Back off SMS queue after gateway throttling

src/jobs/expireTokens.job.js

@@ -78,7 +78,11 @@ async function expireTokens() {
       if (token.customer_phone) {
         sms.sendSMS(
           token.customer_phone,
-          messages.tokenExpired(token.device_name, token.plan_name)
+          messages.tokenExpired(token.device_name, token.plan_name),
+          {
+            ttl: 6 * 60 * 60,
+            priority: sms.priorities.low,
+          }
         ).catch((err) => {
           console.error(`[expireTokens] Expiry SMS failed for ${token.code}:`, err.message);
         });

src/services/sms.js

@@ -2,16 +2,17 @@ const axios = require('axios');
 const crypto = require('crypto');
 const db    = require('../config/db');
 
-const SEND_INTERVAL_MS = Number(process.env.SMS_SEND_INTERVAL_MS || 1500);
-const MAX_ATTEMPTS = Number(process.env.SMS_MAX_ATTEMPTS || 3);
-const RATE_LIMIT_BACKOFF_MS = Number(process.env.SMS_RATE_LIMIT_BACKOFF_MS || 15000);
-const MAX_BACKOFF_MS = Number(process.env.SMS_MAX_BACKOFF_MS || 30000);
+const SEND_INTERVAL_MS = Number(process.env.SMS_SEND_INTERVAL_MS || 5000);
+const MAX_ATTEMPTS = Number(process.env.SMS_MAX_ATTEMPTS || 4);
+const RATE_LIMIT_BACKOFF_MS = Number(process.env.SMS_RATE_LIMIT_BACKOFF_MS || 60000);
+const MAX_BACKOFF_MS = Number(process.env.SMS_MAX_BACKOFF_MS || 180000);
 const DEFAULT_TTL_SECONDS = 24 * 60 * 60;
 const DEFAULT_PRIORITY = 0;
 const HIGH_PRIORITY = 100;
 
 let sendQueue = Promise.resolve();
 let lastSendAt = 0;
+let rateLimitUntil = 0;
 
 function normalizePhone(phone) {
   const d = phone.replace(/\D/g, '');
@@ -46,6 +47,9 @@ function retryAfterMs(err) {
 }
 
 async function waitForTurn() {
+  const cooldownMs = Math.max(0, rateLimitUntil - Date.now());
+  if (cooldownMs > 0) await delay(cooldownMs);
+
   const elapsed = Date.now() - lastSendAt;
   const waitMs = Math.max(0, SEND_INTERVAL_MS - elapsed);
   if (waitMs > 0) await delay(waitMs);
@@ -108,11 +112,15 @@ async function sendWithRetry(to, message, options) {
       const statusCode = err.response?.status;
       const isRateLimited = statusCode === 429;
       const canRetry = isRateLimited && attempt < MAX_ATTEMPTS;
+      const gatewayWait = retryAfterMs(err);
+      const backoffMs = Math.min(gatewayWait || RATE_LIMIT_BACKOFF_MS * attempt, MAX_BACKOFF_MS);
+
+      if (isRateLimited) {
+        rateLimitUntil = Math.max(rateLimitUntil, Date.now() + backoffMs);
+      }
 
       if (!canRetry) break;
 
-      const gatewayWait = retryAfterMs(err);
-      const backoffMs = Math.min(gatewayWait || RATE_LIMIT_BACKOFF_MS * attempt, MAX_BACKOFF_MS);
       console.warn(`[SMS] Rate limited for ${to}; retrying attempt ${attempt + 1}/${MAX_ATTEMPTS} in ${backoffMs}ms`);
       await delay(backoffMs);
     }