fix: preserve max_output_tokens in transformed requests

Author: ndycode

lib/request/request-transformer.ts

@@ -1088,7 +1088,6 @@ export async function transformRequestBody(
 	body.include = resolveInclude(modelConfig, body);
 
 	// Remove unsupported parameters
-	body.max_output_tokens = undefined;
 	body.max_completion_tokens = undefined;
 
 	return body;

test/request-transformer.test.ts

@@ -1437,14 +1437,24 @@ describe('Request Transformer Module', () => {
 			expect(result.input![0].role).toBe('user');
 		});
 
-		it('should remove unsupported parameters', async () => {
+		it('should preserve max_output_tokens while removing max_completion_tokens', async () => {
 			const body: RequestBody = {
 				model: 'gpt-5',
 				input: [],
 				max_output_tokens: 1000,
 				max_completion_tokens: 2000,
 			};
 			const result = await transformRequestBody(body, codexInstructions);
+			expect(result.max_output_tokens).toBe(1000);
+			expect(result.max_completion_tokens).toBeUndefined();
+		});
+
+		it('should leave max_output_tokens unset when not provided', async () => {
+			const body: RequestBody = {
+				model: 'gpt-5',
+				input: [],
+			};
+			const result = await transformRequestBody(body, codexInstructions);
 			expect(result.max_output_tokens).toBeUndefined();
 			expect(result.max_completion_tokens).toBeUndefined();
 		});