fix(stats): Use request model as fallback for stats logging (#8423)

packages/core/src/code_assist/converter.test.ts

@@ -299,6 +299,17 @@ describe('converter', () => {
         codeAssistRes.response.automaticFunctionCallingHistory,
       );
     });
+
+    it('should handle modelVersion', () => {
+      const codeAssistRes: CaGenerateContentResponse = {
+        response: {
+          candidates: [],
+          modelVersion: 'gemini-2.5-pro',
+        },
+      };
+      const genaiRes = fromGenerateContentResponse(codeAssistRes);
+      expect(genaiRes.modelVersion).toEqual('gemini-2.5-pro');
+    });
   });
 
   describe('toContents', () => {

packages/core/src/code_assist/converter.ts

@@ -80,6 +80,7 @@ interface VertexGenerateContentResponse {
   automaticFunctionCallingHistory?: Content[];
   promptFeedback?: GenerateContentResponsePromptFeedback;
   usageMetadata?: GenerateContentResponseUsageMetadata;
+  modelVersion?: string;
 }
 
 export interface CaCountTokenRequest {
@@ -137,6 +138,7 @@ export function fromGenerateContentResponse(
   out.automaticFunctionCallingHistory = inres.automaticFunctionCallingHistory;
   out.promptFeedback = inres.promptFeedback;
   out.usageMetadata = inres.usageMetadata;
+  out.modelVersion = inres.modelVersion;
   return out;
 }