Choose one: Manual updates for Backdrop CMS, or the Pantheon upstream
One of the benefits of hosting a website on Pantheon, is that the dashboard can notify you when there are available updates for the core code of your CMS (Backdrop CMS, Drupal, or WordPress).
Pantheon does this by comparing the code you are running on your own website, to the latest available code in the matching Pantheon "upstream". For Backdrop CMS websites, the Pantheon "upstream" is the backdrop-pantheon
repository on GitHub.