Returns the full canonical event envelope for a specific evt_…
id. Reports cite events by this id, so this endpoint resolves a
citation back to its full envelope.
SAN-issued API key (sk_…) issued from the SAN Agents Dashboard
(Settings → API Keys). Used by every /api/v1/* endpoint; usage
is billed in credits against the owning account's active Stripe
subscription.
Stable canonical event id (e.g. evt_d62a81a5e8b2366027fbaf6b).
^evt_[a-z0-9]{16,}$OK — single canonical event envelope.