feat: cc/codex support account retry

backend/internal/handler/gateway_handler.go

@@ -3,6 +3,7 @@ package handler
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -127,66 +128,134 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 		platform = apiKey.Group.Platform
 	}
 
-	// 选择支持该模型的账号
-	var account *service.Account
 	if platform == service.PlatformGemini {
-		account, err = h.geminiCompatService.SelectAccountForModel(c.Request.Context(), apiKey.GroupID, sessionHash, req.Model)
-	} else {
-		account, err = h.gatewayService.SelectAccountForModel(c.Request.Context(), apiKey.GroupID, sessionHash, req.Model)
-	}
-	if err != nil {
-		h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts: "+err.Error(), streamStarted)
-		return
-	}
+		account, err := h.geminiCompatService.SelectAccountForModel(c.Request.Context(), apiKey.GroupID, sessionHash, req.Model)
+		if err != nil {
+			h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts: "+err.Error(), streamStarted)
+			return
+		}
 
-	// 检查预热请求拦截（在账号选择后、转发前检查）
-	if account.IsInterceptWarmupEnabled() && isWarmupRequest(body) {
-		if req.Stream {
-			sendMockWarmupStream(c, req.Model)
-		} else {
-			sendMockWarmupResponse(c, req.Model)
+		// 检查预热请求拦截（在账号选择后、转发前检查）
+		if account.IsInterceptWarmupEnabled() && isWarmupRequest(body) {
+			if req.Stream {
+				sendMockWarmupStream(c, req.Model)
+			} else {
+				sendMockWarmupResponse(c, req.Model)
+			}
+			return
 		}
-		return
-	}
 
-	// 3. 获取账号并发槽位
-	accountReleaseFunc, err := h.concurrencyHelper.AcquireAccountSlotWithWait(c, account.ID, account.Concurrency, req.Stream, &streamStarted)
-	if err != nil {
-		log.Printf("Account concurrency acquire failed: %v", err)
-		h.handleConcurrencyError(c, err, "account", streamStarted)
-		return
-	}
-	if accountReleaseFunc != nil {
-		defer accountReleaseFunc()
-	}
+		// 3. 获取账号并发槽位
+		accountReleaseFunc, err := h.concurrencyHelper.AcquireAccountSlotWithWait(c, account.ID, account.Concurrency, req.Stream, &streamStarted)
+		if err != nil {
+			log.Printf("Account concurrency acquire failed: %v", err)
+			h.handleConcurrencyError(c, err, "account", streamStarted)
+			return
+		}
+		if accountReleaseFunc != nil {
+			defer accountReleaseFunc()
+		}
 
-	// 转发请求
-	var result *service.ForwardResult
-	if platform == service.PlatformGemini {
-		result, err = h.geminiCompatService.Forward(c.Request.Context(), c, account, body)
-	} else {
-		result, err = h.gatewayService.Forward(c.Request.Context(), c, account, body)
-	}
-	if err != nil {
-		// 错误响应已在Forward中处理，这里只记录日志
-		log.Printf("Forward request failed: %v", err)
+		// 转发请求
+		result, err := h.geminiCompatService.Forward(c.Request.Context(), c, account, body)
+		if err != nil {
+			// 错误响应已在Forward中处理，这里只记录日志
+			log.Printf("Forward request failed: %v", err)
+			return
+		}
+
+		// 异步记录使用量（subscription已在函数开头获取）
+		go func(result *service.ForwardResult, usedAccount *service.Account) {
+			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+			defer cancel()
+			if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
+				Result:       result,
+				ApiKey:       apiKey,
+				User:         apiKey.User,
+				Account:      usedAccount,
+				Subscription: subscription,
+			}); err != nil {
+				log.Printf("Record usage failed: %v", err)
+			}
+		}(result, account)
 		return
 	}
 
-	// 异步记录使用量（subscription已在函数开头获取）
-	go func() {
-		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-		defer cancel()
-		if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
-			Result:       result,
-			ApiKey:       apiKey,
-			User:         apiKey.User,
-			Account:      account,
-			Subscription: subscription,
-		}); err != nil {
-			log.Printf("Record usage failed: %v", err)
+	const maxAccountSwitches = 3
+	switchCount := 0
+	failedAccountIDs := make(map[int64]struct{})
+	lastFailoverStatus := 0
+
+	for {
+		// 选择支持该模型的账号
+		account, err := h.gatewayService.SelectAccountForModelWithExclusions(c.Request.Context(), apiKey.GroupID, sessionHash, req.Model, failedAccountIDs)
+		if err != nil {
+			if len(failedAccountIDs) == 0 {
+				h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts: "+err.Error(), streamStarted)
+				return
+			}
+			h.handleFailoverExhausted(c, lastFailoverStatus, streamStarted)
+			return
+		}
+
+		// 检查预热请求拦截（在账号选择后、转发前检查）
+		if account.IsInterceptWarmupEnabled() && isWarmupRequest(body) {
+			if req.Stream {
+				sendMockWarmupStream(c, req.Model)
+			} else {
+				sendMockWarmupResponse(c, req.Model)
+			}
+			return
 		}
-	}()
+
+		// 3. 获取账号并发槽位
+		accountReleaseFunc, err := h.concurrencyHelper.AcquireAccountSlotWithWait(c, account.ID, account.Concurrency, req.Stream, &streamStarted)
+		if err != nil {
+			log.Printf("Account concurrency acquire failed: %v", err)
+			h.handleConcurrencyError(c, err, "account", streamStarted)
+			return
+		}
+
+		// 转发请求
+		result, err := h.gatewayService.Forward(c.Request.Context(), c, account, body)
+		if accountReleaseFunc != nil {
+			accountReleaseFunc()
+		}
+		if err != nil {
+			var failoverErr *service.UpstreamFailoverError
+			if errors.As(err, &failoverErr) {
+				failedAccountIDs[account.ID] = struct{}{}
+				if switchCount >= maxAccountSwitches {
+					lastFailoverStatus = failoverErr.StatusCode
+					h.handleFailoverExhausted(c, lastFailoverStatus, streamStarted)
+					return
+				}
+				lastFailoverStatus = failoverErr.StatusCode
+				switchCount++
+				log.Printf("Account %d: upstream error %d, switching account %d/%d", account.ID, failoverErr.StatusCode, switchCount, maxAccountSwitches)
+				continue
+			}
+			// 错误响应已在Forward中处理，这里只记录日志
+			log.Printf("Forward request failed: %v", err)
+			return
+		}
+
+		// 异步记录使用量（subscription已在函数开头获取）
+		go func(result *service.ForwardResult, usedAccount *service.Account) {
+			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+			defer cancel()
+			if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
+				Result:       result,
+				ApiKey:       apiKey,
+				User:         apiKey.User,
+				Account:      usedAccount,
+				Subscription: subscription,
+			}); err != nil {
+				log.Printf("Record usage failed: %v", err)
+			}
+		}(result, account)
+		return
+	}
 }
 
 // Models handles listing available models
@@ -314,6 +383,28 @@ func (h *GatewayHandler) handleConcurrencyError(c *gin.Context, err error, slotT
 		fmt.Sprintf("Concurrency limit exceeded for %s, please retry later", slotType), streamStarted)
 }
 
+func (h *GatewayHandler) handleFailoverExhausted(c *gin.Context, statusCode int, streamStarted bool) {
+	status, errType, errMsg := h.mapUpstreamError(statusCode)
+	h.handleStreamingAwareError(c, status, errType, errMsg, streamStarted)
+}
+
+func (h *GatewayHandler) mapUpstreamError(statusCode int) (int, string, string) {
+	switch statusCode {
+	case 401:
+		return http.StatusBadGateway, "upstream_error", "Upstream authentication failed, please contact administrator"
+	case 403:
+		return http.StatusBadGateway, "upstream_error", "Upstream access forbidden, please contact administrator"
+	case 429:
+		return http.StatusTooManyRequests, "rate_limit_error", "Upstream rate limit exceeded, please retry later"
+	case 529:
+		return http.StatusServiceUnavailable, "overloaded_error", "Upstream service overloaded, please retry later"
+	case 500, 502, 503, 504:
+		return http.StatusBadGateway, "upstream_error", "Upstream service temporarily unavailable"
+	default:
+		return http.StatusBadGateway, "upstream_error", "Upstream request failed"
+	}
+}
+
 // 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 {

backend/internal/handler/openai_gateway_handler.go

@@ -3,6 +3,7 @@ package handler
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -127,49 +128,74 @@ func (h *OpenAIGatewayHandler) Responses(c *gin.Context) {
 	// Generate session hash (from header for OpenAI)
 	sessionHash := h.gatewayService.GenerateSessionHash(c)
 
-	// Select account supporting the requested model
-	log.Printf("[OpenAI Handler] Selecting account: groupID=%v model=%s", apiKey.GroupID, reqModel)
-	account, err := h.gatewayService.SelectAccountForModel(c.Request.Context(), apiKey.GroupID, sessionHash, reqModel)
-	if err != nil {
-		log.Printf("[OpenAI Handler] SelectAccount failed: %v", err)
-		h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts: "+err.Error(), streamStarted)
-		return
-	}
-	log.Printf("[OpenAI Handler] Selected account: id=%d name=%s", account.ID, account.Name)
+	const maxAccountSwitches = 3
+	switchCount := 0
+	failedAccountIDs := make(map[int64]struct{})
+	lastFailoverStatus := 0
 
-	// 3. Acquire account concurrency slot
-	accountReleaseFunc, err := h.concurrencyHelper.AcquireAccountSlotWithWait(c, account.ID, account.Concurrency, reqStream, &streamStarted)
-	if err != nil {
-		log.Printf("Account concurrency acquire failed: %v", err)
-		h.handleConcurrencyError(c, err, "account", streamStarted)
-		return
-	}
-	if accountReleaseFunc != nil {
-		defer accountReleaseFunc()
-	}
+	for {
+		// Select account supporting the requested model
+		log.Printf("[OpenAI Handler] Selecting account: groupID=%v model=%s", apiKey.GroupID, reqModel)
+		account, err := h.gatewayService.SelectAccountForModelWithExclusions(c.Request.Context(), apiKey.GroupID, sessionHash, reqModel, failedAccountIDs)
+		if err != nil {
+			log.Printf("[OpenAI Handler] SelectAccount failed: %v", err)
+			if len(failedAccountIDs) == 0 {
+				h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts: "+err.Error(), streamStarted)
+				return
+			}
+			h.handleFailoverExhausted(c, lastFailoverStatus, streamStarted)
+			return
+		}
+		log.Printf("[OpenAI Handler] Selected account: id=%d name=%s", account.ID, account.Name)
 
-	// Forward request
-	result, err := h.gatewayService.Forward(c.Request.Context(), c, account, body)
-	if err != nil {
-		// Error response already handled in Forward, just log
-		log.Printf("Forward request failed: %v", err)
-		return
-	}
+		// 3. Acquire account concurrency slot
+		accountReleaseFunc, err := h.concurrencyHelper.AcquireAccountSlotWithWait(c, account.ID, account.Concurrency, reqStream, &streamStarted)
+		if err != nil {
+			log.Printf("Account concurrency acquire failed: %v", err)
+			h.handleConcurrencyError(c, err, "account", streamStarted)
+			return
+		}
 
-	// Async record usage
-	go func() {
-		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-		defer cancel()
-		if err := h.gatewayService.RecordUsage(ctx, &service.OpenAIRecordUsageInput{
-			Result:       result,
-			ApiKey:       apiKey,
-			User:         apiKey.User,
-			Account:      account,
-			Subscription: subscription,
-		}); err != nil {
-			log.Printf("Record usage failed: %v", err)
+		// Forward request
+		result, err := h.gatewayService.Forward(c.Request.Context(), c, account, body)
+		if accountReleaseFunc != nil {
+			accountReleaseFunc()
+		}
+		if err != nil {
+			var failoverErr *service.UpstreamFailoverError
+			if errors.As(err, &failoverErr) {
+				failedAccountIDs[account.ID] = struct{}{}
+				if switchCount >= maxAccountSwitches {
+					lastFailoverStatus = failoverErr.StatusCode
+					h.handleFailoverExhausted(c, lastFailoverStatus, streamStarted)
+					return
+				}
+				lastFailoverStatus = failoverErr.StatusCode
+				switchCount++
+				log.Printf("Account %d: upstream error %d, switching account %d/%d", account.ID, failoverErr.StatusCode, switchCount, maxAccountSwitches)
+				continue
+			}
+			// Error response already handled in Forward, just log
+			log.Printf("Forward request failed: %v", err)
+			return
 		}
-	}()
+
+		// Async record usage
+		go func(result *service.OpenAIForwardResult, usedAccount *service.Account) {
+			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+			defer cancel()
+			if err := h.gatewayService.RecordUsage(ctx, &service.OpenAIRecordUsageInput{
+				Result:       result,
+				ApiKey:       apiKey,
+				User:         apiKey.User,
+				Account:      usedAccount,
+				Subscription: subscription,
+			}); err != nil {
+				log.Printf("Record usage failed: %v", err)
+			}
+		}(result, account)
+		return
+	}
 }
 
 // handleConcurrencyError handles concurrency-related errors with proper 429 response
@@ -178,6 +204,28 @@ func (h *OpenAIGatewayHandler) handleConcurrencyError(c *gin.Context, err error,
 		fmt.Sprintf("Concurrency limit exceeded for %s, please retry later", slotType), streamStarted)
 }
 
+func (h *OpenAIGatewayHandler) handleFailoverExhausted(c *gin.Context, statusCode int, streamStarted bool) {
+	status, errType, errMsg := h.mapUpstreamError(statusCode)
+	h.handleStreamingAwareError(c, status, errType, errMsg, streamStarted)
+}
+
+func (h *OpenAIGatewayHandler) mapUpstreamError(statusCode int) (int, string, string) {
+	switch statusCode {
+	case 401:
+		return http.StatusBadGateway, "upstream_error", "Upstream authentication failed, please contact administrator"
+	case 403:
+		return http.StatusBadGateway, "upstream_error", "Upstream access forbidden, please contact administrator"
+	case 429:
+		return http.StatusTooManyRequests, "rate_limit_error", "Upstream rate limit exceeded, please retry later"
+	case 529:
+		return http.StatusServiceUnavailable, "upstream_error", "Upstream service overloaded, please retry later"
+	case 500, 502, 503, 504:
+		return http.StatusBadGateway, "upstream_error", "Upstream service temporarily unavailable"
+	default:
+		return http.StatusBadGateway, "upstream_error", "Upstream request failed"
+	}
+}
+
 // handleStreamingAwareError handles errors that may occur after streaming has started
 func (h *OpenAIGatewayHandler) handleStreamingAwareError(c *gin.Context, status int, errType, message string, streamStarted bool) {
 	if streamStarted {

backend/internal/service/gateway_service.go

@@ -81,6 +81,15 @@ type ForwardResult struct {
 	FirstTokenMs *int // 首字时间（流式请求）
 }
 
+// UpstreamFailoverError indicates an upstream error that should trigger account failover.
+type UpstreamFailoverError struct {
+	StatusCode int
+}
+
+func (e *UpstreamFailoverError) Error() string {
+	return fmt.Sprintf("upstream error: %d (failover)", e.StatusCode)
+}
+
 // GatewayService handles API gateway operations
 type GatewayService struct {
 	accountRepo         AccountRepository
@@ -274,19 +283,26 @@ func (s *GatewayService) SelectAccount(ctx context.Context, groupID *int64, sess
 
 // SelectAccountForModel 选择支持指定模型的账号（粘性会话+优先级+模型映射）
 func (s *GatewayService) SelectAccountForModel(ctx context.Context, groupID *int64, sessionHash string, requestedModel string) (*Account, error) {
+	return s.SelectAccountForModelWithExclusions(ctx, groupID, sessionHash, requestedModel, nil)
+}
+
+// SelectAccountForModelWithExclusions selects an account supporting the requested model while excluding specified accounts.
+func (s *GatewayService) SelectAccountForModelWithExclusions(ctx context.Context, groupID *int64, sessionHash string, requestedModel string, excludedIDs map[int64]struct{}) (*Account, error) {
 	// 1. 查询粘性会话
 	if sessionHash != "" {
 		accountID, err := s.cache.GetSessionAccountID(ctx, sessionHash)
 		if err == nil && accountID > 0 {
-			account, err := s.accountRepo.GetByID(ctx, accountID)
-			// 使用IsSchedulable代替IsActive，确保限流/过载账号不会被选中
-			// 同时检查模型支持
-			if err == nil && account.IsSchedulable() && (requestedModel == "" || account.IsModelSupported(requestedModel)) {
-				// 续期粘性会话
-				if err := s.cache.RefreshSessionTTL(ctx, sessionHash, stickySessionTTL); err != nil {
-					log.Printf("refresh session ttl failed: session=%s err=%v", sessionHash, err)
+			if _, excluded := excludedIDs[accountID]; !excluded {
+				account, err := s.accountRepo.GetByID(ctx, accountID)
+				// 使用IsSchedulable代替IsActive，确保限流/过载账号不会被选中
+				// 同时检查模型支持
+				if err == nil && account.IsSchedulable() && (requestedModel == "" || account.IsModelSupported(requestedModel)) {
+					// 续期粘性会话
+					if err := s.cache.RefreshSessionTTL(ctx, sessionHash, stickySessionTTL); err != nil {
+						log.Printf("refresh session ttl failed: session=%s err=%v", sessionHash, err)
+					}
+					return account, nil
 				}
-				return account, nil
 			}
 		}
 	}
@@ -307,6 +323,9 @@ func (s *GatewayService) SelectAccountForModel(ctx context.Context, groupID *int
 	var selected *Account
 	for i := range accounts {
 		acc := &accounts[i]
+		if _, excluded := excludedIDs[acc.ID]; excluded {
+			continue
+		}
 		// 检查模型支持
 		if requestedModel != "" && !acc.IsModelSupported(requestedModel) {
 			continue
@@ -394,6 +413,16 @@ func (s *GatewayService) shouldRetryUpstreamError(account *Account, statusCode i
 	return !account.ShouldHandleErrorCode(statusCode)
 }
 
+// shouldFailoverUpstreamError determines whether an upstream error should trigger account failover.
+func (s *GatewayService) shouldFailoverUpstreamError(statusCode int) bool {
+	switch statusCode {
+	case 401, 403, 429, 529:
+		return true
+	default:
+		return statusCode >= 500
+	}
+}
+
 // Forward 转发请求到Claude API
 func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *Account, body []byte) (*ForwardResult, error) {
 	startTime := time.Now()
@@ -478,9 +507,19 @@ func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *A
 
 	// 处理重试耗尽的情况
 	if resp.StatusCode >= 400 && s.shouldRetryUpstreamError(account, resp.StatusCode) {
+		if s.shouldFailoverUpstreamError(resp.StatusCode) {
+			s.handleRetryExhaustedSideEffects(ctx, resp, account)
+			return nil, &UpstreamFailoverError{StatusCode: resp.StatusCode}
+		}
 		return s.handleRetryExhaustedError(ctx, resp, c, account)
 	}
 
+	// 处理可切换账号的错误
+	if resp.StatusCode >= 400 && s.shouldFailoverUpstreamError(resp.StatusCode) {
+		s.handleFailoverSideEffects(ctx, resp, account)
+		return nil, &UpstreamFailoverError{StatusCode: resp.StatusCode}
+	}
+
 	// 处理错误响应（不可重试的错误）
 	if resp.StatusCode >= 400 {
 		return s.handleErrorResponse(ctx, resp, c, account)
@@ -692,10 +731,7 @@ func (s *GatewayService) handleErrorResponse(ctx context.Context, resp *http.Res
 	return nil, fmt.Errorf("upstream error: %d", resp.StatusCode)
 }
 
-// handleRetryExhaustedError 处理重试耗尽后的错误
-// OAuth 403：标记账号异常
-// API Key 未配置错误码：仅返回错误，不标记账号
-func (s *GatewayService) handleRetryExhaustedError(ctx context.Context, resp *http.Response, c *gin.Context, account *Account) (*ForwardResult, error) {
+func (s *GatewayService) handleRetryExhaustedSideEffects(ctx context.Context, resp *http.Response, account *Account) {
 	body, _ := io.ReadAll(resp.Body)
 	statusCode := resp.StatusCode
 
@@ -707,6 +743,18 @@ func (s *GatewayService) handleRetryExhaustedError(ctx context.Context, resp *ht
 		// API Key 未配置错误码：不标记账号状态
 		log.Printf("Account %d: upstream error %d after %d retries (not marking account)", account.ID, statusCode, maxRetries)
 	}
+}
+
+func (s *GatewayService) handleFailoverSideEffects(ctx context.Context, resp *http.Response, account *Account) {
+	body, _ := io.ReadAll(resp.Body)
+	s.rateLimitService.HandleUpstreamError(ctx, account, resp.StatusCode, resp.Header, body)
+}
+
+// handleRetryExhaustedError 处理重试耗尽后的错误
+// OAuth 403：标记账号异常
+// API Key 未配置错误码：仅返回错误，不标记账号
+func (s *GatewayService) handleRetryExhaustedError(ctx context.Context, resp *http.Response, c *gin.Context, account *Account) (*ForwardResult, error) {
+	s.handleRetryExhaustedSideEffects(ctx, resp, account)
 
 	// 返回统一的重试耗尽错误响应
 	c.JSON(http.StatusBadGateway, gin.H{
@@ -717,7 +765,7 @@ func (s *GatewayService) handleRetryExhaustedError(ctx context.Context, resp *ht
 		},
 	})
 
-	return nil, fmt.Errorf("upstream error: %d (retries exhausted)", statusCode)
+	return nil, fmt.Errorf("upstream error: %d (retries exhausted)", resp.StatusCode)
 }
 
 // streamingResult 流式响应结果

backend/internal/service/openai_gateway_service.go

@@ -129,15 +129,22 @@ func (s *OpenAIGatewayService) SelectAccount(ctx context.Context, groupID *int64
 
 // SelectAccountForModel selects an account supporting the requested model
 func (s *OpenAIGatewayService) SelectAccountForModel(ctx context.Context, groupID *int64, sessionHash string, requestedModel string) (*Account, error) {
+	return s.SelectAccountForModelWithExclusions(ctx, groupID, sessionHash, requestedModel, nil)
+}
+
+// SelectAccountForModelWithExclusions selects an account supporting the requested model while excluding specified accounts.
+func (s *OpenAIGatewayService) SelectAccountForModelWithExclusions(ctx context.Context, groupID *int64, sessionHash string, requestedModel string, excludedIDs map[int64]struct{}) (*Account, error) {
 	// 1. Check sticky session
 	if sessionHash != "" {
 		accountID, err := s.cache.GetSessionAccountID(ctx, "openai:"+sessionHash)
 		if err == nil && accountID > 0 {
-			account, err := s.accountRepo.GetByID(ctx, accountID)
-			if err == nil && account.IsSchedulable() && account.IsOpenAI() && (requestedModel == "" || account.IsModelSupported(requestedModel)) {
-				// Refresh sticky session TTL
-				_ = s.cache.RefreshSessionTTL(ctx, "openai:"+sessionHash, openaiStickySessionTTL)
-				return account, nil
+			if _, excluded := excludedIDs[accountID]; !excluded {
+				account, err := s.accountRepo.GetByID(ctx, accountID)
+				if err == nil && account.IsSchedulable() && account.IsOpenAI() && (requestedModel == "" || account.IsModelSupported(requestedModel)) {
+					// Refresh sticky session TTL
+					_ = s.cache.RefreshSessionTTL(ctx, "openai:"+sessionHash, openaiStickySessionTTL)
+					return account, nil
+				}
 			}
 		}
 	}
@@ -158,6 +165,9 @@ func (s *OpenAIGatewayService) SelectAccountForModel(ctx context.Context, groupI
 	var selected *Account
 	for i := range accounts {
 		acc := &accounts[i]
+		if _, excluded := excludedIDs[acc.ID]; excluded {
+			continue
+		}
 		// Check model support
 		if requestedModel != "" && !acc.IsModelSupported(requestedModel) {
 			continue
@@ -221,6 +231,20 @@ func (s *OpenAIGatewayService) GetAccessToken(ctx context.Context, account *Acco
 	}
 }
 
+func (s *OpenAIGatewayService) shouldFailoverUpstreamError(statusCode int) bool {
+	switch statusCode {
+	case 401, 403, 429, 529:
+		return true
+	default:
+		return statusCode >= 500
+	}
+}
+
+func (s *OpenAIGatewayService) handleFailoverSideEffects(ctx context.Context, resp *http.Response, account *Account) {
+	body, _ := io.ReadAll(resp.Body)
+	s.rateLimitService.HandleUpstreamError(ctx, account, resp.StatusCode, resp.Header, body)
+}
+
 // Forward forwards request to OpenAI API
 func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, account *Account, body []byte) (*OpenAIForwardResult, error) {
 	startTime := time.Now()
@@ -288,6 +312,10 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 
 	// Handle error response
 	if resp.StatusCode >= 400 {
+		if s.shouldFailoverUpstreamError(resp.StatusCode) {
+			s.handleFailoverSideEffects(ctx, resp, account)
+			return nil, &UpstreamFailoverError{StatusCode: resp.StatusCode}
+		}
 		return s.handleErrorResponse(ctx, resp, c, account)
 	}