One message, one action

A message is never sent to every action in an area. It reaches exactly one action in each app, chosen in this order:

1. 1An explicit wire for that event and username.
2. 2A username-scoped wire, which also limits what that username can reach.
3. 3A clear automatic name match, used only as a fallback.

If nothing clearly fits, the message is marked unrouted instead of guessed.