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SeedsJun 2026

Building an agent harness from scratch. Build log #1

What a harness actually is, why it matters more than the model, and the smallest loop that keeps a long-running agent honest.

18:05

Build log

First build log: what a harness actually is, why it matters more than the model, and the smallest loop that keeps a long-running agent honest.

  • The harness is the product; the model is a component.
  • Verification loops are the difference between a demo and a system.
  • Start with the smallest loop that can catch its own mistakes.