Opus refactors an ML repo, then ships a subtle bug that still lets training run
alex_peys · x · 2026-08-04
Opus rewrote the code — and introduced a subtle bug
The author says they gave Opus an ML repo, and it complained that version 5.6’s code was “inelegant.” It then rewrote the code, but introduced a very subtle bug: the training runs still complete, yet the system no longer works correctly.
It’s a small but very relatable example of why model-generated refactors can look impressive while hiding correctness issues.
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