function set_first_party_cookie() { if (!isset($_COOKIE['user_id'])) { $user_id = 'user_' . wp_generate_uuid4(); setcookie('user_id', $user_id, time() + (30 * 24 * 60 * 60), "/", $_SERVER['HTTP_HOST'], false, true); } } add_action('init', 'set_first_party_cookie');