DEV Community

Cover image for What Is Harness Engineering? OpenAI’s Agent-First Codex Playbook (2026)
Rohit Raj
Rohit Raj

Posted on • Originally published at rohitraj.tech

What Is Harness Engineering? OpenAI’s Agent-First Codex Playbook (2026)

Originally published on rohitraj.tech

Harness engineering is the discipline of building the scaffolding — docs, golden rules, custom linters, and agent-to-agent review loops — that lets AI coding agents ship reliable software at scale. OpenAI coined the term after building a ~1M-line beta product in 5 months with zero hand-written code using Codex. Here is what a harness actually contains, the architecture that makes it work, when it pays off, when to skip it, and how I run a smaller version of it today.


Read the full version with code samples, diagrams, and architecture details: What Is Harness Engineering? OpenAI’s Agent-First Codex Playbook (2026)

More engineering notes: rohitraj.tech/en/notes

Top comments (0)