FA-58775 / Loan amortization schedules / Member archive

Installment due date calendar: weekend detection · case 05

Due dates on Saturdays are not rolled.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

x = {'first_due': [y, m, d] (d may exceed the month length), 'count', 'roll': 'none'|'following'|'modified_following', 'holidays': ISO dates}. Installment i falls in month m+i on the anchor day d clamped to the month length (later months return to d). Unless roll is 'none', a Saturday, Sunday or holiday rolls forward to the next business day; under modified_following a roll that leaves the month instead rolls back to the previous business day. Return ISO date strings.

Why this case matters

Amortization engines drive borrower statements, payoff quotes and investor remittances; a misplaced rounding step, boundary or ordering rule compounds across hundreds of periods.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: weekend detection	`["2024-08-05", "2024-09-05", "2024-10-05"]`	`["2024-08-05", "2024-09-05", "2024-10-07"]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.