Function record_delivered 

pub(crate) fn record_delivered(
    wan: &WanIdentityStore,
    verdict: &WanVerdict,
    row: &CarriedRow,
    now: i64,
)

After a verified message was delivered locally: remember it, so the same (instance, agent, msgid) is a replay from now on (§2.5). Not before delivery — the relay’s own release-and-redeliver must not look like one.