There's no backreference for it, though, which I don't really like. It'd be better if a cross-post was approved and then the object itself updated a crossposts collection or something. I was toying with the idea of maybe using Offer to signify that action, but I wasn't too invested in making it happen.

I am understanding it correctly?

This sounds similar to a "repost" in blogo-verse.

And the current implementation (with separate entities) is more similar to quote posts.

Namely, tribalism exists in all corners of the fediverse (related; see Jaz' "million fediverses" blog post). It is more pronounced in the threadiverse because there are explicit fences around communities, e.g. sports team, political leanings, etc.

There is the potential for abuse to occur if cross-posting were made available to users. e.g. enabling dogpiling by cross-posting to a community who does not share the values of the original post.

In and of itself that's not a reason to not move forward with this. I went ahead and implemented cross-posting in NodeBB itself, but only locally. That is, remote posts can be cross-posted to local categories, but not the other way around. It's worth noting that me doing this already enables the dogpiling behaviour, though NodeBB forums in general aren't really all that tribalistic so in practice there have been no issues.

As far as I know, Piefed and Lemmy still treat cross-posts as separate entities. However, they both have independent implementations where similar posts (those that have the same Link, I think) are "linked" in a manner of sorts. Browsing the comments of one post would show comments from similar posts across different communities.

NodeBB does not do this because we do not group content together by Link.

I am not married to the Announce([Article|Note|Page]) approach, so I am definitely open to Create([Article|Note|Page]) with a back-reference. I think I went the former direction because there is a known fallback mechanism — the Announce is treated as a share/boost/repost as normal. However, sending the Create also is fine I think.

1. However, do we need a backreference? In my limited research, it seems that Piefed, et al. picks the first Group actor and associates the post with that community. If I sent over a Create(Article) with two Group actors addressed, could Piefed associate the post with the first, and initiate a cross-post with the remaining Group actors?
2. Secondly, is how to handle sync. 1b12 relies on communities having reciprocal followers in order for two-way synchronization to be established. On my end since I know it is cross-posted I will now send 1b12 activities to cross-posted communities, but can Piefed, et al. send 1b12 activities back as well, in the absence of followers?

cc @andrew_s@piefed.social @nutomic@lemmy.ml @melroy@kbin.melroy.org @bentigorlich@gehirneimer.de

This would be an add-on logic of sorts, where each topic has a canonical category, but can also be cross-posted to other communities/categories.

Duplicating the object would mean the discussion is split between objects. The ideal implementation would be the same object present in multiple categories/communities. Is there desire for this in the threadiverse?

If the link goes to a controversial news article and it's get posted into pro- and against- community/group the comments will spiral out of control and it won't be a pleasant place.

Maybe it could be implemented as a toggle per group/instance within one fedi software. It shouldn't be in Activity Pub protocol.

Mastodon is currently working on a spec for their groups implementation.

Any links to this and/or discussion of how it relates to other FEPs?

Create a new post (Create -> Page to the instance that hosts the community, which in turn does Announce -> Create -> Page to followers) and add an extra field to the Page which is the URL of the original post. That will establish the association.

To reject the cross-post, return HTTP 400 (403?) to the POST to the inbox on the initial Create -> Page ? Or send a Reject activity, either way is fine but the 400 seems easiest. Lemmy returns 400 for a lot of things so we have some prior art in that direction.

So I think I would want granularity, deciding whether my content is linked or cross posted, and whether I want to treat the remote discussion as a cross post to my comments section. But I would definitely want it to be the same object. In as far as I would have any duplication the cross post would be best thought of as nested under the post object.

Currently, when a user addresses multiple communities, then the existing software (NodeBB included) uses the first one. How the rest of the addressed communities are handled is what's of interest here.

I am posting to this from Mastodon, which interfaces with communities on lemmy/pie very awkwardly (but not zero percent).
A good cross posting solution would be one where a user can simply tag the extra communities, like a reply, as then it would be relatively cross platform friendly, and the communities on the other side/server would look for in their database posts with the community tagged / mentioned group 'superuser', say @ examplecommunity @ server.com when they load the community page, regardless if on the actual creation event they only 'officially' store it under one community.
IDK yet (I'll prolly look it up someday) how all these different platforms are organizing their database, but I'm imagining a table like poster | category | tags + msg + mentions | getting pulled when you go to a category; then you could turn off looking at cross-posts that are only in the category because of a tag/mention.

The second point is that a "cross-post" could have multiple meanings, including manually creating a new post about a link already present in multiple communities. What I'm hoping to describe is a common way that items can be cross-posted natively between instances, while hopefully preserving their reply-trees.

It is supposed to be a federated network, cross-posting is important for many fedi users.

also, if platforms intergrated better it would help discovery and help new and old users of fedi.

There are two parts to this:

1. There is an indicator if there is other post that links to the same website/image.
2. Crosshposts are just a copy of the text with quote markdown.