Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-20T17:01:43+00:00	DMARC	—	VALID	`f18f15f1d682…`
2026-08-20T17:01:43+00:00	SPF	—	VALID	`158d8c554dd7…`