2026 · Field notes

The harness is the product

The model is a commodity. It changes every few months, and when it does, you want to swap it in an afternoon, not rebuild your company around it.

What does not change is the harness: your data, your workflows, your evaluations, and your business rules. That is the part that is genuinely yours, and it is the part that decides whether an agent survives contact with your business.

What lives in a harness

• The data foundation and identity spine the agent reads from.
• The tools and permissions it is allowed to use.
• The evaluations that measure every change before it ships.
• The business rules and governance that make the output defensible.

Why it matters

Build the harness well and the model becomes a swappable part. Switching costs collapse, the difference between off-the-shelf and custom melts away, and you own the thing that makes you different.

That is the part we build.