After a theme deploy you want the zone empty, not a long TTL. The control panel can do it; production should call the 2013 OAuth REST API.

Composer SDK (PHP 2.x)

composer require netdna/netdna
$api = new NetDNA('ALIAS', 'CONSUMER_KEY', 'CONSUMER_SECRET');
$api->delete('/zones/pull.json/' . $zoneId . '/cache');

Single URL

$api->delete('/zones/pull.json/' . $zoneId . '/cache', [
  'file' => '/wp-content/themes/site/style.css',
]);

Keys live in the control panel under Account. Auth docs: authentication. SDK post: PHP SDK 2.0.0. Product notes: instant purge.

There is no inbound “purge complete” webhook in the 2013 API. Wait for HTTP 200, then continue CI. See purge from deploy.