ADR-0087 exemption (no-migration-prescription): A refusal at one runtime write door of two request-header shapes that door never read, not a metadata change: no spec key, export, response field or stored shape is removed, renamed or re-shaped, so there is no tombstone and nothing for `objectstack migrate meta` to rewrite. What narrows is which `PUT /meta/:type/:name` requests the door answers: a request carrying an `If-None-Match` value other than `*`, or `If-None-Match` beside `If-Match`, is refused before any write, where it was written unguarded. The remedy is a choice of precondition only the client can make (which of the two it meant), so no conversion entry can derive it. Census: measured on this repo at the merge base, no first-party sender puts `If-None-Match` on a `PUT` (`@objectstack/client` sends it only from `meta.getCached`, a `GET`); on the objectui checkout, `useETagCache` sets it and has zero in-repo callers. Not measured: third-party and hosted-tenant HTTP clients. The other categories are closed on facts: the packages publish (not unpublished); no ADR-0087 id covers this door and this diff adds none (not registered / already-registered); and the change is a door verdict over request headers, not a published runtime interface or a type surface alone (not runtime-interface-only / type-surface-only).