The Agentic Engineer
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Issue #31 | September 23, 2026
TL;DR
- 800,000 LINES OF PRODUCTION RUST. One developer led the project. AI agents authored most of 128 PRs over 14.5 weeks. GitHub Copilot's runtime now backs VS Code, Visual Studio, Excel, Outlook, Copilot CLI, and every cloud agent session. Cold-start performance improved dramatically. GA as of Sep 14.
- THE SEPTEMBER COORDINATOR WAVE. Three companies shipped the same coordinator primitive in 7 days: Cursor (Sep 10), OpenAI (Sep 10), and Anthropic's Claude Code (Sep 17). Each breaks a goal into parallel cloud threads with shared memory, one branch per thread. Five independent builders also converged this week on Jev's bounded judgment layer as the right decision architecture for high-volume state machines.
- Tool of the Week: Amazon Bedrock AgentCore Runtime (V2). V1: 5.4 seconds for a 200 MB image, up to 30 seconds at 2 GB. V2: approximately 2 seconds at P75 regardless of image size. Memory billing now tracks actual usage as it changes through the session. Set platformVersion=V2 to activate.
The Big One
800,000 Lines: GitHub Rewrites the Copilot Runtime With AI Agents
~430,000 lines of TypeScript, converted into 800,000+ lines of Rust in 14.5 weeks. One developer led the project while the rest of the Copilot team kept shipping new features throughout. That runtime now backs VS Code, Visual Studio, Word, Excel, PowerPoint, Outlook, Copilot CLI, and every cloud agent session at GitHub.
AI agents wrote most of the Rust across 128 PRs. Averaging ~6,500 lines per PR, these were bulk translation batches — which is precisely why 135 incremental releases, not PR review, was the real verification mechanism. The project ran through those releases pre-release channel first, so regressions got caught before they hit the main channel.
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