Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-21T10:13:31+00:00	DMARC	—	INVALID	`12a658513c7d…`
2026-08-21T10:13:31+00:00	SPF	—	VALID	`b8212d2f2f08…`