Whether the local user sent this message.
OptionalNotThe user's own message did not go out: the send failed, or a BeforeSendData handler canceled it. The chat marks it
"Not sent", with a Retry that sends it again. Absent on a message that went out and on everyone else's.
The sender's display name.
OptionalSenderThe sender's participant identity, when known.
The message text.
Epoch-ms timestamp.
One chat message rendered in the chat panel (sourced from the LiveKit data channel).