A minimal static test harness deployed via GitHub Pages, used to validate that the GTM Web Container (GTM-TTZ2JRGD) correctly fires a purchase event into the Server-Side Tagging pipeline built in shopify-ga4-mass-balance-monitor.

This is a validation tool, not a production system. It exists solely to confirm that a client-side dataLayer.push() purchase event is captured by the GTM Web Container and forwarded through the deployed SST proxy.

How it works:

• Loads the GTM Web Container snippet.
• Displays a "Fire Test Purchase Event" button.
• On click, pushes a synthetic purchase event with a test transaction ID (SST-TEST-*) to dataLayer.
• Used with GTM Preview/Tag Assistant to confirm the event reaches the Server Container.

See the SST case study for the full validation evidence produced using this environment.