Designing a System End to End
The capstone — one problem, a home-timeline feed, designed the whole way through with the method from post one: clarify, estimate, contract, then high-level to deep-dive to bottleneck, naming the trade-off at every step and drawing on all seven earlier posts.
The capstone: one worked design end to end — requirements, estimation, API and data model, high-level architecture, and deep dives applying the whole series (scaling, caching, sharding, consistency, async, reliability) with explicit trade-offs.