
Agent Harnesses — The Model Was Never the Bottleneck
Tejas Kumar took one of the worst models you can still rent — gpt-3.5-turbo — gave it one fixed prompt and one task (upvote a story on Hacker News), and made it reliable without ever touching the prompt or swapping the model. He did it across five git branches by engineering everything around the model: tools, context, guardrails, a verify step, a login handler. This is a hands-on, build-it-with-me walk through that repo and the idea underneath it — an AI harness is everything except the model weights.








