Stable: the provider supplies it or derives it from its own ids, never at random.
Optional dataOptional reason?: MeetingLeaveReasonWhy the bot left, on left.
Optional seconds?: numberThe seconds the worker counted, on usage, left, done and crashed.
Optional text?: stringA chat message's text.
Optional sender?: stringWho sent a chat message or a stop command.
Optional participantThe provider's reference for a participant who joined or left.
Optional participantHow many participants besides the bot, on in_call and when one joins or leaves.
Optional message?: stringAn error's description, on error; on left, the provider's word for why the run ended, which bot:left carries beside the reason.
Optional supplierWhat the provider's supplier measured so far, on any report: recorded whatever the run's state, a terminal one included.
One report from a provider, in the channel's terms, as the provider's parser returns it.