Send a discussion message

mutation sendThreadDiscussionMessage($input: SendThreadDiscussionMessageInput!) {
  sendThreadDiscussionMessage(input: $input) {
    threadDiscussionMessage {
      id
      threadDiscussionId
    }
    error {
      message
      type
      code
      fields {
        field
        message
        type
      }
    }
  }
}

{
  "input": {
    "threadDiscussionId": "td_01HXXXXXXXXXXXXXXXXXXXXXXX",
    "markdownContent": "Following up on this — any update?"
  }
}