(function () {
  // Wait for DOM ready
  document.addEventListener('DOMContentLoaded', function () {
    document.querySelectorAll('.archive-tree-year').forEach(function (summary) {
      var details = summary.parentElement;
      var year = summary.querySelector('a')?.textContent?.trim();
      if (!year) return;
      var key = 'archive_tree_year_' + year;
      // Restore state
      var open = localStorage.getItem(key);
      if (open === 'true') {
        details.setAttribute('open', '');
      } else if (open === 'false') {
        details.removeAttribute('open');
      }
      // Listen for toggle
      details.addEventListener('toggle', function () {
        localStorage.setItem(key, details.open ? 'true' : 'false');
      });
    });
  });
})();