FA-3871 / Text processing / Open access

Removing a record terminator erases empty trailing records · case 01

Removing a record terminator erases empty trailing records.

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 at most one terminal CRLF or LF; preserve lone CR and prior terminators.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Remove at most one terminal CRLF or LF; preserve lone CR and prior terminators.

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

Case contract

Remove at most one terminal CRLF or LF; preserve lone CR and prior terminators.

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.rstrip('\r\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\n'), 'a\n')
check('boundary 2', solve('a\r\n'), 'a')
check('boundary 3', solve('a\r'), 'a\r')
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`	`a`	Passed
boundary 3	`a`	`a`	Failed
boundary 4	`a`	`a`	Passed

SHA-256 / d5a78416955c65eb6b09708fde27a8cd51012fac390e6dc3f3f719d6846d8d5a

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] if x.endswith(('\r','\n')) 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\n\n'), 'a\n')
check('boundary 2', solve('a\r\n'), 'a')
check('boundary 3', solve('a\r'), 'a\r')
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`	`a`	Failed
boundary 3	`a`	`a`	Failed
boundary 4	`a`	`a`	Passed

SHA-256 / a2cd245b9a47e6295d4f1d82c28b8a8ab3f5d891e1d07bc190c0a85cabfe376f

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 x[:-2] if x.endswith('\r\n') else x[:-1] if x.endswith('\n') 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\n\n'), 'a\n')
check('boundary 2', solve('a\r\n'), 'a')
check('boundary 3', solve('a\r'), 'a\r')
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`	`a`	Passed
boundary 3	`a`	`a`	Passed
boundary 4	`a`	`a`	Passed

SHA-256 / f1be4f80a83c560fc1105229a8ce8ae8ddcea913187da7341943df919f18ae28

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 2026-09-29T14:37:32.190899+00:00.

Case digest / c42f157c6877a663ba1715e94107c1ae1b62dde569791924966ec9b1810fcf2f