Design a GitHub-like user community

## System design: GitHub-like user community Design the backend for a “developer community” product inspired by GitHub’s social layer. ### Core requirements - Users can **sign up/login** and manage a profile. - Users can **follow/unfollow** other users. - Users can create **posts** (text + optional links), and other users can **comment** and **like**. - Each user has a **home feed** showing recent posts from people they follow (reverse-chronological is fine). - Basic **notifications**: someone followed you / commented on your post. ### Non-functional requirements - High read volume (feed reads dominate). Assume a large-scale system; discuss how you would handle high TPS. - Low latency for feed reads (p95 target you choose). - Reasonable consistency (define what must be strongly consistent vs eventually consistent). - Prevent obvious abuse (rate limiting / spam), at least at a high level. ### What to deliver - APIs (high-level request/response shapes are enough). - Data model (tables/collections, key indexes). - Architecture (services, storage, cache, queues/streams). - Feed generation approach (fan-out on write vs fan-out on read), and trade-offs. - Scaling and reliability (sharding/partitioning, replication, backpressure, failure modes).