fix(provider): retain upstream model for gemini compat and ws

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent

)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/internal/service/gemini_messages_compat_service.go

@@ -1028,14 +1028,15 @@ func (s *GeminiMessagesCompatService) Forward(ctx context.Context, c *gin.Contex
 	}
 
 	return &ForwardResult{
-		RequestID:    requestID,
-		Usage:        *usage,
-		Model:        originalModel,
-		Stream:       req.Stream,
-		Duration:     time.Since(startTime),
-		FirstTokenMs: firstTokenMs,
-		ImageCount:   imageCount,
-		ImageSize:    imageSize,
+		RequestID:     requestID,
+		Usage:         *usage,
+		Model:         originalModel,
+		UpstreamModel: mappedModel,
+		Stream:        req.Stream,
+		Duration:      time.Since(startTime),
+		FirstTokenMs:  firstTokenMs,
+		ImageCount:    imageCount,
+		ImageSize:     imageSize,
 	}, nil
 }
 
@@ -1241,12 +1242,13 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 				estimated := estimateGeminiCountTokens(body)
 				c.JSON(http.StatusOK, map[string]any{"totalTokens": estimated})
 				return &ForwardResult{
-					RequestID:    "",
-					Usage:        ClaudeUsage{},
-					Model:        originalModel,
-					Stream:       false,
-					Duration:     time.Since(startTime),
-					FirstTokenMs: nil,
+					RequestID:     "",
+					Usage:         ClaudeUsage{},
+					Model:         originalModel,
+					UpstreamModel: mappedModel,
+					Stream:        false,
+					Duration:      time.Since(startTime),
+					FirstTokenMs:  nil,
 				}, nil
 			}
 			setOpsUpstreamError(c, 0, safeErr, "")
@@ -1310,12 +1312,13 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 				estimated := estimateGeminiCountTokens(body)
 				c.JSON(http.StatusOK, map[string]any{"totalTokens": estimated})
 				return &ForwardResult{
-					RequestID:    "",
-					Usage:        ClaudeUsage{},
-					Model:        originalModel,
-					Stream:       false,
-					Duration:     time.Since(startTime),
-					FirstTokenMs: nil,
+					RequestID:     "",
+					Usage:         ClaudeUsage{},
+					Model:         originalModel,
+					UpstreamModel: mappedModel,
+					Stream:        false,
+					Duration:      time.Since(startTime),
+					FirstTokenMs:  nil,
 				}, nil
 			}
 			// Final attempt: surface the upstream error body (passed through below) instead of a generic retry error.
@@ -1350,12 +1353,13 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 			estimated := estimateGeminiCountTokens(body)
 			c.JSON(http.StatusOK, map[string]any{"totalTokens": estimated})
 			return &ForwardResult{
-				RequestID:    requestID,
-				Usage:        ClaudeUsage{},
-				Model:        originalModel,
-				Stream:       false,
-				Duration:     time.Since(startTime),
-				FirstTokenMs: nil,
+				RequestID:     requestID,
+				Usage:         ClaudeUsage{},
+				Model:         originalModel,
+				UpstreamModel: mappedModel,
+				Stream:        false,
+				Duration:      time.Since(startTime),
+				FirstTokenMs:  nil,
 			}, nil
 		}
 
@@ -1527,14 +1531,15 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 	}
 
 	return &ForwardResult{
-		RequestID:    requestID,
-		Usage:        *usage,
-		Model:        originalModel,
-		Stream:       stream,
-		Duration:     time.Since(startTime),
-		FirstTokenMs: firstTokenMs,
-		ImageCount:   imageCount,
-		ImageSize:    imageSize,
+		RequestID:     requestID,
+		Usage:         *usage,
+		Model:         originalModel,
+		UpstreamModel: mappedModel,
+		Stream:        stream,
+		Duration:      time.Since(startTime),
+		FirstTokenMs:  firstTokenMs,
+		ImageCount:    imageCount,
+		ImageSize:     imageSize,
 	}, nil
 }
 

backend/internal/service/gemini_messages_compat_service_test.go

 package service
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -15,6 +16,30 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+type geminiCompatHTTPUpstreamStub struct {
+	response *http.Response
+	err      error
+	calls    int
+	lastReq  *http.Request
+}
+
+func (s *geminiCompatHTTPUpstreamStub) Do(req *http.Request, proxyURL string, accountID int64, accountConcurrency int) (*http.Response, error) {
+	s.calls++
+	s.lastReq = req
+	if s.err != nil {
+		return nil, s.err
+	}
+	if s.response == nil {
+		return nil, fmt.Errorf("missing stub response")
+	}
+	resp := *s.response
+	return &resp, nil
+}
+
+func (s *geminiCompatHTTPUpstreamStub) DoWithTLS(req *http.Request, proxyURL string, accountID int64, accountConcurrency int, enableTLSFingerprint bool) (*http.Response, error) {
+	return s.Do(req, proxyURL, accountID, accountConcurrency)
+}
+
 // TestConvertClaudeToolsToGeminiTools_CustomType 测试custom类型工具转换
 func TestConvertClaudeToolsToGeminiTools_CustomType(t *testing.T) {
 	tests := []struct {
@@ -170,6 +195,42 @@ func TestGeminiHandleNativeNonStreamingResponse_DebugDisabledDoesNotEmitHeaderLo
 	require.False(t, logSink.ContainsMessage("[GeminiAPI]"), "debug 关闭时不应输出 Gemini 响应头日志")
 }
 
+func TestGeminiMessagesCompatServiceForward_PreservesRequestedModelAndMappedUpstreamModel(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Request = httptest.NewRequest(http.MethodPost, "/v1/messages", nil)
+
+	httpStub := &geminiCompatHTTPUpstreamStub{
+		response: &http.Response{
+			StatusCode: http.StatusOK,
+			Header:     http.Header{"x-request-id": []string{"gemini-req-1"}},
+			Body:       io.NopCloser(strings.NewReader(`{"candidates":[{"content":{"parts":[{"text":"hello"}]}}],"usageMetadata":{"promptTokenCount":10,"candidatesTokenCount":5}}`)),
+		},
+	}
+	svc := &GeminiMessagesCompatService{httpUpstream: httpStub, cfg: &config.Config{}}
+	account := &Account{
+		ID:   1,
+		Type: AccountTypeAPIKey,
+		Credentials: map[string]any{
+			"api_key": "test-key",
+			"model_mapping": map[string]any{
+				"claude-sonnet-4": "claude-sonnet-4-20250514",
+			},
+		},
+	}
+	body := []byte(`{"model":"claude-sonnet-4","max_tokens":16,"messages":[{"role":"user","content":"hello"}]}`)
+
+	result, err := svc.Forward(context.Background(), c, account, body)
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, "claude-sonnet-4", result.Model)
+	require.Equal(t, "claude-sonnet-4-20250514", result.UpstreamModel)
+	require.Equal(t, 1, httpStub.calls)
+	require.NotNil(t, httpStub.lastReq)
+	require.Contains(t, httpStub.lastReq.URL.String(), "/models/claude-sonnet-4-20250514:")
+}
+
 func TestConvertClaudeMessagesToGeminiGenerateContent_AddsThoughtSignatureForToolUse(t *testing.T) {
 	claudeReq := map[string]any{
 		"model":      "claude-haiku-4-5-20251001",

backend/internal/service/openai_ws_forwarder.go

@@ -2328,6 +2328,7 @@ func (s *OpenAIGatewayService) forwardOpenAIWSV2(
 		RequestID:       responseID,
 		Usage:           *usage,
 		Model:           originalModel,
+		UpstreamModel:   mappedModel,
 		ServiceTier:     extractOpenAIServiceTier(reqBody),
 		ReasoningEffort: extractOpenAIReasoningEffort(reqBody, originalModel),
 		Stream:          reqStream,
@@ -2945,6 +2946,7 @@ func (s *OpenAIGatewayService) ProxyResponsesWebSocketFromClient(
 					RequestID:       responseID,
 					Usage:           usage,
 					Model:           originalModel,
+					UpstreamModel:   mappedModel,
 					ServiceTier:     extractOpenAIServiceTierFromBody(payload),
 					ReasoningEffort: extractOpenAIReasoningEffortFromBody(payload, originalModel),
 					Stream:          reqStream,