Export .jsonl

Write simple structured logs for later analysis.

import { writeFileSync } from 'node:fs';
import { appendFile } from 'node:fs/promises';

const path = './runs.jsonl';
writeFileSync(path, '', { flag: 'w' });

export async function logLine(obj: unknown) {
  await appendFile(path, JSON.stringify(obj) + '\n');
}