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

pattern action must name a pattern

Error message

pattern action must name a pattern

What it means

Actions with the pattern: prefix must carry a non-empty, non-whitespace-only value (checked via value.strip()). A bare "pattern:" or "pattern: " passes the ':' split and prefix check but names no layout pattern, so the rule could never resolve to a pattern at apply time — hence rejected up front.

Source

Thrown at src/ui-ux-pro-max/scripts/reasoning_contract.py:96

        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(
            pattern.search(normalized)
            for pattern in CONDITION_PATTERNS.get(condition, ()))
        if not active:
            continue
        result["activated"].append({"condition": condition, "actions": list(actions)})
        for action in actions:
            prefix, value = action.split(":", 1)

View on GitHub (pinned to a38d04c3d5)

Solutions

1. Fill in a concrete pattern name, e.g. "pattern:hero-split" or "pattern:card-grid".
2. If no pattern is intended, delete the whole pattern: action from the array (arrays just must stay non-empty overall).
3. Lint payloads with parse_decision_rules before committing so empty placeholders fail fast.

Example fix

// before
{"if_hero_needed": ["pattern:"]}

// after
{"if_hero_needed": ["pattern:hero-split"]}

for a in all_actions:
    prefix, _, value = a.partition(":")
    if prefix == "pattern" and not value.strip():
        raise ValueError(f"pattern action missing a name: {a!r}")

When it happens

Trigger: _validate_action("pattern:"), _validate_action("pattern: ") — i.e. a decision-rule JSON containing a pattern action whose value was never filled in or was lost in editing.

Common situations: Template rule blocks where the pattern name is a placeholder; truncation of a CSV cell mid-action; deleting the value but leaving the prefix while refactoring 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/20f61bbb3117cce0. Report an issue: GitHub.