I filed an issue on the lemmy and kbin issue trackers to address duplicate communities. If you have an #ActivityPub development experience/knowledge, please take a look and offer feedback. If not, please offer any feedback here.
I wonder if something like a hashtag system, or built in multi-communities would be a good solution. It’s definitely something I’d say needs to be addressed at some point, but I’m not sure what would be a good solution, especially as I’m not yet familiar with the specifics of ActivityPub. The solution you pose seems to be a good step in the right direction.
I’ll also say, I don’t think limiting communities to a single instance is the answer, because if that instance ever goes down for whatever reason, the whole community is gone. It should be distributed across instances by design, imo. I’ve seen some people suggesting this, so I wanted to address it.
A distributed system is different from a federated system and from my understanding, much more complex. If the proposal I submitted is implemented, then I think that would solve your concern.
Imagine [email protected] and [email protected] follow each other via my proposal. A user who doesn’t know anything about that following relationship can post a link at [email protected] and it can show up in [email protected]. If either community goes down, the other community should be able to maintain all existing posts. There is the question of what happens to users of the community that went down (they may not know about the other community and can’t visit the community they know about to check its sidebar because its down now)
