Egregoros

@a

this is backwards -- to:Public = "public", cc:Public = "unlisted"

Will fix, thanks.

generally it doesn't matter if to/cc is used for the followers collection. what actually matters is that to/cc does not contain Public again to/cc doesn't matter here, a "direct" post is simply one where every audience member can be mapped to an account instead of a collection or unknown

Technically that is true. That would be a more lenient case of what I wrote. But I think Mastodon uses the more rigid way of addressing where FO is using to for both mentions and Collections. And DMs are the same except the follower Collection is gone. It also makes more sense that way, you aren't carbon-copying your post to your followers, you are actively addressing it to them via the Collection. If the Collection didn't exist, cc would be the appropriate place for all the Actors in that case I think.

I'll think about it, if I can reword it a little bit to be more open, but I don't really agree that addressing should be inferred the way you are describing. Another reason for being more strict in the addressing inference is because you cannot add more scopes as easily. At least not by inventing new URI similar to as:Public, like ak:Bubble for addressing Akkoma's bubble thing. The URI would have to be specific to that instance for it to work, but point stands. (I don't think bubble addressing should exist either btw.)