I'm writing a custom, private app that handles downloadable products. I'd set it up so that the download links are sent out when an order payment notification is received, but I'm realising now that this is only triggered when an order is 'fulfilled' from the back-end, while we want to send the links out as soon as they are paid for rather than waiting for our staff to manually fulfil the orders.
What's complicating things is that we also sell physical products, sometimes in the same cart, so we cannot simply fulfil upon order creation.
Does anyone have any info on which APIs/workflows I should look at to achieve this please? Perhaps I need to respond to a different notification event that is triggered on order placement, and then tell Shopify to fulfil the downloadable products individually?
We're on Plus so I've had a look at Flow, but it doesn't seem to allow this sort of control.