readiness
One-call tenant-onboarding probe: readiness:query:status rolls up every config key and secret declared required: true across all mounted features and reports which still lack a usable value for the calling tenant, plus a single ready boolean. Provider-features under an r.extensionSelector-declared extension point count only while their provider is the selected one — a tenant on the inmemory mail transport is not blocked by unset SMTP keys. Mount it (together with config and secrets) when an admin UI needs a settings checklist before the first mail-send or file-write; the per-concern lists stay available via config:query:readiness and secrets:query:list.