Insert a follow-up message and start another asynchronous turn. Use messages to refine a result, answer the agent, redirect the research, or request another artifact.

The response includes a messageId. The corresponding user_message event carries the same value, allowing the client to confirm delivery.

Attach previously uploaded files by including their file_ids in the attachments array (see the Upload endpoint). A session can hold at most 100 distinct files totaling 10GB across all turns; files already attached to this session can be referenced again without consuming another slot.

If the session is paused for insufficient quota, resolve the usage limit and resume it via POST /api/v2/sessions/:sessionId/resume (or the Elicit web interface) before sending another message.

Example

curl -X POST https://elicit.com/api/v2/sessions/agents/{sessionId}/messages \
  -H "Authorization: Bearer elk_live_your_key_here" \
  -H "Content-Type: application/json" \
  -d '{"message":"Focus on randomized controlled trials only."}'

{
  "message": "Focus on randomized controlled trials only.",
  "attachments": [
    {
      "file_id": "a1b2c3d4-e5f6-4a7b-8c9d-0e1f2a3b4c5d"
    }
  ]
}