curl --request POST \
  --url https://docs.mosoo.ai/api/v1/threads/{threadId}/files \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "fileId": "01J0000000000000000000000J"
}
'

{
  "file": {
    "committed": true,
    "createdAt": "2026-05-19T00:02:00.000Z",
    "id": "01J0000000000000000000000J",
    "kind": "attachment",
    "mimeType": "text/plain",
    "name": "brief.txt",
    "size": 19
  }
}