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simonw, I find it almost shocking how you had the chance to talk directly with the engineer who built this, and even when he directly says things that contradict what Cursor's own CEO said, you didn't push back a single iota.

Is the takeaway here that it's fine for a CEO to claim "it even has a custom JS VM!" on Twitter/X, then afterwards the engineer explains: "The JavaScript engine isn’t working yet" and "the agents decided to pause it", and this is all OK? Not a single pushback about this very obvious contradiction? This is just one example of many, and again, since it seems to be repeated: no, no one thinks this was supposed to rival Chrome, what a trite way of trying to change the narrative.

I understand you don't want to spook future potential interviewees, but damn if that didn't feel like you suddenly are trying to defend Cursor here, instead of being curious about what actually happened. It doesn't feel curious, it feels like we're all giving up the fight against unneeded hype, exaggeration and degradation of quality.

What happened with balanced perspectives, where we don't just take people for their words, and when we notice something is off, we bring it up?

On a separate note, I actually emailed Wilson Lin too, asking if I could ask questions about it. While he initially accepted, I never actually received any answers. I'm glad to you were able to get someone from Cursor to clarify a bit at least, even though we're still just scratching the surface. I just wish we had a bit more integrity in the ecosystem and community I guess.

Basically your arguments are:

1) The CEO said there was a JS engine, but it didn't work.

2) It didn't build when they published the blog post.

Therefore it lacks integrity! Except that it built (I took Simon's words for it), and building a browser is beside the point, there are a few other big projects listed (Java LSP, Windows 7 emulator, Excel, etc.)

The blog stated:

"Our goal is to understand how far we can push the frontier of agentic coding for projects that typically take human teams months to complete.

This post describes what we've learned from running hundreds of concurrent agents on a single project, coordinating their work, and watching them write over a million lines of code and trillions of tokens."

They didn't set the goal of building a browser. It's an experiment about coordinating AI agents within a context of a complex software project, yet you complained they exaggerating about a JS engine?

The blog post itself is one of the first that describes a large scale experiment of agents, what works, what doesn't. There is very little hype. They didn't say it's game changing or Cursor is the best AI tool.

> The blog post itself is one of the first that describes a large scale experiment of agents, what works, what doesn't. There is very little hype. They didn't say it's game changing or Cursor is the best AI tool.

Three days later, and I took it upon myself to replicate their experiment, except just me + one more agent, here is the results: https://emsh.cat/one-human-one-agent-one-browser/

In short, I think Cursor massively oversold their accomplishment here.

Honestly, grilling him about what the CEO had tweeted didn't even cross my mind.

I wanted to get to the truth of what had actually been built and how. If that contradicts what the CEO said then great, the truth is now out there - anyone is free to call that out and use my video as ammunition.

I just had a look to see what Michael Truell had said about the project, here it is: https://x.com/mntruell/status/2011562190286045552

> We built a browser with GPT-5.2 in Cursor. It ran uninterrupted for one week.

> It's 3M+ lines of code across thousands of files. The rendering engine is from-scratch in Rust with HTML parsing, CSS cascade, layout, text shaping, paint, and a custom JS VM.

> It kind of works! It still has issues and is of course very far from Webkit/Chromium parity, but we were astonished that simple websites render quickly and largely correctly.

This doesn't strike me as the world's most dishonest tweet, though it exaggerates what was achieved. There IS a JS VM in there but it's feature-flagged off. The from-scratch is misleading because there are libraries handling certain aspects - most notably Taffy - which we discussed in the interview.

I just ran "cloc" and to my surprise it counted 3,036,403 (I had thought the 3M was an exaggeration) though only 1,658,651 of that was Rust.

"It kind of works" is a fair assessment IMO!

I don't think "Let's talk about your CEO exaggerating what you built on Twitter" would have added much to the interview.

I did make sure to go over the controversies I thought were material to the project, which is why I dug into the dependencies and talked about QuickJS and Taffy.

> Honestly, grilling him about what the CEO had tweeted didn't even cross my mind.

That's not the full meaning of what I meant either, I'm assuming you also read the initial blog post they posted? It's also has a bunch of similar inaccurate statements.

> I wanted to get to the truth of what had actually been built and how.

It's a shame that you seemed to have reviewed that from the point of after a human stepped in to fix the codebase, which happened way after they first published the blog post. Maybe now it compiles and builds, but how does that answer to the fact that it wasn't at the time of publishing?

There is a "hole" of two days without commits, presumably when the engineer was busy writing the blog post, and that's the point they "sold" as "this is what was produced by the experiment". To then let them spend more human engineering time to patch the codebase, and review if from after the human fixed it, seems like completely missing the point.

> I don't think "Let's talk about your CEO exaggerating what you built on Twitter" would have added much to the interview.

What would have added a whole lot more to the ecosystem's understanding on how feasible this sort of things actually are in reality, would have been to talk about what that same person you interviewed first wrote in the blog post, and what turned out to be real at the time they published it.

The blog post had just a couple of paragraphs about the browser project, all of them accurate: https://cursor.com/blog/scaling-agents#running-for-weeks

> To test this system, we pointed it at an ambitious goal: building a web browser from scratch. The agents ran for close to a week, writing over 1 million lines of code across 1,000 files. You can explore the source code on GitHub.

> Despite the codebase size, new agents can still understand it and make meaningful progress. Hundreds of workers run concurrently, pushing to the same branch with minimal conflicts.

The commits that knocked the project into shape so other people could build the code were handled by agents as well.

I really don't think there's a notable scandal here.

I don't think there is a "scandal" here neither, companies lie and exaggerate all the time and it's becoming normalized. With that said, I think it's important to record when it happens and exactly how it happens, because not only does it help people in the future to know what to look out for, it also serves as a historical record to refer to when you start to see repeating patterns.

Agree to disagree about "all of them accurate", I've already made my case elsewhere and doesn't really help anyone to re-iterate here what's public already.

What's not true in the two paragraphs I quoted there? I'm afraid I think I need that re-iterated!

Is this just about the usage of the term "from scratch"?

Which two day gap without commits? The blog was posted on Jan 14. There were commits on Jan 14 all the ways to Jan 18.

https://github.com/wilsonzlin/fastrender/commits/main/

Surely this would be push back to the CEO, not the engineer? The engineer is presumably the one telling the truth.

Either of them. If the CEO refuses to answer, you ask others. If you get a chance to talk with them, you ask them about it. Just ignoring the elephant in the room and hoping that the unclear details gets forgotten helps no one except Cursor here.

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