Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T15:28:57+00:00	DMARC	—	INVALID	`12a658513c7d…`
2026-08-20T15:28:57+00:00	SPF	—	VALID	`fd55f9bcdffb…`