Rewriting Bun in Rust

Jarred Sumner, creator of Bun, detailed the decision to rewrite the JavaScript runtime from Zig to Rust, citing memory management challenges. The rewrite was largely automated using AI coding agents, leveraging Bun's TypeScript test suite as a conformance suite. This marks a significant shift in software engineering practices, where AI agents enable large-scale rewrites that were previously considered inadvisable.