@dominik I am working on several documents that fill the gaps in the ActivityPub specification:
- FEP-fe34: Origin-based security model: this one covers authentication and authorization.
- FEP-2277: ActivityPub core types: this one is about the classification of objects. It can be later used to create a better vocabulary where nonsense such as Like of a Like activity doesn't exist.
- ActivityPub for developers: a collection of various best practices.
Eventually this work will be either incorporated into the next version of W3C ActivityPub, or will become a separate specification.