Migrating the GitHub Copilot runtime to Rust, using Copilot
GitHub author Stephen Toub describes how the team, using the GitHub Copilot app and CLI, fully rewrote the Copilot agent runtime from TypeScript/Node.js into 832,378 lines of production Rust, with AI agents writing most of the code across 128 pull requests — a project that would normally take one or two person-years was completed by a single developer in a few months.
Why it matters: The author lived through the entire migration and shares first-hand data on code volume, release cadence, and cache hit rates, offering a viable path for agent-driven large-scale rewrites.