FA-66726 / Airline fare rule evaluation / Open access

Unrecognised suffix tokens silently dropped · case 01

A corrupted basis such as MH14ZZ decodes as valid with no flags.

Verified by executionVariant 1 · 12 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Unknown tokens are skipped rather than rejected.

VERIFIED REPAIR

Reject any token outside CH, IN and NR.

Unsuccessful approach: Rejecting only tokens with digits still accepts invented letter tokens and records them as flags.

Case contract

Input: a fare basis string. Grammar: RBD letter A-Z (ASCII uppercase, else 'ERR_BASIS'), optional season H|L, optional day code W (WEEKEND) | X (WEEKDAY), optional advance purchase digits of any length (default 0), then two-letter tokens from CH, IN, NR (otherwise or odd length -> 'ERR_TOKEN'). Return {'rbd','season','days','ap','flags'}.

Why this case matters

Fare basis codes pack booking class, season, day-of-week application, advance purchase and passenger/penalty indicators into a positional code.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(x):
    s = x
    if not s or not ('A' <= s[0] <= 'Z'): return 'ERR_BASIS'
    out = {'rbd': s[0], 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}
    i = 1
    if i < len(s) and s[i] in 'HL':
        out['season'] = s[i]
        i += 1
    if i < len(s) and s[i] in 'WX':
        out['days'] = 'WEEKEND' if s[i] == 'W' else 'WEEKDAY'
        i += 1
    j = i
    while j < len(s) and s[j].isdigit():
        j += 1
    out['ap'] = int(s[i:j]) if j > i else 0
    rest = s[j:]
    if len(rest) % 2: return 'ERR_TOKEN'
    for k in range(0, len(rest), 2):
        tok = rest[k:k + 2]
        if tok not in ('CH', 'IN', 'NR'): continue
        out['flags'].append(tok)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['full basis', 'QLX8NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 8, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW110IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 110, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW3NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 3, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'NHX120', {'rbd': 'N', 'season': 'H', 'days': 'WEEKDAY', 'ap': 120, 'flags': []}], ['sampled case 2', 'qX14C', 'ERR_BASIS'], ['sampled case 3', 'THW', {'rbd': 'T', 'season': 'H', 'days': 'WEEKEND', 'ap': 0, 'flags': []}]], [['full basis', 'QLX9NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 9, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW120IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 120, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW4NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 4, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', '7W1', 'ERR_BASIS'], ['sampled case 2', 'q1', 'ERR_BASIS'], ['sampled case 3', 'qHXZZ', 'ERR_BASIS']], [['full basis', 'QLX10NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 10, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW130IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 130, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW5NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 5, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'VLXINC', 'ERR_TOKEN'], ['sampled case 2', 'QHW30CH', {'rbd': 'Q', 'season': 'H', 'days': 'WEEKEND', 'ap': 30, 'flags': ['CH']}], ['sampled case 3', 'B14CHIN', {'rbd': 'B', 'season': None, 'days': 'ANY', 'ap': 14, 'flags': ['CH', 'IN']}]], [['full basis', 'QLX11NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 11, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW140IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 140, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW6NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 6, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'MZZIN', 'ERR_TOKEN'], ['sampled case 2', 'MLC', 'ERR_TOKEN'], ['sampled case 3', 'THIN', {'rbd': 'T', 'season': 'H', 'days': 'ANY', 'ap': 0, 'flags': ['IN']}]], [['full basis', 'QLX12NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 12, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW150IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 150, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW7NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 7, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'LLWNRNR', {'rbd': 'L', 'season': 'L', 'days': 'WEEKEND', 'ap': 0, 'flags': ['NR', 'NR']}], ['sampled case 2', 'NHXNRZZ', 'ERR_TOKEN'], ['sampled case 3', 'TNR', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': ['NR']}]]]
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
full basis	`{'ap': 8, 'days': 'WEEKDAY', 'flags': ['NR', 'CH'], 'rbd': 'Q', 'season': 'L'}`	`{'ap': 8, 'days': 'WEEKDAY', 'flags': ['NR', 'CH'], 'rbd': 'Q', 'season': 'L'}`	Passed
three-digit advance purchase	`{'ap': 110, 'days': 'WEEKEND', 'flags': ['IN'], 'rbd': 'V', 'season': 'H'}`	`{'ap': 110, 'days': 'WEEKEND', 'flags': ['IN'], 'rbd': 'V', 'season': 'H'}`	Passed
rbd only	`{'ap': 0, 'days': 'ANY', 'flags': [], 'rbd': 'Y', 'season': None}`	`{'ap': 0, 'days': 'ANY', 'flags': [], 'rbd': 'Y', 'season': None}`	Passed
weekend without season	`{'ap': 3, 'days': 'WEEKEND', 'flags': ['NR'], 'rbd': 'K', 'season': None}`	`{'ap': 3, 'days': 'WEEKEND', 'flags': ['NR'], 'rbd': 'K', 'season': None}`	Passed
unknown suffix token	`{'ap': 14, 'days': 'ANY', 'flags': [], 'rbd': 'M', 'season': 'H'}`	`ERR_TOKEN`	Failed
odd suffix length	`ERR_TOKEN`	`ERR_TOKEN`	Passed
non-ASCII leading letter	`ERR_BASIS`	`ERR_BASIS`	Passed
lowercase basis	`ERR_BASIS`	`ERR_BASIS`	Passed
digits right after rbd	`{'ap': 21, 'days': 'ANY', 'flags': ['CH'], 'rbd': 'T', 'season': None}`	`{'ap': 21, 'days': 'ANY', 'flags': ['CH'], 'rbd': 'T', 'season': None}`	Passed
sampled case 1	`{'ap': 120, 'days': 'WEEKDAY', 'flags': [], 'rbd': 'N', 'season': 'H'}`	`{'ap': 120, 'days': 'WEEKDAY', 'flags': [], 'rbd': 'N', 'season': 'H'}`	Passed
sampled case 2	`ERR_BASIS`	`ERR_BASIS`	Passed
sampled case 3	`{'ap': 0, 'days': 'WEEKEND', 'flags': [], 'rbd': 'T', 'season': 'H'}`	`{'ap': 0, 'days': 'WEEKEND', 'flags': [], 'rbd': 'T', 'season': 'H'}`	Passed

SHA-256 / 5a3e8959d0d3a7b96804dbebf8df8eaf2e534c173a4ce3a2040d7a802dbceb43

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(x):
    s = x
    if not s or not ('A' <= s[0] <= 'Z'): return 'ERR_BASIS'
    out = {'rbd': s[0], 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}
    i = 1
    if i < len(s) and s[i] in 'HL':
        out['season'] = s[i]
        i += 1
    if i < len(s) and s[i] in 'WX':
        out['days'] = 'WEEKEND' if s[i] == 'W' else 'WEEKDAY'
        i += 1
    j = i
    while j < len(s) and s[j].isdigit():
        j += 1
    out['ap'] = int(s[i:j]) if j > i else 0
    rest = s[j:]
    if len(rest) % 2: return 'ERR_TOKEN'
    for k in range(0, len(rest), 2):
        tok = rest[k:k + 2]
        if any(ch.isdigit() for ch in tok): return 'ERR_TOKEN'
        out['flags'].append(tok)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['full basis', 'QLX8NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 8, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW110IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 110, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW3NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 3, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'NHX120', {'rbd': 'N', 'season': 'H', 'days': 'WEEKDAY', 'ap': 120, 'flags': []}], ['sampled case 2', 'qX14C', 'ERR_BASIS'], ['sampled case 3', 'THW', {'rbd': 'T', 'season': 'H', 'days': 'WEEKEND', 'ap': 0, 'flags': []}]], [['full basis', 'QLX9NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 9, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW120IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 120, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW4NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 4, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', '7W1', 'ERR_BASIS'], ['sampled case 2', 'q1', 'ERR_BASIS'], ['sampled case 3', 'qHXZZ', 'ERR_BASIS']], [['full basis', 'QLX10NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 10, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW130IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 130, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW5NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 5, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'VLXINC', 'ERR_TOKEN'], ['sampled case 2', 'QHW30CH', {'rbd': 'Q', 'season': 'H', 'days': 'WEEKEND', 'ap': 30, 'flags': ['CH']}], ['sampled case 3', 'B14CHIN', {'rbd': 'B', 'season': None, 'days': 'ANY', 'ap': 14, 'flags': ['CH', 'IN']}]], [['full basis', 'QLX11NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 11, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW140IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 140, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW6NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 6, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'MZZIN', 'ERR_TOKEN'], ['sampled case 2', 'MLC', 'ERR_TOKEN'], ['sampled case 3', 'THIN', {'rbd': 'T', 'season': 'H', 'days': 'ANY', 'ap': 0, 'flags': ['IN']}]], [['full basis', 'QLX12NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 12, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW150IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 150, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW7NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 7, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'LLWNRNR', {'rbd': 'L', 'season': 'L', 'days': 'WEEKEND', 'ap': 0, 'flags': ['NR', 'NR']}], ['sampled case 2', 'NHXNRZZ', 'ERR_TOKEN'], ['sampled case 3', 'TNR', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': ['NR']}]]]
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
full basis	`{'ap': 8, 'days': 'WEEKDAY', 'flags': ['NR', 'CH'], 'rbd': 'Q', 'season': 'L'}`	`{'ap': 8, 'days': 'WEEKDAY', 'flags': ['NR', 'CH'], 'rbd': 'Q', 'season': 'L'}`	Passed
three-digit advance purchase	`{'ap': 110, 'days': 'WEEKEND', 'flags': ['IN'], 'rbd': 'V', 'season': 'H'}`	`{'ap': 110, 'days': 'WEEKEND', 'flags': ['IN'], 'rbd': 'V', 'season': 'H'}`	Passed
rbd only	`{'ap': 0, 'days': 'ANY', 'flags': [], 'rbd': 'Y', 'season': None}`	`{'ap': 0, 'days': 'ANY', 'flags': [], 'rbd': 'Y', 'season': None}`	Passed
weekend without season	`{'ap': 3, 'days': 'WEEKEND', 'flags': ['NR'], 'rbd': 'K', 'season': None}`	`{'ap': 3, 'days': 'WEEKEND', 'flags': ['NR'], 'rbd': 'K', 'season': None}`	Passed
unknown suffix token	`{'ap': 14, 'days': 'ANY', 'flags': ['ZZ'], 'rbd': 'M', 'season': 'H'}`	`ERR_TOKEN`	Failed
odd suffix length	`ERR_TOKEN`	`ERR_TOKEN`	Passed
non-ASCII leading letter	`ERR_BASIS`	`ERR_BASIS`	Passed
lowercase basis	`ERR_BASIS`	`ERR_BASIS`	Passed
digits right after rbd	`{'ap': 21, 'days': 'ANY', 'flags': ['CH'], 'rbd': 'T', 'season': None}`	`{'ap': 21, 'days': 'ANY', 'flags': ['CH'], 'rbd': 'T', 'season': None}`	Passed
sampled case 1	`{'ap': 120, 'days': 'WEEKDAY', 'flags': [], 'rbd': 'N', 'season': 'H'}`	`{'ap': 120, 'days': 'WEEKDAY', 'flags': [], 'rbd': 'N', 'season': 'H'}`	Passed
sampled case 2	`ERR_BASIS`	`ERR_BASIS`	Passed
sampled case 3	`{'ap': 0, 'days': 'WEEKEND', 'flags': [], 'rbd': 'T', 'season': 'H'}`	`{'ap': 0, 'days': 'WEEKEND', 'flags': [], 'rbd': 'T', 'season': 'H'}`	Passed

SHA-256 / 04272215b61bf00123fc13f47f5a16365a91e672f3543da09b8204b65e2b0059

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(x):
    s = x
    if not s or not ('A' <= s[0] <= 'Z'): return 'ERR_BASIS'
    out = {'rbd': s[0], 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}
    i = 1
    if i < len(s) and s[i] in 'HL':
        out['season'] = s[i]
        i += 1
    if i < len(s) and s[i] in 'WX':
        out['days'] = 'WEEKEND' if s[i] == 'W' else 'WEEKDAY'
        i += 1
    j = i
    while j < len(s) and s[j].isdigit():
        j += 1
    out['ap'] = int(s[i:j]) if j > i else 0
    rest = s[j:]
    if len(rest) % 2: return 'ERR_TOKEN'
    for k in range(0, len(rest), 2):
        tok = rest[k:k + 2]
        if tok not in ('CH', 'IN', 'NR'): return 'ERR_TOKEN'
        out['flags'].append(tok)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['full basis', 'QLX8NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 8, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW110IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 110, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW3NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 3, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'NHX120', {'rbd': 'N', 'season': 'H', 'days': 'WEEKDAY', 'ap': 120, 'flags': []}], ['sampled case 2', 'qX14C', 'ERR_BASIS'], ['sampled case 3', 'THW', {'rbd': 'T', 'season': 'H', 'days': 'WEEKEND', 'ap': 0, 'flags': []}]], [['full basis', 'QLX9NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 9, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW120IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 120, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW4NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 4, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', '7W1', 'ERR_BASIS'], ['sampled case 2', 'q1', 'ERR_BASIS'], ['sampled case 3', 'qHXZZ', 'ERR_BASIS']], [['full basis', 'QLX10NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 10, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW130IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 130, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW5NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 5, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'VLXINC', 'ERR_TOKEN'], ['sampled case 2', 'QHW30CH', {'rbd': 'Q', 'season': 'H', 'days': 'WEEKEND', 'ap': 30, 'flags': ['CH']}], ['sampled case 3', 'B14CHIN', {'rbd': 'B', 'season': None, 'days': 'ANY', 'ap': 14, 'flags': ['CH', 'IN']}]], [['full basis', 'QLX11NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 11, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW140IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 140, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW6NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 6, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'MZZIN', 'ERR_TOKEN'], ['sampled case 2', 'MLC', 'ERR_TOKEN'], ['sampled case 3', 'THIN', {'rbd': 'T', 'season': 'H', 'days': 'ANY', 'ap': 0, 'flags': ['IN']}]], [['full basis', 'QLX12NRCH', {'rbd': 'Q', 'season': 'L', 'days': 'WEEKDAY', 'ap': 12, 'flags': ['NR', 'CH']}], ['three-digit advance purchase', 'VHW150IN', {'rbd': 'V', 'season': 'H', 'days': 'WEEKEND', 'ap': 150, 'flags': ['IN']}], ['rbd only', 'Y', {'rbd': 'Y', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': []}], ['weekend without season', 'KW7NR', {'rbd': 'K', 'season': None, 'days': 'WEEKEND', 'ap': 7, 'flags': ['NR']}], ['unknown suffix token', 'MH14ZZ', 'ERR_TOKEN'], ['odd suffix length', 'BL3NRC', 'ERR_TOKEN'], ['non-ASCII leading letter', 'ÉL7', 'ERR_BASIS'], ['lowercase basis', 'qlx7', 'ERR_BASIS'], ['digits right after rbd', 'T21CH', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 21, 'flags': ['CH']}], ['sampled case 1', 'LLWNRNR', {'rbd': 'L', 'season': 'L', 'days': 'WEEKEND', 'ap': 0, 'flags': ['NR', 'NR']}], ['sampled case 2', 'NHXNRZZ', 'ERR_TOKEN'], ['sampled case 3', 'TNR', {'rbd': 'T', 'season': None, 'days': 'ANY', 'ap': 0, 'flags': ['NR']}]]]
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
full basis	`{'ap': 8, 'days': 'WEEKDAY', 'flags': ['NR', 'CH'], 'rbd': 'Q', 'season': 'L'}`	`{'ap': 8, 'days': 'WEEKDAY', 'flags': ['NR', 'CH'], 'rbd': 'Q', 'season': 'L'}`	Passed
three-digit advance purchase	`{'ap': 110, 'days': 'WEEKEND', 'flags': ['IN'], 'rbd': 'V', 'season': 'H'}`	`{'ap': 110, 'days': 'WEEKEND', 'flags': ['IN'], 'rbd': 'V', 'season': 'H'}`	Passed
rbd only	`{'ap': 0, 'days': 'ANY', 'flags': [], 'rbd': 'Y', 'season': None}`	`{'ap': 0, 'days': 'ANY', 'flags': [], 'rbd': 'Y', 'season': None}`	Passed
weekend without season	`{'ap': 3, 'days': 'WEEKEND', 'flags': ['NR'], 'rbd': 'K', 'season': None}`	`{'ap': 3, 'days': 'WEEKEND', 'flags': ['NR'], 'rbd': 'K', 'season': None}`	Passed
unknown suffix token	`ERR_TOKEN`	`ERR_TOKEN`	Passed
odd suffix length	`ERR_TOKEN`	`ERR_TOKEN`	Passed
non-ASCII leading letter	`ERR_BASIS`	`ERR_BASIS`	Passed
lowercase basis	`ERR_BASIS`	`ERR_BASIS`	Passed
digits right after rbd	`{'ap': 21, 'days': 'ANY', 'flags': ['CH'], 'rbd': 'T', 'season': None}`	`{'ap': 21, 'days': 'ANY', 'flags': ['CH'], 'rbd': 'T', 'season': None}`	Passed
sampled case 1	`{'ap': 120, 'days': 'WEEKDAY', 'flags': [], 'rbd': 'N', 'season': 'H'}`	`{'ap': 120, 'days': 'WEEKDAY', 'flags': [], 'rbd': 'N', 'season': 'H'}`	Passed
sampled case 2	`ERR_BASIS`	`ERR_BASIS`	Passed
sampled case 3	`{'ap': 0, 'days': 'WEEKEND', 'flags': [], 'rbd': 'T', 'season': 'H'}`	`{'ap': 0, 'days': 'WEEKEND', 'flags': [], 'rbd': 'T', 'season': 'H'}`	Passed

SHA-256 / 5de9b405b2165848e4f3e4a27bdd92ef4850af13db3e71daaeceaff2c4310abb

Verification & scope

A stipulated toy fare-rule contract with invented constants; it is not an ATPCO or carrier tariff implementation and makes no claim of industry-standard conformance. 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 2026-09-29T14:47:46.296447+00:00.

Case digest / 2f63bbf0b5737d0ad4545765487b632d4ee08cc8ac7c88da2e33738639fc89ce