Migrating the GitHub Copilot runtime to Rust, using Copilot

Migrating the GitHub Copilot runtime to Rust, using Copilot Stephen Toub · @stephentoub September 16, 2026 | Updated September 23, 2026 | 65 minutes Share: The GitHub Copilot CLI , GitHub Copilot app , and GitHub Copilot SDK are all backed by the Copilot agent runtime, an agentic harness that can be embedded into applications and services. It was originally written in TypeScript on Node.js and the V8 JavaScript engine for what is now the GitHub Copilot cloud agent (CCA), and the runtime stayed on that stack as the runtime and its capabilities grew rapidly.

This Funding is relevant to the technology intelligence record because it involves GitHub, Microsoft, Intel, GitHub Copilot. The source article should remain the factual reference for follow-up coverage.

• Stephen Toub · @stephentoub September 16, 2026 | Updated September 23, 2026 | 65 minutes Share: The GitHub Copilot CLI , GitHub Copilot app , and GitHub Copilot SDK are all backed by the Copilot agent runtime, an agentic harness that can be embedded into applications and services.
• It was originally written in TypeScript on Node.js and the V8 JavaScript engine for what is now the GitHub Copilot cloud agent (CCA), and the runtime stayed on that stack as the runtime and its capabilities grew rapidly.
• Using the GitHub Copilot app and the Copilot CLI, we completely rewrote the runtime into more than 800,000 lines of production Rust.
• AI agents wrote most of the code, spanning 128 pull requests that landed in main and shipped incrementally rather than waiting for a single cutover at the end.
• The few inevitable regressions were discovered and fixed quickly along the way, while the performance of the runtime improved by orders of magnitude.
• A project that would have taken a whole team of developers a year or two before agents was now completed primarily by a single developer, in only a few months, all while the rest of the team continued to greatly expand the runtime’s capabilities and reach.