nextlevelbuilder/ui-ux-pro-max-skill · error · SystemExit

Invalid JSON file {path}: {error}

Error message

Invalid JSON file {path}: {error}

What it means

load_json() in the relevance evaluation harness parses fixture/manifest JSON strictly: JSONDecodeError (syntax), OSError (unreadable/missing file), and ValueError are all converted into SystemExit with the offending path. The parse_constant hook also makes NaN/Infinity/-Infinity a ValueError, so even syntactically valid JSON containing those constants is rejected.

Source

Thrown at scripts/evaluate-relevance.py:31

FIXTURE_DIR = RUNTIME_DIR / "tests/fixtures"
sys.path.insert(0, str(RUNTIME_DIR))
sys.path.insert(0, str(ROOT / "scripts"))

from core import (AVAILABLE_STACKS, CSV_CONFIG, DATA_DIR, STACK_CONFIG,
                  search, search_stack)  # noqa: E402
from design_system import DesignSystemGenerator, _palette_is_dark  # noqa: E402
from relevance_metrics import (REQUIRED_METRICS, check_thresholds, grades_for_results, ndcg_at_k,
                               precision_at_k, reciprocal_rank, validate_fixture,
                               validate_manifest)  # noqa: E402


def load_json(path):
    def reject_constant(value):
        raise ValueError(f"non-RFC JSON numeric constant: {value}")
    try:
        return json.loads(path.read_text(encoding="utf-8"), parse_constant=reject_constant)
    except (json.JSONDecodeError, OSError, ValueError) as error:
        raise SystemExit(f"Invalid JSON file {path}: {error}") from error


def runtime_fingerprint():
    paths = [
        RUNTIME_DIR / "core.py",
        RUNTIME_DIR / "design_system.py",
        RUNTIME_DIR / "reasoning_contract.py",
    ]
    paths += sorted(DATA_DIR.rglob("*.csv"))
    digest = hashlib.sha256()
    for path in paths:
        digest.update(path.relative_to(ROOT).as_posix().encode() + b"\0")
        digest.update(path.read_bytes() + b"\0")
    return digest.hexdigest()


def oracle_fingerprint(cases_path=None):
    """Bind approvals to the judgments and the code that grades them."""

View on GitHub (pinned to a38d04c3d5)

Solutions

1. Validate the file with a strict parser: `python3 -m json.tool <file>` shows the syntax error location.
2. Remove NaN/Infinity constants — use null or omit the key.
3. Check the path passed via --cases/--thresholds/--baseline exists and is readable from the CWD you run from.
4. Re-save without BOM (plain UTF-8) if the error points at character 0.

Example fix

# before
{"grades": [3, NaN]}
# after
{"grades": [3, null]}

import json
from pathlib import Path

def strict_load(path: Path):
    text = path.read_text(encoding='utf-8-sig')  # strips BOM if present
    def reject(c):
        raise ValueError(f'{c} is not allowed in fixtures')
    return json.loads(text, parse_constant=reject)

# fail before evaluation if any input file is bad
strict_load(Path('tests/fixtures/relevance-cases.json'))

When it happens

Trigger: Running scripts/evaluate-relevance.py with a --cases/--thresholds/--baseline file that has a trailing comma, unquoted keys, a BOM, or NaN/Infinity literals; pointing the flag at a file that doesn't exist or isn't readable; a fixture hand-edited and saved with smart quotes.

Common situations: Editing relevance-cases.json and leaving a trailing comma; Python json.dump emitting NaN when allow_nan isn't disabled; passing a relative path from the wrong CWD; BOM/CRLF artifacts from Windows editors.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Invalid relevance fixture:\n- {errors}
• Invalid threshold manifest:\n- {manifest_errors}
• Relevance gate failed:\n- {failures}
• duplicate decision-rule key: {}
• decision rules must be a JSON object

AI-assisted analysis of nextlevelbuilder/ui-ux-pro-max-skill@a38d04c3d5 (2026-08-14). Data as JSON: /api/errors/1c44c6ce28d62b30. Report an issue: GitHub.