import numpy as np
import pandas as pd


def build_node_features(df: pd.DataFrame, users: pd.DataFrame):
    """
    Returns zero node features.

    This is intentional: the benchmark is designed so that static structural
    features carry NO signal. Only temporal memory (TGN) can solve the task.
    XGBoost / GNN with static features must fail — proving temporal necessity.
    """
    user_ids = users["user_id"].values
    return np.zeros((len(user_ids), 2), dtype=np.float32)