Does there exist a brief write-up of how content is federated out? Do different #ActivityPub implementors federate content differently? (@stesnac suggests so!)
Here's my head-canon at present... when a note is created, the note is sent to all followers. If users are mentioned, the note is also sent to those users' inboxes.
If a note is addressed to the public collection, do it just get blasted to all known instances' inboxes?
