function createPlanTodayReadiness({ identity, inspect, concurrency = 3 }) {
  const workerCount = Math.max(1, Math.floor(Number(concurrency) || 1));
  let generation = 0;

  async function run(items) {
    const runGeneration = ++generation;
    const candidates = Array.from(items || []);
    const results = new Array(candidates.length);
    let next = 0;

    async function worker() {
      while (next < candidates.length) {
        const index = next;
        next += 1;
        const item = candidates[index];
        let result;
        try {
          result = await inspect(item);
        } catch (_error) {
          result = { status:'unverified' };
        }
        results[index] = [identity(item), result];
      }
    }

    await Promise.all(Array.from(
      { length:Math.min(workerCount, candidates.length) },
      () => worker(),
    ));
    if (runGeneration !== generation) return null;
    return Object.fromEntries(results);
  }

  function cancel() {
    generation += 1;
  }

  return { run, cancel };
}

if (typeof module !== 'undefined' && module.exports) module.exports = createPlanTodayReadiness;