First cut

server/src/sms/reply.ts

@@ -0,0 +1,30 @@
+import { logger, maskPhone } from '../logger.js';
+
+const TELNYX_API_KEY = process.env.TELNYX_API_KEY || '';
+
+export async function sendSms(to: string, from: string, body: string): Promise<void> {
+  if (!TELNYX_API_KEY) {
+    logger.warn({ event: 'sms.send_skipped', to: maskPhone(to) }, 'No TELNYX_API_KEY, skipping SMS send');
+    logger.info({ event: 'sms.would_send', body }, 'SMS body (dev mode)');
+    return;
+  }
+
+  try {
+    const resp = await fetch('https://api.telnyx.com/v2/messages', {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        Authorization: `Bearer ${TELNYX_API_KEY}`,
+      },
+      body: JSON.stringify({ from, to, text: body }),
+    });
+
+    if (!resp.ok) {
+      logger.error({ event: 'sms.send_failed', status: resp.status }, 'Failed to send SMS');
+    } else {
+      logger.info({ event: 'sms.sent', to: maskPhone(to) }, 'SMS sent');
+    }
+  } catch (err) {
+    logger.error({ event: 'sms.send_error', error: (err as Error).message }, 'SMS send error');
+  }
+}