Your Agent Harness Will Break

Your agent harness will break. Thanks Steve Yegge!

Steve Yegge spent a lot of time building Gas Town, his agent harness. It worked brilliantly with Opus up to version 4.6. Then Opus 4.7 arrived with a new behavioral tic and Gas Town basically burned down. Not because the code suddenly stopped working. The model changed and invalidated assumptions the harness was built on.

This is exactly the kind of lock-in most people don’t even see. You don’t only lock yourself to an API or some vendor-specific tool call. You lock yourself to how the current model interprets your prompts, follows your workflows and behaves inside your harness. None of that is a stable interface. There is no versioning for it. There is no migration guide. The next model comes out, everybody switches immediately because the benchmark numbers are better and three weeks later you notice that your carefully “optimized” setup has become worse.

Yegge has now given up on reusable harnesses and says they need to be “chemically bonded” to the application. He built another one for his game because of course he did. But this time it belongs to the actual project and grew out of the actual work. Not a generic harness package designed by somebody who doesn’t know the application, the team or what the agents are supposed to achieve.

He also makes a good point about skills. Public skills expire or become irrelevant when the models change. Private skills are different because they contain knowledge about your project and how you work. The model cannot magically know that. That’s the stuff worth keeping. Not 500 lines of tricks for making the current Claude version behave.

So yes, look at Gas Town, Wheelhouse and all the other agent setups people publish. There are good ideas in them. Steal those ideas. But don’t adopt the whole thing and pretend you now own an “AI operating system.” You installed somebody else’s assumptions about a model that will probably behave differently next month.

Read Steve Yegge’s The Shape of Things to Come, Part 1: The Continuous Thunderdome.

Originally posted on LinkedIn.