Possible to upload batch transaction data to the cart (not the gateway)?

We have a partner that offers our inventory on their Web site. We are looking for a way to allow that partner to accept orders from their site and send us order data securely in some kind of batch format.

I don't see a contribution that would allow a store admin to accept a CSV (or XML file or whatever) with complete payment and shipping information for batch processing on our side. We would basically want to receive the CSV with all the order info and loop through the orders in the context of the cart so that each order would decrement the inventory as appropriate and then do the normal auth and cap, enter the shipping info, etc. into our database just like a normal local order would.

Is there a contribution that provides something similar? Any words of advice on this process?

I have been through much of the FAQ and forum content and have not seen anything exactly like this. TIA for your thoughts.