You now know how to design a news feed.
Architecture: FeedPage → FeedList → FeedItem with clear boundaries.
State: Normalized posts and users. Separate feed ordering.
Performance: Virtualization for long lists. Lazy load images.
Interactions: Optimistic updates for likes. Cursor pagination.
Real-time: WebSocket or SSE. Buffer new posts, don't auto-insert.
Accessibility: Focus management, keyboard navigation, screen reader support.
Interview tip: Walk through RADIO framework. Spend time on virtualization and optimistic updates.