The Message object

One line on a thread. Posting a user message starts or resumes a run.

Listing a thread returns messages in sequence. Posting a message does not return the assistant reply — it returns 202 and a run.

Accepted:

{
  "run_id": "7c9e6679-7425-40de-944b-e07fc1f90ae7",
  "thread_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "state": "running"
}

Listed:

{
  "id": "9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d",
  "role": "user",
  "content": "Send 50 USDC to Jane",
  "run_id": "7c9e6679-7425-40de-944b-e07fc1f90ae7",
  "seq": 1,
  "created_at": "2026-08-16T11:58:01Z"
}

If a run on the thread is awaiting_input, the next POST is the answer and the run resumes. Otherwise a new run starts.

Attributes

id · uuid

Unique identifier for the message. Present on list, not on the 202.

role · enum

user, assistant, or system.

content · string

Message text.

run_id · uuid

Run that produced or accepted this message.

seq · integer

Position on the thread.

created_at · timestamp

When the message was written.

thread_id · uuid

Thread the run belongs to. Present on the 202.

state · enum

Run state at accept time. See The Run object.

Endpoints

• Send a message — POST /v1/loom/threads/:thread_id/messages
• List messages — GET /v1/loom/threads/:thread_id/messages