# Requirement change

We are overstocked on tea, so from now on: **buy two teas, get the third free.** No voucher code,
no opting in — anyone with three teas in their basket gets one of them free, automatically.

It repeats. Six teas means two free. Seven teas still means two free — you need the third one in
the group before the group counts.

Things I want to be explicit about, because this is where these offers go wrong:

- **The line does not change.** If someone has three teas, the basket still shows three teas at 450
  each, coming to 1350. The free one is a **discount**, not a missing item. The customer wants to
  see what they saved, and the warehouse still has to pick three.
- **It applies before the vouchers.** Knock the free tea off first, then work the percentage out on
  what is left. Three teas with `SAVE10` on them: 450 off for the free tea, leaving 900, then 10%
  of *that* — 90 — so 540 off in total. Not 10% of 1350.
- **It is tea only.** Three mugs is three mugs. Nothing else in the catalogue is on offer.
- **Delivery still follows the discounts.** A big enough tea order can be pushed back under the
  free-delivery threshold by its own offer, and that is fine — same rule as the vouchers.
- Everything else is untouched: same catalogue, same prices, same paging, same rounding, same
  voucher behaviour.
