Function parse_public_idempotency_key_at 

pub fn parse_public_idempotency_key_at(
    key: &str,
    now: i64,
) -> Result<i64, StatementRunError>

Parse one canonical public idempotency key (sql1.<13-digit-unix-ms>.<32-lowercase-hex>) against the caller’s now, returning its mint time. Future skew beyond SQL_IDEMPOTENCY_MAX_FUTURE_SKEW_MS is refused.