Topic removal from a category/community
Technical Discussion
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There are lots of other uses for
Move. A community whole could move instances, a user could move instances, etc.Yeah you're right,
Movehas some prior art for account migrations so it's worth some thinking through.I'd like to work together on this though. I'm working through context ownership and inheritance first, but once that FEP is drafted I can move on to this.
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Yes, a Delete activity is sent to all instances with actors that follow the category/community. Those instances then delete their local copy. In Lemmy/PieFed there is no distinction between deletion and removal.
The deletes are soft so it is possible to un-delete by sending an Undo activity. PieFed keeps soft-deleted posts (topics, in NodeBB language) for a few days then after a week deletes the content from the database.
All of these activities are enclosed in an
Announceand the http POST is signed using the community key. So in a way the content 'belongs' to the community, not to the original author. With that model of ownership the idea of removal redundant - a post without a community is not a post.Tangentially - it would be good to come up with a way to move a topic to another category and federate that so the move can happen on other instances, too. We could go off-piste and create a
Moveactivity, or useRemove(from old topic/comm) followed byAdd(to new topic/comm) to do the same thing. I feel more inclined to go withMoveas it's a single atomic operation that either succeeds or fails, despite it not being in the spec.The AP spec is so badly stretched by various implementation-specific differences that I don't think it's worth being ideological about adherence to it it anymore.
rimu@piefed.social said in Topic removal from a category/community:
> All of these activities are enclosed in an Announce and the http POST is signed using the community key. So in a way the content 'belongs' to the community, not to the original author.Oh that's right! That makes sense. Having the community sign the activity (and the
Announcewrapper) would effectively differentiate it from a simple author-initiated content deletion.The impetus for this question was that occasionally I will move topics out of a category for being off topic. Federated copies don't see this change reflected, so both Move and Delete are things I want to federate out in lockstep with Piefed and Lemmy.
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Yes, a Delete activity is sent to all instances with actors that follow the category/community. Those instances then delete their local copy. In Lemmy/PieFed there is no distinction between deletion and removal.
The deletes are soft so it is possible to un-delete by sending an Undo activity. PieFed keeps soft-deleted posts (topics, in NodeBB language) for a few days then after a week deletes the content from the database.
All of these activities are enclosed in an
Announceand the http POST is signed using the community key. So in a way the content 'belongs' to the community, not to the original author. With that model of ownership the idea of removal redundant - a post without a community is not a post.Tangentially - it would be good to come up with a way to move a topic to another category and federate that so the move can happen on other instances, too. We could go off-piste and create a
Moveactivity, or useRemove(from old topic/comm) followed byAdd(to new topic/comm) to do the same thing. I feel more inclined to go withMoveas it's a single atomic operation that either succeeds or fails, despite it not being in the spec.The AP spec is so badly stretched by various implementation-specific differences that I don't think it's worth being ideological about adherence to it it anymore.
@rimu Still, I think it would be nice to deprecate
Deleteand slowly migrate toRemove(target: context), since both PieFed and Lemmy implement the context collection now.My server rejects
Deleteif its actor is different from object's owner, and I have to treatAnnounce(Delete)as a special case where the normal processing logic doesn't apply. -
@rimu Still, I think it would be nice to deprecate
Deleteand slowly migrate toRemove(target: context), since both PieFed and Lemmy implement the context collection now.My server rejects
Deleteif its actor is different from object's owner, and I have to treatAnnounce(Delete)as a special case where the normal processing logic doesn't apply.Possibly although the differences of federation between the threadiverse and the rest of the fediverse go way beyond deletes. FEP 1b12 is a whole thing, chipping away at it piece by piece would be slow going.
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Possibly although the differences of federation between the threadiverse and the rest of the fediverse go way beyond deletes. FEP 1b12 is a whole thing, chipping away at it piece by piece would be slow going.
Personally I think 1b12 doesn't need to be changed or hacked around. It doesn't specifically call for federating out deletes so I'd think any solution we come up with together would work with that FEP, not go against it.
cc silverpill@mitra.social (if your app notifies you of new replies without a direct mention I'll stop tagging you too)
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Personally I think 1b12 doesn't need to be changed or hacked around. It doesn't specifically call for federating out deletes so I'd think any solution we come up with together would work with that FEP, not go against it.
cc silverpill@mitra.social (if your app notifies you of new replies without a direct mention I'll stop tagging you too)
I also think that backfill will have a side effect of connecting the threadiverse and the rest of the fediverse.
Exposing context collections will mean consumers will be able to see both *verses. Once Mastodon starts consuming them I predict you will start seeing much more engagement from the microblogs.
The same would apply if Piefed or Lemmy begin consuming them as well.
That is an angle I had not even considered until now!
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Personally I think 1b12 doesn't need to be changed or hacked around. It doesn't specifically call for federating out deletes so I'd think any solution we come up with together would work with that FEP, not go against it.
cc silverpill@mitra.social (if your app notifies you of new replies without a direct mention I'll stop tagging you too)
if your app notifies you of new replies without a direct mention I'll stop tagging you too
Inclusion in
toorccis enough to generate a notification. -
Possibly although the differences of federation between the threadiverse and the rest of the fediverse go way beyond deletes. FEP 1b12 is a whole thing, chipping away at it piece by piece would be slow going.
rimu@piefed.social silverpill@mitra.social I gave this a bit more thought and I am coming around to the idea that
Removecould work.I am assuming that when Piefed sends
Announce(Delete(Object))this is only understood by Piefed? Not Lemmy (and certainly not NodeBB, yet)...In that case, a move to a simpler
Remove(target: context)signed and acted on by the community actor, would send a more explicit message that the object was removed from the community.The "1b12-speaking" portion of it would be an
Undo(Announce(Create)), although once again I am not even sure if that action is understood by Piefed/Lemmy. -
only understood by Piefed? Not Lemmy
No, that's a Lemmy thing too.
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only understood by Piefed? Not Lemmy
No, that's a Lemmy thing too.
Oh okay. I wasn't sure about that since I don't think it's documented in the FEP, though it's been awhile since I've given it a read through.
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only understood by Piefed? Not Lemmy
No, that's a Lemmy thing too.
rimu@piefed.social Do you send the
Undo(Announce(Create))as well for microblog compatibility? -
Looks like for Mastodon we just do a bare
Delete. -
Looks like for Mastodon we just do a bare
Delete.rimu@piefed.social got it, thanks. How do you reconcile the Delete coming from outside your domain? I would figure Mastodon would drop those Deletes.
Edit: that was confusing wording... I mean — how do you sign a Delete for an object that doesn't belong to your instance?
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We only federate the deletion if it is in one of our local communities.
The activity is signed by the person who did it, so if Mastodon detects that the person deleting is not the author and doesn't know how to find out if someone is a moderator or not, that's their problem.
Mastodon has been dropping the ball on groups support for years so I didn't even bother to find out if they handle it well - I bet they don't.
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We only federate the deletion if it is in one of our local communities.
The activity is signed by the person who did it, so if Mastodon detects that the person deleting is not the author and doesn't know how to find out if someone is a moderator or not, that's their problem.
Mastodon has been dropping the ball on groups support for years so I didn't even bother to find out if they handle it well - I bet they don't.
so if Mastodon detects that the person deleting is not the author and doesn’t know how to find out if someone is a moderator or not, that’s their problem.
It is not their problem. If your actor
Deletes an object that is owned by a different server, then your implementation of ActivityPub standard is incorrect:https://www.w3.org/TR/activitypub/#delete-activity-inbox
The side effect of receiving this is that (assuming the
objectis owned by the sending actor / server) the server receiving the delete activity SHOULD remove its representation of the object with the sameid -
so if Mastodon detects that the person deleting is not the author and doesn’t know how to find out if someone is a moderator or not, that’s their problem.
It is not their problem. If your actor
Deletes an object that is owned by a different server, then your implementation of ActivityPub standard is incorrect:https://www.w3.org/TR/activitypub/#delete-activity-inbox
The side effect of receiving this is that (assuming the
objectis owned by the sending actor / server) the server receiving the delete activity SHOULD remove its representation of the object with the sameidI think
Announce(Delete(Object))skirts around that, though. Maybe not if you're being technical about it, but the shape of the activity is different enough to mean something else in 1b12-land:- A community/group-actor announced a
Delete - The object may or may not belong to the same domain as the community/group-actor or
Deleteactor - Verify that the community/group-actor and
Deleteactor are same-origin (might not need this if cross-instance moderation is a thing) - Verify that the
Deleteactor is a moderator of the community/group-actor as per 1b12
- A community/group-actor announced a
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@julian @rimu No, when one object is embedded in another, it doesn't change its behavior. A
Deleteactivity wrapped inAnnouncedoesn't mean something else, it exists as an independent object that can be fetched by itsid.The invalid
Deleteactivity worked for Lemmy only because they didn't care about federation with non-forum software. But it can't work in the multi-app network without ugly hacks like checking remote server's NodeInfo. -
@julian @rimu No, when one object is embedded in another, it doesn't change its behavior. A
Deleteactivity wrapped inAnnouncedoesn't mean something else, it exists as an independent object that can be fetched by itsid.The invalid
Deleteactivity worked for Lemmy only because they didn't care about federation with non-forum software. But it can't work in the multi-app network without ugly hacks like checking remote server's NodeInfo.Perhaps resolvable contexts can be a solution for this then.
I have been implementing topic deletion logic in NodeBB, and while I can send out
Announce(Delete(Object))whereObjectis the root-level post, it occasionally would send outDeletes where the sender is not the owner of the object. This is the 1b12-speaking logic.In 7888-speaking logic,
Objectwould be the local context collection. A receiver would be able to resolve the context URL to the appropriate local representation and delete it as needed. This would also satisfy the "sender needs to own the object" constraint. -
Hey rimu@piefed.social, I sent over this activity but I wasn't able to make crust delete that representation.
{ "id": "https://bb.devnull.land/post/2#activity/announce/delete/1759851369554", "type": "Announce", "actor": "https://bb.devnull.land/category/2", "to": [ "https://www.w3.org/ns/activitystreams#Public" ], "cc": [ "https://bb.devnull.land/category/2/followers" ], "object": { "id": "https://bb.devnull.land/topic/2#activity/delete/1759851369554", "type": "Delete", "actor": "https://bb.devnull.land/uid/1", "to": [ "https://www.w3.org/ns/activitystreams#Public" ], "cc": [ "https://bb.devnull.land/category/2/followers" ], "origin": "https://bb.devnull.land/category/2", "object": "https://bb.devnull.land/post/2" } }Am I missing something?
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Delete(Context)? This is very unusual because other collections are not created or deleted, they are server-generated views.I assume this problem arises when you create a topic for a remote post? Perhaps deletion of such topics shouldn't be federated?
Or you can generate
Announce(Remove(object: root, target: Context))It would be valid from the authorization point of view.
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I feel like that being explicit is more advantageous. There are some subtle edge cases that it helps work around.
Thanks nutomic@lemmy.ml for your attention :)
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Token revocation and userinfo endpoint are also implemented. iss indication on redirects is also recommended, but not planned yet
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I believe CIMD is planned, and at some point expiring access tokens & refresh tokens will also land, and maybe in a distant future DPoP too.
DCR has a client registration proliferation problem, which is why Mastodon want CIMD.
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So, as far as I can tell, Mastodon supports:
Authorization code flow PKCE Authorization server metadataIt doesn't seem to support:
OAuth Dynamic Client Registration Client ID Metadata DocumentsIt instead uses a proprietary endpoint.
thisismissem is that about right? Is there work underway to support CIMD (preferred) or dynamic registration (less good but a more established standard)?
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@julian Nice workaround. They should describe it in the FEP
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This way, @DailyRucks gives out permission slips which are “shaped” in a way that is instantly verifiable, no database and no internal state required.
The only problem is that the ID of the quoting post is an arbitrary URI, and passing full URIs as query string parameters is brittle. It seems to work for Mastodon post IDs, but other platforms might have more complex URI schemas.
I guess we'll see what happens! 😀
Project website with link to the git repository: https://fietkau.software/daily_rucks
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That's why it's not possible to simply reply “ya sure” to every quote verification request. The response has to affirmatively state which quote it is for.
So I thought, instead of keeping a list of prior quotes in a local database, why not embed them in the ID (URI) of the verification stamp? That way the code could simply echo them back out for any future request.
Turns out this works! You can see an example here: https://fietkau.software/daily_rucks/ap/quoteAuth?stamp=2025-11-08;https%3A%2F%2Fexample.com%2Fsome-post
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While reading FEP-044f, I had an idea for getting around that requirement. It's difficult to explain without getting extremely technical, but I think it could be interesting for platform implementers who want to offer blanket quotability to Mastodon users, but who have shied away from FEP-044f for its state management requirements.
Basically, a quote authorization stamp payload (see https://codeberg.org/fediverse/fep/src/branch/main/fep/044f/fep-044f.md#example-of-quoteauthorization) has to contain the IDs of the quoting post and the quoted post.
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