def should_continue(history: list, current: _ResultProto,
                    confidence_drop_threshold: float = 0.1) -> bool:
    """Decide whether the iteration loop should run another pass.

    Three reasons to stop, in order of priority:
      1. Candidates are stable (same set as last pass): nothing new will be found.
      2. Suggested keywords are stable: the LLM is repeating itself.
      3. Confidence is decreasing past the threshold: the loop is making things worse.
    """
    if history:
        prev = history[-1]
        if getattr(prev, "candidates", None) == current.candidates:
            return False
        if getattr(prev, "suggested_keywords", None) == current.suggested_keywords:
            return False
        prev_conf = getattr(prev, "confidence", None)
        if prev_conf is not None and current.confidence < prev_conf - confidence_drop_threshold:
            return False
    return current.needs_iteration()