| @medusajs/promotion | patch |
|---|
fix(promotion): apply buy-get promotions independently of line item order
A buyget promotion whose target product is also listed in its own buy_rules was applied or not depending purely on the order of line items in the cart, and when it was not applied nothing surfaced — no error, no adjustment, the cart silently stayed at full price.
Two things caused it. sortByPrice in buy-get.ts never returned 0, so for equally priced items it claimed a strict ordering that does not exist and left the result up to the sort implementation. The buy-side selection then greedily reserved the first buy_rules_min_quantity eligible items and subtracted them from the target's available quantity, so whenever the target item was the one reserved, the promotion was dropped even though a valid assignment existed.
The comparators now return 0 for equal prices (also in sort-by-price.ts, where sortLineItemByPriceAscending and sortShippingLineByPriceAscending had the same problem), and the buy side now prefers items that cannot serve as targets before falling back to target-eligible ones. Buy X get X on a single product is unaffected.