Codex wrote 1.3 million lines and still couldn't get it done; Claude ported the TypeScript compiler in two weeks.

Beating AI News Flash: Renowned developer Theo has open-sourced tsc-rs. He had AI port Microsoft's TypeScript 7 compiler, written in Go, to Rust, covering the compiler, type checker, and language server, with the goal of directly replacing the official tsc. Theo said he did not read a single line of the generated code from start to finish.

The project lasted about five months. Theo initially used tools such as Codex, calling multiple OpenAI models, and generated over 1.3 million lines of Rust code, but compatibility never broke through about 84%. Calculated at API list prices, the tokens consumed were worth more than $400,000.

Later, he switched to Claude Opus 5.5. The model directly abandoned the previous code and re-ported from scratch. It produced a runnable initial version in 10 hours and completed the main work within two weeks, with token consumption calculated at API prices of about $24,000.

Tests show that tsc-rs has passed 181,711 tests ported from Go. Across 120 open-source projects, the check results are basically consistent with Microsoft's Go version, with only a small number of known behavioral differences. According to performance tests on another 60 open-source projects, the Rust version's average type-checking time is about half that of the Go version.