Harness engineering: leveraging Codex in an agent-first world

The post that coined "harness engineering". A team built an internal product over five months with, by its own account, zero manually written lines: on the order of a million lines across application, infrastructure and tooling, roughly 1,500 pull requests from a team that grew from three engineers to seven, averaging 3.5 PRs per engineer per day. The engineers' job became designing the environment — repository knowledge as the system of record, mechanically enforced architecture and taste, plans as versioned artifacts, and a recurring agent-driven cleanup the post calls garbage collection.