At a moment when nobody yet knows how to review that much AI-generated code, Bun's answer — automate the review too — collides head-on with Zig's, which had banned exactly that kind of contribution months earlier as "invariably garbage."

In six months, "harness" has gone from internal jargon to the word that organises the whole sector. Behind the rebrand sits a number that is hard to ignore: the environment around the model explains more variance in the outcome than the model itself.