**#ActivityPub support in #Madblog**

[julian@fietkau.social]

@fabio @liaizon Oh excellent! Please let me know when the new version is live on your blog and I'll test again.

[fabio@manganiello.eu]

@julian@activitypub.space @general@activitypub.space that would be very cool, but from my understanding Person vs. Group actor are mutually exclusive, so I can't have both on the same handle right?

If that's the case I may have to rethink a bit of the current single-user approach - I guess that I'll need a @user@example.com Person actor (or optionally multiple of them) and a @blog@example.com Group actor. Which AFAIK is similar to what #WriteFreely does, but it requires me to rethink a bit of the general design.

I've braindumped my thoughts here for now https://git.platypush.tech/blacklight/madblog/issues/21, thanks for the feedback!

[julian@activitypub.space]

@fabio@manganiello.eu

> from my understanding Person vs. Group actor are mutually exclusive, so I can't have both on the same handle right?

Correct, while you can have webfinger resolve both a group actor and person actor from a single handle, that gets messy quickly because how the receiving end handles this is not specified. Mastodon for example only takes the first entry, which crucially means if a community and user have the same handle, then one of the actors is inaccessible to Mastodon.

Here are some quick answers to the open questions:

Should the Person actor have its own inbox?
Yes, the Person actor and the Group actor are two separate identities (as far as anybody outside of your instance is concerned.

Outbox representation — Should the Group's outbox contain the Announce
activities, the inner Create activities, or both?

This is optional (at least for NodeBB). If you investigate NodeBB's actors, all of their outboxes return an empty OrderedCollection because I simply haven't gotten around to it yet, and I don't know many implementations that read it. Federation works fine without it, but it would make sense to follow Lemmy or Piefed's lead here.

Backwards compatibility — Should Madblog support a "hybrid" mode that sends both Create (for Mastodon) and Announce (for threadiverse)?

Mastodon will correctly de-duplicate the object so sending both Create(Note/Article) and Announce(Create(Note/Article)) is fine. The former serves non-threadiverse followers, and the latter ensures threadiverse syncronization capability.

Separate keypair for the Person actor? If the Person actor eventually needs to sign requests (e.g. for inbox delivery), it would need its own keypair.

I believe so. It was trivial for me to just generate keypairs for everybody, so I don't know off-hand whether things break if your Person actor doesn't have one. It might not resolve in some implementations?

[Guest]

@fabio @fabio Will it also work with profile parameter? We have to specify the profile because ActivityPub specification requires it:

ActivityPub

The ActivityPub protocol is a decentralized social networking protocol based upon the [ActivityStreams] 2.0 data format. It provides a client to server API for creating, updating and deleting content, as well as a federated server to server API for delivering notifications and content.

(www.w3.org)

[Guest]

@julian

If you investigate NodeBB's actors, all of their outboxes return an empty OrderedCollection because I simply haven't gotten around to it yet, and I don't know many implementations that read it.

I read from outboxes all the time. But I can't do that with NodeBB

Outbox doesn't have an `id` · Issue #13478 · NodeBB/NodeBB

NodeBB version v4.4.2 NodeBB git hash No response NodeJS version No response Installed NodeBB plugins No response Database type No response Database version No response Exact steps to cause this issue Retrieve outbox What you expected I ...

GitHub (github.com)

[Guest]

@fabio @fabio In your curl command, the closing quote (") is missing after https://www.w3.org/ns/activitystreams. When I make a request with the full media type string, the server still returns text/html

[fabio@manganiello.eu]

@silverpill@mitra.social @fabio@manganiello.blog you're right, I completely overlooked that. Also the Python HTTP machinery isn't as clever as I thought so I had to trim parameters manually, but it should work now https://git.fabiomanganiello.com/blacklight/madblog/commit/76e7b72337b1ab7406fb307eb163a9a4097fcc0e

❯ curl -I -H 'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"' https://manganiello.blog/article/Madblog-federated-blogging-from-markdown
HTTP/2 200
server: nginx
date: Tue, 10 Mar 2026 19:06:01 GMT
content-type: application/activity+json
content-length: 69389
last-modified: Tue, 10 Mar 2026 18:39:54 GMT
etag: "81d02d339405c0ec"
cache-control: public, max-age=0, must-revalidate
language: en-US

[julian@activitypub.space]

@silverpill@mitra.social I recall Mitra may be one of a select few

Do you use it to backfill a profile? How often do you query the outbox?

[Guest]

@fabio @fabio It's working, thanks!

[Guest]

@julian Yes, to backfill a profile. It is a manual action.

I don't know who else does that, but @jonny is working on adding automatic profile backfill to Mastodon: https://github.com/mastodon/mastodon/pull/34597

[julian@fietkau.social]

@silverpill @julian@activitypub.space I believe @hollo does it as well.

@general

[akavel@merveilles.town]

@fabio I really, really love it!! I wanted to do the same for quite a long time - but I didn't; and now maybe I can eventually steal your code and RIIR in glorious AGPL!

That said, unfortunately at the moment it's not working for me, I can't open it either in my client, or through my instance's search FWIW, through my instance I'm seeing some "503 Remote SSL certificate could not be verified", while the client just spins a throbber endlessly. No idea where the fault lies, but I do remember reading many times that Mastodon is a flustercluck and a fishy citizen in ActivityPub ...

Anyway, huge applause from me regardless, and hopefully one day I can get to fave the actual post on the blog!

[jonny@neuromatch.social]

@fabio@manganiello.eu @fabio@manganiello.blog @blog omg thank you for the python lib. i was getting ready to write one but extremely good to see i can draw from (credit/depend on/etc.) prior art. adding to the inspo docs!!!

[jonny@neuromatch.social]

@silverpill @julian @general Collections are one of the best parts of activitypub/streams and i have no idea why nobody uses them or works on them. like if we embraced the underlying graph structure of the data and used the canonicalization algos that have been developed in the meantime we get all the good parts of atproto (mostly efficient updating, the pds system) basically for free

[jonny@neuromatch.social]

@silverpill @julian @general account backfilling is issue number THIRTY FOUR in mastodon and has >700 thumbs, >200 comments hemming and hawing about how possible it would be for TEN YEARS.

the solution is just "enumerate the outbox" and it's 200 lines.

like we already have a mechanism for reply controls: the reply collection.
for fine-grained post visibility: access control on the outbox collection.
broadcasting feeds and posts between instances: collections
migrations: collections
store and forward, offline-focused AP: collections

and so on.

[django@social.coop]

@julian @silverpill ActivityPub API clients dont need their server to backfill thanks to proxyURL, but Actors will look like they haven’t posted

[julian@activitypub.space]

@django@social.coop sounds like I'll have to implement it sooner rather than later!

[fabio@manganiello.eu]

@akavel@merveilles.town thanks for your response

Did you manage to get to the bottom of it? From the description of the error it sounds like your certificate may be broken? Can you access the blog index from a normal browser? Do you perhaps have a split-domain situation (link != activitypub_link) but the certificate only applies to one?

[fabio@manganiello.eu]

@julian@fietkau.social @liaizon@wake.st it's all live, let me know if it works

[julian@fietkau.social]

@fabio @liaizon New quote test, wooo!

Madblog: A Markdown Folder That Federates Everywhere

Fabio's Blog

Fabio Manganiello (blog.fabiomanganiello.com)

Edit: Yep, looks to be working!