FA-95501 / Shipping rate zone lookup / Open access

Rate card: oldest applicable card chosen · case 01

Superseded rate cards stay in use after a new card takes effect.

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

ROOT CAUSE

Card selection keeps the smallest effective key instead of the largest.

VERIFIED REPAIR

Choose the most recent effective card.

Unsuccessful approach: Ranking by version before date lets a high-version old card beat a newer card.

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 = [[['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['generated mix 26', [[['R0', '2026-2-1', None, 2], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 2], ['R3', '2026-9-30', None, 2]], '2026-3-15'], 'R0'], ['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'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['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 26', [[['R0', '2026-2-1', None, 2], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 2], ['R3', '2026-9-30', None, 2]], '2026-3-15'], 'R0'], ['generated mix 51', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-1-5', None, 3], ['R2', '2026-01-15', None, 2], ['R3', '2026-2-1', '2026-11-1', 2]], '2026-10-1'], 'R3'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['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'], ['generated mix 9', [[['R0', '2026-01-15', '2026-2-1', 1], ['R1', '2025-12-31', '2026-2-1', 3], ['R2', '2026-9-30', '2026-10-1', 3], ['R3', '2026-10-1', '2026-2-1', 1]], '2025-12-31'], 'R1'], ['generated mix 17', [[['R0', '2026-2-1', '2026-11-1', 2], ['R1', '2026-01-15', '2026-10-1', 3], ['R2', '2026-10-1', None, 2]], '2026-11-1'], 'R2'], ['generated mix 25', [[['R0', '2026-1-5', None, 2], ['R1', '2026-2-1', None, 1]], '2026-9-30'], 'R1']], [['generated mix 39', [[['R0', '2025-12-31', '2026-10-1', 1], ['R1', '2026-01-15', None, 2], ['R2', '2026-1-5', '2026-2-1', 1], ['R3', '2026-1-5', None, 2]], '2026-11-1'], 'R1'], ['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'], ['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'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['generated mix 20', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-11-1', None, 3], ['R2', '2026-9-30', None, 3], ['R3', '2025-12-31', None, 1]], '2026-2-1'], 'R3'], ['generated mix 28', [[['R0', '2026-2-1', '2026-10-1', 1]], '2026-2-1'], 'R0'], ['generated mix 37', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-2-1', None, 1], ['R2', '2026-1-5', None, 2], ['R3', '2026-11-1', '2026-11-1', 1], ['R4', '2026-1-5', '2026-2-1', 3]], '2026-11-1'], 'R1']], [['generated mix 61', [[['R0', '2026-1-5', None, 2], ['R1', '2026-11-1', None, 3], ['R2', '2025-12-31', None, 1]], '2026-2-1'], 'R0'], ['generated mix 72', [[['R0', '2026-10-1', '2026-10-1', 1], ['R1', '2026-1-5', '2026-11-1', 3], ['R2', '2026-10-1', '2026-11-1', 3], ['R3', '2026-9-30', '2026-2-1', 3], ['R4', '2026-01-15', None, 2]], '2026-3-15'], 'R4'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['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'], ['generated mix 31', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-01-15', None, 3], ['R2', '2026-10-1', None, 3], ['R3', '2026-10-1', '2026-2-1', 2], ['R4', '2026-11-1', '2026-11-1', 2]], '2026-10-15'], 'R2'], ['generated mix 39', [[['R0', '2025-12-31', '2026-10-1', 1], ['R1', '2026-01-15', None, 2], ['R2', '2026-1-5', '2026-2-1', 1], ['R3', '2026-1-5', None, 2]], '2026-11-1'], 'R1'], ['generated mix 47', [[['R0', '2026-2-1', '2026-11-1', 3], ['R1', '2025-12-31', '2026-10-1', 1], ['R2', '2026-10-1', '2026-11-1', 1], ['R3', '2026-10-1', '2026-10-1', 2]], '2026-2-1'], 'R0']], [['generated mix 78', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2025-12-31', None, 1], ['R2', '2026-9-30', '2026-2-1', 2], ['R3', '2026-10-1', None, 2], ['R4', '2026-01-15', '2026-10-1', 1]], '2026-2-1'], 'R4'], ['generated mix 37', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-2-1', None, 1], ['R2', '2026-1-5', None, 2], ['R3', '2026-11-1', '2026-11-1', 1], ['R4', '2026-1-5', '2026-2-1', 3]], '2026-11-1'], 'R1'], ['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'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['generated mix 43', [[['R0', '2026-11-1', '2026-10-1', 2], ['R1', '2026-9-30', None, 3], ['R2', '2026-2-1', '2026-11-1', 3], ['R3', '2025-12-31', '2026-2-1', 2], ['R4', '2026-1-5', '2026-2-1', 1]], '2026-3-15'], 'R2'], ['generated mix 51', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-1-5', None, 3], ['R2', '2026-01-15', None, 2], ['R3', '2026-2-1', '2026-11-1', 2]], '2026-10-1'], 'R3'], ['generated mix 59', [[['R0', '2025-12-31', None, 2]], '2026-11-1'], '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
unpadded month	`A`	`B`	Failed
generated mix 26	`R2`	`R0`	Failed
expiry exclusive	`B`	`B`	Passed
version tie	`A`	`B`	Failed
future only	`NO_CARD`	`NO_CARD`	Passed
effective same day	`B`	`A`	Failed
id tie	`M`	`M`	Passed
generated mix 8	`NO_CARD`	`NO_CARD`	Passed

SHA-256 / 3f4f728115b945b11e69c3adcedc525e7a70f3bcea30ed82a68441848c846cb5

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 = (ver, d(frm))
        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 = [[['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['generated mix 26', [[['R0', '2026-2-1', None, 2], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 2], ['R3', '2026-9-30', None, 2]], '2026-3-15'], 'R0'], ['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'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['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 26', [[['R0', '2026-2-1', None, 2], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 2], ['R3', '2026-9-30', None, 2]], '2026-3-15'], 'R0'], ['generated mix 51', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-1-5', None, 3], ['R2', '2026-01-15', None, 2], ['R3', '2026-2-1', '2026-11-1', 2]], '2026-10-1'], 'R3'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['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'], ['generated mix 9', [[['R0', '2026-01-15', '2026-2-1', 1], ['R1', '2025-12-31', '2026-2-1', 3], ['R2', '2026-9-30', '2026-10-1', 3], ['R3', '2026-10-1', '2026-2-1', 1]], '2025-12-31'], 'R1'], ['generated mix 17', [[['R0', '2026-2-1', '2026-11-1', 2], ['R1', '2026-01-15', '2026-10-1', 3], ['R2', '2026-10-1', None, 2]], '2026-11-1'], 'R2'], ['generated mix 25', [[['R0', '2026-1-5', None, 2], ['R1', '2026-2-1', None, 1]], '2026-9-30'], 'R1']], [['generated mix 39', [[['R0', '2025-12-31', '2026-10-1', 1], ['R1', '2026-01-15', None, 2], ['R2', '2026-1-5', '2026-2-1', 1], ['R3', '2026-1-5', None, 2]], '2026-11-1'], 'R1'], ['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'], ['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'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['generated mix 20', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-11-1', None, 3], ['R2', '2026-9-30', None, 3], ['R3', '2025-12-31', None, 1]], '2026-2-1'], 'R3'], ['generated mix 28', [[['R0', '2026-2-1', '2026-10-1', 1]], '2026-2-1'], 'R0'], ['generated mix 37', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-2-1', None, 1], ['R2', '2026-1-5', None, 2], ['R3', '2026-11-1', '2026-11-1', 1], ['R4', '2026-1-5', '2026-2-1', 3]], '2026-11-1'], 'R1']], [['generated mix 61', [[['R0', '2026-1-5', None, 2], ['R1', '2026-11-1', None, 3], ['R2', '2025-12-31', None, 1]], '2026-2-1'], 'R0'], ['generated mix 72', [[['R0', '2026-10-1', '2026-10-1', 1], ['R1', '2026-1-5', '2026-11-1', 3], ['R2', '2026-10-1', '2026-11-1', 3], ['R3', '2026-9-30', '2026-2-1', 3], ['R4', '2026-01-15', None, 2]], '2026-3-15'], 'R4'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['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'], ['generated mix 31', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-01-15', None, 3], ['R2', '2026-10-1', None, 3], ['R3', '2026-10-1', '2026-2-1', 2], ['R4', '2026-11-1', '2026-11-1', 2]], '2026-10-15'], 'R2'], ['generated mix 39', [[['R0', '2025-12-31', '2026-10-1', 1], ['R1', '2026-01-15', None, 2], ['R2', '2026-1-5', '2026-2-1', 1], ['R3', '2026-1-5', None, 2]], '2026-11-1'], 'R1'], ['generated mix 47', [[['R0', '2026-2-1', '2026-11-1', 3], ['R1', '2025-12-31', '2026-10-1', 1], ['R2', '2026-10-1', '2026-11-1', 1], ['R3', '2026-10-1', '2026-10-1', 2]], '2026-2-1'], 'R0']], [['generated mix 78', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2025-12-31', None, 1], ['R2', '2026-9-30', '2026-2-1', 2], ['R3', '2026-10-1', None, 2], ['R4', '2026-01-15', '2026-10-1', 1]], '2026-2-1'], 'R4'], ['generated mix 37', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-2-1', None, 1], ['R2', '2026-1-5', None, 2], ['R3', '2026-11-1', '2026-11-1', 1], ['R4', '2026-1-5', '2026-2-1', 3]], '2026-11-1'], 'R1'], ['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'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['generated mix 43', [[['R0', '2026-11-1', '2026-10-1', 2], ['R1', '2026-9-30', None, 3], ['R2', '2026-2-1', '2026-11-1', 3], ['R3', '2025-12-31', '2026-2-1', 2], ['R4', '2026-1-5', '2026-2-1', 1]], '2026-3-15'], 'R2'], ['generated mix 51', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-1-5', None, 3], ['R2', '2026-01-15', None, 2], ['R3', '2026-2-1', '2026-11-1', 2]], '2026-10-1'], 'R3'], ['generated mix 59', [[['R0', '2025-12-31', None, 2]], '2026-11-1'], '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
unpadded month	`B`	`B`	Passed
generated mix 26	`R1`	`R0`	Failed
expiry exclusive	`B`	`B`	Passed
version tie	`B`	`B`	Passed
future only	`NO_CARD`	`NO_CARD`	Passed
effective same day	`A`	`A`	Passed
id tie	`M`	`M`	Passed
generated mix 8	`NO_CARD`	`NO_CARD`	Passed

SHA-256 / 483ca64a0ded3646e136835b445a99d4a2fa3e926991c6e7aa23726333f194e9

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 = [[['unpadded month', [[['A', '2026-2-1', None, 1], ['B', '2026-10-1', None, 1]], '2026-10-15'], 'B'], ['generated mix 26', [[['R0', '2026-2-1', None, 2], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 2], ['R3', '2026-9-30', None, 2]], '2026-3-15'], 'R0'], ['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'], ['future only', [[['A', '2027-1-1', None, 1]], '2026-5-1'], 'NO_CARD'], ['effective same day', [[['A', '2026-3-1', None, 1], ['B', '2025-1-1', None, 1]], '2026-3-1'], 'A'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['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 26', [[['R0', '2026-2-1', None, 2], ['R1', '2025-12-31', '2026-11-1', 3], ['R2', '2025-12-31', None, 2], ['R3', '2026-9-30', None, 2]], '2026-3-15'], 'R0'], ['generated mix 51', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-1-5', None, 3], ['R2', '2026-01-15', None, 2], ['R3', '2026-2-1', '2026-11-1', 2]], '2026-10-1'], 'R3'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['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'], ['generated mix 9', [[['R0', '2026-01-15', '2026-2-1', 1], ['R1', '2025-12-31', '2026-2-1', 3], ['R2', '2026-9-30', '2026-10-1', 3], ['R3', '2026-10-1', '2026-2-1', 1]], '2025-12-31'], 'R1'], ['generated mix 17', [[['R0', '2026-2-1', '2026-11-1', 2], ['R1', '2026-01-15', '2026-10-1', 3], ['R2', '2026-10-1', None, 2]], '2026-11-1'], 'R2'], ['generated mix 25', [[['R0', '2026-1-5', None, 2], ['R1', '2026-2-1', None, 1]], '2026-9-30'], 'R1']], [['generated mix 39', [[['R0', '2025-12-31', '2026-10-1', 1], ['R1', '2026-01-15', None, 2], ['R2', '2026-1-5', '2026-2-1', 1], ['R3', '2026-1-5', None, 2]], '2026-11-1'], 'R1'], ['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'], ['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'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['generated mix 20', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-11-1', None, 3], ['R2', '2026-9-30', None, 3], ['R3', '2025-12-31', None, 1]], '2026-2-1'], 'R3'], ['generated mix 28', [[['R0', '2026-2-1', '2026-10-1', 1]], '2026-2-1'], 'R0'], ['generated mix 37', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-2-1', None, 1], ['R2', '2026-1-5', None, 2], ['R3', '2026-11-1', '2026-11-1', 1], ['R4', '2026-1-5', '2026-2-1', 3]], '2026-11-1'], 'R1']], [['generated mix 61', [[['R0', '2026-1-5', None, 2], ['R1', '2026-11-1', None, 3], ['R2', '2025-12-31', None, 1]], '2026-2-1'], 'R0'], ['generated mix 72', [[['R0', '2026-10-1', '2026-10-1', 1], ['R1', '2026-1-5', '2026-11-1', 3], ['R2', '2026-10-1', '2026-11-1', 3], ['R3', '2026-9-30', '2026-2-1', 3], ['R4', '2026-01-15', None, 2]], '2026-3-15'], 'R4'], ['version tie', [[['A', '2026-1-1', None, 1], ['B', '2026-1-1', None, 2]], '2026-5-1'], 'B'], ['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'], ['generated mix 31', [[['R0', '2026-9-30', '2026-11-1', 1], ['R1', '2026-01-15', None, 3], ['R2', '2026-10-1', None, 3], ['R3', '2026-10-1', '2026-2-1', 2], ['R4', '2026-11-1', '2026-11-1', 2]], '2026-10-15'], 'R2'], ['generated mix 39', [[['R0', '2025-12-31', '2026-10-1', 1], ['R1', '2026-01-15', None, 2], ['R2', '2026-1-5', '2026-2-1', 1], ['R3', '2026-1-5', None, 2]], '2026-11-1'], 'R1'], ['generated mix 47', [[['R0', '2026-2-1', '2026-11-1', 3], ['R1', '2025-12-31', '2026-10-1', 1], ['R2', '2026-10-1', '2026-11-1', 1], ['R3', '2026-10-1', '2026-10-1', 2]], '2026-2-1'], 'R0']], [['generated mix 78', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2025-12-31', None, 1], ['R2', '2026-9-30', '2026-2-1', 2], ['R3', '2026-10-1', None, 2], ['R4', '2026-01-15', '2026-10-1', 1]], '2026-2-1'], 'R4'], ['generated mix 37', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-2-1', None, 1], ['R2', '2026-1-5', None, 2], ['R3', '2026-11-1', '2026-11-1', 1], ['R4', '2026-1-5', '2026-2-1', 3]], '2026-11-1'], 'R1'], ['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'], ['id tie', [[['Z', '2026-1-1', None, 2], ['M', '2026-1-1', None, 2]], '2026-5-1'], 'M'], ['generated mix 43', [[['R0', '2026-11-1', '2026-10-1', 2], ['R1', '2026-9-30', None, 3], ['R2', '2026-2-1', '2026-11-1', 3], ['R3', '2025-12-31', '2026-2-1', 2], ['R4', '2026-1-5', '2026-2-1', 1]], '2026-3-15'], 'R2'], ['generated mix 51', [[['R0', '2026-9-30', '2026-10-1', 2], ['R1', '2026-1-5', None, 3], ['R2', '2026-01-15', None, 2], ['R3', '2026-2-1', '2026-11-1', 2]], '2026-10-1'], 'R3'], ['generated mix 59', [[['R0', '2025-12-31', None, 2]], '2026-11-1'], '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
unpadded month	`B`	`B`	Passed
generated mix 26	`R0`	`R0`	Passed
expiry exclusive	`B`	`B`	Passed
version tie	`B`	`B`	Passed
future only	`NO_CARD`	`NO_CARD`	Passed
effective same day	`A`	`A`	Passed
id tie	`M`	`M`	Passed
generated mix 8	`NO_CARD`	`NO_CARD`	Passed

SHA-256 / 84f033206e79907a6891c09a3b452e19fc4dbc85241a725e751e81ca4d05605a

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 2026-09-29T14:52:14.266872+00:00.

Case digest / d806d9275c78c8062bdcc9a27a91fa4fc463d58401c91a198379a0574b544ca5