#activitypub thonk: delivering to a Collection is nonsensical because a Collection could be an actor. but so can a Group

basically you have implicit behavior "the Collection needs to be expanded to its items which are assumed to all be actors" just like a Group might expand to all its members (except the assumption there is a bit stronger, you can generally expect a Group's members to all be individuals?)

whereas something like WAC makes a distinction between agent, agentGroup, agentClass

i'm not actually sure how something like this could be resolved. clearly there is existing functionality that depends on expanding collections found in the audience addressing properties: specifically, the followers collection, which powers the "followers-only post" feature, which is the primary reason activitypub even got adopted by mastodon in the first place

i guess to make any transition less painful you would probably want to solve multiple problems at the same time? but part of the problem is that it’s not clear what the exact behavior of to/cc should be with respect to this other dimension of something being an actor, a group of actors (like your followers), or a class of actors (like Public). and there’s another dimension after that — splitting delivery from visibility. you can’t actually deliver to Public; it doesn’t have an inbox.

@trwnh
but there is https://codeberg.org/fediverse/fep/src/branch/main/fep/400e/fep-400e.md

@sl007 this has nothing to do with what i was talking about (addressing and delivery via to/cc)