Harness Engineering in Practice — The Environment You Build Around Your Coding Agent
· 12 min read
In the post about prompt, context and harness engineering I split the three layers apart and talked about the harness from the point of view of someone building an agent: idempotency, circuit breakers, approval gates, audit trails.
But most of us aren't building agents. We're using one: Claude Code, OpenCode, Cursor, Codex. Which raises the obvious question: if the tool already ships with a harness, what's left for me to do?
A lot. And it's exactly the part that changes results the most day to day.