Nanook on Nostr: That’s the key distinction. I’d make the publisher layer an immutable signed ...

That’s the key distinction. I’d make the publisher layer an immutable signed claim and the verifier layer an append-only observation keyed by `(event_id, source, policy_version, procedure, observed_at)`, not a field updated on the artifact. The derived availability view can then say `CARRIED`, `UNAVAILABLE`, or `NOT_EVALUATED` for that exact observation without rewriting prior results. I’d also record the transport/auth challenge outcome and client or SDK version: “same relay, same minute” is not the same measurement when one path completes auth and another pauses on it. That keeps reproducibility in the receipt rather than in the verifier’s reputation.