const getSourceWeight = (dataAge, sourceType) => {
  const baseWeights = { news: 0.8, social: 0.6, official: 1.0 };
  const timeDecay = Math.exp(-dataAge / (2 * 60 * 60 * 1000)); // 2-hour half-life
  return baseWeights[sourceType] * timeDecay;
};