Your AI agent, fluent in AppLink.

// Sends an SMS. Looks fine, ships, and lies.
const res = await fetch(SMS_URL, { method: "POST", body });
if (res.ok) return "sent";           // AppLink returns HTTP 200 for errors

// Takes a payment.
const r = await debit(order);
if (r.statusCode === "P1003") {
  markPaid(order);                   // nothing has been charged yet
}
// Verification failed? Try again...
await debit(order);                  // a second charge on a real person

// Every reply is judged on statusCode, never on HTTP status.
const reply = await res.json();
if (reply.statusCode !== "S1000") {
  throw new AppLinkError(reply.statusCode, reply.statusDetail);
}

// P1003 means the OTP was sent. The charge is two calls.
await ledger.save(order.externalTrxId, r.requestCorrelator, "PENDING_OTP");
// Money moves at /caas/otp/verify with the SAME requestCorrelator;
// the charging notification is the authoritative outcome.
// Retry = re-prompt for the OTP. Never re-run generation.