Is there some way to trigger adding a specific product to an open cart?

[David R]

Out of curiosity...is the idea to add the free product before or after shipping is calculated? And/or would the customer be able to remove the free item from their cart if they didn't want it, or if there was a shipping cost and they didn't want to pay?

I've got the luxury of working on this in the narrow confines of our situation: the added product is free, shipping is free, these items are not taxable.

There is at least one old thread on this topic where the writer was protesting the propriety of adding an item to a customer's cart. I'm sure the questions of tax and shipping would amplify that if someone is trying to make a general purpose contribution.

In what again is our narrow case, the goal is to have this work automatically without requiring any additional steps on the customer's part, and (ideally) to not allow them to trick the system by removing qualifying items during the process. Failing that last, we will have to screen each order during the promotion to be sure it really qualifies.

[DrByte]

In this older post I made I gave some code examples that might be helpful as inspiration for your situation.