Harness Engineering: Leveraging Codex in an Agent-First World
A LinkedIn post by Dr. Martin Sailer.
AI coding is not the real story.
OpenAI’s Codex article points to the bigger shift: harness engineering.
The standout claim: an internal product built from an empty repo, with no manually written human code — roughly 1M lines, 1,500 PRs, and around 10x faster delivery.
The lesson is not “developers are obsolete.” It’s that the leverage moves from writing code to engineering the harness the agents run inside — the loop, the guardrails, the verification, the structure that makes agent output reliable.