(function (root, factory) {
  if (typeof module !== 'undefined' && module.exports) module.exports = factory;
  else {
    const base = new URL('./', root.location.href).pathname;
    const originalFetch = root.fetch.bind(root);
    const boundary = factory({
      cookie: () => root.document.cookie,
      origin: root.location.origin,
      base,
      fetchImpl: originalFetch,
      localStorage: root.localStorage,
      sessionStorage: root.sessionStorage,
      indexedDB: root.indexedDB,
      caches: root.caches,
      serviceWorker: root.navigator?.serviceWorker,
      MessageChannel: root.MessageChannel,
      location: root.location,
      confirmAction: message => root.confirm(message),
      onExpired: () => root.dispatchEvent(new CustomEvent('stackchain:session-expired')),
      onClearError: error => {
        root.dispatchEvent(new CustomEvent('stackchain:device-clear-failed', { detail: error.message }));
        root.alert('Signed out, but private queued work could not be cleared. Close other Stackchain tabs and clear this site’s data.');
      },
    });
    root.fetch = boundary.fetch;
    const attach = () => {
      const button = root.document.getElementById('sign-out');
      if (button) button.addEventListener('click', () => boundary.signOut());
      const allDevicesButton = root.document.getElementById('sign-out-all');
      if (allDevicesButton) allDevicesButton.addEventListener('click', () => boundary.signOutAllDevices());
      const devicesButton = root.document.getElementById('active-devices');
      const devicesSheet = root.document.getElementById('active-devices-sheet');
      const devicesList = root.document.getElementById('active-devices-list');
      const devicesStatus = root.document.getElementById('active-devices-status');
      const closeDevices = root.document.getElementById('close-active-devices');
      const renderDevices = async () => {
        devicesStatus.textContent = 'Loading active devices…';
        devicesList.replaceChildren();
        try {
          const devices = await boundary.listActiveDevices();
          devices.forEach(device => {
            const row = root.document.createElement('article');
            row.className = 'active-device';
            const details = root.document.createElement('div');
            const label = root.document.createElement('strong');
            label.textContent = device.device_label;
            const timing = root.document.createElement('span');
            timing.className = 'small muted';
            timing.textContent = `Signed in ${new Date(device.created_at * 1000).toLocaleString()} · expires ${new Date(device.expires_at * 1000).toLocaleString()}`;
            details.append(label, timing);
            if (device.current) {
              const current = root.document.createElement('span');
              current.className = 'active-device-current';
              current.textContent = 'This device';
              details.append(current);
            }
            const revoke = root.document.createElement('button');
            revoke.type = 'button';
            revoke.textContent = device.current ? 'Sign out' : 'Revoke';
            revoke.addEventListener('click', async () => {
              if (device.current) await boundary.signOut();
              else if (await boundary.revokeActiveDevice(device)) await renderDevices();
            });
            row.append(details, revoke);
            devicesList.append(row);
          });
          devicesStatus.textContent = devices.length ? `${devices.length} active device${devices.length === 1 ? '' : 's'}` : 'No active devices.';
        } catch (_error) {
          devicesStatus.textContent = 'Active devices could not be loaded. Try again.';
        }
      };
      if (devicesButton && devicesSheet) devicesButton.addEventListener('click', () => {
        devicesSheet.hidden = false;
        closeDevices?.focus();
        renderDevices();
      });
      if (closeDevices && devicesSheet) closeDevices.addEventListener('click', () => {
        devicesSheet.hidden = true;
        devicesButton?.focus();
      });
      boundary.resumeQueuedWork();
    };
    root.navigator?.serviceWorker?.addEventListener?.('message', event => boundary.handleServiceWorkerMessage(event));
    if (root.document.readyState === 'loading') root.document.addEventListener('DOMContentLoaded', attach);
    else attach();
    root.stackchainSession = boundary;
  }
})(typeof window !== 'undefined' ? window : this, function createSessionBoundary({
  cookie, origin, base, fetchImpl, localStorage, sessionStorage, indexedDB, caches, serviceWorker, MessageChannel, location, confirmAction,
  onExpired = () => {},
  onClearError = () => {},
}) {
  const SAFE_METHODS = new Set(['GET', 'HEAD', 'OPTIONS']);
  let expirationStarted = false;

  async function handleRemoteRevocation() {
    if (expirationStarted) return;
    expirationStarted = true;
    await clearPrivateDeviceData();
    location.replace(base + 'login?reason=session-revoked');
  }

  async function handleServiceWorkerMessage(event) {
    if (event?.data?.type === 'stackchain-session-revoked') {
      await handleRemoteRevocation();
    }
  }

  function csrfToken() {
    const entry = String(cookie?.() || '').split(';')
      .map(value => value.trim())
      .find(value => value.startsWith('stackchain_csrf='));
    return entry ? decodeURIComponent(entry.slice('stackchain_csrf='.length)) : '';
  }

  function isSameOrigin(input) {
    try { return new URL(String(input?.url || input), origin).origin === origin; }
    catch (_error) { return false; }
  }

  async function sessionFetch(input, options = {}) {
    const method = String(options.method || input?.method || 'GET').toUpperCase();
    const requestOptions = { ...options };
    if (!SAFE_METHODS.has(method) && isSameOrigin(input)) {
      const headers = new Headers(options.headers || input?.headers || {});
      const csrf = csrfToken();
      if (csrf) headers.set('X-CSRF-Token', csrf);
      requestOptions.headers = headers;
    }
    const response = await fetchImpl(input, requestOptions);
    if (response.status === 401 && isSameOrigin(input) && !expirationStarted) {
      expirationStarted = true;
      const payload = await response.clone().json().catch(() => ({}));
      if (payload.code === 'session_revoked') {
        expirationStarted = false;
        await handleRemoteRevocation();
      } else {
        onExpired();
        location.replace(base + 'login?reason=session-expired');
      }
    }
    return response;
  }

  function removeDashboardStorage(storage) {
    if (!storage) return;
    const keys = [];
    try {
      for (let index = 0; index < storage.length; index += 1) {
        const key = storage.key(index);
        if (key?.startsWith('stackchain.')) keys.push(key);
      }
      keys.forEach(key => storage.removeItem(key));
    } catch (_error) { /* Cookie invalidation still protects server data. */ }
  }

  async function stopWorkerOutbox() {
    const registration = await serviceWorker?.ready;
    if (!registration?.active || !MessageChannel) return;
    await new Promise((resolve, reject) => {
      const channel = new MessageChannel();
      const timeout = setTimeout(() => reject(new Error('Background outbox purge timed out.')), 3000);
      channel.port1.onmessage = event => {
        clearTimeout(timeout);
        if (event.data?.ok) resolve();
        else reject(new Error(event.data?.error || 'Background outbox purge failed.'));
      };
      registration.active.postMessage({ type: 'stackchain-purge-outbox' }, [channel.port2]);
    });
  }

  function deletePrivateOutbox() {
    if (!indexedDB) return Promise.resolve();
    return new Promise((resolve, reject) => {
      let request;
      try { request = indexedDB.deleteDatabase('stackchain-background-outbox-v1'); }
      catch (error) { reject(error); return; }
      request.onsuccess = () => resolve();
      request.onerror = () => reject(request.error || new Error('IndexedDB deletion failed.'));
      request.onblocked = () => reject(new Error('IndexedDB deletion was blocked.'));
    });
  }

  async function clearPrivateDeviceData() {
    removeDashboardStorage(localStorage);
    if (sessionStorage !== localStorage) removeDashboardStorage(sessionStorage);
    try {
      await stopWorkerOutbox();
      await deletePrivateOutbox();
    } catch (_error) {
      const error = new Error('Could not clear private queued work from this device.');
      onClearError(error);
      throw error;
    }
    try {
      const keys = await caches?.keys?.() || [];
      await Promise.all(keys.filter(key => key.startsWith('stackchain-dashboard-')).map(key => caches.delete(key)));
    } catch (_error) { /* A later service-worker activation can clear stale caches. */ }
  }

  async function listActiveDevices() {
    const response = await sessionFetch(base + 'api/v1/sessions');
    if (!response.ok) throw new Error('Could not load active devices');
    const payload = await response.json();
    return Array.isArray(payload.devices) ? payload.devices : [];
  }

  async function revokeActiveDevice(device) {
    if (!device?.management_id || device.current) return false;
    const confirmed = confirmAction?.(`Sign out ${device.device_label}?`);
    if (!confirmed) return false;
    const response = await sessionFetch(
      base + 'api/v1/sessions/' + encodeURIComponent(device.management_id),
      { method: 'DELETE' },
    );
    if (!response.ok) throw new Error('Could not revoke active device');
    return true;
  }

  async function signOut() {
    try {
      await sessionFetch(base + 'api/v1/session', { method: 'DELETE' });
    } finally {
      await clearPrivateDeviceData();
      location.assign(base + 'login');
    }
  }

  async function signOutAllDevices() {
    const confirmed = confirmAction?.('Sign out every device? You will need to sign in again everywhere.');
    if (!confirmed) return false;
    const response = await sessionFetch(base + 'api/v1/sessions', { method: 'DELETE' });
    if (!response.ok) throw new Error('Could not sign out all devices');
    await clearPrivateDeviceData();
    location.assign(base + 'login');
    return true;
  }

  async function resumeQueuedWork() {
    try {
      const registration = await serviceWorker?.ready;
      registration?.active?.postMessage({ type: 'stackchain-resume-outbox' });
    } catch (_error) { /* Background Sync is optional; foreground delivery remains available. */ }
  }

  return {
    fetch: sessionFetch,
    signOut,
    signOutAllDevices,
    listActiveDevices,
    revokeActiveDevice,
    clearPrivateDeviceData,
    handleServiceWorkerMessage,
    resumeQueuedWork,
  };
});