LLM call failed (iteration 1): HTTP 400: cli-proxy-api: { "error": { "code": 400, "message": "{"type":"error","error":{"type":"invalid_request_error","message":"This model does not support assistant message prefill. The conversation must end with a user message."},"request_id":"req_vrtx_011CZ8HvZR4X1MrCi3LUccJz"}", "status": "INVALID_ARGUMENT" } }