Incorrect (logic duplicated in components):

// app/components/user-card.js
class UserCard extends Component {
  get formattedDate() {
    const date = new Date(this.args.user.createdAt);
    const now = new Date();
    const diffMs = now - date;
    const diffDays = Math.floor(diffMs / (1000 * 60 * 60 * 24));

    if (diffDays === 0) return 'Today';
    if (diffDays === 1) return 'Yesterday';
    if (diffDays < 7) return `${diffDays} days ago`;
    return date.toLocaleDateString();
  }
}

// app/components/post-card.js - same logic duplicated!
class PostCard extends Component {
  get formattedDate() {
    // Same implementation...
  }
}