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

invalid decision-rule JSON: {}

Error message

invalid decision-rule JSON: {}

What it means

parse_decision_rules wraps json.loads and converts any json.JSONDecodeError into this ValueError with the underlying parse error appended. The decision-rule grammar only accepts well-formed JSON objects, so trailing commas, single quotes, comments, or truncation fail here before semantic validation begins.

Source

Thrown at src/ui-ux-pro-max/scripts/reasoning_contract.py:72

    for condition, signals in CONDITION_SIGNALS.items()
}


def _object_without_duplicates(pairs):
    result = {}
    for key, value in pairs:
        if key in result:
            raise ValueError("duplicate decision-rule key: {}".format(key))
        result[key] = value
    return result


def parse_decision_rules(raw):
    """Parse the canonical condition -> action-array representation."""
    try:
        rules = json.loads(raw or "{}", object_pairs_hook=_object_without_duplicates)
    except json.JSONDecodeError as error:
        raise ValueError("invalid decision-rule JSON: {}".format(error)) from error
    if not isinstance(rules, dict):
        raise ValueError("decision rules must be a JSON object")
    for condition, actions in rules.items():
        if condition not in ALLOWED_CONDITIONS:
            raise ValueError("unknown decision-rule condition: {}".format(condition))
        if not isinstance(actions, list) or not actions:
            raise ValueError("{} must map to a non-empty action array".format(condition))
        for action in actions:
            _validate_action(action)
        if len(actions) != len(set(actions)):
            raise ValueError("{} contains duplicate actions".format(condition))
    return rules


def _validate_action(action):
    if not isinstance(action, str) or ":" not in action:
        raise ValueError("action must use a known prefix: {}".format(action))
    prefix, value = action.split(":", 1)

View on GitHub (pinned to a38d04c3d5)

Solutions

1. Copy the JSON string into a linter or `python3 -m json.tool` to find the exact syntax offset reported in the message.
2. Quote all keys and string values with double quotes; remove trailing commas and comments.
3. If the payload comes from a CSV column, check the cell was not truncated or line-wrapped on import.

Example fix

// before
{'if_mobile': ['mode:dark'],}  // single quotes + trailing comma

// after
{"if_mobile": ["mode:dark"]}

import json
try:
    candidate = json.loads(raw)
except json.JSONDecodeError as exc:
    raise ValueError(f"payload is not valid JSON at line {exc.lineno} col {exc.colno}: {exc.msg}") from exc
# only then hand to parse_decision_rules for contract checks

try:
    rules = rc.parse_decision_rules(raw)
except ValueError as exc:
    if 'invalid decision-rule JSON' in str(exc):
        show_json_syntax_error(raw, str(exc))  # message embeds json's own position info
    raise

When it happens

Trigger: parse_decision_rules(raw) with raw like `{if_mobile: [...]}` (unquoted key), `{"a": [1,],}` (trailing comma), a string truncated by a CSV field limit, or None passed through as '{}' only when raw is falsy — a non-empty malformed string still hits json.loads.

Common situations: Writing rule JSON inline in a CSV cell and forgetting quotes around condition keys; shell heredocs mangling quotes; spreadsheet export truncating long cells.

Related errors

• duplicate decision-rule key: {}
• decision rules must be a JSON object
• {} must map to a non-empty action array
• {} contains duplicate actions
• Unterminated quoted CSV field

AI-assisted analysis of nextlevelbuilder/ui-ux-pro-max-skill@a38d04c3d5 (2026-08-14). Data as JSON: /api/errors/bfd599964ce693c9. Report an issue: GitHub.