FA-3816 / Serialization / Open access

Unknown template fields are deleted · case 01

Unknown template fields are deleted.

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: Substitute $name and ${name} from fixed mapping a=one; unknown names remain literal; $$ emits one dollar.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Substitute $name and ${name} from fixed mapping a=one; unknown names remain literal; $$ emits one dollar.

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

Case contract

Substitute $name and ${name} from fixed mapping a=one; unknown names remain literal; $$ emits one dollar.

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 string.Template(x).substitute({'a':'one'})
    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('$missing'), '$missing')
check('boundary 2', solve('${a} $$'), 'one $')
check('boundary 3', solve('$a'), 'one')
check('boundary 4', solve('plain'), 'plain')
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	`{'error': 'KeyError'}`	`$missing`	Failed
boundary 2	`one $`	`one $`	Passed
boundary 3	`one`	`one`	Passed
boundary 4	`plain`	`plain`	Passed

SHA-256 / 9ca3c67217bfb5b46b2a07f56432e8699f998d528131a999796e79ae7c96689e

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'\$\{?(\w+)\}?',lambda m:{'a':'one'}.get(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('$missing'), '$missing')
check('boundary 2', solve('${a} $$'), 'one $')
check('boundary 3', solve('$a'), 'one')
check('boundary 4', solve('plain'), 'plain')
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		`$missing`	Failed
boundary 2	`one $$`	`one $`	Failed
boundary 3	`one`	`one`	Passed
boundary 4	`plain`	`plain`	Passed

SHA-256 / 1c539c5c40dcc2396f11c558ba13c3585bae5564f1da80349a32ff9c5aae3d9f

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 string.Template(x).safe_substitute({'a':'one'})
    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('$missing'), '$missing')
check('boundary 2', solve('${a} $$'), 'one $')
check('boundary 3', solve('$a'), 'one')
check('boundary 4', solve('plain'), 'plain')
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	`$missing`	`$missing`	Passed
boundary 2	`one $`	`one $`	Passed
boundary 3	`one`	`one`	Passed
boundary 4	`plain`	`plain`	Passed

SHA-256 / 36fa3723303ddd15894d4d729270e078864dae9e4dd6980b1ab04bf6917ee699

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 2026-09-29T14:37:31.320656+00:00.

Case digest / 36b9c720f6118550af587c2a6663acf5c0643e79375b72149f327090372e0d28