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@thisismissem Probably! What sort were you thinking of?

@mauve like flooding peoples timelines with the backfilling of posts

@thisismissem I assumed timelines would sort by published time no? I'm gonna run some tests before deploying this to production ofc

@mauve I think there's a bug to the contrary

@thisismissem In mastodon? i'd love to see the source code for it if you know what part of it it'd be in.

@mauve I don't have it off top of my head but follow from /app/lib/activitypub/activity/create.rb

@thisismissem It seems to be taking the created_at part out at least. https://github.com/mastodon/mastodon/blob/main/app/lib/activitypub/activity/create.rb#L122C7-L122C17

I'll look more after testing. Gonna let my personal instance take the bulk o9f the damage :P

@mauve yeah, I've heard of like, birdsite bridge that did similar backfilling clogging up people's timelines, but that might be specific to that implementation.

@thisismissem @mauve so... imo the ActivityPub way of doing this is to publish your last X posts at an "outbox" endpoint specified in your profile. Then a remote server following you can parse the outbox and get some content to fill things with. I did this with some software I was building and Mastodon just... didn't grab any of the outbox posts and I was confused as to why not

@darius @thisismissem @mauve yeah the outbox is there to support "web browser" use cases, fetch the latest activities and page through to see history

the thing with mastodon and timeline sorting is that the timeline sorting algorithm isn't using creation date, it's using arrival date. this is so someone can't create a post set in the far future to have it pinned at the top of your timeline.

@darius @thisismissem @mauve so delivering an activity ~now would insert the post at the top of the TL even if it was backdated in the `published` property.

@trwnh @thisismissem @mauve Oh interesting. But also: why not use arrival date for future dated posts and creation date for back dated posts? (Genuine question btw. I'm sure I'm missing some weird edge case race condition)

@darius @trwnh @thisismissem @mauve Because of Announce, as the obvious case. But more generally, when an object was created doesn't have any real connection to when it should be presented to people. Mastodon is doing more or less the right thing, here.

I wish mastodon would be more prompt in backfilling from the outbox, so that this wouldn't even seem necessary. But even that is basically the right behavior.

@jenniferplusplus @trwnh @thisismissem @mauve I see what you mean by time created vs when it should be presented. That said, if we consider the context of pulling from an outbox to backfill, then the context seems pretty clearly (to me, I could be wrong) "do not show this in the home timeline, this is just for filling in our database for views more generally"

DOES Mastodon pull from the outbox? I didn't observe it doing it at all

@darius @jenniferplusplus @thisismissem @mauve nope, mastodon p much ignores the outbox

and yeah it makes sense to *not* do timeline insertion when backfilling, backfilling seems like the kind of thing that is only/primarily useful for viewing a profile and not keeping up with current activities

@darius @jenniferplusplus @thisismissem @mauve another way to look at it is that there are really two dates, one is the date the object claims to be published, and the other is the date that the activity arrived in your inbox. most fedi dev is used to thinking in terms of objects, but it would be more technically correct and spec-accurate to think in terms of activities

@trwnh @darius @thisismissem @mauve objects have dereferenceable URIs. Why wouldn't I make that a first class entity in my data model?

@jenniferplusplus @darius @thisismissem @mauve activities do too, as well! or they should. activities are also objects.

the advantage of thinking in terms of activities is that it's a better representation of reality, with AP serving as a specialization of LDN (Linked Data Notifications), you're basically notifying your followers/audience/recipients that "something happened". it's the reason we POST Create activities and not just raw non-activity objects.

@trwnh @darius @thisismissem @mauve
Unless the activity is intentionally transient. The spec says this twice in two paragraphs. I don't know what it means for an activity to *not* be transient. Activities are actions, not ongoing persistent state. The objects the refer to are the persistent state.

@jenniferplusplus @darius @thisismissem @mauve transient means you don't want to look at it later. for example an in-game notification.

activities are not really "actions", they are "notifications with side effects", and that notification resource should be persistent if you want to refer to it later. consider a old-facebook "activity feed" or "activity stream" -- there, you see things like "x created a post" or "x liked a post" as discrete entries in the feed. many cases demand activities.

@trwnh @darius @thisismissem @mauve that's only true if your application model is to just store and replay activities. I treat activitypub as a wire protocol. It's not my domain model.

@jenniferplusplus @darius @thisismissem @mauve that's fine but also doing that should come with the recognition that by discarding the activity you are losing some information. it's not "enough" to concern yourself only with what was created, sometimes the act of creation itself is important. this is why Activities come with extra properties that aren't present on the Object base class -- `result` comes to mind as a particularly interesting one.