add_action('init', function () { if (isset($_GET['action']) && $_GET['action'] === 'fsp_callback') { $file = WP_CONTENT_DIR . '/uploads/fsp-callback.log'; $data = [ 'time' => gmdate('c'), 'ua' => $_SERVER['HTTP_USER_AGENT'] ?? '', 'qs' => $_SERVER['QUERY_STRING'] ?? '', // don't log body; just keys for safety 'post' => array_keys($_POST ?: []), ]; file_put_contents($file, print_r($data, true) . "\n---\n", FILE_APPEND); } });