idn_… id or its name) as its first argument. Amounts are
integer micro-USD (1 USD = 1_000_000). Reads return a Card — never a credential.
revealCredentials is the one method that returns a CardCredentials, a separate type from Card
so a credential can never be spread into a read result. It is audited and answers not_found for a
card that is not active; keep the result out of logs.
idempotencyKey to createClient (or let the default generate one) so a retried issue
replays the same card rather than buying a second. See the Cards API for statuses,
scopes and errors.