FA-2906 / Text processing / Open access

Capitalization leaves an uppercase tail · case 01

Capitalization leaves an uppercase tail.

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: Capitalize the first character and lowercase the remainder using Unicode rules.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Capitalize the first character and lowercase the remainder using Unicode rules.

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

Case contract

Capitalize the first character and lowercase the remainder using Unicode rules.

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[:1].upper()+x[1:]
    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('hELLO'), 'Hello')
check('boundary 2', solve('two WORDS'), 'Two words')
check('boundary 3', solve('ǳABC'), 'ǲabc')
check('boundary 4', solve(''), '')
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	`HELLO`	`Hello`	Failed
boundary 2	`Two WORDS`	`Two words`	Failed
boundary 3	`ǱABC`	`ǲabc`	Failed
boundary 4			Passed

SHA-256 / 27a6e212dfa5a7b6668a36c437358f757e5c590a1b6e223148bba0e302c37b6d

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.title()
    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('hELLO'), 'Hello')
check('boundary 2', solve('two WORDS'), 'Two words')
check('boundary 3', solve('ǳABC'), 'ǲabc')
check('boundary 4', solve(''), '')
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	`Hello`	`Hello`	Passed
boundary 2	`Two Words`	`Two words`	Failed
boundary 3	`ǲabc`	`ǲabc`	Passed
boundary 4			Passed

SHA-256 / 6c2da461dc3a926aa6b5f1940dd400915729e0b8454e015e52ff95057db5e7a7

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.capitalize()
    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('hELLO'), 'Hello')
check('boundary 2', solve('two WORDS'), 'Two words')
check('boundary 3', solve('ǳABC'), 'ǲabc')
check('boundary 4', solve(''), '')
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	`Hello`	`Hello`	Passed
boundary 2	`Two words`	`Two words`	Passed
boundary 3	`ǲabc`	`ǲabc`	Passed
boundary 4			Passed

SHA-256 / df4aee8c140afabd53f0b827763ef49360ecc32fbbe7d85697be0a54570e4b70

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 2026-09-29T14:37:18.805817+00:00.

Case digest / 31a4c1e7eb9a01138158006987d723302bd7b26cc7d1b40a68b419ba104bbe45