the way extensibility works in a closed-world #fediverse is that "every implementer talks to every other implementer". or maybe there is a central registry of extensions that everyone submits to their authority, as stewards of the "protocol" that is used to build the "network". this trades out the n:n relation between implementers and other implementers, for an n:1 relation between implementers and the central registry.
the way extensibility works in an open-world #Web is you just do it.
11/?