"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!


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(00:00) - Intro

(01:34) - Welcome to Paris: Tool Tourists vs. Champions
League

(02:35) - The Codex Turning Point: From 5.2 to Days of
Uninterrupted Work

(05:53) - Codex Without the Word "Code": Explaining It to
Mittelstand

(08:12) - Inside OpenAI: From Model Speed to "Just Ask Codex"

(12:50) - From Chatbot to Harness: What Has Actually Changed

(16:57) - Why OpenAI Open-Sourced the Codex Harness

(18:36) - The End of Prompt Engineering: Just Talk to Codex

(22:39) - Monorepos: How Google, OpenAI and Blackboat
Organize Code

(25:23) - Slack, Agent Signatures and the FTE Question

(28:16) - Trust and Sandboxing: How Codex Asks for Permission

(32:22) - Computer Use: When the Agent Takes Over Your Mac

(34:27) - The Numbers: 8x Codex Growth, Germany at 10x

(36:48) - Beyond Code: Onboarding Codex for Non-Developers

(38:36) - ChatGPT vs. Codex: One Model, One Harness, Two
Audiences

(43:05) - Security: From Prompt Injection to Daybreak

(49:22) - Sparkle of AGI: /goal – Codex's Most Ambitious Mode

(54:11) - Still Too Shy: The Final Take and Goodbye