Hello, a merchant sent us a video of being unable to use our app to add a replacement line item to the POS cart during the exchange process. We have reproduced the error and surfaced the error message (see image).
The workflow in this case is:
Return or exchange > Add exchange items > Swipe down to minimize the built-in product search and use POS app tile to try and add product > error
Are there plans to allow for third party apps to add add line items for exchanges? Thanks.
Hey @derrick 
Just confirming this is expected with the current POS extension target coverage. During an in-progress return or exchange, the cart isn’t editable through the POS Extensions Cart API, which is why addLineItem or bulkCartUpdate returns “Cart is not editable during return or exchange.”
The built-in product selector can add exchange items, but third-party extensions don’t currently have Cart API access during that step. The exchange extension targets available today run after the exchange is completed and expose the Order API instead.
I can’t confirm any future plans or timeline, but in-exchange Cart API access is definitely a fair thing to flag. For now, the built-in product search is the available workaround.
One distinction I just wanted to mention. It looks like in your screenshot that the Cart API mutation is being blocked, but this doesn’t necessarily establish that Cart Transform itself is incompatible. If a transform also fails when the item is added through the built-in selector, let me know and we can look at that separately.
Let me know if I can pass on a feature request for you and I’d be happy to as well - hope this helps a little bit!
Thanks @Alan_G, if you could pass this along as a feature request, that’d be appreciated.
No worries @derrick - this has been passed along. I’ll mark this thread as closed but let me know if I can help out with anything else on my end here.
