Receive webhooks

import express from 'express';
const app = express();

app.post('/webhooks/sly',
  express.raw({ type: '*/*' }),  // raw body — critical
  async (req, res) => {
    // verify + handle
  }
);

const wh = await sly.webhooks.create({
  url: 'https://api.yourapp.example/webhooks/sly',
  events: [
    'transfer.completed',
    'transfer.failed',
    'stream.alert',
    'approval.requested',
  ],
  description: 'Production payments worker',
});

// wh.secret — SAVE THIS (shown once)
process.env.SLY_WEBHOOK_SECRET = wh.secret;

import { verifyWebhook } from '@sly_ai/sdk';

app.post('/webhooks/sly', express.raw({ type: '*/*' }), (req, res) => {
  let event;
  try {
    event = verifyWebhook(
      req.body,
      req.headers['x-sly-signature'] as string,
      process.env.SLY_WEBHOOK_SECRET!,
    );
  } catch {
    return res.status(400).end();
  }

  // event is typed — handle it
  handle(event);
  res.status(200).end();
});

async function handle(event) {
  if (await seenEvents.has(event.id)) return;
  await seenEvents.add(event.id, { ttl: '48h' });
  await processEvent(event);
}

app.post('/webhooks/sly', ..., async (req, res) => {
  // verify
  await queue.enqueue(event);  // background worker processes
  res.status(200).end();
});

async function processEvent(event) {
  switch (event.type) {
    case 'transfer.completed':
      await markInvoicePaid(event.data.transfer);
      break;

    case 'transfer.failed':
      await notifyOps(event.data.transfer);
      break;

    case 'stream.alert':
      const { stream, alert } = event.data;
      if (alert.severity === 'warning') await topUpStream(stream);
      if (alert.severity === 'critical') await pageOps(stream);
      break;

    case 'approval.requested':
      await postToSlack(event.data.approval);
      break;
  }
}

ngrok http 3000
# use the ngrok URL as the webhook URL

curl -X POST https://sandbox.getsly.ai/v1/webhooks/wh_.../test

const deliveries = await sly.webhooks.listDeliveries(wh.id, {
  status: 'failed',
  since: '2026-04-20',
});

if (deliveries.data.length > 0) {
  // something's wrong — inspect
}

await sly.webhooks.bulkReplay(wh.id, {
  since: '2026-04-20T00:00:00Z',
  only_failed: true,
});