fix(openai): fail over passthrough 429 and 529

backend/internal/service/openai_gateway_service.go

@@ -2544,7 +2544,11 @@ func (s *OpenAIGatewayService) forwardOpenAIPassthrough(
 	defer func() { _ = resp.Body.Close() }()
 
 	if resp.StatusCode >= 400 {
-		// 透传模式不做 failover（避免改变原始上游语义），按上游原样返回错误响应。
+		// 透传模式默认保持原样代理；但 429/529 属于网关必须兜底的
+		// 上游容量类错误，应先触发多账号 failover 以维持基础 SLA。
+		if shouldFailoverOpenAIPassthroughResponse(resp.StatusCode) {
+			return nil, s.handleFailoverErrorResponsePassthrough(ctx, resp, c, account, body)
+		}
 		return nil, s.handleErrorResponsePassthrough(ctx, resp, c, account, body)
 	}
 
@@ -2727,6 +2731,58 @@ func (s *OpenAIGatewayService) buildUpstreamRequestOpenAIPassthrough(
 	return req, nil
 }
 
+func shouldFailoverOpenAIPassthroughResponse(statusCode int) bool {
+	switch statusCode {
+	case http.StatusTooManyRequests, 529:
+		return true
+	default:
+		return false
+	}
+}
+
+func (s *OpenAIGatewayService) handleFailoverErrorResponsePassthrough(
+	ctx context.Context,
+	resp *http.Response,
+	c *gin.Context,
+	account *Account,
+	requestBody []byte,
+) error {
+	body, _ := io.ReadAll(io.LimitReader(resp.Body, 2<<20))
+
+	upstreamMsg := strings.TrimSpace(extractUpstreamErrorMessage(body))
+	upstreamMsg = sanitizeUpstreamErrorMessage(upstreamMsg)
+	upstreamDetail := ""
+	if s.cfg != nil && s.cfg.Gateway.LogUpstreamErrorBody {
+		maxBytes := s.cfg.Gateway.LogUpstreamErrorBodyMaxBytes
+		if maxBytes <= 0 {
+			maxBytes = 2048
+		}
+		upstreamDetail = truncateString(string(body), maxBytes)
+	}
+	setOpsUpstreamError(c, resp.StatusCode, upstreamMsg, upstreamDetail)
+	logOpenAIInstructionsRequiredDebug(ctx, c, account, resp.StatusCode, upstreamMsg, requestBody, body)
+	if s.rateLimitService != nil {
+		_ = s.rateLimitService.HandleUpstreamError(ctx, account, resp.StatusCode, resp.Header, body)
+	}
+	appendOpsUpstreamError(c, OpsUpstreamErrorEvent{
+		Platform:             account.Platform,
+		AccountID:            account.ID,
+		AccountName:          account.Name,
+		UpstreamStatusCode:   resp.StatusCode,
+		UpstreamRequestID:    resp.Header.Get("x-request-id"),
+		Passthrough:          true,
+		Kind:                 "failover",
+		Message:              upstreamMsg,
+		Detail:               upstreamDetail,
+		UpstreamResponseBody: upstreamDetail,
+	})
+	return &UpstreamFailoverError{
+		StatusCode:      resp.StatusCode,
+		ResponseBody:    body,
+		ResponseHeaders: resp.Header.Clone(),
+	}
+}
+
 func (s *OpenAIGatewayService) handleErrorResponsePassthrough(
 	ctx context.Context,
 	resp *http.Response,

backend/internal/service/openai_oauth_passthrough_test.go

@@ -48,6 +48,22 @@ func (u *httpUpstreamRecorder) DoWithTLS(req *http.Request, proxyURL string, acc
 	return u.Do(req, proxyURL, accountID, accountConcurrency)
 }
 
+type openAIPassthroughFailoverRepo struct {
+	stubOpenAIAccountRepo
+	rateLimitCalls []time.Time
+	overloadCalls  []time.Time
+}
+
+func (r *openAIPassthroughFailoverRepo) SetRateLimited(_ context.Context, _ int64, resetAt time.Time) error {
+	r.rateLimitCalls = append(r.rateLimitCalls, resetAt)
+	return nil
+}
+
+func (r *openAIPassthroughFailoverRepo) SetOverloaded(_ context.Context, _ int64, until time.Time) error {
+	r.overloadCalls = append(r.overloadCalls, until)
+	return nil
+}
+
 var structuredLogCaptureMu sync.Mutex
 
 type inMemoryLogSink struct {
@@ -527,6 +543,8 @@ func TestOpenAIGatewayService_OAuthPassthrough_UpstreamErrorIncludesPassthroughF
 
 	_, err := svc.Forward(context.Background(), c, account, originalBody)
 	require.Error(t, err)
+	require.True(t, c.Writer.Written(), "非 429/529 的 passthrough 错误应继续原样写回客户端")
+	require.Equal(t, http.StatusBadRequest, rec.Code)
 
 	// should append an upstream error event with passthrough=true
 	v, ok := c.Get(OpsUpstreamErrorsKey)
@@ -535,29 +553,116 @@ func TestOpenAIGatewayService_OAuthPassthrough_UpstreamErrorIncludesPassthroughF
 	require.True(t, ok)
 	require.NotEmpty(t, arr)
 	require.True(t, arr[len(arr)-1].Passthrough)
+	require.Equal(t, "http_error", arr[len(arr)-1].Kind)
 }
 
-func TestOpenAIGatewayService_OAuthPassthrough_429PersistsRateLimit(t *testing.T) {
+func TestOpenAIGatewayService_OpenAIPassthrough_429And529TriggerFailover(t *testing.T) {
 	gin.SetMode(gin.TestMode)
+	originalBody := []byte(`{"model":"gpt-5.2","stream":false,"instructions":"local-test-instructions","input":[{"type":"text","text":"hi"}]}`)
+
+	newAccount := func(accountType string) *Account {
+		account := &Account{
+			ID:             123,
+			Name:           "acc",
+			Platform:       PlatformOpenAI,
+			Type:           accountType,
+			Concurrency:    1,
+			Extra:          map[string]any{"openai_passthrough": true},
+			Status:         StatusActive,
+			Schedulable:    true,
+			RateMultiplier: f64p(1),
+		}
+		switch accountType {
+		case AccountTypeOAuth:
+			account.Credentials = map[string]any{"access_token": "oauth-token", "chatgpt_account_id": "chatgpt-acc"}
+		case AccountTypeAPIKey:
+			account.Credentials = map[string]any{"api_key": "sk-test"}
+		}
+		return account
+	}
+
+	testCases := []struct {
+		name        string
+		accountType string
+		statusCode  int
+		body        string
+		assertRepo  func(t *testing.T, repo *openAIPassthroughFailoverRepo, start time.Time)
+	}{
+		{
+			name:        "oauth_429_rate_limit",
+			accountType: AccountTypeOAuth,
+			statusCode:  http.StatusTooManyRequests,
+			body: func() string {
+				resetAt := time.Now().Add(7 * 24 * time.Hour).Unix()
+				return fmt.Sprintf(`{"error":{"message":"The usage limit has been reached","type":"usage_limit_reached","resets_at":%d}}`, resetAt)
+			}(),
+			assertRepo: func(t *testing.T, repo *openAIPassthroughFailoverRepo, _ time.Time) {
+				require.Len(t, repo.rateLimitCalls, 1)
+				require.Empty(t, repo.overloadCalls)
+				require.True(t, time.Until(repo.rateLimitCalls[0]) > 24*time.Hour)
+			},
+		},
+		{
+			name:        "oauth_529_overload",
+			accountType: AccountTypeOAuth,
+			statusCode:  529,
+			body:        `{"error":{"message":"server overloaded","type":"server_error"}}`,
+			assertRepo: func(t *testing.T, repo *openAIPassthroughFailoverRepo, start time.Time) {
+				require.Empty(t, repo.rateLimitCalls)
+				require.Len(t, repo.overloadCalls, 1)
+				require.WithinDuration(t, start.Add(10*time.Minute), repo.overloadCalls[0], 5*time.Second)
+			},
+		},
+		{
+			name:        "apikey_429_rate_limit",
+			accountType: AccountTypeAPIKey,
+			statusCode:  http.StatusTooManyRequests,
+			body: func() string {
+				resetAt := time.Now().Add(7 * 24 * time.Hour).Unix()
+				return fmt.Sprintf(`{"error":{"message":"The usage limit has been reached","type":"usage_limit_reached","resets_at":%d}}`, resetAt)
+			}(),
+			assertRepo: func(t *testing.T, repo *openAIPassthroughFailoverRepo, _ time.Time) {
+				require.Len(t, repo.rateLimitCalls, 1)
+				require.Empty(t, repo.overloadCalls)
+				require.True(t, time.Until(repo.rateLimitCalls[0]) > 24*time.Hour)
+			},
+		},
+		{
+			name:        "apikey_529_overload",
+			accountType: AccountTypeAPIKey,
+			statusCode:  529,
+			body:        `{"error":{"message":"server overloaded","type":"server_error"}}`,
+			assertRepo: func(t *testing.T, repo *openAIPassthroughFailoverRepo, start time.Time) {
+				require.Empty(t, repo.rateLimitCalls)
+				require.Len(t, repo.overloadCalls, 1)
+				require.WithinDuration(t, start.Add(10*time.Minute), repo.overloadCalls[0], 5*time.Second)
+			},
+		},
+	}
 
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
 			rec := httptest.NewRecorder()
 			c, _ := gin.CreateTestContext(rec)
 			c.Request = httptest.NewRequest(http.MethodPost, "/v1/responses", bytes.NewReader(nil))
 			c.Request.Header.Set("User-Agent", "codex_cli_rs/0.1.0")
 
-	originalBody := []byte(`{"model":"gpt-5.2","stream":false,"instructions":"local-test-instructions","input":[{"type":"text","text":"hi"}]}`)
-	resetAt := time.Now().Add(7 * 24 * time.Hour).Unix()
 			resp := &http.Response{
-		StatusCode: http.StatusTooManyRequests,
+				StatusCode: tc.statusCode,
 				Header: http.Header{
 					"Content-Type": []string{"application/json"},
-			"x-request-id": []string{"rid-rate-limit"},
+					"x-request-id": []string{"rid-failover"},
 				},
-		Body: io.NopCloser(strings.NewReader(fmt.Sprintf(`{"error":{"message":"The usage limit has been reached","type":"usage_limit_reached","resets_at":%d}}`, resetAt))),
+				Body: io.NopCloser(strings.NewReader(tc.body)),
 			}
 			upstream := &httpUpstreamRecorder{resp: resp}
-	repo := &openAIWSRateLimitSignalRepo{}
-	rateSvc := &RateLimitService{accountRepo: repo}
+			repo := &openAIPassthroughFailoverRepo{}
+			rateSvc := &RateLimitService{
+				accountRepo: repo,
+				cfg: &config.Config{
+					RateLimit: config.RateLimitConfig{OverloadCooldownMinutes: 10},
+				},
+			}
 
 			svc := &OpenAIGatewayService{
 				cfg:              &config.Config{Gateway: config.GatewayConfig{ForceCodexCLI: false}},
@@ -565,25 +670,28 @@ func TestOpenAIGatewayService_OAuthPassthrough_429PersistsRateLimit(t *testing.T
 				rateLimitService: rateSvc,
 			}
 
-	account := &Account{
-		ID:             123,
-		Name:           "acc",
-		Platform:       PlatformOpenAI,
-		Type:           AccountTypeOAuth,
-		Concurrency:    1,
-		Credentials:    map[string]any{"access_token": "oauth-token", "chatgpt_account_id": "chatgpt-acc"},
-		Extra:          map[string]any{"openai_passthrough": true},
-		Status:         StatusActive,
-		Schedulable:    true,
-		RateMultiplier: f64p(1),
-	}
-
+			account := newAccount(tc.accountType)
+			start := time.Now()
 			_, err := svc.Forward(context.Background(), c, account, originalBody)
 			require.Error(t, err)
-	require.Equal(t, http.StatusTooManyRequests, rec.Code)
-	require.Contains(t, rec.Body.String(), "usage_limit_reached")
-	require.Len(t, repo.rateLimitCalls, 1)
-	require.WithinDuration(t, time.Unix(resetAt, 0), repo.rateLimitCalls[0], 2*time.Second)
+
+			var failoverErr *UpstreamFailoverError
+			require.ErrorAs(t, err, &failoverErr)
+			require.Equal(t, tc.statusCode, failoverErr.StatusCode)
+			require.False(t, c.Writer.Written(), "429/529 passthrough 应返回 failover 错误给上层换号，而不是直接向客户端写响应")
+
+			v, ok := c.Get(OpsUpstreamErrorsKey)
+			require.True(t, ok)
+			arr, ok := v.([]*OpsUpstreamErrorEvent)
+			require.True(t, ok)
+			require.NotEmpty(t, arr)
+			require.True(t, arr[len(arr)-1].Passthrough)
+			require.Equal(t, "failover", arr[len(arr)-1].Kind)
+			require.Equal(t, tc.statusCode, arr[len(arr)-1].UpstreamStatusCode)
+
+			tc.assertRepo(t, repo, start)
+		})
+	}
 }
 
 func TestOpenAIGatewayService_OAuthPassthrough_NonCodexUAFallbackToCodexUA(t *testing.T) {