"Just Ask Codex": Inside OpenAI's Own Working Culture | Romain Huet, OpenAI

What happens when the best engineers at OpenAI stop writing code by hand? How does a coding tool turn into a command center for agents that work for days without you in the loop? And why has Germany quietly become one of OpenAI's top five markets for Codex?

In this episode of AI to the DNA, the podcast for everyone who wants to really understand and apply AI, I sit down with Romain Huet, Head of Developer Experience at OpenAI and one of the key people behind Codex. We meet in Paris at OpenAI's local office, right after the team shipped GPT 5.5 and a wave of new Codex capabilities. Romain previously led product at Stripe and is now building the layer where developers, and increasingly everyone else, meet the models.

You can also watch this episode as a video podcast on my YouTube channel.

We talk about why Codex started as a coding tool, why it became something much bigger, and how OpenAI's own teams, from engineering to finance, now use it as their daily working surface. Romain explains why the jump from GPT 5.2 to 5.3 Codex was the real turning point, and what it means that even the best engineers no longer write code by hand.

From there we go deep into the architecture behind it: the open-source Codex harness, the layer that connects models, tools, files and your computer. We discuss what a harness actually is, why OpenAI made it public, and why prompt engineering as we knew it is essentially gone. We also dig into the harder questions, sandboxing, computer use, prompt injection, and how the new code review capabilities of GPT 5.5 are already preventing real production incidents at companies like Datadog.

Finally, Romain walks us through what excites him most right now: /goal, the command that lets Codex relentlessly pursue an ambitious goal across days of uninterrupted work. We close on a simple but uncomfortable insight: the models are so good now that the real bottleneck has become our own imagination.

I'm Christoph Magnussen and at AI to the DNA, I'm not just asking how to use AI. I’m asking why it works the way it does. This podcast is for everyone who wants to move beyond tool-tourism and master the real craft of AI: Learning to think, work, and build side by side with intelligent systems!