InterceptType) {
-	var msgID, text string
+	var msgID, text, stopReason string
 	var outputTokens int
 
 	switch interceptType {
@@ -1140,24 +1190,42 @@ func sendMockInterceptResponse(c *gin.Context, model string, interceptType Inter
 		msgID = "msg_mock_suggestion"
 		text = ""
 		outputTokens = 1
+		stopReason = "end_turn"
+	case InterceptTypeMaxTokensOneHaiku:
+		msgID = generateRealisticMsgID()
+		text = "#"
+		outputTokens = 1
+		stopReason = "max_tokens" // max_tokens=1 探测请求的 stop_reason 应为 max_tokens
 	default: // InterceptTypeWarmup
 		msgID = "msg_mock_warmup"
 		text = "New Conversation"
 		outputTokens = 2
+		stopReason = "end_turn"
 	}
 
-	c.JSON(http.StatusOK, gin.H{
-		"id":          msgID,
-		"type":        "message",
-		"role":        "assistant",
-		"model":       model,
-		"content":     []gin.H{{"type": "text", "text": text}},
-		"stop_reason": "end_turn",
+	// 构建完整的响应格式（与 Claude API 响应格式一致）
+	response := gin.H{
+		"model":         model,
+		"id":            msgID,
+		"type":          "message",
+		"role":          "assistant",
+		"content":       []gin.H{{"type": "text", "text": text}},
+		"stop_reason":   stopReason,
+		"stop_sequence": nil,
 		"usage": gin.H{
-			"input_tokens":  10,
+			"input_tokens":                10,
+			"cache_creation_input_tokens": 0,
+			"cache_read_input_tokens":     0,
+			"cache_creation": gin.H{
+				"ephemeral_5m_input_tokens": 0,
+				"ephemeral_1h_input_tokens": 0,
+			},
 			"output_tokens": outputTokens,
+			"total_tokens":  10 + outputTokens,
 		},
-	})
+	}
+
+	c.JSON(http.StatusOK, response)
 }
 
 func billingErrorDetails(err error) (status int, code, message string) {