# Cowork was built quickly, with safety as the hard part

Markdown copy of https://realalpha.app/s/cowork-was-built-quickly-with-safety-as-the-hard-part/ on Real Alpha, the best minutes from long interviews with the people building AI. Cite and link the page, not this copy.

- Speaker: [Boris Cherny](https://realalpha.app/builders/boris-cherny/) · Boris Cherny is creator and Head of Claude Code at Anthropic. · Created Claude Code at Anthropic and leads its team; previously spent about five years at Meta.
- Host: [Gergely Orosz](https://realalpha.app/people/gergely-orosz/) · Host, The Pragmatic Engineer · Spent four years at Uber heading mobile, web and backend teams; shipped part of its payments system.
- Show: The Pragmatic Engineer
- Episode: [Building Claude Code with Boris Cherny](https://realalpha.app/v/julbw1JuAz0/), Mar 4, 2026
- Moment: 1:05:11 to 1:11:24 of the episode (6 min), playing on https://realalpha.app/s/cowork-was-built-quickly-with-safety-as-the-hard-part/; the episode from there: https://realalpha.app/v/julbw1JuAz0/?t=3911

## Quote

> “A lot of the **complexity actually is about safety** because we know, like I said, we know the user is non-technical.”
> — [Boris Cherny](https://realalpha.app/builders/boris-cherny/) at [1:09:01](https://realalpha.app/v/julbw1JuAz0/?t=4141) · The Pragmatic Engineer

## Takeaways

1. Non-engineers were already finding ways to use Claude Code.
2. The small team built Cowork in about 10 days.
3. Safety and permissions added much of the hidden complexity.

## About this segment

Cowork grew from non-engineers using Claude Code and was prototyped by a small team in about 10 days. Boris Cherny says the deeper work was protecting non-technical users with guardrails, a virtual machine, and permission controls.

From “Building Claude Code with Boris Cherny”, Mar 4, 2026. [Watch the full episode](https://realalpha.app/v/julbw1JuAz0/)

## Transcript

Transcribed by machine (Whisper) from the episode’s audio, so a word may be off here and there.

[1:05:16](https://realalpha.app/v/julbw1JuAz0/?t=3916) let's let's talk about cloud co-work uh it's one of the very impressive things about us it looks great so i tried it out it's inside cloud you have the co-work tab there and you can i feel it's a lot more visual way of running agents interacting with them one of the surprising things i just heard that it was built in 10 days can can you take us through like what it took to build it and what does it actually mean was it from the idea or like from the decision of of building it and how big was the team building it?

[1:05:44](https://realalpha.app/v/julbw1JuAz0/?t=3944) The team was really small. It was just a few people. For a long time, we felt that there is some product to be built for non-engineers. The reason we felt this is for a long time, people that were using quad code are non-engineers. And so, you know, in the product world, when you see latent demand, you see people jumping through hoops to use a product that was not designed for them. That's a really good sign it's time to build another product that is built just for them.

[1:06:11](https://realalpha.app/v/julbw1JuAz0/?t=3971) There's all these people on Twitter that there's this one guy that was using QuadCode to like monitor his tomato plants. I just, I love this. It was like, he had like a webcam set up and the quad was like, oh my God, I'm so happy that our plant is budding. And because it had like a webcam and just like every day it was like monitoring it. And it was so happy that the tomatoes were growing. There was someone that was using QuadCode to, you know, recover photos off of a corrupted hard drive.

[1:06:35](https://realalpha.app/v/julbw1JuAz0/?t=3995) And it was like his wedding photos. Wow. You know, like I said, our entire finance team at Anthropic uses QuadCode. Our sales team uses QuadCode. So there's just all these people that are non-engineers that were using it. And at that point, QuadCode, it's available in a lot of form factors, right? Like we started in a terminal, then we expanded and we added support for IDEs. So we have extensions for, you know, every VS Code-based IDE, every JetBrains-based IDE.

[1:07:01](https://realalpha.app/v/julbw1JuAz0/?t=4021) There's also iOS and Android apps. There's the desktop app. There's web. So then there's like Slack and GitHub apps. So we kind of expanded to all these places to make QuadCode easier for engineers. But ultimately, none of these are built still for non-engineers. And so CloudCode evolved a lot, but it still felt like there's a there's kind of a gap and there's a product that could make this even easier for people.

[1:07:24](https://realalpha.app/v/julbw1JuAz0/?t=4044) And so for the last couple of months, the team was kind of hacking around and just saying, like, what is the right product? And at some point, someone came up with this idea of like, what if we just take CloudCode, add some guardrails? So, for example, co-work ships with a virtual machine. This is one of the many ways that we make sure it's really safe, especially for non-technical users that don't want to read like bash commands to figure out what it what it's doing and they were hacking on this i think it was something like 10 days until end or something it was just fully built with quad code uh and then we shipped it and can you give us a sense of like the complexity behind an app like this and if we can walk through like what parts needed to be built because from the outside it's a little bit hard to tell like is this just a nice ui wrapper

[1:08:06](https://realalpha.app/v/julbw1JuAz0/?t=4086) that's you know like i don't know like a few hundred lines of code i'm just being obviously i'm i'm provocative here or behind the scenes it's actually a really complex piece of software and the reason i ask is like uber is a great example where people look at the app it looks really simple i work there and i know it's it's really really complex because you don't see a lot of the complexity there's a lot of regional things there's a lot of back-end things that are all hidden so from just from looking at it cloud co-work it's hard to tell how much of this is is additional business logic that needed to be carefully thought out versus it's actually just a nice little thin wrapper on top of the the model in some places i think there's less complexity than you would think in some places there's more complexity so on the product side it's quite

[1:08:46](https://realalpha.app/v/julbw1JuAz0/?t=4126) simple um because it's just the quad desktop app so you know you download the quad app it's well it's a single desktop app it has a tab for co-work it has a tab for code it has a tab for chat so it is just one app and we're able to inherit a lot of that product logic there's some UI rendering code under the hood, you know, it's just the same quad code running as the same quad agent SDK that powers quad code. A lot of the complexity actually is about safety because we know, like I said, we know the user is non-technical. And so we just want to make sure they have a good experience. And so, for example, if someone launches the app and then, you know, like they delete a bunch of family photos, that's really not good. And so we wanted to make sure that we protect against this. So you can't accidentally do that. And so that's where a lot of the guard

[1:09:26](https://realalpha.app/v/julbw1JuAz0/?t=4166) rails came from. So there's a bunch of classifiers running on the back end. This is for safety and again, extra mitigations for things like prompt injection and, you know, risks like this around security. On the front end, there's an entire virtual machine that we ship. There's a bunch of operating system level integrations to make sure people don't accidentally delete things. So just around safety, there's a lot there. And then we also had to rethink the permission system because we inherit the permission system from quad code.

[1:09:55](https://realalpha.app/v/julbw1JuAz0/?t=4195) But also for co-work, actually a big part of the value is not just running locally, but it's using all of your tools the way that quad code uses it. But the thing is for non-technical users, your tools aren't really available as CLIs. Some of them are available for MCP. Many of them are available in a browser. And so co-work is really, really good when you pair it with a Chrome extension. And this is the way that I usually use it.

[1:10:17](https://realalpha.app/v/julbw1JuAz0/?t=4217) So, you know, for example, I use it every week to do project management for the team. we have like we have a spreadsheet that tracks kind of at a really high level what everyone's working on and this is kind of my personal way of project managing you know other people like i said use asana other people use notes or whatever for my own test i don't use anything but kind of for the team overall i have the spreadsheet and i have co-work kind of check in and i i just ask co-work every week hey can you look at the rows for any status that has not been filled out can you just ping the engineer on slack and so it'll open one tab in chrome for the spreadsheet it'll open another tab with slack and then it'll just start messaging engineers in slack and it just one shots it there's like one engineer's name for some reason it can't autocomplete um but

[1:10:58](https://realalpha.app/v/julbw1JuAz0/?t=4258) everyone everything else it just gets and so this is actually like from a safety point of view we also thought pretty deeply about this chrome extension how this works and how the permissioning model should interact with this local permissioning model so there's also a bunch of code to kind of make sure that that's that feels smooth and what's the tech side behind this i assume a lot of will similar to the the cloud app but is it is it electron typescript those kind of things or