How Building Software Is Changing at Anthropic: Inside the Claude Managed Agents Project and the Bun Rewrite
Summary
Gergely's on-site deep dive inside Anthropic: the 6-month Claude Managed Agents project (still needed full PRDs and cross-team planning despite AI), Jarred Sumner's 11-day/$165K Bun Zig-to-Rust rewrite, and what's changed vs. unchanged in engineering practice — teams stay 6-8 people, but now run 3-8 parallel projects with a 2-engineer cap per individual project.
Why this signal
The most comprehensive, concrete look this cycle at how a real AI-native org runs end-to-end development at scale — directly comparable to Thomas Engineering's situation and full of specific, adoptable details (PRDs still matter for complex coordination; verification takes longer than implementation now).
Original email
The Pragmatic Engineer · 7/28/2026
How building software is changing at Anthropic