Add customisation for product when adding to cart

[derekjwhitten]

I'm creating a module which should add a customisation to a product once the product is added to the cart.

I'm using the hookActionCartSave hook to trigger my code when an item is added to the cart.  After adding an item to the cart (via the regular add to cart button on a product page) the product is added but the customisation is not.  From my investigation, it feels like my code is trying to add the customisation before the initial product is actually in the cart and so id_customization is not being set in the cart_product table for the product.

Is someone able to help with the flow here? What hook should I be using to add a customisation to an item that has just been added to the cart?