Today new apmodel features:
- User can add and override (required inheritance the class) own model to loader (core models is can't override, show warning)
- apmodel supports to preload json-ld schema from local (example, schema.org, activitystreams 2.0)
For example, you can also modify extensions provided by Mastodon to be usable within an Actor (if you modify an Actor, its child inheritance won't be updated, so you'll need to modify those too... though Actors are designed to use the default value __apmodel_base__ via AS_URI, so they aren't included in the loader in the first place...).
If you have a fediverse account, you can reply to this note from your own instance. Search https://hackers.pub/ap/notes/019a5a7f-8ef0-7033-9a93-9129f037aa6f on your instance and reply to it.