Retries and error handling

app.post('/nexor-webhook', verifyNexorSignature, async (req, res) => {
  const { event_id } = req.body;
  const claim = await eventStore.claim(event_id, { leaseMs: 60_000 });

  if (claim.status === 'completed') {
    return res.status(200).send('Already processed');
  }

  if (claim.status === 'in_progress') {
    return res.status(503).send('Processing in progress');
  }

  const { ownerToken } = claim;

  try {
    await processEvent(req.body);
    await eventStore.complete(event_id, ownerToken);
    return res.status(200).send('OK');
  } catch (error) {
    await eventStore.release(event_id, ownerToken);
    return res.status(500).send('Processing failed');
  }
});