if ('serviceWorker' in navigator) {
  window.addEventListener('load', () => {
    navigator.serviceWorker.register('/sw.js', { scope: '/' })
      .then((reg) => {
        console.log('SW registered:', reg.scope);

        reg.addEventListener('updatefound', () => {
          const newWorker = reg.installing;
          if (newWorker) {
            newWorker.addEventListener('statechange', () => {
              if (newWorker.state === 'installed' && navigator.serviceWorker.controller) {
                console.log('New SW version available. Refresh to update.');
              }
            });
          }
        });
      })
      .catch((err) => {
        console.error('SW registration failed:', err);
      });
  });
}