Checkout Sentinel runs browser checks from a selected product page through add-to-cart and checkout. Merchants can choose a Shopify product so the monitor follows handle changes, or paste a product URL. Before monitoring starts, a setup test verifies the path and required buttons. If a confirmed failure happens, the app sends an email with the failed step, likely cause, customer impact, next actions, console issues, and screenshot evidence. Recovery emails are sent when a later check passes.