Cursor's latest "browser experiment" implied success without evidence

The comment that points out that this week-long experiment produced nothing more than a non-functional wrapper for Servo (an existing Rust browser) should be at the top:

https://news.ycombinator.com/item?id=46649046

The blog[0] is worded rather conservatively but on Twitter [2] the claim is pretty obvious and the hype effect is achieved [2]

CEO stated "We built a browser with GPT-5.2 in Cursor"

instead of

"by dividing agents into planners and workers we managed to get them busy for weeks creating thousands of commits to the main branch, resolving merge conflicts along the way. The repo is 1M+ lines of code but the code does not work (yet)"

[0] https://cursor.com/blog/scaling-agents

[1] https://x.com/kimmonismus/status/2011776630440558799

[2] https://x.com/mntruell/status/2011562190286045552

[3]https://www.reddit.com/r/singularity/comments/1qd541a/ceo_of...

I really doubt this marketing approach is effective. Isn't this just shooting themselves in the foot? My actual experience with Cursor has been: their design is excellent and the UX is great—it handles frontend work reasonably well. But as soon as you go deeper, it becomes very prone to serious bugs. While the addition of Claude's new models has helped somewhat, the results are still not as good as Google's Antigravity (despite its poor UX and numerous bugs). What's worse, even with this much-hyped Claude model, you can easily blow through the $20 subscription limit in just a few days. Maybe they're betting on models becoming 10x better and 10x cheaper, but that seems unlikely to happen anytime soon.

I'm eager to find out if this was actually successfully compiled at one point (otherwise how did they get the screenshots?), so I'm running `cargo check` for each of the last 100 commits to see if anything works. Will update here with the results once it's ready.

Edit: As mentioned, I ran `cargo check` on all the last 100 commits, and seems every single of them failed in some way: https://gist.github.com/embedding-shapes/f5d096dd10be44ff82b...

If you look at the original Cursor post, they say they are currently running similar experiments, for instance, this Excel clone:

https://github.com/wilson-anysphere/formula

The Actions overview is impressive: There have been 160,469 workflow runs, of which 247 succeeded. The reason the workflows are failing is because they have exceeded their spending limit. Of course, the agents couldn't care less.

The CEO said

> 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.

"From scratch" sounds very impressive. "custom JS VM" is as well. So let's take a look at the dependencies [1], where we find

- html5ever

- cssparser

- rquickjs

That's just servo [2], a Rust based browser initially built by Mozilla (and now maintained by Igalia [3]) but with extra steps. So this supposed "from scratch" browser is just calling out to code written by humans. And after all that it doesn't even compile! It's just plain slop.

[1] - https://github.com/wilsonzlin/fastrender/blob/main/Cargo.tom...

[2] - https://github.com/servo/servo

[3] - https://blogs.igalia.com/mrego/servo-2025-stats/

I think the original post was just headline bait. There is such a fast news cycle around AI that many people would take "Thousands of AI agents collaborate to make a web browser" at face value.

The latest commit now builds and runs (at least on my Mac). It’s tragically broken and the code is…dunno…something. 3m lines of something.

I couldn’t make it render the apple page that was on the Cursor promo. Maybe they’ve used some other build.

I haven’t studied the project that this is a comment on, but: The article notices that something that compiles, runs, and renders a trivial HTML page might be a good starting point, and I would certainly agree with that when it’s humans writing the code. But is it the only way? Instead of maintaining “builds and runs” as a constant and varying what it does, can it make sense to have “a decent-sized subset of browser functionality” as a constant and varying the “builds and runs” bit? (Admittedly, that bit does not seem to be converging here, but I’m curious in more general terms.)

These are stories that solely exist just to sell shovels and would cause one uninformed CEO to layoff actual humans.

I wonder who they actually tried to impress with that? People who understand and appreciate the difficulty of building a browser from scratch would surely be interested to understand what you (or your Agent) did to a degree that they would understand if you didn’t.

Key phrase "They never actually claim this browser is working and functional " This is what most AI "successes" turn out to be when you apply even a modicum of scrutiny.

Out of curiosity, what is the most difficult thing about building a browser?

> company claims they "built a browser" from scratch

> looks inside

> completely useless and busted

30 billion dollar VS Code fork everyone. When we do start looking at these people for what they are: snake oil salesmen.

They slop laundered the FOSS Servo code into a broken mess and called it a browser, but dumbasses with money will make line go up based on lies. EFF right off.

Cursor CEO got grilled in HN for a good reason.

Lesson 1:

Always take any pronouncement from an AI company (heavily dependent on VC and public sentiment on AI) with a heavy grain of salt..

hype over reality

I’m building an AI startup myself and I know that world and its full of hypsters and hucksters unfortunately - also social media communication + low attention span + AI slop communication is a blight upon todays engineering culture

This is why AI skeptics exist. We’re now at the point where you can make entirely unsubstantiated claims about AI capability, and even many folks on HN will accept it with a complete lack of discernment. The hype is out of control.

Are you telling me AI bros lying about their products? No way that ever happened…