TIL: #Mastodon specifically treats actor URIs with the pattern `https:///actor` as instance actors.'n'n #fedidev #ActivityPub
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<del datetime="2025-10-12T21:34:00+09:00">TIL: #Mastodon specifically treats actor URIs with the pattern
https://<domain>/actoras instance actors.</del> <ins datetime="2025-10-12T21:34:00+09:00">Turns out I misread the code. 😅</ins>#fedidev #ActivityPub
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Where are you seeing this?
Mastodon does serve its instance actor as
/actor, however it doesn't actually track the "instance actor" as a concept, because there's actually no way to do so. fep-2677 doesn't define one, it just says the instance actor must be an Application, and adds a reference to that actor to NodeInfo.That is, from the actor document alone, there is no way to know if it is the "instance actor" (remembering too that AP doesn't have any notion of an "instance" or "server")
Likewise, internally in Mastodon, the instance actor record will have the ID of -99.
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@thisismissem@activitypub.space Ah, I seem to have misread the code. I was confused by Mastodon serving its own instance actor from
/actor. Thanks for the clarification!
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@evan that makes sense. I've just updated NodeBB to allow for the use of a manual override marker. The limit and even the marker is now customizable per-instance, and I do use the ellipsis when truncating text.
Hopefully that resolves the engagement issue while still preserving the intent of b2b8 :smile:
As for the use of an LLM to generate a summary, I think I will defer on that, since that might be a source of surprise for those not expecting the invocation of a LLM :sweat_smile:
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@julian So, there are a few ways to handle this.
First, the b2b8 recommendation on the summary is just a guideline, not a strict requirement (thus the 'about').
A common practice in news-style text is that the first paragraph is a lede that summarizes the article's main points.
For example, in this article, Lawrence Summers Will Resign From Harvard After Epstein Revelations, the first paragraph is:
> Lawrence H. Summers, a Harvard University economist and the school’s former president, will resign from teaching at the end of the academic year, according to a Harvard spokesman.
Some bloggers follow a similar practice, especially since blogging software often uses the first paragraph as the summary in RSS and Atom feeds.
I think if I were generating a summary for long-form text, I'd use these techniques in roughly descending order:
Manual override; an optional way for the user to define a summary manually - either with a marker in the text, or with a separate input element (I think WordPress does this). Use the whole text if it meets the rough guidelines (~1 paragraph, a few sentences, about 500 chars) in b2b8. Use the first paragraph if it meets the rough guidelines (a few sentences, about 500 chars) in b2b8. Truncate the first paragraph and include an ellipsis ().This is also something that LLMs are pretty good at. So, maybe rather than truncating (last option), consider using an LLM to generate a summary that meets the boundary requirements.
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Hey @evan@cosocial.ca, I'm watching your lightning talk at FOSDEM! I'm simultaneously glad it's less than 10 minutes, but sad it's not longer too :stuck_out_tongue_closed_eyes:
(Everyone else, want to watch it? Here it is)
Some questions I'm jotting down while I'm watching it
I can see the user on ActivityPub.Space, which is how it's supposed to work. Would I be able to follow this user from a non-Person? If integrating into NodeBB, I'd maybe want the Application actor itself to follow it.
Love how you head off concerns about consent issues with a slide about how it's not scraping, mass-following, etc. So it uses relays, such as the ones on relaylist.com?
Let's talk about how we can get NodeBB sharing data to tags.pub by default (or by admin opt-out switch.
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@julian @saskia @evan or do you think that anybody knows , that #stupidhashtag in the system is https://mastodon.social/tags/stupidhashtag and it's type is https://www.w3.org/ns/activitystreams/hashtag
But as far as I know, this type is not specified at all!
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@julian @saskia @evan A tag, a hashtag, a SKOS concept, all IRI or URL! Users don't see the concept behind it. If we developers do it right!
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@naturzukunft2026@mastodon.social absolutely not, sorry.
For the simple reason that it requires user education, and ain't nobody going to go around teaching 7bn people how to use SKOS.
The beauty (and admittedly a downside and source of a lot of noise) is the hashtag's ubiquity and simplicity. Anyone can make one, anyone can name it whatever they want.
