// Get $app
/** @var \Bolt\Extension\BoltAuth\Auth\AccessControl\Session $authSession */
$authSession = $app['auth.session'];
if ($authSession->hasAuthorisation()) {
/** @var \Bolt\Extension\BoltAuth\Auth\AccessControl\Authorisation $auth */
$auth = $authSession->getAuthorisation();
/** @var \Bolt\Extension\BoltAuth\Auth\Storage\Entity\Account $account */
$account = $auth->getAccount();
/** @var string $authId */
$authId = $account->getGuid();
}