The harness is the product
Not a slogan. A 3×3 factorial puts a number on it, and the number is larger than most people expect.
A model has no memory, no filesystem, no clock, and no ability to act. Everything that makes it useful — that it can read your repo, that it stops when it is done, that it cannot delete your home directory, that it remembers yesterday — is code someone else wrote.
The strong form of the claim is that the harness is the product and the model is a component of it. That sounds like positioning. It is measurable.
A study ran three near-tied frontier models across three harnesses of increasing sophistication on the same benchmark subset. Comparing harness-induced variance to model-induced variance, what ratio did they find?
The rest of this lesson unlocks when you commit above.