Serverless фоновые задачи на той же платформе, что и ваши API

export async function handler(event) {
  const { reportId, userId } = JSON.parse(event.body || '{}');
  if (!reportId) return { statusCode: 400, body: JSON.stringify({ error: 'reportId required' }) };
  // Enqueue the slow export job — returns immediately
  const { instanceId: jobId } = await global.durable.startNew('export-report', undefined, { reportId, userId });
  // Client polls GET /export-status/:jobId or receives a webhook when done
  return { statusCode: 202, body: JSON.stringify({ jobId }) };
}

export async function handler(event) {
  const { reportId, userId } = event.payload;
  // Idempotency key — safe to retry
  const existing = await db.exports.findByReportAndUser(reportId, userId);
  if (existing?.status === 'done') return { url: existing.url };
  const rows = await buildReport(reportId);
  const url = await storage.upload(rows, { key: `reports/${reportId}.csv` });
  await db.exports.upsert({ reportId, userId, url, status: 'done' });
  await notify(userId, { url });
  return { url };
}