FA-3781 / Parsing / Open access

Column tracking does not reset after a newline · case 01

Column tracking does not reset after a newline.

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: Given text and a valid codepoint offset, return one-based line and zero-based column; newline itself belongs to preceding line.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Given text and a valid codepoint offset, return one-based line and zero-based column; newline itself belongs to preceding line.

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

Case contract

Given text and a valid codepoint offset, return one-based line and zero-based column; newline itself belongs to preceding line.

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 [1,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(['a\nbc', 3]), [2, 1])
check('boundary 2', solve(['a\nb', 1]), [1, 1])
check('boundary 3', solve(['\n', 1]), [2, 0])
check('boundary 4', solve(['', 0]), [1, 0])
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	`[1, 3]`	`[2, 1]`	Failed
boundary 2	`[1, 1]`	`[1, 1]`	Passed
boundary 3	`[1, 1]`	`[2, 0]`	Failed
boundary 4	`[1, 0]`	`[1, 0]`	Passed

SHA-256 / d89033c48f182b1239bda986eba9022e5e4b21661439c1d7b73849d523e01b22

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[0][:x[1]].count('\n')+1,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(['a\nbc', 3]), [2, 1])
check('boundary 2', solve(['a\nb', 1]), [1, 1])
check('boundary 3', solve(['\n', 1]), [2, 0])
check('boundary 4', solve(['', 0]), [1, 0])
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	`[2, 3]`	`[2, 1]`	Failed
boundary 2	`[1, 1]`	`[1, 1]`	Passed
boundary 3	`[2, 1]`	`[2, 0]`	Failed
boundary 4	`[1, 0]`	`[1, 0]`	Passed

SHA-256 / b4e9835d9daf4f219706ec25fa5761fc547fc078f6d725030ef5c2dd1ca5b014

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[0][:x[1]].count('\n')+1,x[1]-(x[0].rfind('\n',0,x[1])+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(['a\nbc', 3]), [2, 1])
check('boundary 2', solve(['a\nb', 1]), [1, 1])
check('boundary 3', solve(['\n', 1]), [2, 0])
check('boundary 4', solve(['', 0]), [1, 0])
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	`[2, 1]`	`[2, 1]`	Passed
boundary 2	`[1, 1]`	`[1, 1]`	Passed
boundary 3	`[2, 0]`	`[2, 0]`	Passed
boundary 4	`[1, 0]`	`[1, 0]`	Passed

SHA-256 / 78d3142a668ff71596d20f1ea493ea9e6e3c5ba7e80c876e61ecdc440e86005d

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 2026-09-29T14:37:30.807561+00:00.

Case digest / 496e9d775773fb2d0a0eb81c128b2250d6b735532f0b405a01a74a0087e30665