FEP-2277: ActivityPub core types has been submitted to the FEP repository.
I made several changes based on the feedback, but they are minor. There are parallel discussions at W3C GitHub, where I was told that core types don't exist, or don't matter, but this is obviously wrong, because many requirements in AP and AS depend on definitions of "collection", "activity" and other core types. Classification of objects based on their properties still seems to be the best solution.
Also, due to an uncertainty about the future of SocialHub (where many accounts are going to be suspended soon), I didn't create a discussion topic there. If you have any suggestions or feedback, please reply here or open an issue at https://codeberg.org/silverpill/feps/issues.