Re: [development] where to document additions to the core API?

2) spam this mailing list about it and hope everyone who might like to know is subscribed?

Didn't you just do that? ;-) Anyways ... You correctly note that this has no migration impact. Isn't it enough to just add doxygen comments for it, and it will end up in api.drupal.org eventually? It would not hurt to keep a list of those and announce on the development mailing list periodically. Perhaps as they come in, and once when 4.8/5.0 is released for a consolidated list.