Returns the full canonical event envelope for an evt_… id —
same shape as GET /api/v1/events/{eventId}. A nominal
$0.0001 fee covers the discovery surface so this route can be
mounted under the x402 payment middleware and advertised through
the Bazaar discovery directory.
The eventId path parameter is shape-validated against
^evt_[a-z0-9]{16,}$ before payment, so a malformed id is
rejected with 400 and never charged.
Base64-encoded signed payment payload as defined by the
x402 protocol. Omit on the first attempt to
receive the 402 challenge in the PAYMENT-REQUIRED response
header; include it on the retry to settle payment and receive
the resource.
The legacy header name X-PAYMENT is also accepted by the
server for backward compatibility — clients may send either,
but Payment-Signature is preferred.
See x402.org for the on-the-wire shape of
the PaymentRequired challenge and the settlement receipt
returned in the PAYMENT-RESPONSE response header.
Stable canonical event id (e.g. evt_d62a81a5e8b2366027fbaf6b).
^evt_[a-z0-9]{16,}$OK — single canonical event envelope.