Sorcerers and Their Brooms: Sherwin Wu on How AI Is Rewriting Engineering at OpenAI

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Overview

Sherwin Wu leads engineering for OpenAI's API and developer platform. Because so many AI startups build on those APIs, host Lenny Rachitsky framed him as having an unusually broad view of where the industry is heading. The conversation covers several connected questions: what software engineering looks like when nearly all code is generated by an agent, how managers should adapt, why many corporate AI rollouts may be failing, and what builders should expect from models over the next year or two. Wu's position throughout is that this is an unusually exciting and unsettled window. The job of engineers, and eventually many other jobs, is being redefined, and the people who engage now get to help set the new standards.

29 min read
3:33

A barometer: how much of OpenAI's code does AI write?

Wu said he still writes code occasionally. For managers like him, using AI tools is now far easier than coding by hand, and all of his own code, along with that of some other engineering managers at OpenAI, is written by Codex. He said it is hard to measure exactly how much code across the company is AI-authored, because the vast majority of it, "close to 100%," is usually generated by AI first and then edited.

What OpenAI does track is adoption. According to Wu, about 95% of engineers use Codex daily, and 100% of pull requests are reviewed by Codex, so essentially any code merged into production has had Codex look at it and suggest changes. He also reported that engineers who use Codex more open about 70% more PRs than those who use it less. He added that the gap is widening as heavy users get more efficient, and that it may have grown since he last checked.

When Lenny asked whether it was fair to say that 100% of OpenAI's code is written by Codex, Wu declined that framing. He would not claim that all code running in production was written by AI, and attribution is hard. His estimate was that almost every engineer uses Codex heavily for all their tasks, so the vast majority of code is probably authored by it.

He also noted that trust is still uneven. Some engineers trust Codex less than others, but he said that almost every day he talks to someone who was surprised by what it could do, and each person's threshold for letting the model work on its own keeps rising. He cited a line from Kevin Weil, whom he described as OpenAI's VP of science: "This is the worst the models will ever be." Lenny mentioned that the developer of OpenClaw had recently said they trust Codex's output enough to feel almost certain they could commit it straight to master. Wu called them a great Codex user who gives the team close feedback.

7:00

From writing code to casting spells

Asked how the engineer's job will look in one to two years, Wu said it is likely to change significantly, and that engineers are in a rare moment, perhaps the next 12 to 24 months, when they get to work things out themselves and set their own standards.

He agreed with the common observation that individual-contributor engineers are becoming tech leads who manage "fleets and fleets of agents." Many engineers on his team have 10 to 20 threads in progress at once. These are not all actively running Codex jobs, but they are parallel lines of work that the engineer checks in on, steers, and gives feedback to. The work has shifted from writing code to something close to managing.

His favorite metaphor for this comes from Structure and Interpretation of Computer Programs (SICP), the MIT textbook that taught Scheme in the introductory programming course and has a cult following. He remembers the book's opening, which likens programming to sorcery: programmers are wizards, programming languages are incantations, and the challenge is finding the incantation that makes the program do what you want. The book is often called "the wizard book" for that reason, and Wu, who dated it to around 1980, said the metaphor has lasted. In his reading, programming languages have always been incantations that got steadily easier to use, and the current AI wave is the next step. Now the incantations are literal, because you can tell Codex or Cursor exactly what you want and it goes and does it.

He pushed the metaphor further to The Sorcerer's Apprentice from Fantasia. Mickey finds the sorcerer's hat, sets the brooms to work, falls asleep, and wakes to a flood that the old sorcerer has to clean up. Wu called this "vibe coding at its greatest." The point he draws is that these incantations are very high-leverage, but you have to know what you are doing. Running 20 Codex threads takes skill, seniority, and thought, so that the models do not go off the rails. You cannot walk away and ignore them. At the same time, a senior engineer who is proficient with these tools can now do far more, and Wu said this is also what makes the work fun: "It literally feels like we're wizards now." Lenny added a guest's comparison to a genie granting wishes, and Wu mentioned the monkey's paw: you get what you asked for, but with side effects.

12:29

The stress of agents that won't cooperate, and a team with no escape hatch

Lenny raised a growing complaint: people feel stressed when their agents stall and they feel they are wasting time. Wu said this happens constantly, and that it is where the interesting problems currently lie, because neither the models nor the tools are perfect and people are still learning how to work with them.

He described an internal experiment in which one team maintains a codebase written 100% by Codex. Normally, when an agent cannot build what you need, you have an escape hatch: you roll up your sleeves and write it yourself, perhaps with tab completion in Cursor. This team has deliberately given that up, so their only question is how to get the agent to do the task. Wu said OpenAI expects to publish a blog post on what they have learned.

One lesson he shared is that when a coding agent fails, the cause is usually context. The task was underspecified, or the agent did not have enough information about how something should be done. The fix is to encode the tribal knowledge in engineers' heads into the repository, through code comments, code structure, Markdown files, skills, or other resources the model can read. Taking away the option of not using AI, he said, forced the team to work through problems everyone will have to solve to lean fully into agents.

15:20

Code review: from 10–15 minutes to 2–3

More PRs means more code review, and Lenny asked how OpenAI keeps that from becoming a grind. Wu said the tasks people hand to models first tend to be the most annoying and boring parts of engineering, which is part of why the job is more fun now. He personally hated code review. At his first job out of college, at Quora, he owned the newsfeed code, which everyone touched, so he would log in every morning to 20 to 30 reviews, procrastinate, and watch the pile grow to 50.

He said Codex is very good at reviewing code, and that GPT-5.2 in particular has become strong at it, especially when steered well. Because Codex reviews every PR and leaves suggestions, a review that used to take 10 to 15 minutes can sometimes take two to three. For small PRs, people sometimes skip human review and rely on Codex as the "second pair of eyes" that catches anything dumb.

OpenAI has also automated much of the post-push process with Codex. Wu said that what frustrates engineers most is getting code into production after writing it: tests, lint errors, review. Internal tools now have Codex fix simple lint errors, patch them, and restart CI. The aim is to reduce the engineer's work at each step, and the result, he said, is that engineers can merge and ship many more PRs.

Lenny asked about the circularity of Codex writing and then reviewing its own code. Wu acknowledged it and returned to the brooms: OpenAI is careful about which PRs are reviewed only by Codex, and most people still look at their own PRs. He described the shift as going from 100% attention to about 30%, not to zero. OpenAI tests many models internally but uses external models less, because it wants to dogfood its own. Internal model variants can provide a different perspective in review, which he said works well.

19:32

How the manager's job is changing

Wu said the manager role has changed less than the engineer's, since "there's no Codex for managers" yet, although he uses Codex for some managerial tasks. He sees trends that suggest where things are heading.

The first is that Codex, and perhaps AI across society, disproportionately empowers top performers and high-agency people. That widens the spread of productivity within a team. His long-standing management philosophy is to spend most of his time with top performers, keeping them unblocked, productive, and heard, and he thinks this matters even more now. His example was the 100%-Codex team: letting them run with it has paid off. He also described a group of engineers exploring best practices for working with the model. He considers that very high-leverage, and OpenAI spreads what they learn through knowledge-sharing sessions and documents. Lenny linked this to Marc Andreessen's recent line on the podcast that AI makes good people better and great people exceptional.

The second trend concerns span of control. During performance reviews, Wu said, ChatGPT connected to internal knowledge such as GitHub, Notion, and Google Docs can quickly build a picture of what someone did over the past 12 months and draft a deep-research-style report. His view is that just as engineers now manage 20 to 30 Codex threads, these tools may let managers run teams much larger than the typical six to eight in software engineering. He compared this to support and operations, where handing more work to agents lets a team do more and a manager oversee more people. He said some OpenAI engineering managers already handle large teams effectively with these tools.

31:41

The surgeon and the manager who looks around corners

Asked for other management lessons, Wu said his philosophy has mostly stayed the same over time. To be concrete about the top-performer principle, he said it means spending more than 50% of your time with roughly your top 10%.

His guiding image comes from The Mythical Man-Month, which he believes was written in the 1970s. The book predicted that software teams might be organized like surgical teams: one surgeon operates, and everyone else, nurses, residents, fellows, exists to support that person and hand over the scalpel when asked. Wu said this did not really happen, since software is far more collaborative. But he tries to make each person on his team feel like the surgeon, as though an army is supporting them, when really it is just him as manager. In practice that means looking around corners and clearing organizational blockers. He argued this matters even more with AI: when engineers are producing PR after PR, the bottleneck is usually organizational or process-related. The ideal is a manager who already has the scalpel ready before the surgeon asks.

Lenny suggested AI could help anticipate these blockers. Wu said he had not tried it but found the idea compelling: ask ChatGPT, connected to company knowledge, Notion, and Slack, what his team's active blockers are and how he could help, and even what blockers are likely next month.

24:16

The second- and third-order effects of the one-person billion-dollar startup

When asked what people are not yet pricing in, Wu chose the idea of the one-person billion-dollar startup, which he thinks Sam Altman may have been the first to describe. He finds the idea exciting but thinks people overlook its knock-on effects.

The second-order effect, as he sees it: if one person can build a billion-dollar company, it is also much easier for anyone to start a company at all. He expects a large boom in startups and small businesses. He pointed to the verticalization already visible in AI startups, where building a tool for one domain works well because the builder deeply understands the use case. Extrapolated, there could be 100 times more such companies. Supporting a single one-person billion-dollar company might take a hundred small startups building bespoke software for it, and he suggested we could enter "a golden age of B2B SaaS." In his framing, there might be one billion-dollar solo company, a hundred $100 million startups, and tens of thousands of $10 million businesses. For an individual, a $10 million business means being set for life.

The third-order effect, which he flagged as increasingly uncertain, concerns venture capital. If the world fills with micro-companies building software for one or two owners, the startup and VC ecosystems will change. There might be a few large platform players, while the number of startups capable of venture-scale 100x or 1,000x returns could shrink. Companies worth $10 million to $50 million are poor venture returns but great for high-agency individuals. He declined Lenny's joking request for a fourth-order effect.

Lenny pushed back. From running his own business, which he said is not venture-scale, the volume of support requests makes a solo billion-dollar company hard to imagine unless contract size is very high or the operator relies on contractors. Wu agreed partly but offered a different picture. The solo founder would not personally dispatch AI to handle every ticket. Instead, a crowd of tiny startups, perhaps 10 or 20 building support software specifically for podcasts and newsletters, each possibly run by one person, would sell tailored tools to them. As the cost of building software collapses, companies may outsource more and stay smaller. He repeated that this is highly uncertain. Lenny offered his own candidate for a fourth-order effect: as more things compete for attention, distribution and audience become increasingly valuable.

37:31

Why many enterprise AI deployments may be negative ROI

Wu had previously told Lenny that many companies' AI deployments may have negative ROI. He clarified that he does not see quantitative figures, since this is hard to measure, but that from watching companies try to adopt AI, he would not be surprised. He also linked it to a sentiment he sees outside tech that AI is being forced on people.

His first observation is that Silicon Valley, X, and software engineering are bubbles. Most people, including most Americans, are not engineers, are not "AI-pilled," and do not follow model releases. Power users talk about skills, AGENTS.md, and MCP, but when Wu talks to employees at customer companies, they are attempting very basic things with little understanding of how the technology works.

His recommendation is to pair top-down buy-in with bottom-up adoption. Top-down means executives commit to becoming AI-first, buy the tools, and back the effort. Bottom-up means employees doing the actual work are excited, willing to learn, build best practices, and share them. He said this is how it played out at OpenAI: the company always wanted to be AI-centric, but adoption really took off with Codex and similar tools that let employees apply AI to their own work. Because work differs so much across engineering, finance, operations, and sales, the "last mile" has to be worked out from below. When deployment is a pure executive mandate, the result is a workforce that knows it is supposed to use the tools, perhaps sees usage on its performance reviews, doesn't know what to do, and has nobody to learn from.

His concrete advice is to form, or even staff full-time, an internal "tiger team" that explores capabilities, applies them to specific workflows, shares knowledge, and generates excitement. He said these teams usually aren't made up of software engineers, since many companies have none, and they are expensive and hard to hire. The people who tend to light up are technical-adjacent: for example, a support or operations lead who doesn't code but is an Excel wizard and loves the tools. Wu summed it up in terms of his management philosophy: find the high performers in AI adoption and empower them with hackathons, seminars, and knowledge sharing.

44:00

"The models will eat your scaffolding for breakfast"

Lenny raised Wu's view that listening to customers isn't always the right strategy in AI. Wu said it isn't much of a hot take, since you should obviously talk to customers. His point is that the field and the models change so fast that they disrupt themselves, especially in tooling and scaffolding.

He quoted a phrase from an X post by Nicolas Bustamante, founder of Fintool, who was sharing lessons from building AI agents for financial services: "The models will eat your scaffolding for breakfast." Wu traced the history. When ChatGPT launched in 2022, models were raw, and developers built layers of scaffolding such as agent frameworks and vector stores to steer them. Around 2023, he said, many believed vector stores would be the main way to bring organizational context into models, which meant embedding every corpus and tuning vector search to retrieve the right information at the right time. As models improved, a better approach turned out to be removing much of that logic, trusting the model, and giving it search tools, which could be any kind of search, including plain files on a file system. Vector stores still have uses, and many companies still use them, but he said the assumption that a whole ecosystem would be built around them has changed. He also said agent frameworks now seem somewhat less useful.

He applied the same reasoning to today's fashionable scaffolding, skills files and file-based context management. He could imagine models eventually managing that themselves, or the field moving to some paradigm that is hard to predict. So if you only follow customer requests, which at any moment reflect a local maximum ("I want a better vector store," "I want a better agent framework"), you risk building for that local maximum. He admitted that OpenAI's API team has been guilty of this and taken turns it shouldn't have. Lenny compared this to "The Bitter Lesson" in machine learning, and Wu agreed that there is a version of it for building with AI, one "we're all learning day in and day out."

His advice to builders is: "Make sure you're building for where the models are going and not where they are today." The startups he has seen do well build products around a capability that is maybe 80% of the way there. The product almost works, and then a model upgrade makes it click. He gave the example of something that half-worked with o3 and then became possible with GPT-5.1 or 5.2. Because models improve so quickly, the wait often isn't long.

50:28

What models should do in the next 12 to 18 months

Wu named two areas he is watching. The first is task length. He referred to the METR benchmark, which tracks how long a software engineering task a model can complete 50% or 80% of the time. From memory, he put frontier models at multi-hour tasks at 50% reliability and just under an hour at 80%. He called the chart sobering because it also plots earlier models, which makes the trend clear. He thinks today's products, including coding tools used interactively in the CLI, are optimized for tasks of at most about 10 minutes. Some people push Codex to multi-hour tasks, but he sees that as the exception. If the trend holds, he expects models within 12 to 18 months that can handle multi-hour tasks coherently, and perhaps eventually something like a six-hour, day-long task that you dispatch and leave running. Products built around that will look very different. You would still want to give feedback, he said, and "you probably don't" want it to run completely unsupervised for a day. The range of things models can do would expand substantially.

The second area is multimodality, mainly audio. He expects audio models, especially native speech-to-speech models, to get much better over the next 6 to 12 months, and mentioned interesting work on new model types and architectures for audio. He considers audio hugely underrated in enterprise settings. Everyone talks about coding, which is text, but a large share of the world's business, services, and operations happens through speech.

53:47

Business process automation as the underrated opportunity

Wu is bullish on applying AI to business processes, and he again said this is overlooked because of the Silicon Valley bubble. He distinguishes open-ended knowledge work from repeatable processes. Software engineering is open-ended and not repeatable, since you don't build the same feature twice, which is why tools like Codex, given open-ended goals to explore, do well. He placed data science and some strategic finance in that same category.

Much of the economy, he said, runs on repeatable operations that a manager has refined over time, usually written up as a standard operating procedure that people shouldn't deviate from. In engineering, ingenuity comes from deviation, but calling a support line or a utility company means someone is following one of these procedures and a set of rules about what they can and cannot do for you. The opportunity he sees is automating these processes with high determinism, fully integrated with business data, business decisions, and an enterprise's various systems.

When big enterprises ask him how AI will reshape their company over the next 20 years, he says software engineering is part of the story but the business-process side may look even more different. He was careful about size: he doesn't know whether this opportunity is larger or smaller in absolute terms than software, which is itself huge. But he considers it definitely larger than you would guess from how little it is discussed on X.

57:35

Will OpenAI squash your startup?

To the question founders ask most, how to avoid being crushed by OpenAI, Wu's answer was that the market is so large that startups shouldn't overthink it. Every startup he has seen fizzle out failed because it built something customers didn't want, not because OpenAI, Google, or another lab squashed it. Even in crowded spaces like coding, he said, Cursor has grown huge because people love the product. As a sign of how big the opportunity is, he pointed out that the Overton window for VCs has shifted: they now invest in directly competing companies. He called this "the most empowering thing in the world" for founders, since building something some people really love can lead to a very valuable business.

He also described OpenAI's own stance. He said Sam Altman and Greg Brockman have reinforced from the top that OpenAI sees itself as an ecosystem and platform company, and that the API was its first product. He gave several examples. Every model released in OpenAI's products also ships in the API, including Codex models tuned for the Codex harness. OpenAI tries to keep the platform neutral and doesn't block competitors from its models. It has been testing "Sign in with ChatGPT." He described OpenAI as perhaps an aircraft carrier that still benefits from raising the tide for everyone, and said the API has grown significantly because OpenAI operates this way.

He grounded this in OpenAI's charter: build AGI, and spread its benefits to all of humanity. ChatGPT tries to reach everyone, but OpenAI launched the API early, around 2020 by his recollection, because it did not believe it could reach every corner of the world alone. It needs others to build things like "the customer support bot for podcasters and newsletter hosts." The ChatGPT apps SDK, owned by the ChatGPT team but built closely with his, follows the same logic: ChatGPT has about 800 million weekly active users, which Wu described as roughly 10% of the world and growing fast, and opening that audience to other companies should help expand it further.

Lenny praised the fact that the free version of ChatGPT is not so different from the most capable model. Wu agreed, pointing to OpenAI's work in health and education, and said the free model has become far smarter since 2022 and now gives people GPT-5. He compared it to how ordinary people use the same iPhone as billionaires: for $20 a month you use essentially the same AI they use, and for $200 you get the same Pro model, though he suspects billionaires mostly use the Plus-tier models day to day.

1:05:34

The layers of OpenAI's developer platform

Wu described the API as layers of increasing abstraction. At the bottom is the Responses API, the most popular endpoint, which he said is optimized for long-running agents. You give the model text, it works for a while, you can poll it, and eventually you get a response. It is deliberately unopinionated and lets developers build almost anything.

Above that is the Agents SDK, which has also become very popular. It helps build what people traditionally think of as an agent: an AI running in a loop that may delegate to sub-agents, with guardrails and orchestration of a "swarm" of agents. Wu noted the irony that this is itself scaffolding, adding "we'll see where this all goes." Above that are tools for the meta-level work of deploying agents: AgentKit and widgets, UI components for quickly building a polished interface on top of the API or the Agents SDK, since agent UIs tend to look alike. There is also an Evals API for testing quantitatively whether a model, agent, or workflow is performing. Developers can use the whole stack to build an agent quickly or go as far down as the Responses API for maximum flexibility.

1:11:45

Lightning round: books, anime, home networks, and pricing houses

For books, Wu recommended the novel There Is No Antimemetics Division by qntm, about a government agency fighting things that make you forget them. He finished it in two days and found it creative, fresh, and unintentionally funny. For nonfiction, he recommended two books on the US and China: Dan Wang's Breakneck, whose contrast between a "lawyerly" US and an "engineering" China he found persuasive, and Patrick McGee's Apple in China, which appealed to him as an Apple fan for both its account of Apple's relationship with China and its inside detail about the company. With two kids and a busy job he watches little TV, but he is a big anime fan and enjoyed season 3 of Jujutsu Kaisen. He believes Japanese anime creates novel plots and worlds that Western media has shied away from. His favorite recent product is Ubiquiti's home networking and security cameras, which he called "the Apple of home networking," mainly because of the software and its mobile, Apple TV, and iPad apps. His life motto is "never feel sorry for yourself," a reminder that you always have the agency to pull yourself up.

Lenny asked about Wu's earlier work at Opendoor, where Wu worked on the models that decided how much to offer for a house. Wu named three variables that were more important than expected. High-voltage power lines lower prices a lot, which Wu fully understood only after standing next to a buzzing line in Dallas and realizing families don't want their kids near it. Floor plans were very important but extremely hard to quantify. The team measured things like kitchen width and style and where the primary bedroom was, but sometimes a house wouldn't sell and the ops team would go in and say it was a floor-plan issue you could only feel in person. Floor plans often weren't even digitized; a handful of people held paper plans for homes in places like Phoenix and Dallas. Finally, curb appeal, down to the front door, mattered more than he expected. He recalled a Zillow book that reportedly found front-door replacement to be the highest-ROI home improvement.

1:08:29

Don't take the next two to three years for granted

Wu's closing message was that the next two to three years will be some of the most fun in tech and startups for a long time. He entered the workforce in 2014 and said the first couple of years were great, followed by roughly five or six years when tech wasn't very exciting. The past three years have been the most energizing period of his career, and he expects the next two to three to continue that, before the wave eventually plays out and progress becomes more incremental. Until then, he said, people will explore, invent, and change how we work, and he is trying not to take it for granted himself.

His advice for not missing it is to engage. You don't need to be a software engineer. Use the tools, learn what they can and cannot do, and watch how that boundary moves as models improve, rather than sitting back and letting it pass. On the anxiety of keeping up, he admitted he is a bad example because he is "chronically online" on X and OpenAI's Slack. From watching others, though, he said much of the flood is noise, driven by the industry's frantic pace and by how X works as a product. His suggestion is to start small with one or two tools: install the Codex client and experiment, or connect ChatGPT to a few data sources such as Notion, Slack, and GitHub and see what it can and cannot do.