The harness, not the model: how to make a weak or local model reliable enough to ship

If you've tried to point a local model — Qwen, a quantized Llama, whatever fits on your GPU — at a real task in a real repo, you already know the feeling. It starts confidently. It edits three files. It announces it's done. And then you run the tests and half of them are red, one of the files it "edited" is byte-for-byte unchanged, and the...