json_path selects the wrong property for names ending in a newline #1589

A property name ending in a newline is rendered with dot notation in ValidationError.json_path. Python's $ regex anchor matches just before a final newline, so "x\n" is treated as though it were an identifier. A consumer using jsonpath-ng then selects "x" rather than the invalid property "x\n".

Reproduced on main, commit c497561ea0a95f5aac09cd63d15eb1420eb7bbec, Python 3.12.4/macOS:

from jsonschema import Draft202012Validator
import jsonpath_ng

instance = {"x": "valid", "x\n": 1}
schema = {"properties": {"x\n": {"type": "string"}}}
error, = Draft202012Validator(schema).iter_errors(instance)

print(repr(error.json_path))
print([match.value for match in jsonpath_ng.parse(error.json_path).find(instance)])

Observed:

'$.x\n'
['valid']

Expected: the path selects the property actually associated with the validation error, whose value is 1. The existing bracket-notation branch produces "$['x\n']", which round-trips the property name correctly with the parser already used in this project's path-rendering tests.

Using fullmatch(elem) instead of match(elem) for _JSON_PATH_COMPATIBLE_PROPERTY_PATTERN fixes the classification. A regression case added to TestJsonPathRendering fails before the change and passes afterward, including its parser round-trip assertion. This is a follow-up edge case to #1389/#1390; the existing quote and backslash handling can stay as it is.

Validation of the candidate patch:

• Path/exception tests: 76 passed (75 passed and the new test failed before the fix).
• Full suite: 8,298 passed, 232 skipped.
• Repository mypy check: passes (25 files).
• Ruff: passes for the changed files.

The tested patch is available at https://github.com/shreyans-chowdry/jsonschema/commit/06208f1c7a671f5f2e10384e252932e81e951ed7.

This was found during source inspection and investigated, implemented, and tested with OpenAI Codex assistance. It was not observed in a production application. Since the repository currently restricts external PRs, this report includes the candidate patch for maintainer consideration; no upstream PR has been opened.