I have one certain product that needs to be in the cart under certain circumstances. I have been looking at the Ubercart api documentation and I don't see any hooks that would be the obvious place to see if a certain item exists prior to checkout.
I could use the hook_add_to_cart hook to add the special item whenever the first item is added, but I'm concerned that the visitor may remove the item and then complete the purchase without the required item.
Any suggestions how to make sure the special item is in the cart on checkout?