Since message ids are unique across channels, there isn't technically a reason why a single action channel cannot be used for multiple target channels.
We could either:
Not require a channel_id in the com.alwaysallthetime.action.metadata channel annotation, or
Have an alternate key – channel_ids that is an array of channel ids to be used with the action channel.
Since message ids are unique across channels, there isn't technically a reason why a single action channel cannot be used for multiple target channels.
We could either: