FA-59386 / Subscription proration billing / Open access
Month-end anchored renewal dates: year carry · case 01
Renewals that roll into January keep the old year.
ROOT CAUSE
The year carry is computed from the elapsed months only, ignoring the anchor month offset.
THE FAILURE
The year carry is computed from the elapsed months only, ignoring the anchor month offset.
Unsuccessful approach: The attempt subtracts one before dividing, so January renewals stay in the prior year.
Case contract
Input {anchor [y,m,d], n, interval months}. Renewal i (1..n) falls interval*i months after the anchor month, on the anchor day clamped to that month's length (so a 31st anchor returns to the 31st whenever possible). Return the list of [y, m, d].
Why this case matters
Month-end anchors must not drift to the 28th after February, and leap years change the clamp.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
import calendar
N = 1
observations = []
def solve(x):
y, m, d = x['anchor']
out = []
for i in range(1, x['n'] + 1):
total = (m - 1) + i * x['interval']
ny, nm = y + i * x['interval'] // 12, total % 12 + 1
dim = calendar.monthrange(ny, nm)[1]
out.append([ny, nm, min(d, dim)])
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'anchor': [2024, 7, 30], 'n': 7, 'interval': 3}, [[2024, 10, 30], [2025, 1, 30], [2025, 4, 30], [2025, 7, 30], [2025, 10, 30], [2026, 1, 30], [2026, 4, 30]]), ('regression', {'anchor': [2025, 5, 31], 'n': 10, 'interval': 2}, [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2026, 1, 31], [2026, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2027, 1, 31]]), ('partial-repair probe', {'anchor': [2019, 5, 29], 'n': 11, 'interval': 2}, [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]]), ('partial-repair probe', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('normal control', {'anchor': [2023, 3, 28], 'n': 14, 'interval': 3}, [[2023, 6, 28], [2023, 9, 28], [2023, 12, 28], [2024, 3, 28], [2024, 6, 28], [2024, 9, 28], [2024, 12, 28], [2025, 3, 28], [2025, 6, 28], [2025, 9, 28], [2025, 12, 28], [2026, 3, 28], [2026, 6, 28], [2026, 9, 28]]), ('normal control', {'anchor': [2024, 2, 29], 'n': 6, 'interval': 2}, [[2024, 4, 29], [2024, 6, 29], [2024, 8, 29], [2024, 10, 29], [2024, 12, 29], [2025, 2, 28]]), ('normal control', {'anchor': [2025, 8, 28], 'n': 1, 'interval': 1}, [[2025, 9, 28]]), ('normal control', {'anchor': [2025, 1, 29], 'n': 8, 'interval': 1}, [[2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29]])], [('regression', {'anchor': [2025, 5, 31], 'n': 10, 'interval': 2}, [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2026, 1, 31], [2026, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2027, 1, 31]]), ('regression', {'anchor': [2019, 5, 29], 'n': 11, 'interval': 2}, [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]]), ('partial-repair probe', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('partial-repair probe', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('normal control', {'anchor': [2025, 4, 28], 'n': 8, 'interval': 12}, [[2026, 4, 28], [2027, 4, 28], [2028, 4, 28], [2029, 4, 28], [2030, 4, 28], [2031, 4, 28], [2032, 4, 28], [2033, 4, 28]]), ('normal control', {'anchor': [2025, 3, 31], 'n': 7, 'interval': 12}, [[2026, 3, 31], [2027, 3, 31], [2028, 3, 31], [2029, 3, 31], [2030, 3, 31], [2031, 3, 31], [2032, 3, 31]]), ('normal control', {'anchor': [2025, 1, 31], 'n': 9, 'interval': 1}, [[2025, 2, 28], [2025, 3, 31], [2025, 4, 30], [2025, 5, 31], [2025, 6, 30], [2025, 7, 31], [2025, 8, 31], [2025, 9, 30], [2025, 10, 31]]), ('normal control', {'anchor': [2019, 1, 30], 'n': 2, 'interval': 1}, [[2019, 2, 28], [2019, 3, 30]])], [('regression', {'anchor': [2019, 5, 29], 'n': 11, 'interval': 2}, [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]]), ('regression', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('partial-repair probe', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('partial-repair probe', {'anchor': [2019, 12, 29], 'n': 7, 'interval': 1}, [[2020, 1, 29], [2020, 2, 29], [2020, 3, 29], [2020, 4, 29], [2020, 5, 29], [2020, 6, 29], [2020, 7, 29]]), ('normal control', {'anchor': [2025, 5, 16], 'n': 3, 'interval': 12}, [[2026, 5, 16], [2027, 5, 16], [2028, 5, 16]]), ('normal control', {'anchor': [2025, 4, 28], 'n': 7, 'interval': 1}, [[2025, 5, 28], [2025, 6, 28], [2025, 7, 28], [2025, 8, 28], [2025, 9, 28], [2025, 10, 28], [2025, 11, 28]]), ('normal control', {'anchor': [2024, 5, 31], 'n': 3, 'interval': 1}, [[2024, 6, 30], [2024, 7, 31], [2024, 8, 31]]), ('normal control', {'anchor': [2019, 7, 22], 'n': 2, 'interval': 2}, [[2019, 9, 22], [2019, 11, 22]])], [('regression', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('regression', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('partial-repair probe', {'anchor': [2019, 10, 29], 'n': 10, 'interval': 1}, [[2019, 11, 29], [2019, 12, 29], [2020, 1, 29], [2020, 2, 29], [2020, 3, 29], [2020, 4, 29], [2020, 5, 29], [2020, 6, 29], [2020, 7, 29], [2020, 8, 29]]), ('partial-repair probe', {'anchor': [2023, 3, 28], 'n': 12, 'interval': 1}, [[2023, 4, 28], [2023, 5, 28], [2023, 6, 28], [2023, 7, 28], [2023, 8, 28], [2023, 9, 28], [2023, 10, 28], [2023, 11, 28], [2023, 12, 28], [2024, 1, 28], [2024, 2, 28], [2024, 3, 28]]), ('normal control', {'anchor': [2024, 3, 30], 'n': 12, 'interval': 12}, [[2025, 3, 30], [2026, 3, 30], [2027, 3, 30], [2028, 3, 30], [2029, 3, 30], [2030, 3, 30], [2031, 3, 30], [2032, 3, 30], [2033, 3, 30], [2034, 3, 30], [2035, 3, 30], [2036, 3, 30]]), ('normal control', {'anchor': [2025, 7, 30], 'n': 1, 'interval': 3}, [[2025, 10, 30]]), ('normal control', {'anchor': [2024, 10, 28], 'n': 10, 'interval': 12}, [[2025, 10, 28], [2026, 10, 28], [2027, 10, 28], [2028, 10, 28], [2029, 10, 28], [2030, 10, 28], [2031, 10, 28], [2032, 10, 28], [2033, 10, 28], [2034, 10, 28]]), ('normal control', {'anchor': [2023, 7, 30], 'n': 3, 'interval': 1}, [[2023, 8, 30], [2023, 9, 30], [2023, 10, 30]])], [('regression', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('regression', {'anchor': [2019, 12, 29], 'n': 7, 'interval': 1}, [[2020, 1, 29], [2020, 2, 29], [2020, 3, 29], [2020, 4, 29], [2020, 5, 29], [2020, 6, 29], [2020, 7, 29]]), ('partial-repair probe', {'anchor': [2023, 11, 17], 'n': 7, 'interval': 1}, [[2023, 12, 17], [2024, 1, 17], [2024, 2, 17], [2024, 3, 17], [2024, 4, 17], [2024, 5, 17], [2024, 6, 17]]), ('partial-repair probe', {'anchor': [2019, 9, 29], 'n': 6, 'interval': 2}, [[2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29]]), ('normal control', {'anchor': [2019, 7, 29], 'n': 2, 'interval': 2}, [[2019, 9, 29], [2019, 11, 29]]), ('normal control', {'anchor': [2019, 10, 29], 'n': 11, 'interval': 12}, [[2020, 10, 29], [2021, 10, 29], [2022, 10, 29], [2023, 10, 29], [2024, 10, 29], [2025, 10, 29], [2026, 10, 29], [2027, 10, 29], [2028, 10, 29], [2029, 10, 29], [2030, 10, 29]]), ('normal control', {'anchor': [2019, 3, 29], 'n': 9, 'interval': 1}, [[2019, 4, 29], [2019, 5, 29], [2019, 6, 29], [2019, 7, 29], [2019, 8, 29], [2019, 9, 29], [2019, 10, 29], [2019, 11, 29], [2019, 12, 29]]), ('normal control', {'anchor': [2024, 5, 31], 'n': 5, 'interval': 1}, [[2024, 6, 30], [2024, 7, 31], [2024, 8, 31], [2024, 9, 30], [2024, 10, 31]])]]
for i, (label, args, expected) in enumerate(fixtures[N-1]):
check("%s %d" % (label, i), solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| regression 0 | [[2024, 10, 30], [2024, 1, 30], [2024, 4, 30], [2025, 7, 30], [2025, 10, 30], [2025, 1, 30], [2025, 4, 30]] | [[2024, 10, 30], [2025, 1, 30], [2025, 4, 30], [2025, 7, 30], [2025, 10, 30], [2026, 1, 30], [2026, 4, 30]] | Failed |
| regression 1 | [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2025, 1, 31], [2025, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2026, 1, 31]] | [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2026, 1, 31], [2026, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2027, 1, 31]] | Failed |
| partial-repair probe 2 | [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2019, 1, 29], [2019, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2020, 1, 29], [2020, 3, 29]] | [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]] | Failed |
| partial-repair probe 3 | [[2023, 1, 31], [2023, 2, 28], [2023, 3, 31], [2023, 4, 30], [2023, 5, 31], [2023, 6, 30], [2023, 7, 31]] | [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]] | Failed |
| normal control 4 | [[2023, 6, 28], [2023, 9, 28], [2023, 12, 28], [2024, 3, 28], [2024, 6, 28], [2024, 9, 28], [2024, 12, 28], [2025, 3, 28], [2025, 6, 28], [2025, 9, 28], [2025, 12, 28], [2026, 3, 28], [2026, 6, 28], [2026, 9, 28]] | [[2023, 6, 28], [2023, 9, 28], [2023, 12, 28], [2024, 3, 28], [2024, 6, 28], [2024, 9, 28], [2024, 12, 28], [2025, 3, 28], [2025, 6, 28], [2025, 9, 28], [2025, 12, 28], [2026, 3, 28], [2026, 6, 28], [2026, 9, 28]] | Passed |
| normal control 5 | [[2024, 4, 29], [2024, 6, 29], [2024, 8, 29], [2024, 10, 29], [2024, 12, 29], [2025, 2, 28]] | [[2024, 4, 29], [2024, 6, 29], [2024, 8, 29], [2024, 10, 29], [2024, 12, 29], [2025, 2, 28]] | Passed |
| normal control 6 | [[2025, 9, 28]] | [[2025, 9, 28]] | Passed |
| normal control 7 | [[2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29]] | [[2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29]] | Passed |
SHA-256 / 1872c4149d069ec66973400692e420d2adf889f1e2f647633e54fb9515c10920
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
import calendar
N = 1
observations = []
def solve(x):
y, m, d = x['anchor']
out = []
for i in range(1, x['n'] + 1):
total = (m - 1) + i * x['interval']
ny, nm = y + (total - 1) // 12, total % 12 + 1
dim = calendar.monthrange(ny, nm)[1]
out.append([ny, nm, min(d, dim)])
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'anchor': [2024, 7, 30], 'n': 7, 'interval': 3}, [[2024, 10, 30], [2025, 1, 30], [2025, 4, 30], [2025, 7, 30], [2025, 10, 30], [2026, 1, 30], [2026, 4, 30]]), ('regression', {'anchor': [2025, 5, 31], 'n': 10, 'interval': 2}, [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2026, 1, 31], [2026, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2027, 1, 31]]), ('partial-repair probe', {'anchor': [2019, 5, 29], 'n': 11, 'interval': 2}, [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]]), ('partial-repair probe', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('normal control', {'anchor': [2023, 3, 28], 'n': 14, 'interval': 3}, [[2023, 6, 28], [2023, 9, 28], [2023, 12, 28], [2024, 3, 28], [2024, 6, 28], [2024, 9, 28], [2024, 12, 28], [2025, 3, 28], [2025, 6, 28], [2025, 9, 28], [2025, 12, 28], [2026, 3, 28], [2026, 6, 28], [2026, 9, 28]]), ('normal control', {'anchor': [2024, 2, 29], 'n': 6, 'interval': 2}, [[2024, 4, 29], [2024, 6, 29], [2024, 8, 29], [2024, 10, 29], [2024, 12, 29], [2025, 2, 28]]), ('normal control', {'anchor': [2025, 8, 28], 'n': 1, 'interval': 1}, [[2025, 9, 28]]), ('normal control', {'anchor': [2025, 1, 29], 'n': 8, 'interval': 1}, [[2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29]])], [('regression', {'anchor': [2025, 5, 31], 'n': 10, 'interval': 2}, [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2026, 1, 31], [2026, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2027, 1, 31]]), ('regression', {'anchor': [2019, 5, 29], 'n': 11, 'interval': 2}, [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]]), ('partial-repair probe', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('partial-repair probe', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('normal control', {'anchor': [2025, 4, 28], 'n': 8, 'interval': 12}, [[2026, 4, 28], [2027, 4, 28], [2028, 4, 28], [2029, 4, 28], [2030, 4, 28], [2031, 4, 28], [2032, 4, 28], [2033, 4, 28]]), ('normal control', {'anchor': [2025, 3, 31], 'n': 7, 'interval': 12}, [[2026, 3, 31], [2027, 3, 31], [2028, 3, 31], [2029, 3, 31], [2030, 3, 31], [2031, 3, 31], [2032, 3, 31]]), ('normal control', {'anchor': [2025, 1, 31], 'n': 9, 'interval': 1}, [[2025, 2, 28], [2025, 3, 31], [2025, 4, 30], [2025, 5, 31], [2025, 6, 30], [2025, 7, 31], [2025, 8, 31], [2025, 9, 30], [2025, 10, 31]]), ('normal control', {'anchor': [2019, 1, 30], 'n': 2, 'interval': 1}, [[2019, 2, 28], [2019, 3, 30]])], [('regression', {'anchor': [2019, 5, 29], 'n': 11, 'interval': 2}, [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]]), ('regression', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('partial-repair probe', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('partial-repair probe', {'anchor': [2019, 12, 29], 'n': 7, 'interval': 1}, [[2020, 1, 29], [2020, 2, 29], [2020, 3, 29], [2020, 4, 29], [2020, 5, 29], [2020, 6, 29], [2020, 7, 29]]), ('normal control', {'anchor': [2025, 5, 16], 'n': 3, 'interval': 12}, [[2026, 5, 16], [2027, 5, 16], [2028, 5, 16]]), ('normal control', {'anchor': [2025, 4, 28], 'n': 7, 'interval': 1}, [[2025, 5, 28], [2025, 6, 28], [2025, 7, 28], [2025, 8, 28], [2025, 9, 28], [2025, 10, 28], [2025, 11, 28]]), ('normal control', {'anchor': [2024, 5, 31], 'n': 3, 'interval': 1}, [[2024, 6, 30], [2024, 7, 31], [2024, 8, 31]]), ('normal control', {'anchor': [2019, 7, 22], 'n': 2, 'interval': 2}, [[2019, 9, 22], [2019, 11, 22]])], [('regression', {'anchor': [2023, 12, 31], 'n': 7, 'interval': 1}, [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]]), ('regression', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('partial-repair probe', {'anchor': [2019, 10, 29], 'n': 10, 'interval': 1}, [[2019, 11, 29], [2019, 12, 29], [2020, 1, 29], [2020, 2, 29], [2020, 3, 29], [2020, 4, 29], [2020, 5, 29], [2020, 6, 29], [2020, 7, 29], [2020, 8, 29]]), ('partial-repair probe', {'anchor': [2023, 3, 28], 'n': 12, 'interval': 1}, [[2023, 4, 28], [2023, 5, 28], [2023, 6, 28], [2023, 7, 28], [2023, 8, 28], [2023, 9, 28], [2023, 10, 28], [2023, 11, 28], [2023, 12, 28], [2024, 1, 28], [2024, 2, 28], [2024, 3, 28]]), ('normal control', {'anchor': [2024, 3, 30], 'n': 12, 'interval': 12}, [[2025, 3, 30], [2026, 3, 30], [2027, 3, 30], [2028, 3, 30], [2029, 3, 30], [2030, 3, 30], [2031, 3, 30], [2032, 3, 30], [2033, 3, 30], [2034, 3, 30], [2035, 3, 30], [2036, 3, 30]]), ('normal control', {'anchor': [2025, 7, 30], 'n': 1, 'interval': 3}, [[2025, 10, 30]]), ('normal control', {'anchor': [2024, 10, 28], 'n': 10, 'interval': 12}, [[2025, 10, 28], [2026, 10, 28], [2027, 10, 28], [2028, 10, 28], [2029, 10, 28], [2030, 10, 28], [2031, 10, 28], [2032, 10, 28], [2033, 10, 28], [2034, 10, 28]]), ('normal control', {'anchor': [2023, 7, 30], 'n': 3, 'interval': 1}, [[2023, 8, 30], [2023, 9, 30], [2023, 10, 30]])], [('regression', {'anchor': [2024, 12, 29], 'n': 10, 'interval': 1}, [[2025, 1, 29], [2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29], [2025, 10, 29]]), ('regression', {'anchor': [2019, 12, 29], 'n': 7, 'interval': 1}, [[2020, 1, 29], [2020, 2, 29], [2020, 3, 29], [2020, 4, 29], [2020, 5, 29], [2020, 6, 29], [2020, 7, 29]]), ('partial-repair probe', {'anchor': [2023, 11, 17], 'n': 7, 'interval': 1}, [[2023, 12, 17], [2024, 1, 17], [2024, 2, 17], [2024, 3, 17], [2024, 4, 17], [2024, 5, 17], [2024, 6, 17]]), ('partial-repair probe', {'anchor': [2019, 9, 29], 'n': 6, 'interval': 2}, [[2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29]]), ('normal control', {'anchor': [2019, 7, 29], 'n': 2, 'interval': 2}, [[2019, 9, 29], [2019, 11, 29]]), ('normal control', {'anchor': [2019, 10, 29], 'n': 11, 'interval': 12}, [[2020, 10, 29], [2021, 10, 29], [2022, 10, 29], [2023, 10, 29], [2024, 10, 29], [2025, 10, 29], [2026, 10, 29], [2027, 10, 29], [2028, 10, 29], [2029, 10, 29], [2030, 10, 29]]), ('normal control', {'anchor': [2019, 3, 29], 'n': 9, 'interval': 1}, [[2019, 4, 29], [2019, 5, 29], [2019, 6, 29], [2019, 7, 29], [2019, 8, 29], [2019, 9, 29], [2019, 10, 29], [2019, 11, 29], [2019, 12, 29]]), ('normal control', {'anchor': [2024, 5, 31], 'n': 5, 'interval': 1}, [[2024, 6, 30], [2024, 7, 31], [2024, 8, 31], [2024, 9, 30], [2024, 10, 31]])]]
for i, (label, args, expected) in enumerate(fixtures[N-1]):
check("%s %d" % (label, i), solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| regression 0 | [[2024, 10, 30], [2024, 1, 30], [2025, 4, 30], [2025, 7, 30], [2025, 10, 30], [2025, 1, 30], [2026, 4, 30]] | [[2024, 10, 30], [2025, 1, 30], [2025, 4, 30], [2025, 7, 30], [2025, 10, 30], [2026, 1, 30], [2026, 4, 30]] | Failed |
| regression 1 | [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2025, 1, 31], [2026, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2026, 1, 31]] | [[2025, 7, 31], [2025, 9, 30], [2025, 11, 30], [2026, 1, 31], [2026, 3, 31], [2026, 5, 31], [2026, 7, 31], [2026, 9, 30], [2026, 11, 30], [2027, 1, 31]] | Failed |
| partial-repair probe 2 | [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2019, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2020, 1, 29], [2021, 3, 29]] | [[2019, 7, 29], [2019, 9, 29], [2019, 11, 29], [2020, 1, 29], [2020, 3, 29], [2020, 5, 29], [2020, 7, 29], [2020, 9, 29], [2020, 11, 29], [2021, 1, 29], [2021, 3, 29]] | Failed |
| partial-repair probe 3 | [[2023, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]] | [[2024, 1, 31], [2024, 2, 29], [2024, 3, 31], [2024, 4, 30], [2024, 5, 31], [2024, 6, 30], [2024, 7, 31]] | Failed |
| normal control 4 | [[2023, 6, 28], [2023, 9, 28], [2023, 12, 28], [2024, 3, 28], [2024, 6, 28], [2024, 9, 28], [2024, 12, 28], [2025, 3, 28], [2025, 6, 28], [2025, 9, 28], [2025, 12, 28], [2026, 3, 28], [2026, 6, 28], [2026, 9, 28]] | [[2023, 6, 28], [2023, 9, 28], [2023, 12, 28], [2024, 3, 28], [2024, 6, 28], [2024, 9, 28], [2024, 12, 28], [2025, 3, 28], [2025, 6, 28], [2025, 9, 28], [2025, 12, 28], [2026, 3, 28], [2026, 6, 28], [2026, 9, 28]] | Passed |
| normal control 5 | [[2024, 4, 29], [2024, 6, 29], [2024, 8, 29], [2024, 10, 29], [2024, 12, 29], [2025, 2, 28]] | [[2024, 4, 29], [2024, 6, 29], [2024, 8, 29], [2024, 10, 29], [2024, 12, 29], [2025, 2, 28]] | Passed |
| normal control 6 | [[2025, 9, 28]] | [[2025, 9, 28]] | Passed |
| normal control 7 | [[2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29]] | [[2025, 2, 28], [2025, 3, 29], [2025, 4, 29], [2025, 5, 29], [2025, 6, 29], [2025, 7, 29], [2025, 8, 29], [2025, 9, 29]] | Passed |
SHA-256 / d18d1b85d73ecbe5f010d62692d3667d5778d552102dfcabcd3eee30f6dbcaff
HELD IN THE MEMBER ARCHIVE
The verified repair and its recorded checks are member-only.
This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.
Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.
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Sign in to the archive ↗Verification & scope
A deterministic teaching model of a stipulated billing rule. It makes no claim to reproduce any billing provider's exact behaviour and is not billing software. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.
Observations recorded using Python 3.12.14 at 2026-09-29T14:46:35.845712+00:00.
Case digest / 335ff8b4a3b6fccfd5ee443c5ccf0754ff48536860a6955287b81dc2f4214c3b