DELETE returned 204 for a library owned by another user, having deleted
nothing. The caller (Daedalus) recorded the workspace as cleaned up and
dropped its own row, while the Library survived holding its globally-unique
name — so that name could never be reused, and nothing anywhere recorded why.
An unowned library now returns 409 owner_conflict, reusing the code the create
path already emits for the same condition. Ownership stays opaque on GET (404
as before): the disclosure concern is about reads, and a delete that silently
does nothing is the worse failure.
A genuinely absent library still returns 204 — that idempotency is relied upon
and is correct.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
