Nobody can tell me what a cardholder with a promo code actually pays

Problem Description

We ship the new checkout discount logic in three weeks, and the only written source is the pricing note below. Product wrote it in a hurry. It has three switches in it - the loyalty card, the order total, and the promo code field - and it describes them one at a time, in whatever order they occurred to whoever was typing.

Support has already asked twice what a cardholder who enters a promo code should be charged, and I cannot answer it from the text. I would rather find every question of that shape now than after the tester files it as a bug and product tells us it was "obviously" meant the other way.

The test lead wants one document he can take into the review with product, so whatever is missing gets decided by a person instead of by whoever writes the code first.

Output Specification

Produce discount-rules-analysis.md containing:

1. The switches that decide what a customer pays, one per line, each phrased so a tester can set it on its own.
2. Every distinct thing the note can produce - a discount, a shipping result, a plain full-price charge - listed separately.
3. A table giving the expected result for every possible setting of those switches, including settings the note never talks about.
4. Any setting whose result you could not work out from the note, written up as an open question for product rather than filled in with your best guess.
5. The checkout cases QA should run, taken from that table.

Out of scope: arithmetic against a real basket, anything about the payment provider, and writing any code. This is a review document only.

Input Files

Extract the following files before beginning.

=============== FILE: docs/checkout-discount-note.md ===============

Checkout discounts (draft note, v3)

Loyalty cardholders get 10% off the basket.

Orders of EUR 75 or more ship free. Below that, shipping is EUR 4.90.

A promo code entered at checkout takes 15% off the basket. Codes are open to everyone - there is no restriction on who is allowed to type one in, and the field is shown on every checkout.

Percentage discounts do not combine. A basket gets one percentage off, not two.

Shipping is worked out from the basket total before any percentage discount is applied, so a discount never moves an order across the EUR 75 line.

Note from Marta (2026-05-02): the 15% code is the summer campaign. Finance wants reporting to keep campaign discounts and card discounts apart, so whichever one applies has to be recorded distinctly on the order.