{
  "id": "evt_abc123",
  "object": "event",
  "type": "payment_intent.confirmed",
  "api_version": "2026-04-01",
  "created_at": "2026-04-01T20:00:12Z",
  "data": {
    // Event-specific payload (see below)
  }
}

{
  "id": "pi_xyz789",
  "object": "payment_intent",
  "status": "confirmed",
  "amount": 4.50,
  "currency": "usd",
  "net_amount": 4.455,
  "fee": 0.045,
  "fee_rate": 0.01,
  "merchant_id": "mer_abc123",
  "payment_address": "0x1a2b3c4d5e6f...abcdef",
  "tx_hash": "0xabc123...def456",
  "chain": "base",
  "token": "USDC",
  "sender_address": "0x9876...5432",
  "confirmed_at": "2026-04-01T20:00:12Z",
  "block_number": 12345678,
  "metadata": {
    "order_id": "order_456",
    "terminal_id": "pos_01"
  }
}

{
  "id": "pi_xyz789",
  "object": "payment_intent",
  "status": "expired",
  "amount": 4.50,
  "currency": "usd",
  "merchant_id": "mer_abc123",
  "expired_at": "2026-04-01T20:05:00Z",
  "metadata": {
    "order_id": "order_456"
  }
}

app.post('/webhooks/stablegenius', async (req, res) => {
  // Return 200 immediately
  res.status(200).json({ received: true });

  // Process asynchronously
  const event = req.body;
  await processEvent(event);
});

async function processEvent(event) {
  // Check if we've already processed this event
  const exists = await db.events.findOne({ event_id: event.id });
  if (exists) return; // Already processed

  // Record the event
  await db.events.insert({ event_id: event.id, processed_at: new Date() });

  // Handle the event
  switch (event.type) {
    case 'payment_intent.confirmed':
      await markOrderPaid(event.data);
      break;
    case 'payment_intent.expired':
      await handleExpiredPayment(event.data);
      break;
  }
}