Production Realities: Economics, Security, and Governance

You can build a working agent. Running it across thousands of repositories and hundreds of engineers is a different problem, and it is mostly not a capability problem. As the "Everything About Codex" guide puts it, at scale "the question is never can the agent write the code. It is can you prove what every agent touched, constrain what it can reach, and review what it ships." This chapter is about those questions: the economics that surprise teams, the security incidents that made 2026 a wake-up call, and the governance that turns a capable agent into a deployable one. It is lighter on code because the lessons are mostly judgment, but it ends with a small cost model because cost is the lesson teams underestimate most.