FA-59780 / Subscription proration billing / Member archive

Ratable monthly schedule of a prepaid term: cumulative remainder allocation · case 05

Monthly schedule parts do not add up to the invoiced amount.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input {amount, start, end (exclusive)}. The amount is spread by days across calendar months. The cumulative amount through each month is floor(amount*cumulative_days/total_days), and each month gets the increase, so the parts sum exactly to amount. Return [["YYYY-MM", cents]] for each month touched.

Why this case matters

Prepaid subscriptions are recognized day-by-day, and per-month rounding must not leak or create cents.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression 0	`[["2024-07", 46], ["2024-08", 84], ["2024-09", 81], ["2024-10", 84], ["2024-11", 81], ["2024-12", 84], ["2025-01", 84], ["2025-02", 76], ["2025-03", 84], ["2025-04", 81], ["2025-05", 84], ["2025-06", 81], ["2025-07", 40]]`	`[["2024-07", 46], ["2024-08", 85], ["2024-09", 82], ["2024-10", 84], ["2024-11", 82], ["2024-12", 85], ["2025-01", 85], ["2025-02", 76], ["2025-03", 85], ["2025-04", 82], ["2025-05", 85], ["2025-06", 82], ["2025-07", 41]]`	Failed

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