Fix Shopping Cart Add-Item Bug

Our site’s checkout flow has hit a snag: it’s a straight-up functionality bug in the Shopping Cart/Checkout area that prevents products from being added to the cart at all. Everything else renders fine, but the moment a user taps “Add to Cart” nothing appears in the cart icon, the mini-cart stays empty, and the session never registers the SKU.

I need someone to dive into the existing codebase, track down the root cause, and push a clean fix without disturbing any other checkout logic. The stack is PHP 8.1 on the backend with a small sprinkle of vanilla JS and some jQuery on the front, so familiarity there will help you move quickly. Git access and a staging URL are ready for you the moment we kick off.

Deliverable
• A commit (or pull request) that restores normal add-to-cart behaviour across modern browsers
• Brief notes outlining the cause and the lines modified so future merges stay painless
• Confirmation that the fix survives a quick regression test on staging

Acceptance criteria
1. Clicking “Add to Cart” updates the cart count and reflects the item on both the mini-cart and full cart page.
2. No existing checkout or payment flow is broken by the patch.
3. Solution is deployed to staging and passes my own smoke test before we mark this completed.

If the above sounds straightforward and you have a moment today or tomorrow, let’s get this bug squashed.