On OIDC-only instances the bootstrap admin (first SSO user) rarely carries the configured admin claim, so a forced re-login — e.g. after a JWT-secret rotation — re-derived its role purely from claims and demoted it to user, locking the instance out with no recovery. The OIDC login role sync now skips a downgrade that would strip the last remaining admin, and the admin user-update endpoint guards the same case.