{ "id": "msg_123", "session_id": "sess_123", "status": "completed", "attempt": 1, "output": { "parts": [ { "type": "text", "text": "Here is a draft response for the customer..." } ] }, "created_at": "2026-03-31T18:40:00Z", "completed_at": "2026-03-31T18:40:12Z"}
Returns the current message record, including status, attempts, and terminal output when available.This is the canonical polling resource for async message execution.