'covenant'  a fleet swearing ONE shared oath — id required: the oath text,
            the cohort that has sworn, any recorded renouncements.
'pact'      an agreement BETWEEN parties (different obligations, one
            document) — id required: parties, terms, each side's
            self-asserted status, the shared thread.
'witness'   chain-evidenced drift plus public portfolio pledges. With an
            id (a vow id): that vow's record. Without: the Witness card
            plus the whole pledge register.

A register records what was claimed; it never renders a verdict. A signed
Witness *reading* is paid, on POST /api/witness/reading.