FA-60554 / Loyalty points ledgers / Member archive

Promotion stacking rules: non-stackable tie-break · case 04

When two exclusive promos tie, the promo with the higher id is recorded as applied.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Input {base, promos:[{id,kind,value,stackable,cap}]}. A multiplier promo (value in percent) gives floor(base*(value-100)/100) extra; a fixed promo gives value. Each extra is capped at cap when cap > 0. All stackable extras apply; of the non-stackable promos only the single best capped extra applies (ties to the lower id), in addition to the stackable ones. Return {bonus, applied ids sorted}.

Why this case matters

Member point balances, statements and the program liability depend on this ledger rule.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
tie on value	`{"applied": [7, 9], "bonus": 304}`	`{"applied": [3, 9], "bonus": 304}`	Failed

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