FA-60440 / Loyalty points ledgers / Member archive

Rolling tier qualification with soft landing: window start · case 05

Activity from thirteen months ago still counts toward status.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input {events:[[month,qualifying pts]], eval_month, current_tier, thresholds}. Qualifying points are summed over months eval-11..eval inclusive. The earned tier is the highest tier whose threshold is met (>=). Upgrades take effect fully; downgrades drop at most one level per evaluation. Tiers: member < silver < gold < platinum. Return {qualifying, earned, tier}.

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
window edges	`{"earned": "gold", "qualifying": 25005, "tier": "gold"}`	`{"earned": "silver", "qualifying": 5005, "tier": "silver"}`	Failed

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