refactor: improve model resolution and normalization logic for OpenAI integration

backend/internal/service/openai_gateway_service.go

@@ -1778,29 +1778,29 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 	}
 
 	// 对所有请求执行模型映射（包含 Codex CLI）。
-	mappedModel := account.GetMappedModel(reqModel)
-	if mappedModel != reqModel {
-		logger.LegacyPrintf("service.openai_gateway", "[OpenAI] Model mapping applied: %s -> %s (account: %s, isCodexCLI: %v)", reqModel, mappedModel, account.Name, isCodexCLI)
-		reqBody["model"] = mappedModel
+	billingModel := account.GetMappedModel(reqModel)
+	if billingModel != reqModel {
+		logger.LegacyPrintf("service.openai_gateway", "[OpenAI] Model mapping applied: %s -> %s (account: %s, isCodexCLI: %v)", reqModel, billingModel, account.Name, isCodexCLI)
+		reqBody["model"] = billingModel
 		bodyModified = true
-		markPatchSet("model", mappedModel)
+		markPatchSet("model", billingModel)
 	}
+	upstreamModel := billingModel
 
 	// 针对所有 OpenAI 账号执行 Codex 模型名规范化，确保上游识别一致。
 	if model, ok := reqBody["model"].(string); ok {
-		normalizedModel := normalizeCodexModel(model)
-		if normalizedModel != "" && normalizedModel != model {
-			logger.LegacyPrintf("service.openai_gateway", "[OpenAI] Codex model normalization: %s -> %s (account: %s, type: %s, isCodexCLI: %v)",
-				model, normalizedModel, account.Name, account.Type, isCodexCLI)
-			reqBody["model"] = normalizedModel
-			mappedModel = normalizedModel
+		upstreamModel = resolveOpenAIUpstreamModel(model)
+		if upstreamModel != "" && upstreamModel != model {
+			logger.LegacyPrintf("service.openai_gateway", "[OpenAI] Upstream model resolved: %s -> %s (account: %s, type: %s, isCodexCLI: %v)",
+				model, upstreamModel, account.Name, account.Type, isCodexCLI)
+			reqBody["model"] = upstreamModel
 			bodyModified = true
-			markPatchSet("model", normalizedModel)
+			markPatchSet("model", upstreamModel)
 		}
 
 		// 移除 gpt-5.2-codex 以下的版本 verbosity 参数
 		// 确保高版本模型向低版本模型映射不报错
-		if !SupportsVerbosity(normalizedModel) {
+		if !SupportsVerbosity(upstreamModel) {
 			if text, ok := reqBody["text"].(map[string]any); ok {
 				delete(text, "verbosity")
 			}
@@ -1824,7 +1824,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 			disablePatch()
 		}
 		if codexResult.NormalizedModel != "" {
-			mappedModel = codexResult.NormalizedModel
+			upstreamModel = codexResult.NormalizedModel
 		}
 		if codexResult.PromptCacheKey != "" {
 			promptCacheKey = codexResult.PromptCacheKey
@@ -1941,7 +1941,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 			"forward_start account_id=%d account_type=%s model=%s stream=%v has_previous_response_id=%v",
 			account.ID,
 			account.Type,
-			mappedModel,
+			upstreamModel,
 			reqStream,
 			hasPreviousResponseID,
 		)
@@ -2030,7 +2030,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 				isCodexCLI,
 				reqStream,
 				originalModel,
-				mappedModel,
+				upstreamModel,
 				startTime,
 				attempt,
 				wsLastFailureReason,
@@ -2131,7 +2131,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 				firstTokenMs,
 				wsAttempts,
 			)
-			wsResult.UpstreamModel = mappedModel
+			wsResult.UpstreamModel = upstreamModel
 			return wsResult, nil
 		}
 		s.writeOpenAIWSFallbackErrorResponse(c, account, wsErr)
@@ -2236,14 +2236,14 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 		var usage *OpenAIUsage
 		var firstTokenMs *int
 		if reqStream {
-			streamResult, err := s.handleStreamingResponse(ctx, resp, c, account, startTime, originalModel, mappedModel)
+			streamResult, err := s.handleStreamingResponse(ctx, resp, c, account, startTime, originalModel, upstreamModel)
 			if err != nil {
 				return nil, err
 			}
 			usage = streamResult.usage
 			firstTokenMs = streamResult.firstTokenMs
 		} else {
-			usage, err = s.handleNonStreamingResponse(ctx, resp, c, account, originalModel, mappedModel)
+			usage, err = s.handleNonStreamingResponse(ctx, resp, c, account, originalModel, upstreamModel)
 			if err != nil {
 				return nil, err
 			}
@@ -2267,7 +2267,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 			RequestID:       resp.Header.Get("x-request-id"),
 			Usage:           *usage,
 			Model:           originalModel,
-			UpstreamModel:   mappedModel,
+			UpstreamModel:   upstreamModel,
 			ServiceTier:     serviceTier,
 			ReasoningEffort: reasoningEffort,
 			Stream:          reqStream,