A lot communities have "Posts older than 365 days will be removed." in their description, but what does this mean exactly? It never says.

• The database of posts only goes as far as 1 year, everything older gets wiped? I hope and assume that's not it.
• Posts with links to articles older than a year get removed?
• If a thread is over a year old, no new comments will be added?

Couldn't cross-post, so linked instead.

The posts in that community will be deleted after that many days. For remote communities this only affects the local copy of each post and the post will still exist on the source instance and other instances (unless they too delete their copies). For local communities the deletion federates so the post is removed everywhere.

PieFed is intended to run for decades and storage costs money so admins can set how long they want to retain content for, on a per-community basis. It's up to them to decide what is worth keeping forever and what should be trimmed.

AFAIK piefed.social has 'forever' for the retention of all local communities and only trims remote communities. In some communities piefed.social only keeps posts for very short periods, like 28 days, because it's the kind of content people look at once and has no lasting value beyond that.

Can moderators/admins control the time period before threads/posts are deleted?
I've been nursing the idea of a gimmicky instance with ephemeral threads but I've been thinking more 1-2 weeks rather than a year.

Yes it can be set to anything from 1 week to 10 years.

It's set by the admin but moderators should have a good enough relationship with them to be able to ask for it to be set to something that suits their needs.

This is great, I was afraid I'd have to employ some sort of moderator bots to do it.
Thanks.

That's pretty cool! Can it be set to retain more "popular" posts for longer? :o Because there's a lot of communities where it makes sense to not keep the average post around for too long (like casual chatting/news communities) but sometimes a really good post comes up (like a cool guide or discussion) that would absolutely be worth keeping for longer. Usually upvotes/comments are a pretty good indicator of that

That's a good idea but currently we don't have that level of granularity.

When I made it I assumed that most communities would be 'forever' and the auto-deletion would only be used on communities that the admin really didn't consider worth having in the first place. I don't know if that's how it has turned out in practice, 2 years later.