FA-95051 / Warehouse slotting and bin packing / Open access

FEFO putaway: mixed lot bin chosen by distance only · case 01

The receipt joins a nearby bin with a distant expiry while a bin with a matching expiry is available.

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

ROOT CAUSE

Mixed-lot candidates are ranked by travel distance, ignoring expiry gap.

VERIFIED REPAIR

Rank mixed-lot bins by expiry gap, then distance, then bin id.

Unsuccessful approach: Keeping the expiry gap but skipping distance picks a farther bin on expiry ties.

Case contract

bins [[bin, sku|None, lot, expiry_day, qty, capacity, distance]]; receipt [sku, lot, expiry_day, qty]. A bin is empty when sku is None or qty is 0. Preference: (1) non-empty bin with same sku and lot and room (capacity-qty >= receipt qty), nearest then id; (2) same sku, different lot, expiry within 30 days either way, room; smallest expiry gap, nearest, id; (3) empty bin with capacity >= qty, nearest then id; else "HOLD".

Why this case matters

FEFO storage keeps lots with similar expiry together so the earliest expiring stock ships first.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(bins, receipt):
    sku, lot, exp, q = receipt
    def room(b):
        return b[5] - b[4] >= q
    def empty(b):
        return b[1] is None or b[4] == 0
    same_lot = [b for b in bins if not empty(b) and b[1] == sku and b[2] == lot and room(b)]
    if same_lot:
        return min(same_lot, key=lambda b: (b[6], b[0]))[0]
    mixed = [b for b in bins if not empty(b) and b[1] == sku and b[2] != lot and abs(b[3] - exp) <= 30 and room(b)]
    if mixed:
        return min(mixed, key=lambda b: (b[6], b[0]))[0]
    free = [b for b in bins if empty(b) and b[5] >= q]
    if free:
        return min(free, key=lambda b: (b[6], b[0]))[0]
    return 'HOLD'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['generated mix 17', [[['B0', 'S2', 'L2', 120, 0, 20, 8], ['B1', 'S1', 'L2', 131, 5, 40, 3], ['B2', 'S2', 'L2', 100, 10, 20, 8], ['B3', 'S2', 'L2', 100, 10, 60, 6], ['B4', 'S1', 'L3', 100, 30, 40, 3], ['B5', 'S1', 'L1', 145, 10, 60, 5]], ['S1', 'L4', 150, 20]], 'B5'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 7', [[['B0', 'S1', 'L1', 130, 10, 40, 3], ['B1', 'S2', 'L3', 160, 30, 20, 2], ['B2', 'S1', 'L2', 145, 0, 20, 1]], ['S2', 'L4', 130, 20]], 'B2']], [['generated mix 52', [[['B0', None, None, 0, 0, 20, 9], ['B1', 'S1', 'L3', 120, 10, 60, 1], ['B2', 'S1', 'L3', 120, 40, 20, 9], ['B3', 'S1', 'L2', 100, 40, 60, 4]], ['S1', 'L4', 100, 10]], 'B3'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['expiry 31 days', [[['A', 'S1', 'L2', 131, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'E'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 10', [[['B0', 'S2', 'L2', 145, 5, 20, 4], ['B1', 'S1', 'L2', 120, 5, 40, 1], ['B2', None, None, 0, 0, 40, 5]], ['S1', 'L4', 150, 30]], 'B1'], ['generated mix 18', [[['B0', None, None, 0, 0, 60, 7], ['B1', 'S1', 'L2', 145, 5, 60, 3], ['B2', 'S1', 'L2', 120, 40, 40, 7], ['B3', None, None, 0, 0, 20, 9], ['B4', None, None, 0, 0, 20, 9]], ['S1', 'L4', 130, 10]], 'B1']], [['generated mix 75', [[['B0', 'S1', 'L1', 120, 30, 60, 8], ['B1', None, None, 0, 0, 40, 8], ['B2', 'S1', 'L3', 130, 10, 60, 2]], ['S1', 'L4', 100, 30]], 'B0'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 31 days', [[['A', 'S1', 'L2', 131, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'E'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['generated mix 21', [[['B0', 'S1', 'L3', 130, 40, 60, 3], ['B1', 'S1', 'L3', 145, 30, 40, 7], ['B2', 'S1', 'L2', 130, 40, 60, 4], ['B3', 'S2', 'L2', 120, 30, 40, 3], ['B4', 'S1', 'L3', 160, 30, 60, 2], ['B5', 'S1', 'L3', 160, 40, 40, 7]], ['S2', 'L4', 150, 10]], 'B3'], ['generated mix 29', [[['B0', None, None, 0, 0, 60, 5], ['B1', 'S1', 'L3', 100, 0, 60, 7], ['B2', 'S2', 'L2', 160, 40, 60, 7], ['B3', 'S1', 'L3', 131, 30, 60, 3], ['B4', 'S1', 'L1', 145, 10, 20, 4], ['B5', 'S2', 'L1', 130, 5, 40, 3], ['B6', 'S2', 'L2', 160, 40, 60, 5]], ['S1', 'L2', 100, 30]], 'B0']], [['generated mix 39', [[['B0', 'S1', 'L2', 120, 30, 20, 3], ['B1', 'S1', 'L3', 145, 0, 20, 4], ['B2', None, None, 0, 0, 40, 6], ['B3', 'S1', 'L3', 131, 30, 60, 9], ['B4', 'S1', 'L1', 100, 5, 60, 7], ['B5', None, None, 0, 0, 40, 4], ['B6', 'S2', 'L2', 100, 30, 60, 6]], ['S1', 'L4', 130, 10]], 'B3'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 32', [[['B0', 'S1', 'L3', 145, 40, 40, 7], ['B1', None, None, 0, 0, 40, 3]], ['S2', 'L4', 150, 20]], 'B1'], ['generated mix 41', [[['B0', 'S1', 'L2', 160, 30, 60, 7], ['B1', 'S1', 'L2', 160, 40, 60, 3], ['B2', 'S1', 'L3', 100, 0, 60, 7], ['B3', 'S2', 'L2', 130, 10, 60, 9], ['B4', 'S1', 'L2', 160, 0, 20, 4], ['B5', 'S2', 'L2', 100, 30, 40, 4]], ['S2', 'L1', 130, 30]], 'B3']], [['generated mix 56', [[['B0', 'S2', 'L3', 120, 40, 20, 4], ['B1', 'S1', 'L3', 131, 0, 20, 8], ['B2', 'S1', 'L1', 130, 30, 40, 1], ['B3', 'S1', 'L1', 131, 5, 40, 7], ['B4', 'S2', 'L3', 160, 5, 20, 1], ['B5', 'S1', 'L3', 100, 10, 40, 7]], ['S1', 'L4', 100, 10]], 'B5'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['generated mix 43', [[['B0', 'S1', 'L1', 120, 30, 40, 4], ['B1', None, None, 0, 0, 20, 9]], ['S1', 'L4', 130, 10]], 'B0'], ['generated mix 51', [[['B0', 'S2', 'L3', 130, 40, 60, 6], ['B1', 'S1', 'L1', 130, 40, 40, 1], ['B2', 'S1', 'L1', 100, 30, 40, 8], ['B3', 'S1', 'L1', 145, 0, 20, 2]], ['S2', 'L1', 100, 30]], 'HOLD']]]
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
generated mix 17	`B1`	`B5`	Failed
generated mix 1	`B2`	`B2`	Passed
same lot preferred	`A`	`A`	Passed
expiry 30 days later	`A`	`A`	Passed
residual label empty	`R`	`R`	Passed
nothing	`HOLD`	`HOLD`	Passed
room exact	`A`	`A`	Passed
generated mix 7	`B2`	`B2`	Passed

SHA-256 / 33def7f567dd9cd87d618bb13e0953878576caeba6f5e1d66040892523cb44e3

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(bins, receipt):
    sku, lot, exp, q = receipt
    def room(b):
        return b[5] - b[4] >= q
    def empty(b):
        return b[1] is None or b[4] == 0
    same_lot = [b for b in bins if not empty(b) and b[1] == sku and b[2] == lot and room(b)]
    if same_lot:
        return min(same_lot, key=lambda b: (b[6], b[0]))[0]
    mixed = [b for b in bins if not empty(b) and b[1] == sku and b[2] != lot and abs(b[3] - exp) <= 30 and room(b)]
    if mixed:
        return min(mixed, key=lambda b: (abs(b[3] - exp), b[0]))[0]
    free = [b for b in bins if empty(b) and b[5] >= q]
    if free:
        return min(free, key=lambda b: (b[6], b[0]))[0]
    return 'HOLD'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['generated mix 17', [[['B0', 'S2', 'L2', 120, 0, 20, 8], ['B1', 'S1', 'L2', 131, 5, 40, 3], ['B2', 'S2', 'L2', 100, 10, 20, 8], ['B3', 'S2', 'L2', 100, 10, 60, 6], ['B4', 'S1', 'L3', 100, 30, 40, 3], ['B5', 'S1', 'L1', 145, 10, 60, 5]], ['S1', 'L4', 150, 20]], 'B5'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 7', [[['B0', 'S1', 'L1', 130, 10, 40, 3], ['B1', 'S2', 'L3', 160, 30, 20, 2], ['B2', 'S1', 'L2', 145, 0, 20, 1]], ['S2', 'L4', 130, 20]], 'B2']], [['generated mix 52', [[['B0', None, None, 0, 0, 20, 9], ['B1', 'S1', 'L3', 120, 10, 60, 1], ['B2', 'S1', 'L3', 120, 40, 20, 9], ['B3', 'S1', 'L2', 100, 40, 60, 4]], ['S1', 'L4', 100, 10]], 'B3'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['expiry 31 days', [[['A', 'S1', 'L2', 131, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'E'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 10', [[['B0', 'S2', 'L2', 145, 5, 20, 4], ['B1', 'S1', 'L2', 120, 5, 40, 1], ['B2', None, None, 0, 0, 40, 5]], ['S1', 'L4', 150, 30]], 'B1'], ['generated mix 18', [[['B0', None, None, 0, 0, 60, 7], ['B1', 'S1', 'L2', 145, 5, 60, 3], ['B2', 'S1', 'L2', 120, 40, 40, 7], ['B3', None, None, 0, 0, 20, 9], ['B4', None, None, 0, 0, 20, 9]], ['S1', 'L4', 130, 10]], 'B1']], [['generated mix 75', [[['B0', 'S1', 'L1', 120, 30, 60, 8], ['B1', None, None, 0, 0, 40, 8], ['B2', 'S1', 'L3', 130, 10, 60, 2]], ['S1', 'L4', 100, 30]], 'B0'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 31 days', [[['A', 'S1', 'L2', 131, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'E'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['generated mix 21', [[['B0', 'S1', 'L3', 130, 40, 60, 3], ['B1', 'S1', 'L3', 145, 30, 40, 7], ['B2', 'S1', 'L2', 130, 40, 60, 4], ['B3', 'S2', 'L2', 120, 30, 40, 3], ['B4', 'S1', 'L3', 160, 30, 60, 2], ['B5', 'S1', 'L3', 160, 40, 40, 7]], ['S2', 'L4', 150, 10]], 'B3'], ['generated mix 29', [[['B0', None, None, 0, 0, 60, 5], ['B1', 'S1', 'L3', 100, 0, 60, 7], ['B2', 'S2', 'L2', 160, 40, 60, 7], ['B3', 'S1', 'L3', 131, 30, 60, 3], ['B4', 'S1', 'L1', 145, 10, 20, 4], ['B5', 'S2', 'L1', 130, 5, 40, 3], ['B6', 'S2', 'L2', 160, 40, 60, 5]], ['S1', 'L2', 100, 30]], 'B0']], [['generated mix 39', [[['B0', 'S1', 'L2', 120, 30, 20, 3], ['B1', 'S1', 'L3', 145, 0, 20, 4], ['B2', None, None, 0, 0, 40, 6], ['B3', 'S1', 'L3', 131, 30, 60, 9], ['B4', 'S1', 'L1', 100, 5, 60, 7], ['B5', None, None, 0, 0, 40, 4], ['B6', 'S2', 'L2', 100, 30, 60, 6]], ['S1', 'L4', 130, 10]], 'B3'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 32', [[['B0', 'S1', 'L3', 145, 40, 40, 7], ['B1', None, None, 0, 0, 40, 3]], ['S2', 'L4', 150, 20]], 'B1'], ['generated mix 41', [[['B0', 'S1', 'L2', 160, 30, 60, 7], ['B1', 'S1', 'L2', 160, 40, 60, 3], ['B2', 'S1', 'L3', 100, 0, 60, 7], ['B3', 'S2', 'L2', 130, 10, 60, 9], ['B4', 'S1', 'L2', 160, 0, 20, 4], ['B5', 'S2', 'L2', 100, 30, 40, 4]], ['S2', 'L1', 130, 30]], 'B3']], [['generated mix 56', [[['B0', 'S2', 'L3', 120, 40, 20, 4], ['B1', 'S1', 'L3', 131, 0, 20, 8], ['B2', 'S1', 'L1', 130, 30, 40, 1], ['B3', 'S1', 'L1', 131, 5, 40, 7], ['B4', 'S2', 'L3', 160, 5, 20, 1], ['B5', 'S1', 'L3', 100, 10, 40, 7]], ['S1', 'L4', 100, 10]], 'B5'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['generated mix 43', [[['B0', 'S1', 'L1', 120, 30, 40, 4], ['B1', None, None, 0, 0, 20, 9]], ['S1', 'L4', 130, 10]], 'B0'], ['generated mix 51', [[['B0', 'S2', 'L3', 130, 40, 60, 6], ['B1', 'S1', 'L1', 130, 40, 40, 1], ['B2', 'S1', 'L1', 100, 30, 40, 8], ['B3', 'S1', 'L1', 145, 0, 20, 2]], ['S2', 'L1', 100, 30]], 'HOLD']]]
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
generated mix 17	`B5`	`B5`	Passed
generated mix 1	`B0`	`B2`	Failed
same lot preferred	`A`	`A`	Passed
expiry 30 days later	`A`	`A`	Passed
residual label empty	`R`	`R`	Passed
nothing	`HOLD`	`HOLD`	Passed
room exact	`A`	`A`	Passed
generated mix 7	`B2`	`B2`	Passed

SHA-256 / 591e9ffd2d4462cdbe867e8b1f80b9730b36d2476052ea246fc68062b8169b76

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(bins, receipt):
    sku, lot, exp, q = receipt
    def room(b):
        return b[5] - b[4] >= q
    def empty(b):
        return b[1] is None or b[4] == 0
    same_lot = [b for b in bins if not empty(b) and b[1] == sku and b[2] == lot and room(b)]
    if same_lot:
        return min(same_lot, key=lambda b: (b[6], b[0]))[0]
    mixed = [b for b in bins if not empty(b) and b[1] == sku and b[2] != lot and abs(b[3] - exp) <= 30 and room(b)]
    if mixed:
        return min(mixed, key=lambda b: (abs(b[3] - exp), b[6], b[0]))[0]
    free = [b for b in bins if empty(b) and b[5] >= q]
    if free:
        return min(free, key=lambda b: (b[6], b[0]))[0]
    return 'HOLD'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['generated mix 17', [[['B0', 'S2', 'L2', 120, 0, 20, 8], ['B1', 'S1', 'L2', 131, 5, 40, 3], ['B2', 'S2', 'L2', 100, 10, 20, 8], ['B3', 'S2', 'L2', 100, 10, 60, 6], ['B4', 'S1', 'L3', 100, 30, 40, 3], ['B5', 'S1', 'L1', 145, 10, 60, 5]], ['S1', 'L4', 150, 20]], 'B5'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 7', [[['B0', 'S1', 'L1', 130, 10, 40, 3], ['B1', 'S2', 'L3', 160, 30, 20, 2], ['B2', 'S1', 'L2', 145, 0, 20, 1]], ['S2', 'L4', 130, 20]], 'B2']], [['generated mix 52', [[['B0', None, None, 0, 0, 20, 9], ['B1', 'S1', 'L3', 120, 10, 60, 1], ['B2', 'S1', 'L3', 120, 40, 20, 9], ['B3', 'S1', 'L2', 100, 40, 60, 4]], ['S1', 'L4', 100, 10]], 'B3'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['expiry 31 days', [[['A', 'S1', 'L2', 131, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'E'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 10', [[['B0', 'S2', 'L2', 145, 5, 20, 4], ['B1', 'S1', 'L2', 120, 5, 40, 1], ['B2', None, None, 0, 0, 40, 5]], ['S1', 'L4', 150, 30]], 'B1'], ['generated mix 18', [[['B0', None, None, 0, 0, 60, 7], ['B1', 'S1', 'L2', 145, 5, 60, 3], ['B2', 'S1', 'L2', 120, 40, 40, 7], ['B3', None, None, 0, 0, 20, 9], ['B4', None, None, 0, 0, 20, 9]], ['S1', 'L4', 130, 10]], 'B1']], [['generated mix 75', [[['B0', 'S1', 'L1', 120, 30, 60, 8], ['B1', None, None, 0, 0, 40, 8], ['B2', 'S1', 'L3', 130, 10, 60, 2]], ['S1', 'L4', 100, 30]], 'B0'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 31 days', [[['A', 'S1', 'L2', 131, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'E'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['generated mix 21', [[['B0', 'S1', 'L3', 130, 40, 60, 3], ['B1', 'S1', 'L3', 145, 30, 40, 7], ['B2', 'S1', 'L2', 130, 40, 60, 4], ['B3', 'S2', 'L2', 120, 30, 40, 3], ['B4', 'S1', 'L3', 160, 30, 60, 2], ['B5', 'S1', 'L3', 160, 40, 40, 7]], ['S2', 'L4', 150, 10]], 'B3'], ['generated mix 29', [[['B0', None, None, 0, 0, 60, 5], ['B1', 'S1', 'L3', 100, 0, 60, 7], ['B2', 'S2', 'L2', 160, 40, 60, 7], ['B3', 'S1', 'L3', 131, 30, 60, 3], ['B4', 'S1', 'L1', 145, 10, 20, 4], ['B5', 'S2', 'L1', 130, 5, 40, 3], ['B6', 'S2', 'L2', 160, 40, 60, 5]], ['S1', 'L2', 100, 30]], 'B0']], [['generated mix 39', [[['B0', 'S1', 'L2', 120, 30, 20, 3], ['B1', 'S1', 'L3', 145, 0, 20, 4], ['B2', None, None, 0, 0, 40, 6], ['B3', 'S1', 'L3', 131, 30, 60, 9], ['B4', 'S1', 'L1', 100, 5, 60, 7], ['B5', None, None, 0, 0, 40, 4], ['B6', 'S2', 'L2', 100, 30, 60, 6]], ['S1', 'L4', 130, 10]], 'B3'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['nothing', [[['X', 'S2', 'L1', 100, 5, 10, 1]], ['S1', 'L1', 100, 20]], 'HOLD'], ['room exact', [[['A', 'S1', 'L1', 100, 20, 40, 9], ['E', None, None, 0, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['generated mix 32', [[['B0', 'S1', 'L3', 145, 40, 40, 7], ['B1', None, None, 0, 0, 40, 3]], ['S2', 'L4', 150, 20]], 'B1'], ['generated mix 41', [[['B0', 'S1', 'L2', 160, 30, 60, 7], ['B1', 'S1', 'L2', 160, 40, 60, 3], ['B2', 'S1', 'L3', 100, 0, 60, 7], ['B3', 'S2', 'L2', 130, 10, 60, 9], ['B4', 'S1', 'L2', 160, 0, 20, 4], ['B5', 'S2', 'L2', 100, 30, 40, 4]], ['S2', 'L1', 130, 30]], 'B3']], [['generated mix 56', [[['B0', 'S2', 'L3', 120, 40, 20, 4], ['B1', 'S1', 'L3', 131, 0, 20, 8], ['B2', 'S1', 'L1', 130, 30, 40, 1], ['B3', 'S1', 'L1', 131, 5, 40, 7], ['B4', 'S2', 'L3', 160, 5, 20, 1], ['B5', 'S1', 'L3', 100, 10, 40, 7]], ['S1', 'L4', 100, 10]], 'B5'], ['generated mix 1', [[['B0', 'S1', 'L2', 130, 5, 40, 9], ['B1', 'S1', 'L2', 160, 10, 60, 9], ['B2', 'S1', 'L2', 130, 10, 40, 2], ['B3', 'S2', 'L1', 120, 0, 40, 3], ['B4', 'S2', 'L2', 130, 30, 20, 6], ['B5', 'S2', 'L3', 130, 40, 20, 3], ['B6', 'S2', 'L2', 130, 30, 20, 8]], ['S1', 'L1', 130, 10]], 'B2'], ['lot code on other sku', [[['X', 'S2', 'L1', 100, 5, 60, 1], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'E'], ['same lot preferred', [[['A', 'S1', 'L1', 100, 10, 40, 9], ['B', 'S1', 'L2', 100, 0, 40, 1]], ['S1', 'L1', 100, 20]], 'A'], ['expiry 30 days later', [[['A', 'S1', 'L2', 130, 10, 60, 5], ['E', None, None, 0, 0, 60, 1]], ['S1', 'L1', 100, 20]], 'A'], ['residual label empty', [[['R', 'S9', 'L7', 50, 0, 60, 2], ['E', None, None, 0, 0, 60, 4]], ['S1', 'L1', 100, 20]], 'R'], ['generated mix 43', [[['B0', 'S1', 'L1', 120, 30, 40, 4], ['B1', None, None, 0, 0, 20, 9]], ['S1', 'L4', 130, 10]], 'B0'], ['generated mix 51', [[['B0', 'S2', 'L3', 130, 40, 60, 6], ['B1', 'S1', 'L1', 130, 40, 40, 1], ['B2', 'S1', 'L1', 100, 30, 40, 8], ['B3', 'S1', 'L1', 145, 0, 20, 2]], ['S2', 'L1', 100, 30]], 'HOLD']]]
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
generated mix 17	`B5`	`B5`	Passed
generated mix 1	`B2`	`B2`	Passed
same lot preferred	`A`	`A`	Passed
expiry 30 days later	`A`	`A`	Passed
residual label empty	`R`	`R`	Passed
nothing	`HOLD`	`HOLD`	Passed
room exact	`A`	`A`	Passed
generated mix 7	`B2`	`B2`	Passed

SHA-256 / a0b11f0aa422151899e07d80c377982c4c92d1efd1e1ecd0c9674b8499006e8b

Verification & scope

Stipulated day-number expiries and a single receipt; no quarantine or multi-bin splits. 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 2026-09-29T14:52:10.140607+00:00.

Case digest / a42276768c331a2f6cd9856b40984d23b8ce4326399eae4c34c6fea1fc2104aa