$api_check = FALSE;
  $headers = getallheaders();
  foreach($headers as $key => $value) {
    if (stripos($key, 'X-API') !== FALSE) {
      $api_check = TRUE;
    }
  }
  // you get the idea ^
  // so contrib modules can get patches to opt-out of expensive hook_init/hook_boot or whatever rendering
  // needs that may be horribly expensive and unnecessary for an API call

  // eg
  // some_awesome_module_init() {
  //   if (i_can_has_api()) {
  //     return;
  //   }
  // // beautiful, world-changing code that sadly does not help w/ teh JSONs...
  // }