The author of Bun, a JavaScript and TypeScript transpiler, bundler, and package manager, has rewritten the project in Rust using Anthropic's Claude Fable model. The rewrite aimed to improve stability and prevent memory leaks, which were issues in the original Zig implementation. The author used a combination of mechanical porting, adversarial review, and testing to ensure the new Rust codebase was correct and maintainable. The rewrite took 11 days and resulted in a 20% reduction in binary size and a 5% improvement in performance.