Authentication history

Immutable persisted observations.

Observed	Signal	Selector	Verdict	Fingerprint
2026-08-21T12:18:21+00:00	DMARC	—	VALID	`21d28dd190c5…`
2026-08-21T12:18:21+00:00	SPF	—	VALID	`d520ce32e2ac…`