What's the largest software project AI can complete on its own?

MirrorCode benchmark tests AI models on large-scale software projects by requiring them to reimplement entire programs without original source code access. Claude Opus 4.7 successfully reimplemented a complex bioinformatics toolkit in 14 hours, a task estimated to take humans weeks. The benchmark ensures fairness by sandboxing models and using unseen end-to-end tests to prevent cheating.