FA-95511 / Shipping rate zone lookup / Open access

Rate card: duplicate card choice unstable · case 01

Among identical date and version cards the largest id is used.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The id tie-break keeps larger ids.

VERIFIED REPAIR

Break remaining ties by smallest card id.

Unsuccessful approach: Dropping the tie-break keeps whichever card was listed first.

Case contract

cards [[card_id, effective_from, expires or None, version]] with dates "Y-M-D" that may lack zero padding. A card applies when effective_from <= ship date < expires. Choose the latest effective_from, then highest version, then smallest card_id. None -> "NO_CARD".

Why this case matters

Carriers publish dated rate cards; each shipment must use the card in force on its ship date.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(cards, ship_date):
    def d(s):
        return tuple(int(x) for x in s.split('-'))
    ship = d(ship_date)
    best = None
    for cid, frm, exp, ver in cards:
        if d(frm) > ship:
            continue
        if exp is not None and ship >= d(exp):
            continue
        key = (d(frm), ver)
        if best is None or key > best[0] or (key == best[0] and cid > best[1]):
            best = (key, cid)
    return best[1] if best else 'NO_CARD'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['generated mix 8', [[['R0', '2026-10-1', '2026-10-1', 1], ['R1', '2026-1-5', None, 3], ['R2', '2026-10-1', '2026-11-1', 3], ['R3', '2026-2-1', None, 3], ['R4', '2026-10-1', None, 3]], '2025-12-31'], 'NO_CARD'], ['generated mix 16', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-9-30', '2026-10-1', 3]], '2026-10-15'], 'R0']], [['generated mix 77', [[['R0', '2026-2-1', None, 1], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 1], ['R3', '2026-2-1', '2026-11-1', 1], ['R4', '2026-2-1', '2026-2-1', 1]], '2026-9-30'], 'R0'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['generated mix 11', [[['R0', '2025-12-31', None, 1]], '2026-9-30'], 'R0'], ['generated mix 19', [[['R0', '2026-9-30', '2026-11-1', 3], ['R1', '2026-11-1', '2026-11-1', 1]], '2025-12-31'], 'NO_CARD']], [['generated mix 70', [[['R0', '2026-11-1', '2026-2-1', 2], ['R1', '2025-12-31', '2026-10-1', 3], ['R2', '2025-12-31', '2026-11-1', 3]], '2026-2-1'], 'R1'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['generated mix 22', [[['R0', '2026-2-1', '2026-2-1', 2], ['R1', '2026-9-30', '2026-2-1', 1], ['R2', '2026-9-30', '2026-11-1', 2], ['R3', '2026-2-1', '2026-2-1', 1], ['R4', '2026-2-1', '2026-10-1', 3]], '2026-3-15'], 'R4'], ['generated mix 30', [[['R0', '2026-1-5', '2026-2-1', 1], ['R1', '2026-11-1', '2026-2-1', 1], ['R2', '2025-12-31', '2026-2-1', 2], ['R3', '2026-10-1', '2026-11-1', 3]], '2026-01-15'], 'R0']], [['generated mix 13', [[['R0', '2026-11-1', '2026-2-1', 3], ['R1', '2025-12-31', '2026-2-1', 3], ['R2', '2025-12-31', '2026-10-1', 3], ['R3', '2026-11-1', '2026-10-1', 2], ['R4', '2026-11-1', None, 1]], '2026-1-5'], 'R1'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['generated mix 34', [[['R0', '2026-10-1', None, 1], ['R1', '2026-11-1', '2026-11-1', 3], ['R2', '2026-1-5', '2026-10-1', 3], ['R3', '2026-10-1', '2026-2-1', 2]], '2026-9-30'], 'R2'], ['generated mix 42', [[['R0', '2026-2-1', '2026-2-1', 2]], '2026-2-1'], 'NO_CARD']], [['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['generated mix 44', [[['R0', '2026-9-30', None, 2], ['R1', '2026-1-5', '2026-11-1', 3]], '2026-9-30'], 'R0'], ['generated mix 52', [[['R0', '2026-11-1', '2026-2-1', 3], ['R1', '2026-11-1', '2026-2-1', 1], ['R2', '2026-1-5', '2026-10-1', 2], ['R3', '2026-9-30', None, 1]], '2026-2-1'], 'R2'], ['generated mix 60', [[['R0', '2025-12-31', None, 1], ['R1', '2026-1-5', None, 3], ['R2', '2026-10-1', '2026-11-1', 1], ['R3', '2026-01-15', '2026-2-1', 1], ['R4', '2026-01-15', None, 2]], '2025-12-31'], 'R0']]]
for label, args, expected in fixtures[N-1]:
    check(label, 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
id tie	`Z`	`M`	Failed
unpadded month	`B`	`B`	Passed
effective same day	`A`	`A`	Passed
future only	`NO_CARD`	`NO_CARD`	Passed
expiry exclusive	`B`	`B`	Passed
version tie	`B`	`B`	Passed
generated mix 8	`NO_CARD`	`NO_CARD`	Passed
generated mix 16	`R0`	`R0`	Passed

SHA-256 / 355ee851f033f8d947b18ce1fe267dbd228df61cb511f563b7860484f2c35776

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(cards, ship_date):
    def d(s):
        return tuple(int(x) for x in s.split('-'))
    ship = d(ship_date)
    best = None
    for cid, frm, exp, ver in cards:
        if d(frm) > ship:
            continue
        if exp is not None and ship >= d(exp):
            continue
        key = (d(frm), ver)
        if best is None or key > best[0]:
            best = (key, cid)
    return best[1] if best else 'NO_CARD'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['generated mix 8', [[['R0', '2026-10-1', '2026-10-1', 1], ['R1', '2026-1-5', None, 3], ['R2', '2026-10-1', '2026-11-1', 3], ['R3', '2026-2-1', None, 3], ['R4', '2026-10-1', None, 3]], '2025-12-31'], 'NO_CARD'], ['generated mix 16', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-9-30', '2026-10-1', 3]], '2026-10-15'], 'R0']], [['generated mix 77', [[['R0', '2026-2-1', None, 1], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 1], ['R3', '2026-2-1', '2026-11-1', 1], ['R4', '2026-2-1', '2026-2-1', 1]], '2026-9-30'], 'R0'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['generated mix 11', [[['R0', '2025-12-31', None, 1]], '2026-9-30'], 'R0'], ['generated mix 19', [[['R0', '2026-9-30', '2026-11-1', 3], ['R1', '2026-11-1', '2026-11-1', 1]], '2025-12-31'], 'NO_CARD']], [['generated mix 70', [[['R0', '2026-11-1', '2026-2-1', 2], ['R1', '2025-12-31', '2026-10-1', 3], ['R2', '2025-12-31', '2026-11-1', 3]], '2026-2-1'], 'R1'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['generated mix 22', [[['R0', '2026-2-1', '2026-2-1', 2], ['R1', '2026-9-30', '2026-2-1', 1], ['R2', '2026-9-30', '2026-11-1', 2], ['R3', '2026-2-1', '2026-2-1', 1], ['R4', '2026-2-1', '2026-10-1', 3]], '2026-3-15'], 'R4'], ['generated mix 30', [[['R0', '2026-1-5', '2026-2-1', 1], ['R1', '2026-11-1', '2026-2-1', 1], ['R2', '2025-12-31', '2026-2-1', 2], ['R3', '2026-10-1', '2026-11-1', 3]], '2026-01-15'], 'R0']], [['generated mix 13', [[['R0', '2026-11-1', '2026-2-1', 3], ['R1', '2025-12-31', '2026-2-1', 3], ['R2', '2025-12-31', '2026-10-1', 3], ['R3', '2026-11-1', '2026-10-1', 2], ['R4', '2026-11-1', None, 1]], '2026-1-5'], 'R1'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['generated mix 34', [[['R0', '2026-10-1', None, 1], ['R1', '2026-11-1', '2026-11-1', 3], ['R2', '2026-1-5', '2026-10-1', 3], ['R3', '2026-10-1', '2026-2-1', 2]], '2026-9-30'], 'R2'], ['generated mix 42', [[['R0', '2026-2-1', '2026-2-1', 2]], '2026-2-1'], 'NO_CARD']], [['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['generated mix 44', [[['R0', '2026-9-30', None, 2], ['R1', '2026-1-5', '2026-11-1', 3]], '2026-9-30'], 'R0'], ['generated mix 52', [[['R0', '2026-11-1', '2026-2-1', 3], ['R1', '2026-11-1', '2026-2-1', 1], ['R2', '2026-1-5', '2026-10-1', 2], ['R3', '2026-9-30', None, 1]], '2026-2-1'], 'R2'], ['generated mix 60', [[['R0', '2025-12-31', None, 1], ['R1', '2026-1-5', None, 3], ['R2', '2026-10-1', '2026-11-1', 1], ['R3', '2026-01-15', '2026-2-1', 1], ['R4', '2026-01-15', None, 2]], '2025-12-31'], 'R0']]]
for label, args, expected in fixtures[N-1]:
    check(label, 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
id tie	`Z`	`M`	Failed
unpadded month	`B`	`B`	Passed
effective same day	`A`	`A`	Passed
future only	`NO_CARD`	`NO_CARD`	Passed
expiry exclusive	`B`	`B`	Passed
version tie	`B`	`B`	Passed
generated mix 8	`NO_CARD`	`NO_CARD`	Passed
generated mix 16	`R0`	`R0`	Passed

SHA-256 / ab60f734c1bcc55e5da0852433f9f93845c516bd701f7c501e58938cafe562ca

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(cards, ship_date):
    def d(s):
        return tuple(int(x) for x in s.split('-'))
    ship = d(ship_date)
    best = None
    for cid, frm, exp, ver in cards:
        if d(frm) > ship:
            continue
        if exp is not None and ship >= d(exp):
            continue
        key = (d(frm), ver)
        if best is None or key > best[0] or (key == best[0] and cid < best[1]):
            best = (key, cid)
    return best[1] if best else 'NO_CARD'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['generated mix 8', [[['R0', '2026-10-1', '2026-10-1', 1], ['R1', '2026-1-5', None, 3], ['R2', '2026-10-1', '2026-11-1', 3], ['R3', '2026-2-1', None, 3], ['R4', '2026-10-1', None, 3]], '2025-12-31'], 'NO_CARD'], ['generated mix 16', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-9-30', '2026-10-1', 3]], '2026-10-15'], 'R0']], [['generated mix 77', [[['R0', '2026-2-1', None, 1], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 1], ['R3', '2026-2-1', '2026-11-1', 1], ['R4', '2026-2-1', '2026-2-1', 1]], '2026-9-30'], 'R0'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['generated mix 11', [[['R0', '2025-12-31', None, 1]], '2026-9-30'], 'R0'], ['generated mix 19', [[['R0', '2026-9-30', '2026-11-1', 3], ['R1', '2026-11-1', '2026-11-1', 1]], '2025-12-31'], 'NO_CARD']], [['generated mix 70', [[['R0', '2026-11-1', '2026-2-1', 2], ['R1', '2025-12-31', '2026-10-1', 3], ['R2', '2025-12-31', '2026-11-1', 3]], '2026-2-1'], 'R1'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['generated mix 22', [[['R0', '2026-2-1', '2026-2-1', 2], ['R1', '2026-9-30', '2026-2-1', 1], ['R2', '2026-9-30', '2026-11-1', 2], ['R3', '2026-2-1', '2026-2-1', 1], ['R4', '2026-2-1', '2026-10-1', 3]], '2026-3-15'], 'R4'], ['generated mix 30', [[['R0', '2026-1-5', '2026-2-1', 1], ['R1', '2026-11-1', '2026-2-1', 1], ['R2', '2025-12-31', '2026-2-1', 2], ['R3', '2026-10-1', '2026-11-1', 3]], '2026-01-15'], 'R0']], [['generated mix 13', [[['R0', '2026-11-1', '2026-2-1', 3], ['R1', '2025-12-31', '2026-2-1', 3], ['R2', '2025-12-31', '2026-10-1', 3], ['R3', '2026-11-1', '2026-10-1', 2], ['R4', '2026-11-1', None, 1]], '2026-1-5'], 'R1'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['generated mix 34', [[['R0', '2026-10-1', None, 1], ['R1', '2026-11-1', '2026-11-1', 3], ['R2', '2026-1-5', '2026-10-1', 3], ['R3', '2026-10-1', '2026-2-1', 2]], '2026-9-30'], 'R2'], ['generated mix 42', [[['R0', '2026-2-1', '2026-2-1', 2]], '2026-2-1'], 'NO_CARD']], [['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['expiry exclusive', [[['A', '2026-1-1', '2026-3-1', 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'B'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['generated mix 44', [[['R0', '2026-9-30', None, 2], ['R1', '2026-1-5', '2026-11-1', 3]], '2026-9-30'], 'R0'], ['generated mix 52', [[['R0', '2026-11-1', '2026-2-1', 3], ['R1', '2026-11-1', '2026-2-1', 1], ['R2', '2026-1-5', '2026-10-1', 2], ['R3', '2026-9-30', None, 1]], '2026-2-1'], 'R2'], ['generated mix 60', [[['R0', '2025-12-31', None, 1], ['R1', '2026-1-5', None, 3], ['R2', '2026-10-1', '2026-11-1', 1], ['R3', '2026-01-15', '2026-2-1', 1], ['R4', '2026-01-15', None, 2]], '2025-12-31'], 'R0']]]
for label, args, expected in fixtures[N-1]:
    check(label, 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
id tie	`M`	`M`	Passed
unpadded month	`B`	`B`	Passed
effective same day	`A`	`A`	Passed
future only	`NO_CARD`	`NO_CARD`	Passed
expiry exclusive	`B`	`B`	Passed
version tie	`B`	`B`	Passed
generated mix 8	`NO_CARD`	`NO_CARD`	Passed
generated mix 16	`R0`	`R0`	Passed

SHA-256 / f06dfb337e460dd7c40e03c5ba462db3b96929392ff7e6293ec9f5520593baab

Verification & scope

Stipulated date format and selection policy. 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 2026-09-29T14:52:14.356210+00:00.

Case digest / 6539f4cac189ca76551c893218ad40978a572f86f16008015e8f7e2ce1a2f767