Bun 1.4: The Controversial AI-Driven Rewrite from Zig to Rust (opens in new tab)

In May 2026, the Bun team did something the software industry has been whispering about for years: they rewrote their entire runtime from Zig to Rust. Not over the course of a year with a dedicated team. In six days. Using AI agents. At nearly a million lines of code,