Harness engineering: leveraging Codex in an agent-first world

February 11, 2026EngineeringHarness engineering: leveraging Codex in an agent-first worldBy Ryan Lopopolo, Member of the Technical StaffLoading…ShareOver the past five months, our team has been running an experiment: building and shipping an internal beta of a software product with 0 lines of manually-written code.The product has internal daily users and external alpha testers. It ships, deploys, breaks, and gets fixed. What’s different is that every line of code—application logic, tests, CI configuration, documentation, observability, and internal tooling—has been written by Codex. We estimate that we built this in about 1/10th the time it would have taken to write the code by hand.Humans steer.

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