AsyncOptions

Optional trailing argument on all six *Async exports for cooperative cancellation.

interface AsyncOptions {
  signal?: AbortSignal;
}

When signal is aborted before or during work, the Promise rejects with AbortError (DOMException on Node 18+). Long-running C++ paths (Monte Carlo, exact enumeration, evaluator benchmark, decideAction MC) poll the signal and stop promptly.

const ac = new AbortController();
const pending = poker.simulateHandOutcomeAsync(
  ['Ah', 'Kh'],
  ['Qh', 'Jh', '2c'],
  500_000,
  42,
  1,
  { signal: ac.signal },
);
// ac.abort(); // rejects pending with AbortError

Applies to: simulateHandOutcomeAsync, parallelHandSimulationAsync, exactHuEquityVsRandomHandAsync, straightMadeFlopToRiverExactProbabilityAsync, decideActionAsync, benchmarkEvaluatorThroughputAsync.