Microsoft used AI agents to port Copilot runtime from C# to Rust for $120K

Microsoft agentically ports Copilot runtime to Rust for $120K

A Microsoft team used an in-house AI agent system called Nachete to rewrite the Copilot runtime from C# to Rust, at a total cost of about $120K. The agents ran 7 iterations—writing code, compiling, and fixing errors—producing 125K lines of Rust that compiled on the first try. Humans only did code review and security audit. The team estimates a manual rewrite would have cost $1.1M and taken 9 months, though the post doesn't detail how that baseline was calculated.

Why it matters: Microsoft used an internal agent to port the Copilot runtime from C# to Rust: 7 iterations, 125K lines, first-try compilation, $120K cost. The human baseline of $1.1M/9 months isn't explained, so I'm discounting that claim. Hits all three HKR axes but it's a single engineering...