FA-59341 / Subscription proration billing / Open access

Daily plan-change proration: remaining day count · case 01

Customers who upgrade are charged and credited for one day fewer than remain in the period.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The change day itself is excluded from the remaining days although service on the new plan starts that day.

VERIFIED REPAIR

Restore the contract rule at the remaining day count step: use `remaining = (e - c).days`.

Unsuccessful approach: The attempt counts the exclusive period end as a service day, prorating one day too many.

Case contract

Input {old, new prices per period, start, end (exclusive), change} dates with start <= change < end. Remaining days = end - change; period days = end - start. Credit = old*remaining/period and charge = new*remaining/period, each rounded half-up. Net = charge - credit; a positive net is due now, a negative net becomes a credit balance. Return [credit, charge, amount_due, credit_balance].

Why this case matters

Mid-cycle plan changes must credit unused time on the old plan and charge the new plan for the same days.

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):
    s = datetime.date(*x['start'])
    e = datetime.date(*x['end'])
    c = datetime.date(*x['change'])
    total = (e - s).days
    remaining = (e - c).days - 1
    def pr(p):
        return (p * remaining * 2 + total) // (2 * total)
    credit = pr(x['old'])
    charge = pr(x['new'])
    net = charge - credit
    return [credit, charge, max(0, net), max(0, -net)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'old': 999, 'new': 1999, 'start': [2023, 10, 16], 'end': [2023, 11, 13], 'change': [2023, 11, 8]}, [178, 357, 179, 0]), ('regression', {'old': 12063, 'new': 1999, 'start': [2024, 10, 16], 'end': [2024, 11, 14], 'change': [2024, 11, 2]}, [4992, 827, 0, 4165]), ('partial-repair probe', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('partial-repair probe', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66])], [('regression', {'old': 12063, 'new': 1999, 'start': [2024, 10, 16], 'end': [2024, 11, 14], 'change': [2024, 11, 2]}, [4992, 827, 0, 4165]), ('regression', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('partial-repair probe', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0])], [('regression', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('regression', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('partial-repair probe', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0])], [('regression', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('regression', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('partial-repair probe', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0]), ('additional oracle', {'old': 7276, 'new': 43371, 'start': [2024, 5, 21], 'end': [2024, 8, 19], 'change': [2024, 6, 13]}, [5417, 32287, 26870, 0])], [('regression', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('regression', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('partial-repair probe', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0]), ('partial-repair probe', {'old': 7276, 'new': 43371, 'start': [2024, 5, 21], 'end': [2024, 8, 19], 'change': [2024, 6, 13]}, [5417, 32287, 26870, 0]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 4900, 'new': 14973, 'start': [2025, 4, 11], 'end': [2025, 5, 10], 'change': [2025, 4, 17]}, [3886, 11875, 7989, 0])]]
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	`[143, 286, 143, 0]`	`[178, 357, 179, 0]`	Failed
regression 1	`[4576, 758, 0, 3818]`	`[4992, 827, 0, 4165]`	Failed
partial-repair probe 2	`[44, 89, 45, 0]`	`[56, 111, 55, 0]`	Failed
partial-repair probe 3	`[3376, 5848, 2472, 0]`	`[3430, 5942, 2512, 0]`	Failed
additional oracle 4	`[1742, 3520, 1778, 0]`	`[1797, 3630, 1833, 0]`	Failed
additional oracle 5	`[5634, 790, 0, 4844]`	`[6761, 948, 0, 5813]`	Failed
additional oracle 6	`[0, 0, 0, 0]`	`[1288, 1222, 0, 66]`	Failed

SHA-256 / 1c7c2d49171d25e851a1d32175b65f7943c14ccdcac0710caba50f9b3ac6e694

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):
    s = datetime.date(*x['start'])
    e = datetime.date(*x['end'])
    c = datetime.date(*x['change'])
    total = (e - s).days
    remaining = (e - c).days + 1
    def pr(p):
        return (p * remaining * 2 + total) // (2 * total)
    credit = pr(x['old'])
    charge = pr(x['new'])
    net = charge - credit
    return [credit, charge, max(0, net), max(0, -net)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'old': 999, 'new': 1999, 'start': [2023, 10, 16], 'end': [2023, 11, 13], 'change': [2023, 11, 8]}, [178, 357, 179, 0]), ('regression', {'old': 12063, 'new': 1999, 'start': [2024, 10, 16], 'end': [2024, 11, 14], 'change': [2024, 11, 2]}, [4992, 827, 0, 4165]), ('partial-repair probe', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('partial-repair probe', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66])], [('regression', {'old': 12063, 'new': 1999, 'start': [2024, 10, 16], 'end': [2024, 11, 14], 'change': [2024, 11, 2]}, [4992, 827, 0, 4165]), ('regression', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('partial-repair probe', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0])], [('regression', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('regression', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('partial-repair probe', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0])], [('regression', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('regression', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('partial-repair probe', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0]), ('additional oracle', {'old': 7276, 'new': 43371, 'start': [2024, 5, 21], 'end': [2024, 8, 19], 'change': [2024, 6, 13]}, [5417, 32287, 26870, 0])], [('regression', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('regression', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('partial-repair probe', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0]), ('partial-repair probe', {'old': 7276, 'new': 43371, 'start': [2024, 5, 21], 'end': [2024, 8, 19], 'change': [2024, 6, 13]}, [5417, 32287, 26870, 0]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 4900, 'new': 14973, 'start': [2025, 4, 11], 'end': [2025, 5, 10], 'change': [2025, 4, 17]}, [3886, 11875, 7989, 0])]]
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	`[214, 428, 214, 0]`	`[178, 357, 179, 0]`	Failed
regression 1	`[5408, 896, 0, 4512]`	`[4992, 827, 0, 4165]`	Failed
partial-repair probe 2	`[67, 133, 66, 0]`	`[56, 111, 55, 0]`	Failed
partial-repair probe 3	`[3484, 6037, 2553, 0]`	`[3430, 5942, 2512, 0]`	Failed
additional oracle 4	`[1851, 3740, 1889, 0]`	`[1797, 3630, 1833, 0]`	Failed
additional oracle 5	`[7888, 1106, 0, 6782]`	`[6761, 948, 0, 5813]`	Failed
additional oracle 6	`[2576, 2444, 0, 132]`	`[1288, 1222, 0, 66]`	Failed

SHA-256 / 91b668170d2bbc58a18120364cd07df73be6e792cbafe2345b48e36549987402

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
import calendar
N = 1
observations = []
def solve(x):
    s = datetime.date(*x['start'])
    e = datetime.date(*x['end'])
    c = datetime.date(*x['change'])
    total = (e - s).days
    remaining = (e - c).days
    def pr(p):
        return (p * remaining * 2 + total) // (2 * total)
    credit = pr(x['old'])
    charge = pr(x['new'])
    net = charge - credit
    return [credit, charge, max(0, net), max(0, -net)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'old': 999, 'new': 1999, 'start': [2023, 10, 16], 'end': [2023, 11, 13], 'change': [2023, 11, 8]}, [178, 357, 179, 0]), ('regression', {'old': 12063, 'new': 1999, 'start': [2024, 10, 16], 'end': [2024, 11, 14], 'change': [2024, 11, 2]}, [4992, 827, 0, 4165]), ('partial-repair probe', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('partial-repair probe', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66])], [('regression', {'old': 12063, 'new': 1999, 'start': [2024, 10, 16], 'end': [2024, 11, 14], 'change': [2024, 11, 2]}, [4992, 827, 0, 4165]), ('regression', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('partial-repair probe', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0])], [('regression', {'old': 999, 'new': 1999, 'start': [2024, 9, 16], 'end': [2024, 12, 15], 'change': [2024, 12, 10]}, [56, 111, 55, 0]), ('regression', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('partial-repair probe', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0])], [('regression', {'old': 4900, 'new': 8489, 'start': [2024, 3, 22], 'end': [2024, 6, 20], 'change': [2024, 4, 18]}, [3430, 5942, 2512, 0]), ('regression', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('partial-repair probe', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('partial-repair probe', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('additional oracle', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0]), ('additional oracle', {'old': 7276, 'new': 43371, 'start': [2024, 5, 21], 'end': [2024, 8, 19], 'change': [2024, 6, 13]}, [5417, 32287, 26870, 0])], [('regression', {'old': 4900, 'new': 9900, 'start': [2024, 1, 10], 'end': [2024, 4, 9], 'change': [2024, 3, 7]}, [1797, 3630, 1833, 0]), ('regression', {'old': 34933, 'new': 4900, 'start': [2024, 12, 28], 'end': [2025, 1, 28], 'change': [2025, 1, 22]}, [6761, 948, 0, 5813]), ('partial-repair probe', {'old': 999, 'new': 4900, 'start': [2025, 1, 22], 'end': [2025, 4, 22], 'change': [2025, 3, 8]}, [500, 2450, 1950, 0]), ('partial-repair probe', {'old': 7276, 'new': 43371, 'start': [2024, 5, 21], 'end': [2024, 8, 19], 'change': [2024, 6, 13]}, [5417, 32287, 26870, 0]), ('additional oracle', {'old': 38640, 'new': 36658, 'start': [2024, 12, 23], 'end': [2025, 1, 22], 'change': [2025, 1, 21]}, [1288, 1222, 0, 66]), ('additional oracle', {'old': 4900, 'new': 9900, 'start': [2024, 6, 18], 'end': [2024, 7, 18], 'change': [2024, 6, 21]}, [4410, 8910, 4500, 0]), ('additional oracle', {'old': 4900, 'new': 14973, 'start': [2025, 4, 11], 'end': [2025, 5, 10], 'change': [2025, 4, 17]}, [3886, 11875, 7989, 0])]]
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	`[178, 357, 179, 0]`	`[178, 357, 179, 0]`	Passed
regression 1	`[4992, 827, 0, 4165]`	`[4992, 827, 0, 4165]`	Passed
partial-repair probe 2	`[56, 111, 55, 0]`	`[56, 111, 55, 0]`	Passed
partial-repair probe 3	`[3430, 5942, 2512, 0]`	`[3430, 5942, 2512, 0]`	Passed
additional oracle 4	`[1797, 3630, 1833, 0]`	`[1797, 3630, 1833, 0]`	Passed
additional oracle 5	`[6761, 948, 0, 5813]`	`[6761, 948, 0, 5813]`	Passed
additional oracle 6	`[1288, 1222, 0, 66]`	`[1288, 1222, 0, 66]`	Passed

SHA-256 / b2504556f4f3a66558183a368adb1680e3759dcdd8c4a29e07e2990c1955581c

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 2026-09-29T14:46:35.447918+00:00.

Case digest / 46f28cbb019e959ef5bc83cef4949d30c43c8fcd03d121694c1b4550d2aa4123