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

action must use a known prefix: {}

Error message

action must use a known prefix: {}

What it means

First check in _validate_action: every action must be a string containing a ':' separator, because actions are parsed as prefix:value (prefix in {constraint, style, pattern, mode}). Non-strings, strings without a colon, or empty values like "mode:" pattern-split failures all raise here with the offending action echoed.

Source

Thrown at src/ui-ux-pro-max/scripts/reasoning_contract.py:89

    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))
    if prefix in TOKEN_ACTION_PREFIXES and not TOKEN_RE.fullmatch(value):
        raise ValueError("invalid {} action value: {}".format(prefix, value))
    if prefix == "pattern" and not value.strip():
        raise ValueError("pattern action must name a pattern")
    if prefix == "mode" and value not in {"dark", "light"}:
        raise ValueError("mode action must be dark or light")


def apply_decision_rules(rules, query):
    """Return deterministic mutations and an audit trail; never execute data."""
    normalized = str(query or "").casefold()
    result = {"activated": [], "style_ids": [], "constraints": [],
              "pattern": None, "mode": None}
    for condition, actions in rules.items():
        active = condition == "must_have" or any(

View on GitHub (pinned to a38d04c3d5)

Solutions

1. Write every action as prefix:value, e.g. "mode:dark", "style:minimal", "pattern:hero-split", "constraint:no-large-images".
2. Quote all actions in the JSON payload so they stay strings.
3. Replace separators: 'mode dark' -> 'mode:dark'.

Example fix

// before
{"must_have": ["dark", 42]}

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

from src.ui_ux_pro_max.scripts.reasoning_contract import ACTION_PREFIXES
import json
for cond, actions in json.loads(raw).items():
    for a in actions:
        if not isinstance(a, str) or ':' not in a or a.split(':', 1)[0] not in ACTION_PREFIXES:
            raise ValueError(f"{cond}: malformed action {a!r}; use prefix:value with prefix in {sorted(ACTION_PREFIXES)}")

def is_wellformed_action(a) -> bool:
    return isinstance(a, str) and ":" in a and a.split(":", 1)[0] in {"constraint", "style", "pattern", "mode"}

When it happens

Trigger: _validate_action receives 42 (int), None, "mode dark" (space instead of colon), "dark" (missing prefix), or "" — reached via parse_decision_rules validating every element of each condition's action array.

Common situations: Mixing action dialects (some systems use space-separated tokens); YAML/JSON autotyping turning a quoted action into a number; forgetting the prefix when authoring rules.

Related errors

• duplicate decision-rule key: {}
• decision rules must be a JSON object
• unknown decision-rule condition: {}
• {} must map to a non-empty action array
• {} contains duplicate actions

AI-assisted analysis of nextlevelbuilder/ui-ux-pro-max-skill@a38d04c3d5 (2026-08-14). Data as JSON: /api/errors/a0a55de63320e217. Report an issue: GitHub.