async function runWithCallback(
  client: HexClient,
  projectId: string,
  params: Record<string, any>,
  onComplete: (result: any) => void,
  onError: (error: Error) => void
) {
  try {
    const { runId } = await client.runProject(projectId, params);
    const poll = async () => {
      const status = await client.getRunStatus(projectId, runId);
      if (status.status === 'COMPLETED') { onComplete(status); return; }
      if (status.status === 'ERRORED' || status.status === 'KILLED') { onError(new Error(status.status)); return; }
      setTimeout(poll, 5000);
    };
    poll();
  } catch (err) { onError(err as Error); }
}

runWithCallback(client, 'project-id', { date: '2025-01-01' },
  (result) => {
    // Send Slack notification, email, etc.
    fetch(process.env.SLACK_WEBHOOK_URL!, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ text: `Hex project completed: ${result.runId}` }),
    });
  },
  (error) => console.error('Run failed:', error)
);