Every type post reads as schema + extension. Added host/blog--type-population (host/blog--take
helper): a type's page shows its instances (posts is-a it, first 24 + count) and its subtypes
(is-a / subtype-of inverses), next to the read-only type definition. Injected in host/blog-post
when host/blog--is-type?. So /article/ shows what an article IS *and* which posts are articles;
/card/ shows its subtypes; every card type / tag / type reads its own definition (all are
is-type?).
blog 194/194 (+ tests: population lists instances + count, a parent type lists subtypes, GET
/article/ shows Population).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>