FA-3881 / Tokenization / Open access

A suffix classifier chooses a shorter compound extension · case 01

A suffix classifier chooses a shorter compound extension.

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: Return .tar.gz, .gz or .txt if present, preferring longest.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Return .tar.gz, .gz or .txt if present, preferring longest.

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

Case contract

Return .tar.gz, .gz or .txt if present, preferring longest.

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 next((p for p in ('.gz','.tar.gz','.txt') if x.endswith(p)),None)
    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.tar.gz'), '.tar.gz')
check('boundary 2', solve('a.gz'), '.gz')
check('boundary 3', solve('a.bin'), None)
check('boundary 4', solve('a.txt'), '.txt')
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	`.gz`	`.tar.gz`	Failed
boundary 2	`.gz`	`.gz`	Passed
boundary 3	`None`	`None`	Passed
boundary 4	`.txt`	`.txt`	Passed

SHA-256 / cf4f5fda8940edf3aea1ca7bff45d3130b822666e0012b79a1547250455852f2

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.rsplit('.',1)[1] if '.' in x else None
    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.tar.gz'), '.tar.gz')
check('boundary 2', solve('a.gz'), '.gz')
check('boundary 3', solve('a.bin'), None)
check('boundary 4', solve('a.txt'), '.txt')
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	`.gz`	`.tar.gz`	Failed
boundary 2	`.gz`	`.gz`	Passed
boundary 3	`.bin`	`None`	Failed
boundary 4	`.txt`	`.txt`	Passed

SHA-256 / 5f483da34592818d45efd8e2b408e82827f1c1960f8ca8a9cc32dcbf7540cb44

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 next((p for p in ('.tar.gz','.gz','.txt') if x.endswith(p)),None)
    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.tar.gz'), '.tar.gz')
check('boundary 2', solve('a.gz'), '.gz')
check('boundary 3', solve('a.bin'), None)
check('boundary 4', solve('a.txt'), '.txt')
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	`.tar.gz`	`.tar.gz`	Passed
boundary 2	`.gz`	`.gz`	Passed
boundary 3	`None`	`None`	Passed
boundary 4	`.txt`	`.txt`	Passed

SHA-256 / d10ea10fc3f1cd97c2e578f89c4d39129d5326bf82c03d911098ac1c58784c95

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 2026-09-29T14:37:32.306724+00:00.

Case digest / 4efe545d6803867ec9df722c929995956239b9d1292cbf841ff7844c82223597