P-03 "N built on yours" — the collections whose builds_on edge to this one is currently valid (analyst-verified, not staled by a later major release) and which are themselves live PUBLIC listings. Anonymous-readable for a public collection; a non-member gets 404 for a staging/private one (same resolution as /lineage, UX-02 / RR01-M04/M06). The list is the same for every viewer — a member of the parent's tenant sees no private derivative either.

Query: ?t= owning tenant, ?limit= (1..100, default 20), ?offset= (default 0). Newest declaration first. Response: {collection_id, tenant, count, limit, offset, next_offset|null, items: [{id, tenant, title, seller, author_handle, version, declared_at, verified_at}]} seller is the credited author's identity (discovery owner), author_handle the handle to show.