ALLOWED_STATUSES = {"not-started", "in-progress", "done"}

def normalize_status(status: str) -> str:
    """
    Säkerställ att status alltid blir en av de tillåtna.
    Om okänd -> default "not-started".
    """
    status = (status or "").strip()
    return status if status in ALLOWED_STATUSES else "not-started"

def validate_todo_fields(title: str, description: str) -> tuple[bool, list[str]]:
    """
    Returnerar (ok, errors).
    """
    errors = []
    if not (title or "").strip():
        errors.append("title_required")
    if not (description or "").strip():
        errors.append("description_required")
    return (len(errors) == 0, errors)