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

decision rules must be a JSON object

Error message

decision rules must be a JSON object

What it means

After successful JSON parsing, parse_decision_rules requires the top-level value to be a dict. If the JSON is valid but is an array, string, number, or null, this ValueError fires. The grammar is condition-name -> action-array, so any other top-level shape is a contract violation.

Source

Thrown at src/ui-ux-pro-max/scripts/reasoning_contract.py:74

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)
    if prefix not in ACTION_PREFIXES:
        raise ValueError("unknown decision-rule action: {}".format(action))

View on GitHub (pinned to a38d04c3d5)

Solutions

1. Wrap the payload as an object keyed by condition: `{"must_have": [...]}` or `{"if_mobile": [...]}`.
2. Fix the producer to serialize the rules dict, not a list of actions.
3. Add an assertion/isinstance check at the call site before passing user-supplied JSON to parse_decision_rules.

Example fix

# before
rules = parse_decision_rules(json.dumps(["mode:dark"]))

# after
rules = parse_decision_rules(json.dumps({"must_have": ["mode:dark"]}))

import json
parsed = json.loads(raw)
if not isinstance(parsed, dict):
    raise ValueError(f"decision rules must be an object, got {type(parsed).__name__}")

def is_rules_object(parsed) -> bool:
    return isinstance(parsed, dict) and all(isinstance(v, list) and v for v in parsed.values())

try:
    rules = rc.parse_decision_rules(raw)
except ValueError as exc:
    if 'must be a JSON object' in str(exc):
        parsed = json.loads(raw)
        raw = json.dumps({"must_have": parsed if isinstance(parsed, list) else [parsed]})
        rules = rc.parse_decision_rules(raw)  # only if this reshape matches your intent

When it happens

Trigger: parse_decision_rules('["mode:dark"]') — a bare action array instead of an object; parse_decision_rules('"if_mobile"'); parse_decision_rules('null') (note: raw=None is coerced to '{}', but the literal string 'null' parses to None and fails this check).

Common situations: A caller stores only the actions list and forgets the condition wrapper; downstream code JSON-encodes a list variable that was supposed to be a rules dict.

Related errors

• duplicate decision-rule key: {}
• {} must map to a non-empty action array
• {} contains duplicate actions
• Invalid JSON file {path}: {error}
• invalid decision-rule JSON: {}

AI-assisted analysis of nextlevelbuilder/ui-ux-pro-max-skill@a38d04c3d5 (2026-08-14). Data as JSON: /api/errors/70e840b40bccbf2f. Report an issue: GitHub.