FA-95361 / Shipping rate zone lookup / Open access

Zone chart: later row wins equal-width overlap · case 01

When two equally narrow rows overlap, the later row overrides the earlier one.

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

ROOT CAUSE

The narrowest comparison is inclusive, so ties replace the earlier match.

THE FAILURE

The narrowest comparison is inclusive, so ties replace the earlier match.

Unsuccessful approach: Breaking ties toward the lower zone is not the listed-order rule.

Case contract

dest is a ZIP string with optional surrounding whitespace, optionally ZIP+4 ("12345-6789"), or a 4-digit ZIP whose leading zero was lost (left-pad one zero). chart [[lo3, hi3, zone]] inclusive ZIP3 ranges; the narrowest matching range wins, earliest listed on equal width. Malformed -> "INVALID"; no match -> "NO_ZONE".

Why this case matters

Carrier zone charts map origin to destination ZIP3 ranges, the first step of rating.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(dest, chart):
    z = dest.strip()
    if len(z) == 10 and z[5] == '-' and z[6:].isdecimal():
        z = z[:5]
    if len(z) == 4 and z.isdecimal():
        z = '0' + z
    if len(z) != 5 or not z.isdecimal():
        return 'INVALID'
    p = int(z[:3])
    best = None
    for lo, hi, zone in chart:
        if lo <= p <= hi:
            if best is None or (hi - lo) <= (best[1] - best[0]):
                best = (lo, hi, zone)
    return best[2] if best else 'NO_ZONE'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['equal width first listed', ['21500', [[210, 219, 2], [215, 224, 9]]], 2], ['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['zip plus four', ['15012-3456', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['range upper edge', ['19999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5], ['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['outside chart', ['40000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'NO_ZONE'], ['lost leading zero', ['2134', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['generated mix 5', ['40000-12a4', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID']], [['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['nested narrowest', ['21700', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 6], ['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['outside chart', ['40000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'NO_ZONE'], ['zip plus four', ['15012-3456', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['generated mix 7', ['09999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['generated mix 15', ['16000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5], ['generated mix 23', ['22000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 3]], [['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['letters', ['123AB', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID'], ['padded', [' 30001\n', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 7], ['lost leading zero', ['2134', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['nested narrowest', ['21700', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 6], ['generated mix 18', ['15000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['generated mix 26', ['\t15000\n', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['generated mix 34', ['15000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4]], [['equal width first listed', ['21500', [[210, 219, 2], [215, 224, 9]]], 2], ['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['lost leading zero', ['2134', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['nested narrowest', ['21700', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 6], ['letters', ['123AB', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID'], ['padded', [' 30001\n', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 7], ['generated mix 30', ['999x1', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID'], ['generated mix 38', ['9999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8]], [['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['equal width first listed', ['21500', [[210, 219, 2], [215, 224, 9]]], 2], ['outside chart', ['40000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'NO_ZONE'], ['zip plus four', ['15012-3456', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['range upper edge', ['19999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5], ['generated mix 41', ['00501', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['generated mix 49', ['10001', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5]]]
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
equal width first listed	`9`	`2`	Failed
equal width plus four	`3`	`7`	Failed
zip plus four	`4`	`4`	Passed
range upper edge	`5`	`5`	Passed
equal width higher zone first	`2`	`9`	Failed
outside chart	`NO_ZONE`	`NO_ZONE`	Passed
lost leading zero	`8`	`8`	Passed
generated mix 5	`INVALID`	`INVALID`	Passed

SHA-256 / e646b3077764f59287283980851d346d3600278b74c21449dd75d631afd3ef11

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(dest, chart):
    z = dest.strip()
    if len(z) == 10 and z[5] == '-' and z[6:].isdecimal():
        z = z[:5]
    if len(z) == 4 and z.isdecimal():
        z = '0' + z
    if len(z) != 5 or not z.isdecimal():
        return 'INVALID'
    p = int(z[:3])
    best = None
    for lo, hi, zone in chart:
        if lo <= p <= hi:
            if best is None or (hi - lo) < (best[1] - best[0]) or ((hi - lo) == (best[1] - best[0]) and zone < best[2]):
                best = (lo, hi, zone)
    return best[2] if best else 'NO_ZONE'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['equal width first listed', ['21500', [[210, 219, 2], [215, 224, 9]]], 2], ['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['zip plus four', ['15012-3456', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['range upper edge', ['19999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5], ['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['outside chart', ['40000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'NO_ZONE'], ['lost leading zero', ['2134', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['generated mix 5', ['40000-12a4', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID']], [['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['nested narrowest', ['21700', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 6], ['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['outside chart', ['40000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'NO_ZONE'], ['zip plus four', ['15012-3456', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['generated mix 7', ['09999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['generated mix 15', ['16000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5], ['generated mix 23', ['22000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 3]], [['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['letters', ['123AB', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID'], ['padded', [' 30001\n', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 7], ['lost leading zero', ['2134', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['nested narrowest', ['21700', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 6], ['generated mix 18', ['15000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['generated mix 26', ['\t15000\n', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['generated mix 34', ['15000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4]], [['equal width first listed', ['21500', [[210, 219, 2], [215, 224, 9]]], 2], ['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['lost leading zero', ['2134', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['nested narrowest', ['21700', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 6], ['letters', ['123AB', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID'], ['padded', [' 30001\n', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 7], ['generated mix 30', ['999x1', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'INVALID'], ['generated mix 38', ['9999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8]], [['equal width higher zone first', ['21600', [[210, 219, 9], [215, 224, 2]]], 9], ['equal width plus four', ['21999-0001', [[200, 299, 1], [210, 219, 7], [215, 224, 3]]], 7], ['equal width first listed', ['21500', [[210, 219, 2], [215, 224, 9]]], 2], ['outside chart', ['40000', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 'NO_ZONE'], ['zip plus four', ['15012-3456', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 4], ['range upper edge', ['19999', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5], ['generated mix 41', ['00501', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 8], ['generated mix 49', ['10001', [[5, 99, 8], [100, 199, 5], [150, 159, 4], [200, 299, 3], [210, 219, 2], [215, 219, 6], [300, 399, 7]]], 5]]]
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
equal width first listed	`2`	`2`	Passed
equal width plus four	`3`	`7`	Failed
zip plus four	`4`	`4`	Passed
range upper edge	`5`	`5`	Passed
equal width higher zone first	`2`	`9`	Failed
outside chart	`NO_ZONE`	`NO_ZONE`	Passed
lost leading zero	`8`	`8`	Passed
generated mix 5	`INVALID`	`INVALID`	Passed

SHA-256 / 14836af3e2a7c30bb897901f9a07a6e716aafd973cdda3745036f164b76cb621

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.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

Stipulated chart rows and input normalization; not a carrier-published chart. 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 2026-09-29T14:52:12.997860+00:00.

Case digest / 87a05d10c521d0e041d023a3d7c8b5b41f2085641bcc9e53172f969f12fad2eb