Feature request: ActivityPub integration

[stefanbohacek]

Describe the Feature

Hi!

Would there be any interest to add ActivityPub support to allow people to enable sharing of their posts in the fediverse, similarly to how Threads handles this?

https://help.instagram.com/760878905943039

This project might provide a good starting point: https://github.com/msonnb/fedisky

Attachments

No response

Describe Alternatives

People can currently opt into having their accounts bridged https://brid.gy, and it works well enough, but I've seen people get confused when they receive a request to enable bridging.

Having an option in the account settings would be more convenient and more people might actually use it.

Additional Context

No response

[jalcine]

This wouldn't be the spot (because it's the appview) but would first need work at the PDS layer (IMO), something that was initially mentioned in blacksky-algorithms/rsky#125.

[jalcine]

Okay, I've been doing some more digging into this for the last two months. This is not a small undertaking (significant in API shape, database size, privacy and a whole bunch of things). I was a bit misspoken when I earlier said that would need to live in the PDS layer.

Federation has to live at the PDS/AppView layer, not here, because stuff like the actor identity, key material, and signed delivery belong to the data layer, not the client (which is the this app). The actual work could live in a new crate, rsky-mastodon-gateway that provides a service that translates between ATProto records and a Mastodon-compatible REST/ActivityPub surface (it could connect to the PDS using the same JWT and make the needed ATProto calls to save work) and a small PDS capability to mint per-account AP RSA keys so the gateway doesn't reach into the PDS's key store directly (or this could live in the gateway itself as an extension, keeping the PDS pure).

What could be shipped here in the meantime without waiting on all of that is a new *Pref slot in the user's existing app.bsky.actor.defs#preferences list — call it shareToFediPref — wired to a settings toggle and a feature flag that flips on once the gateway exposes its capability, so the UX lands today and the federation work tracks separately. That crate/service can then check for this when it's interacting with the Fediverse and conditionally engage with it - because I don't think making it not something you can opt-in or -out of would be expected for the folks currently using rsky-pds.