🤖 fix: limit response model mapping to API output

What:
- capture upstream response data before response model rewriting
- keep proxy request and upstream attempt response models unchanged
- update backend e2e assertions for unmapped recorded response models

Why:
- response model aliases should only affect the final client-facing API response
- database records and operational logs should preserve upstream model identity

Tests:
- go test -count=1 ./internal/executor ./internal/handler ./tests/e2e -run 'Test.*Provider|Test.*ModelMapping|Test.*ResponseModelMapping|TestGenericProxyResponseModelMappingE2E'
- go test -count=1 ./tests/e2e
- go test -count=1 ./...
- pnpm -C web typecheck
- git diff --check

Author: awsl233777

internal/executor/executor.go

@@ -341,7 +341,7 @@ func (e *Executor) processAdapterEvents(eventChan domain.AdapterEventChan, attem
 				}
 			case domain.EventResponseModel:
 				if event.ResponseModel != "" {
-					attempt.ResponseModel = MapResponseModel(event.ResponseModel, responseModelMapping)
+					attempt.ResponseModel = event.ResponseModel
 				}
 			case domain.EventFirstToken:
 				if event.FirstTokenTime > 0 {
@@ -423,7 +423,7 @@ func (e *Executor) processAdapterEventsRealtime(
 				}
 			case domain.EventResponseModel:
 				if ev.ResponseModel != "" {
-					attempt.ResponseModel = MapResponseModel(ev.ResponseModel, responseModelMapping)
+					attempt.ResponseModel = ev.ResponseModel
 					dirty = true
 				}
 			case domain.EventFirstToken:

internal/executor/middleware_dispatch.go

@@ -156,24 +156,24 @@ func (e *Executor) dispatch(c *flow.Ctx) {
 			eventDone := make(chan struct{})
 			go e.processAdapterEventsRealtime(eventChan, attemptRecord, eventDone, clearDetail, responseModelMapping)
 
+			originalWriter := c.Writer
 			var responseWriter http.ResponseWriter
 			var convertingWriter *ConvertingResponseWriter
 			var responseModelWriter *ResponseModelMappingWriter
-			responseCapture := NewResponseCapture(c.Writer)
-			finalWriter := http.ResponseWriter(responseCapture)
+			finalWriter := http.ResponseWriter(originalWriter)
 			if len(responseModelMapping) > 0 {
-				responseModelWriter = NewResponseModelMappingWriter(responseCapture, responseModelMapping, state.isStream)
+				responseModelWriter = NewResponseModelMappingWriter(originalWriter, responseModelMapping, state.isStream)
 				finalWriter = responseModelWriter
 			}
+			responseCapture := NewResponseCapture(finalWriter)
 			if needsConversion {
 				convertingWriter = NewConvertingResponseWriter(
-					finalWriter, e.converter, originalClientType, currentClientType, state.isStream, state.originalRequestBody)
+					responseCapture, e.converter, originalClientType, currentClientType, state.isStream, state.originalRequestBody)
 				responseWriter = convertingWriter
 			} else {
-				responseWriter = finalWriter
+				responseWriter = responseCapture
 			}
 
-			originalWriter := c.Writer
 			c.Writer = responseWriter
 			err := matchedRoute.ProviderAdapter.Execute(c, matchedRoute.Provider)
 			c.Writer = originalWriter

internal/executor/response_capture.go

@@ -23,6 +23,11 @@ func NewResponseCapture(w http.ResponseWriter) *ResponseCapture {
 	}
 }
 
+// SetResponseWriter changes the downstream writer while preserving captured data.
+func (rc *ResponseCapture) SetResponseWriter(w http.ResponseWriter) {
+	rc.ResponseWriter = w
+}
+
 // WriteHeader captures the status code and forwards to underlying writer
 func (rc *ResponseCapture) WriteHeader(code int) {
 	rc.statusCode = code

internal/handler/provider_proxy.go

@@ -140,14 +140,15 @@ func (h *ProviderProxyHandler) directDispatch(provider *domain.Provider) flow.Ha
 		c.Set(flow.KeyProxyRequest, proxyReq)
 
 		responseModelMapping := executor.ResponseModelMappingForProvider(provider)
-		responseCapture := executor.NewResponseCapture(c.Writer)
+		originalWriter := c.Writer
 		var responseModelWriter *executor.ResponseModelMappingWriter
-		responseWriter := http.ResponseWriter(responseCapture)
+		finalWriter := http.ResponseWriter(originalWriter)
 		if len(responseModelMapping) > 0 {
-			responseModelWriter = executor.NewResponseModelMappingWriter(responseCapture, responseModelMapping, isStream)
-			responseWriter = responseModelWriter
+			responseModelWriter = executor.NewResponseModelMappingWriter(originalWriter, responseModelMapping, isStream)
+			finalWriter = responseModelWriter
 		}
-		originalWriter := c.Writer
+		responseCapture := executor.NewResponseCapture(finalWriter)
+		responseWriter := http.ResponseWriter(responseCapture)
 		c.Writer = responseWriter
 		err = adapter.Execute(c, provider)
 		c.Writer = originalWriter
@@ -164,8 +165,6 @@ func (h *ProviderProxyHandler) directDispatch(provider *domain.Provider) flow.Ha
 		proxyReq.ResponseModel = mappedModel
 		if responseModel := extractProviderProxyResponseModel(responseCapture.Body()); responseModel != "" {
 			proxyReq.ResponseModel = responseModel
-		} else if len(responseModelMapping) > 0 {
-			proxyReq.ResponseModel = executor.MapResponseModel(mappedModel, responseModelMapping)
 		}
 		if !clearDetail {
 			proxyReq.ResponseInfo = &domain.ResponseInfo{
@@ -184,6 +183,9 @@ func (h *ProviderProxyHandler) directDispatch(provider *domain.Provider) flow.Ha
 
 		proxyReq.Status = "FAILED"
 		proxyReq.Error = err.Error()
+		if responseModelWriter != nil {
+			responseCapture.SetResponseWriter(originalWriter)
+		}
 		if proxyErr, ok := err.(*domain.ProxyError); ok {
 			if isStream {
 				writeStreamError(responseCapture, proxyErr)

tests/e2e/provider_proxy_test.go

@@ -196,8 +196,8 @@ func TestProviderResponseModelMapping(t *testing.T) {
 	if len(requests.Items) == 0 {
 		t.Fatalf("expected at least one request for provider %d", providerID)
 	}
-	if got := requests.Items[0]["responseModel"]; got != "client-visible-model" {
-		t.Fatalf("expected recorded response model client-visible-model, got %v", got)
+	if got := requests.Items[0]["responseModel"]; got != "upstream-visible-sonnet" {
+		t.Fatalf("expected recorded response model upstream-visible-sonnet, got %v", got)
 	}
 }
 
@@ -236,8 +236,8 @@ func TestGenericProxyResponseModelMappingE2E(t *testing.T) {
 	if len(requests.Items) == 0 {
 		t.Fatalf("expected at least one request for provider %d", providerID)
 	}
-	if got := requests.Items[0]["responseModel"]; got != "client-visible-model" {
-		t.Fatalf("expected recorded response model client-visible-model, got %v", got)
+	if got := requests.Items[0]["responseModel"]; got != "upstream-visible-sonnet" {
+		t.Fatalf("expected recorded response model upstream-visible-sonnet, got %v", got)
 	}
 }
 
@@ -290,7 +290,7 @@ func TestProviderResponseModelMappingStreamsSSE(t *testing.T) {
 	if len(requests.Items) == 0 {
 		t.Fatalf("expected at least one request for provider %d", providerID)
 	}
-	if got := requests.Items[0]["responseModel"]; got != "client-visible-model" {
-		t.Fatalf("expected recorded response model client-visible-model, got %v", got)
+	if got := requests.Items[0]["responseModel"]; got != "upstream-visible-sonnet" {
+		t.Fatalf("expected recorded response model upstream-visible-sonnet, got %v", got)
 	}
 }