Timer adapters

import { StatefulSimulation } from '@jikan0/adapters';

const result = StatefulSimulation.create([{ kind: 'exercise', duration: 1000 }]);
if (!result.ok) console.error(result.issues);
else {
  const timer = result.timer;
  const unsubscribe = timer.onTransition(console.log);
  timer.start();
  // Later: unsubscribe(); timer.dispose();
}

Rejected input preserves state. onTransition reports consumed stages in order. Pause preserves progress; restart restores the current stage; reset restores the initial program. Inject now and schedule for deterministic timing. The default is performance.now(); delayed callbacks catch up, but OS sleep and suspended execution are not guaranteed.

For consumer-owned state, use createElapsedDriver. See numeric bounds.