A field guide to OpenAI Codex best practices for 2026, covering AGENTS.md, planning workflows, test-first verification, and platform-level governance. In 2026, OpenAI Codex has crossed the line from interesting experiment to production tooling that engineering organizations actually depend on. Weekly active developers now exceed 4 million, and rollouts inside Cisco, Nvidia, and Ramp have made Codex a fixture of how code gets written. The interesting question is no longer adoption, it is execution. Which OpenAI Codex best practices actually compound, and which fall apart at team scale? This guide walks through the prompting habits, repo-level configuration, and infrastructure patterns that separate teams that get steady gains from teams that plateau. For platform engineers, the infrastructure layer matters as much as the prompting layer, and that is where Bifrost, the open-source AI gateway from Maxim AI, comes into play.…