Microsoft spent $120,000 to have AI rewrite the Copilot runtime: 430,000 lines of TS turned into 800,000 lines of Rust, 15.9 times faster
Microsoft used AI agents to fully port GitHub Copilot runtime from TypeScript to Rust, costing about $120K tokens and one engineer three weeks. It powers Copilot CLI, App, SDK, and cloud Agent across VS Code, Visual Studio, Excel, Outlook, PowerPoint. TypeScript/Node.js enabled fast development but limited startup and service performance at scale.....