FA-3851 / Parsing / Open access

Removing outer brackets strips unrelated nested delimiters · case 01

Removing outer brackets strips unrelated nested delimiters.

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

ROOT CAUSE

The implementation applies an operation whose text or grammar semantics violate this contract: Remove one outer round-parenthesis pair only if it encloses the entire balanced expression.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Remove one outer round-parenthesis pair only if it encloses the entire balanced expression.

Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.

Case contract

Remove one outer round-parenthesis pair only if it encloses the entire balanced expression.

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 x.strip('()')
    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('((a))'), '(a)')
check('boundary 2', solve('(a)+(b)'), '(a)+(b)')
check('boundary 3', solve('(a+b)'), 'a+b')
check('boundary 4', solve('a'), 'a')
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	`a`	`(a)`	Failed
boundary 2	`a)+(b`	`(a)+(b)`	Failed
boundary 3	`a+b`	`a+b`	Passed
boundary 4	`a`	`a`	Passed

SHA-256 / e028cdc42965e4943c4d8a1d2df66a5c43012cc8506f37648d6b29b5e4f28962

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 x[1:-1] if x.startswith('(') and x.endswith(')') else 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('((a))'), '(a)')
check('boundary 2', solve('(a)+(b)'), '(a)+(b)')
check('boundary 3', solve('(a+b)'), 'a+b')
check('boundary 4', solve('a'), 'a')
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	`(a)`	`(a)`	Passed
boundary 2	`a)+(b`	`(a)+(b)`	Failed
boundary 3	`a+b`	`a+b`	Passed
boundary 4	`a`	`a`	Passed

SHA-256 / b1c54eb629aca4cd6916b38f8de2ffd6509c7e2e757668b119143f4b405bcdfb

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:
        if not x.startswith('(') or not x.endswith(')'): return x
        depth=0
        for i,c in enumerate(x):
            depth+=int(c=='(')-int(c==')')
            if depth==0 and i<len(x)-1: return x
        return x[1:-1]
    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('((a))'), '(a)')
check('boundary 2', solve('(a)+(b)'), '(a)+(b)')
check('boundary 3', solve('(a+b)'), 'a+b')
check('boundary 4', solve('a'), 'a')
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	`(a)`	`(a)`	Passed
boundary 2	`(a)+(b)`	`(a)+(b)`	Passed
boundary 3	`a+b`	`a+b`	Passed
boundary 4	`a`	`a`	Passed

SHA-256 / 124b4047ae344b4698c83bf06ebfd01dd6a0d155fc0d2a994f6492ef83716f16

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 2026-09-29T14:37:31.790402+00:00.

Case digest / c1811d65b45dd2292b21f430382ab17a2421116511136fde7e25c7c39d621fbd