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Why humans are AI’s biggest bottleneck (and what’s coming in 2026) | Alexander Embiricos (OpenAI Codex Product Lead)

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Dec 14, 2025

Guest

Alexander Embiricos

Alexander Embiricos, the Product Lead for OpenAI Codex, shares insights from his journey in AI-driven software development. He discusses the explosive growth of Codex, revealing how human typing speed is the true bottleneck to productivity. Alexander highlights the shift from building software to reviewing AI-generated code and envisions AI as a proactive teammate rather than just a tool. He also emphasizes the importance of coding as a core competence for AI agents and the benefits this technology brings to non-engineering roles.

01:25:13

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Episode notes

00:00 / 00:00

Codex As A Software Engineering Teammate

Codex is positioned as the start of a software engineering teammate that participates across planning, writing, validating, and maintaining code.
Alexander emphasizes proactivity: the agent should do helpful work without constant prompting from humans.

00:00 / 00:00

Integrated Product+Research Drove 20x Growth

Codex grew ~20x since GPT-5 launch and now serves trillions of tokens weekly, driven by model and product integration.
A tightly integrated research+product approach let the team iterate models, APIs, and harnesses together to unlock scale.

00:00 / 00:00

Meet Developers Where They Work

Onboard agents where users already work: ship IDE extensions and CLI tools before cloud-only agents.
Use local sandboxes so agents access dependencies without complex environment setup and users can iterate interactively.

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Speed and culture at OpenAI

05:08 • 2min

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Why OpenAI favors rapid experiments

07:25 • 4min

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What Codex is and how it works

11:35 • 4min

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Codex's explosive growth and usage

15:47 • 1min

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Product decisions that unlocked growth

17:00 • 5min

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Model advances and the agent stack

21:38 • 3min

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Winning by building a proactive teammate

25:00 • 1min

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Chat, GUIs and the super assistant vision

26:24 • 2min

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Why coding is core to agent capability

28:14 • 4min

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Agents sharing scripts and company knowledge

31:54 • 4min

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Shifting bottleneck from building to reviewing

35:54 • 3min

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Spec-driven and chatter-driven development

39:10 • 3min

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Slack integrations and Codex in teams

Codex's internal impact and Sora story

44:14 • 5min

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Atlas, browsers and contextual assistants

49:14 • 4min

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Who benefits beyond engineers

53:41 • 3min

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How to try Codex effectively

56:27 • 9min

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Skills and careers in the AI age

01:05:40 • 4min

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Codex operating training runs and on-call

01:09:38 • 58sec

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AGI timelines and the human bottleneck

01:10:36 • 3min

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Hiring and how to apply to Codex

01:13:41 • 2min

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Lightning round: books, media, values

• Mentioned in 2 episodes

Culture Care

Makoto Fujimura

#2445

• Mentioned in 15 episodes

A Fire upon the Deep

Vernor Vinge

In 'A Fire Upon the Deep', Vernor Vinge explores a vast universe divided into 'zones of thought' where the potential of intelligent life varies greatly. The story begins with a human expedition that awakens a destructive artificial intelligence, the Blight, which threatens to destroy entire civilizations. Two children, Jefri and Johanna Olsndot, escape the initial destruction but are captured by the Tines, an intelligent dog-like alien species with a hive mind. Meanwhile, Ravna Bergsndot, an intergalactic librarian, and her companions embark on a perilous rescue mission to save the children and recover an artifact that could stop the Blight. The novel is renowned for its complex world-building, unique alien cultures, and blend of hard science fiction and high drama.

• Mentioned in 432 episodes

The Lord of the Rings

J.R.R Tolkien

The Lord of the Rings, written by J.R. R. Tolkien, is an epic high fantasy novel set in Middle-earth. The story follows Frodo Baggins, a hobbit who inherits the One Ring from his uncle Bilbo. The Ring, forged by Sauron, holds the power to control all other Rings of Power and must be destroyed in the fires of Mount Doom to prevent Sauron's return. Frodo is joined by a fellowship of other characters, including Gandalf the Grey, Samwise Gamgee, Aragorn, Legolas, Gimli, and Boromir, as they embark on a dangerous quest across Middle-earth. The novel explores themes of good vs. evil, the corrupting influence of power, and the struggle between fate and free will.

#77

• Mentioned in 176 episodes

Radical Candor

Be a Kick-ass Boss Without Losing Your Humanity

Kim Scott

Radical Candor by Kim Scott offers a practical approach to management by emphasizing the importance of caring personally and challenging directly. The book argues that effective managers must find a balance between being empathetic and providing clear, honest feedback. Scott draws from her experiences at Google and Apple to provide actionable lessons on building strong relationships, giving feedback, and creating a collaborative work environment. The book introduces the concept of 'radical candor' as the sweet spot between obnoxious aggression and ruinous empathy, and provides tools and strategies for managers to implement this approach in their daily work.

Alexander Embiricos leads product on Codex, OpenAI’s powerful coding agent, which has grown 20x since August and now serves trillions of tokens weekly. Before joining OpenAI, Alexander spent five years building a pair programming product for engineers. He now works at the frontier of AI-led software development, building what he describes as a software engineering teammate—an AI agent designed to participate across the entire development lifecycle.

We discuss:

1. Why Codex has grown 20x since launch and what product decisions unlocked this growth

2. How OpenAI built the Sora Android app in just 18 days using Codex

3. Why the real bottleneck to AGI-level productivity isn’t model capability—it’s human typing speed

4. The vision of AI as a proactive teammate, not just a tool you prompt

5. The bottleneck shifting from building to reviewing AI-generated work

6. Why coding will be a core competency for every AI agent—because writing code is how agents use computers best

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Transcript: https://www.lennysnewsletter.com/p/why-humans-are-ais-biggest-bottleneck

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My biggest takeaways (for paid newsletter subscribers): https://www.lennysnewsletter.com/i/180365355/my-biggest-takeaways-from-this-conversation

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Where to find Alexander Embiricos:

• X: https://x.com/embirico

• LinkedIn: https://www.linkedin.com/in/embirico

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Where to find Lenny:

• Newsletter: https://www.lennysnewsletter.com

• X: https://twitter.com/lennysan

• LinkedIn: https://www.linkedin.com/in/lennyrachitsky/

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In this episode, we cover:

(00:00) Introduction to Alexander Embiricos

(05:13) The speed and ambition at OpenAI

(11:34) Codex: OpenAI’s coding agent

(15:43) Codex’s explosive growth

(24:59) The future of AI and coding agents

(33:11) The impact of AI on engineering

(44:08) How Codex has impacted the way PMs operate

(45:40) Throwaway code and ubiquitous coding

(47:10) Shipping the Sora Android app

(49:01) Building the Atlas browser

(53:34) Codex’s impact on productivity

(55:35) Measuring progress on Codex

(58:09) Why they are building a web browser

(01:01:58) Non-engineering use cases for Codex

(01:02:53) Codex’s capabilities

(01:04:49) Tips for getting started with Codex

(01:05:37) Skills to lean into in the AI age

(01:10:36) How far are we from a human version of AI?

(01:13:31) Hiring and team growth at Codex

(01:15:47) Lightning round and final thoughts

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Referenced:

• OpenAI: https://openai.com

• Codex: https://openai.com/codex

• Inside ChatGPT: The fastest-growing product in history | Nick Turley (Head of ChatGPT at OpenAI): https://www.lennysnewsletter.com/p/inside-chatgpt-nick-turley

• Dropbox: http://dropbox.com

• Datadog: https://www.datadoghq.com

• Andrej Karpathy on X: https://x.com/karpathy

• The rise of Cursor: The $300M ARR AI tool that engineers can’t stop using | Michael Truell (co-founder and CEO): https://www.lennysnewsletter.com/p/the-rise-of-cursor-michael-truell

• Atlas: https://openai.com/index/introducing-chatgpt-atlas

• How Block is becoming the most AI-native enterprise in the world | Dhanji R. Prasanna: https://www.lennysnewsletter.com/p/how-block-is-becoming-the-most-ai-native

• Goose: https://block.xyz/inside/block-open-source-introduces-codename-goose

• Lessons on building product sense, navigating AI, optimizing the first mile, and making it through the messy middle | Scott Belsky (Adobe, Behance): https://www.lennysnewsletter.com/p/lessons-on-building-product-sense

• Sora Android app: https://play.google.com/store/apps/details?id=com.openai.sora&hl=en_US&pli=1

• The OpenAI Podcast—ChatGPT Atlas and the next era of web browsing: https://www.youtube.com/watch?v=WdbgNC80PMw&list=PLOXw6I10VTv9GAOCZjUAAkSVyW2cDXs4u&index=2

• How to measure AI developer productivity in 2025 | Nicole Forsgren: https://www.lennysnewsletter.com/p/how-to-measure-ai-developer-productivity

• Compiling: https://3d.xkcd.com/303

• Jujutsu Kaisen on Netflix: https://www.netflix.com/title/81278456

• Tesla: https://www.tesla.com

• Radical Candor: From theory to practice with author Kim Scott: https://www.lennysnewsletter.com/p/radical-candor-from-theory-to-practice

• Andreas Embirikos: https://en.wikipedia.org/wiki/Andreas_Embirikos

• George Embiricos: https://en.wikipedia.org/wiki/George_Embiricos: https://en.wikipedia.org/wiki/George_Embiricos

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Recommended books:

• Culture series: https://www.amazon.com/dp/B07WLZZ9WV

• The Lord of the Rings: https://www.amazon.com/Lord-Rings-J-R-R-Tolkien/dp/0544003411

• A Fire Upon the Deep (Zones of Thought series Book 1): https://www.amazon.com/Fire-Upon-Deep-Zones-Thought/dp/1250237750

• Radical Candor: Be a Kick-Ass Boss Without Losing Your Humanity: https://www.amazon.com/Radical-Candor-Kick-Ass-Without-Humanity/dp/1250103509

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Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email podcast@lennyrachitsky.com.

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Lenny may be an investor in the companies discussed.

To hear more, visit www.lennysnewsletter.com

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