Agent Harness Engineering
Engineers who want to understand and build agent systems, not just use them
Prerequisites: Module 19 or equivalent. Python. Claude API key.
Last verified 2026-06-11
Executive summary
You will learn how agents actually work under the hood: the model supplies intelligence, and everything else is a harness you can build. End state is a working minimal agent (loop plus tools plus permissions plus one hook) you wrote yourself, and a mental map of every mechanism in production tools like Claude Code. After this module you can build and reason about agent systems instead of just operating them, evaluate agent products by their harness design, and call yourself a harness engineer with a straight face.
Learning objectives
- Explain the core thesis: agency comes from the model, the product is model plus harness
- Build the minimal agent loop (messages, tool dispatch, stop reason) from scratch
- Add the key harness mechanisms one at a time: permissions, hooks, planning, subagents, skill loading, context compaction
- Understand long-running and multi-agent patterns: task systems, background work, scheduling, agent teams, worktree isolation
- Plug in external capability via MCP
Prefer the live room?
This module also runs inside our in-person bootcamps and workshops in Copenhagen.