Update app.py

app.py

@@ -711,7 +711,7 @@ Answer with just "YES" if web search would be helpful, or "NO" if the available
                print(f"Downloading attachment")
             
             if attachment_name:
-                download_url = f"{api_base_url}/files/{task_id}"
+                download_url = f"{DEFAULT_API_URL}/files/{task_id}"
                 response = requests.get(download_url, timeout=30)
                 response.raise_for_status()
                 temp_dir = tempfile.mkdtemp()