As a new user to all these sites, I’m confused about they interact with each other. For example, on Lemmy, I can view a Mastodon account, but I can’t view that account’s posts. This makes sense, as sorting your home feed by “all” could hypothetically result in your feed getting flooded by popular Mastodon posts.
On the other hand, I understand that Mastodon users can see, reply to Lemmy threads, and subscribe to Lemmy communities. This flow of content makes far more sense than if Lemmy allowed Mastodon posts to be visible.
With all that said, how does Lemmy know to not show Mastodon posts? How does ActivityPub even work? How does ActivityPub understand that certain posts are from certain sites? Aren’t all these sites just different UIs that advertise different servers? I’m not gifted with technical knowledge, but I’m dying to understand how this whole thing works.
Lemmy’s federation code is not as mature as Mastodon’s. Mastodon is probably the most mature codebase in the fediverse. This means that a Mastodon user sees a Lemmy community as just another user, so they can ‘subscribe’ to that community and post to it and join in the comments section of posts they’ve created.
So it’s not so much that Lemmy knows not to show Mastodon content, it’s more that right right now it’s not able to (in a Lemmy-to-Mastodon direction), Lemmy federates very well with other Lemmy instances but not so well with non-Lemmy instances. That will improve as Lemmy gets developed further.
The other thing to bear in mind is that Mastodon and Lemmy present content differently. Mastodon is a microblogging service like Twitter whereas Lemmy is a link aggregator like Reddit. This means that Lemmy content is usually longer and has a title whereas Mastodon content is shorter and has no title. All these things will need to be ironed out as integration deepens.
I appreciate your post. TIL. Thank you. :)