FA-3556 / Lexical grammars / Open access

A custom property omits its required double hyphen · case 01

A custom property omits its required double hyphen.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The recognizer uses '-?[A-Za-z_][A-Za-z0-9_-]*', which admits or omits a token shape forbidden by the stated grammar.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Accept -- followed by an ASCII letter or underscore and then letters/digits/underscore/hyphen.

Unsuccessful approach: The candidate grammar '--[A-Za-z0-9_-]+' still disagrees with the explicit boundary fixtures.

Case contract

Accept -- followed by an ASCII letter or underscore and then letters/digits/underscore/hyphen.

Why this case matters

A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return bool(re.fullmatch('-?[A-Za-z_][A-Za-z0-9_-]*',x))
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('--1'), False)
check('boundary 2', solve('-x'), False)
check('boundary 3', solve('--color'), True)
check('boundary 4', solve('--a-b2'), True)
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
boundary 1	`False`	`False`	Passed
boundary 2	`True`	`False`	Failed
boundary 3	`False`	`True`	Failed
boundary 4	`False`	`True`	Failed

SHA-256 / 62b5d75b550626968838ce67aaea55b548a37780d182c5f5885d814f1e2da79b

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return bool(re.fullmatch('--[A-Za-z0-9_-]+',x))
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('--1'), False)
check('boundary 2', solve('-x'), False)
check('boundary 3', solve('--color'), True)
check('boundary 4', solve('--a-b2'), True)
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
boundary 1	`True`	`False`	Failed
boundary 2	`False`	`False`	Passed
boundary 3	`True`	`True`	Passed
boundary 4	`True`	`True`	Passed

SHA-256 / 560e579edf539d70e1d54a79ce23194f342d07fa50e9dc56b8306fff24510c88

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return bool(re.fullmatch('--[A-Za-z_][A-Za-z0-9_-]*',x))
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('--1'), False)
check('boundary 2', solve('-x'), False)
check('boundary 3', solve('--color'), True)
check('boundary 4', solve('--a-b2'), True)
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
boundary 1	`False`	`False`	Passed
boundary 2	`False`	`False`	Passed
boundary 3	`True`	`True`	Passed
boundary 4	`True`	`True`	Passed

SHA-256 / 1761c379faa9080afd7f8d6dd918f8818d25ad3417f4ee7f674efc2dffc68f98

Verification & scope

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 2026-09-29T14:37:27.443417+00:00.

Case digest / 70d4ac63e9b443f0d8692b6852b0eed1cef1622b887c98e42b4a8ce6b8164ba3