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

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 growth2. How OpenAI built the Sora Android app in just 18 days using Codex3. Why the real bottleneck to AGI-level productivity isn’t model capability—it’s human typing speed4. The vision of AI as a proactive teammate, not just a tool you prompt5. The bottleneck shifting from building to reviewing AI-generated work6. Why coding will be a core competency for every AI agent—because writing code is how agents use computers best—Brought to you by:WorkOS—Modern identity platform for B2B SaaS, free up to 1 million MAUs: https://workos.com/lennyFin—The #1 AI agent for customer service: https://fin.ai/lennyJira Product Discovery—Confidence to build the right thing: https://atlassian.com/lenny/?utm_source=lennypodcast&utm_medium=paid-audio&utm_campaign=fy24q1-jpd-imc—Transcript: https://www.lennysnewsletter.com/p/why-humans-are-ais-biggest-bottleneck—My biggest takeaways (for paid newsletter subscribers): https://www.lennysnewsletter.com/i/180365355/my-biggest-takeaways-from-this-conversation—Where to find Alexander Embiricos:• X: https://x.com/embirico• LinkedIn: https://www.linkedin.com/in/embirico—Where to find Lenny:• Newsletter: https://www.lennysnewsletter.com• X: https://twitter.com/lennysan• LinkedIn: https://www.linkedin.com/in/lennyrachitsky/—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 fut