I know this is an old post, however, Rewardify (apps.shopify.com/rewardify) allows you to manage store credit for your Customers for Online and Shopify POS and works very well. You can refund to store credit and apply store credit towards purchases on Shopify POS using the native store credit payment option. You can even refund Online orders to store credit using Shopify POS. Unfortunately the only option for Online purchases (for the moment) is to allow the Customer to redeem store credit towards a discount before checkout.
Yes.. now we don't have to do any of that mess. We just released FreshCredit which is the first true store credit app for Shopify. No points, codes, or cards that expire. Just cash. Check us in the App Store..
You're exactly right. We aren't allowed to touch the checkout page. So we have to go through the customer's account page. But once the customer logs into their account, they just have to click on the store credit button. They can do that before or after they've added items to their cart and it will work. We've done the best we could within Shopify's constraints!
It is also very strange that a client can pay with any amount of store credit he does not have (Shopify POS)!
I've tried this :
Scratching my head...
I have been using rise! (https://apps.shopify.com/rise-ai). Rise enables you to integrate your online store to your Shopify POS. Also, if you have customer accounts on your online store, you can create a workflow that accumulates store credit into their accounts that can be redeemed both online and your brick and mortar stores. This way it is actually tied to their account.