{"version":1,"type":"story","url":"https://digestai.news/story/microsoft-ports-copilot-runtime-to-rust-using-ai-agents-at-120k-cost","json":"https://digestai.news/story/microsoft-ports-copilot-runtime-to-rust-using-ai-agents-at-120k-cost.json","markdown":"https://digestai.news/story/microsoft-ports-copilot-runtime-to-rust-using-ai-agents-at-120k-cost.md","slug":"microsoft-ports-copilot-runtime-to-rust-using-ai-agents-at-120k-cost","headline":"Microsoft ports Copilot runtime to Rust using AI agents at $120K cost","summary":"Microsoft rewrote the Copilot runtime, which powers GitHub Copilot across VS Code, Office apps and other services, from TypeScript to Rust using AI agents. The migration consumed about $120,000 in AI token usage and roughly three weeks of a developer’s time, spanning 135 releases over a 14.5‑week period with an average of 1.3 port pull requests per day. Agents transformed 430,000 lines of TypeScript into 800,000 lines of production Rust.\n\nA benchmark of 1,000 one‑turn session lifecycles showed the Rust version completing 120 lifecycles per second versus 7.55 for the original TypeScript implementation, a 15.9x speedup, while memory usage fell from 1,383 MB to 126 MB. Stephen Toub, a Microsoft Distinguished Engineer, noted that the agents spent much of the effort gathering information and coordinating across sessions, and highlighted regressions that required human oversight despite successful compilation.","keyPoints":["Port cost $120,000 in AI token usage plus about three weeks of developer time.","Agents rewrote 430,000 TypeScript lines into 800,000 Rust lines across 135 releases in 14.5 weeks.","Benchmark showed Rust runtime handling 120 lifecycles per second versus 7.55 for TypeScript, a 15.9x speedup."],"whyItMatters":"The rewrite demonstrates that AI agents can automate large‑scale code migrations, delivering major performance and memory gains while costing a fraction of manual effort, signaling a new efficiency path for enterprise software development.","category":{"slug":"agents","name":"Agents & Tools","url":"https://digestai.news/category/agents"},"entities":{"companies":["Microsoft","GitHub","Bun","Anthropic"],"models":["GPT-5.6 Sol","Claude Opus 4.8"],"people":["Stephen Toub","Lisa Crossman","Jarred Sumner","Andrew Kelley"]},"firstPublishedAt":"2026-09-20T09:08:52Z","updatedAt":"2026-09-20T09:08:52Z","sourceCount":1,"hasPrimarySource":false,"sources":[{"outlet":"theregister.com","title":"Microsoft agentically ports Copilot runtime to Rust for $120K","url":"https://theregister.com/devops/2026/09/18/microsoft-agentically-ports-copilot-runtime-to-rust-for-120k/5297549","publishedAt":"2026-09-20T09:08:52Z","type":"press","primary":false,"lead":true}],"sourceNotes":null,"discussions":[{"site":"Hacker News","url":"https://news.ycombinator.com/item?id=49773998","points":41}],"thread":null,"cite":{"text":"Digest AI, \"Microsoft ports Copilot runtime to Rust using AI agents at $120K cost\", 20 September 2026, https://digestai.news/story/microsoft-ports-copilot-runtime-to-rust-using-ai-agents-at-120k-cost","publisher":"Digest AI","title":"Microsoft ports Copilot runtime to Rust using AI agents at $120K cost","datePublished":"2026-09-20T09:08:52Z","url":"https://digestai.news/story/microsoft-ports-copilot-runtime-to-rust-using-ai-agents-at-120k-cost"},"generatedBy":"Written by Digest AI's editorial model from the linked sources; the sources are the record.","license":"Headlines, digests and key points are written by Digest AI and may be quoted with a link to the story page. Linked articles belong to their publishers. Terms: https://digestai.news/terms#reuse"}