Ultimately the goal is to make merchants' job easier.
Their pain point are
- remember customers' name and orders
- remember who ordered what
- calculate how much to charge
- how much change to give back
The first component is the "stamp card replacement"
1) Customer scan a RFID card
2) Merchant take or give loyalty points, and if needed, record their name, email and preferences
The second component is the POS system.
Straightforward, except merchants would like to keep multiple orders open and editable.
They will be using this to keep track of what orders need to be fulfilled.
e.g. what coffees they need to make, whose coffee it is, who paid, who haven't
Lastly, I would like to marry these two components into one app.
I have multiple approaches in mind, but you probably have more expertise in this. I am open to any design that achieves the same goal.
1.1: Group of customers all scan their cards, then the first screen will show all of their names, loyalty statuses and preferences. (May need placeholders for new cards).
1.2: Merchant navigates to order menu screen to place the order, and assign items to the customers. (i.e. who ordered what). Merchant should be able to see the individual customers' balance and the total balance, complete the order, and see the new loyalty statuses of the customers
2.1 Scan card to show one customer's loyalty status and preferences
2.2 Merchants complete order for one customer, back to step 1 until all orders have taken
2.3 Once all customers have completed their order, link them together somehow.
Order everything first and then scan the cards and allocate items.
I feel the 3rd option is most useful for the merchants, as the merchant may have to hop between different customer's page as they make up their minds / change their minds. That said, you probably have a much better design that can deal with these complications :)