A developer used AI coding agents to write over 130,000 lines of Rust in a few weeks, building a modern, high-performance multi-Paxos consensus engine to upgrade Azure's Replicated State Library. By leveraging AI-driven code contracts, lightweight spec-driven development, and automated performance tuning, the developer boosted system throughput from 23,000 to 300,000 operations per second. This project highlights the massive productivity gains and practical techniques available when using AI to architect and optimize complex, production-grade distributed systems.