Cache proxy provider catalogues (10 min), reuse vaults and CDMs across one batch licence call, and cache the health update check, /api/services entries and parsed service config.yaml.
Judge a vault KID only on a file whose KID map holds it, tell remote vaults of a bad pair only once another key replaces it, and let the server CDM unflag a pair it returns; the server never flags a CDM-licensed pair. Log FFmpeg stderr on a failed check and name the missing CDM when none is set.