> ## Documentation Index
> Fetch the complete documentation index at: https://www.plain.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# sendChat

> Send a chat message from a support agent (or machine user) to a customer on a CHAT-channel thread.
Either `text` or at least one `attachmentIds` entry must be provided. If `threadId` is omitted a new
thread is created; if supplied the message is appended to the existing thread. An optional `timestamp`
(ISO 8601, must be in the past) allows backdating messages when backfilling historical data.
Requires the `chat:create` permission and the live-chat billing entitlement.