Harness Engineering Explained in 16 Minutes

Harness engineering has three levels, and most people building with AI never get past the first. 🎁 Build your own coding harness with my free course in the community: https://skool.com/leonvanzyl 🚀 Agentic Labs — exclusive AI coding courses, live Q&As, workshops & deep dives: https://skool.com/agentic-labs Most people install Claude Code, Codex or OpenCode, add a few rules, and think that's the whole job. That's only level one of harness engineering. The real gains come when you build your own harness, or one that runs a team of agents for you. Do that and you can make small local models punch above their weight, give a whole team one consistent setup, and leave agents working for days without babysitting them. I walk through all three levels with real examples, ending with a swarm of coding agents working in a 3D office. You'll also see how changing only the harness took one model from 6.7% to almost 70%. Resources Mentioned 🧩 Smol Coder, my coding harness for local models: https://github.com/leonvanzyl/smolcoder 🔁 AutoForge, my harness for long-running coding tasks: https://github.com/AutoForgeAI/autoforge 🧊 cubefarm, my agent swarm in 3D: https://github.com/leonvanzyl/cubefarm 🎥 My Smol Coder video: https://youtu.be/u2vaM7ppzuE ▶️ Watch next: I Built the Simplest Software Factory (You Can Copy It): https://youtu.be/AsvzMlLyQ38 ⏱️ Chapters 0:00 Harness Engineering Explained 1:23 What Is an Agent Harness 3:57 Level 1 Harness Configuration 6:33 Claude Code Hooks 7:54 Level 2 Custom Coding Harness 9:43 Coding Harness for Local LLMs 13:00 Level 3 Orchestration Harness 13:52 AI Software Factory Connect X: https://x.com/leonvz TikTok: https://www.tiktok.com/@leonvanzylofficial Business & sponsorships: leon@cognaitiv.ai