Building Better Coding Agents: A Hands-On Workshop in Harness Engineering

You can start a simple agent with a model and a prompt. But you soon realize that improving it requires adjusting what the model can see, what it can do, how it remembers progress, which model handles each step, and what evidence allows the work to stop. Harness engineering is how those pieces become one working system.

This workshop uses coding agents to make that system concrete. Participants will work through six decisions: choosing a harness, designing tools and retrieval, placing context and memory, routing models and reasoning, controlling goals and validation, and deciding when a task benefits from multiple agents. Through hands-on experiments, we will change these settings and inspect what happens in the trace and final result.

Each exercise is paired with an overview of current research on agent harnesses. Together, the research and experiments show how the major components interact and where each approach reaches its limits. Participants will leave with a practical way to reason about the whole agent, not just its model.