FA-3891 / Parsing / Open access
A folded text header is treated as a separate field · case 01
A folded text header is treated as a separate field.
ROOT CAUSE
The implementation applies an operation whose text or grammar semantics violate this contract: Unfold each LF followed by space/tab into a single space; preserve other LF.
VERIFIED REPAIR
Implement the complete stated contract, including the boundary fixtures: Unfold each LF followed by space/tab into a single space; preserve other LF.
Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.
Case contract
Unfold each LF followed by space/tab into a single space; preserve other LF.
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.replace('\n',' ')
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\n\tb'), 'a b')
check('boundary 2', solve('a\n b'), 'a b')
check('boundary 3', solve('a\nb'), 'a\nb')
check('boundary 4', solve('a\n b'), 'a b')
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 b | a b | Failed |
| boundary 2 | a b | a b | Failed |
| boundary 3 | a b | a
b | Failed |
| boundary 4 | a b | a b | Failed |
SHA-256 / 436c886482f134c41418773a0978fec337c48e3a44ef720221bda9bf5631c82f
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.replace('\n ',' ')
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\n\tb'), 'a b')
check('boundary 2', solve('a\n b'), 'a b')
check('boundary 3', solve('a\nb'), 'a\nb')
check('boundary 4', solve('a\n b'), 'a b')
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
b | a b | Failed |
| boundary 2 | a b | a b | Passed |
| boundary 3 | a
b | a
b | Passed |
| boundary 4 | a b | a b | Failed |
SHA-256 / 6cfb111b4e8effa493ca1fb2af9d2c0e365f8023004628a2942624ca66f6beef
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 re.sub(r'\n[ \x09]+',' ',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\n\tb'), 'a b')
check('boundary 2', solve('a\n b'), 'a b')
check('boundary 3', solve('a\nb'), 'a\nb')
check('boundary 4', solve('a\n b'), 'a b')
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 b | a b | Passed |
| boundary 2 | a b | a b | Passed |
| boundary 3 | a
b | a
b | Passed |
| boundary 4 | a b | a b | Passed |
SHA-256 / a6f92766249857b53a0779b448fb7d32d8b1c83ec082b2216104024ff55877c4
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 2026-09-29T14:37:32.419111+00:00.
Case digest / 53e6215b64bad2113ad310bfa8b4ca9041b9ff3305833d086833855d6725555d