Bun (acquired by Anthropic Dec 2025) announced Zig-to-Rust rewrite using ~50 Claude Code dynamic workflows over 11 days, peaking ~1,300 LOC/min, generating over a million lines of Rust. Pre-release Claude Fable 5 used. Bun v1.3.14 last Zig release; v1.4.0 first Rust. Claims improved memory safety tooling (borrow checker, Miri, fuzzing). Disclosure: team works at Anthropic.