Rust is seemingly the language of the moment, with open-source projects and companies forming an orderly queue to move core software over to the general-purpose programming lingo. The draw? A pursuit of better memory safety and performance.

Now, GitHub has joined the throng. On Wednesday, the company revealed that it has completely rewritten the GitHub Copilot agent runtime — previously built in TypeScript on Node.js and V8 — into more than 800,000 lines of production Rust.

Most notably, however, the Microsoft subsidiary says it used its own Copilot coding agents to carry out the switch. In a blog post marking the migration, Microsoft engineer Stephen Toub says the company used the GitHub Copilot app and the Copilot CLI for the rewrite. The work was spread across 128 pull requests that were merged and shipped incrementally, an approach Toub notes allowed the team to catch and fix regressions along the way.

“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.”

While a major Rust migration is a big deal in its own right, the bigger story here is the leading role that AI played.

“AI agents wrote most of the code,” Toub writes, adding that the alternative would have been a much bigger undertaking.

“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,” he continues.

Source link