FA-3141 / Serialization / Open access
An astral scalar is escaped as a single invalid JSON escape · case 01
An astral scalar is escaped as a single invalid JSON escape.
ROOT CAUSE
The implementation applies an operation whose text or grammar semantics violate this contract: Serialize strings as ASCII-only JSON using surrogate pairs when needed.
VERIFIED REPAIR
Implement the complete stated contract, including the boundary fixtures: Serialize strings as ASCII-only JSON using surrogate pairs when needed.
Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.
Case contract
Serialize strings as ASCII-only JSON using surrogate pairs when needed.
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 json.dumps(x,ensure_ascii=False)
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('😀'), '"\\ud83d\\ude00"')
check('boundary 2', solve('é'), '"\\u00e9"')
check('boundary 3', solve('\n'), '"\\n"')
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 | "😀" | "\ud83d\ude00" | Failed |
| boundary 2 | "é" | "\u00e9" | Failed |
| boundary 3 | "\n" | "\n" | Passed |
| boundary 4 | "a" | "a" | Passed |
SHA-256 / 161947bd98cfbb99c3345a10b115753318702b07abecd06ae8effa5fcbd2e63d
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 '"'+''.join(c if ord(c)<128 else '\\u%04x'%ord(c) for c in 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('😀'), '"\\ud83d\\ude00"')
check('boundary 2', solve('é'), '"\\u00e9"')
check('boundary 3', solve('\n'), '"\\n"')
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 | "\u1f600" | "\ud83d\ude00" | Failed |
| boundary 2 | "\u00e9" | "\u00e9" | Passed |
| boundary 3 | "
" | "\n" | Failed |
| boundary 4 | "a" | "a" | Passed |
SHA-256 / 245683a7b4470dba2f33b849b2c3892da9256bd0eb25f963ff648992db0e9743
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 json.dumps(x,ensure_ascii=True)
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('😀'), '"\\ud83d\\ude00"')
check('boundary 2', solve('é'), '"\\u00e9"')
check('boundary 3', solve('\n'), '"\\n"')
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 | "\ud83d\ude00" | "\ud83d\ude00" | Passed |
| boundary 2 | "\u00e9" | "\u00e9" | Passed |
| boundary 3 | "\n" | "\n" | Passed |
| boundary 4 | "a" | "a" | Passed |
SHA-256 / f3223eae11d91c58c273ca7e65af62ae90d540c52d73076483cfbcb39a4d7c47
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 2026-09-29T14:37:21.701412+00:00.
Case digest / e4655a758ccfc5b35b9c99b5e8900ce1cb8658695935b3245fcec12af39d4200