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Legacy HTML numeric references decode as raw controls · case 01

Legacy HTML numeric references decode as raw controls.

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: Decode HTML references with HTML invalid-codepoint replacement and Windows-1252 remapping.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Decode HTML references with HTML invalid-codepoint replacement and Windows-1252 remapping.

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

Case contract

Decode HTML references with HTML invalid-codepoint replacement and Windows-1252 remapping.

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 re.sub(r'&#(\d+);',lambda m:chr(int(m[1])),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('€'), '€')
check('boundary 2', solve('�'), '�')
check('boundary 3', solve('�'), '�')
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 fixtureActualExpectedOutcome
boundary 1€€Failed
boundary 2�Failed
boundary 3��Failed
boundary 4AAPassed

SHA-256 / 8cfb2f1be5cfc81e6bd027d68bdc0594e5fbbc435fe44c87174cfe80c2b377c3

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 re.sub(r'&#(\d+);',lambda m:'�' if int(m[1])==0 else chr(int(m[1])),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('€'), '€')
check('boundary 2', solve('�'), '�')
check('boundary 3', solve('�'), '�')
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 fixtureActualExpectedOutcome
boundary 1€€Failed
boundary 2��Passed
boundary 3��Failed
boundary 4AAPassed

SHA-256 / 0a7d951f34b15db3eabdade5fc17e880485ef3d4bbb488667e564f19ac8913e2

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 html.unescape(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('€'), '€')
check('boundary 2', solve('�'), '�')
check('boundary 3', solve('�'), '�')
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 fixtureActualExpectedOutcome
boundary 1€€Passed
boundary 2��Passed
boundary 3��Passed
boundary 4AAPassed

SHA-256 / 9801b0a7261ee0ee2e920762156bc2d4e6841acfc8d7413b97a4c43ea19948b0

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 2026-09-29T14:37:23.176758+00:00.

Case digest / 31c991f015af12638ff1275e9956480c03b8f29dac6f2dd6df651b7d3faea4c1