User -> Author’s instance -> Community’s instance -> Notified to all other instances subscribed, to download from author’s instance.
As for your other point, there is no good universal Lemmy linking thing for posts. communities and users have names that work on any instance, but there’s no similar unique identifier for posts.
The original link
ap_idcorresponds to the author’s instance.User@feddit.org posts to community@lemmy.ml. The path the post will take is this:
User -> Author’s instance -> Community’s instance -> Notified to all other instances subscribed, to download from author’s instance.
As for your other point, there is no good universal Lemmy linking thing for posts. communities and users have names that work on any instance, but there’s no similar unique identifier for posts.