Claude Code is entirely vibe-coded for a long time. Bun isn't. You go read and compare the actual Bun code; it reads reasonably well [1].
[1] For example, as a random sample, https://github.com/oven-sh/bun/blob/bun-v1.3.14/src/css/medi... -> https://github.com/oven-sh/bun/blob/4924862cffbf671792d47c92...
Sure, reasonably well at first glance, but to quote the article:
> I rewrote Bun in Rust using about 50 dynamic workflows in Claude Code run continuously over the course of 11 days.
> Excluding comments, Bun is 535,496 lines of Zig.
> How do you review a PR with +1 million lines added? How do you start to build the confidence needed to responsibly merge large quantities of LLM-authored code? A language-independent test suite with a million assertions, adversarial code review and when something does go wrong, fixing the process that generates the code instead of hand-fixing the code.
That’s vibe coding. This blog post is an ad for Claude, nothing more.
You're entitled to call things as you wish, of course, but your definition of "vibe-coding" differs quite a bit from mine.
500k lines in 11 days? With 8-hour working days that's 100 lines per minute. There's no way you're comprehensively reviewing code that quickly.
The code was generated by a LLM, and the output wasn't even read by its user. That's definitely vibe coding.
It's a direct translation without changing the overall code structure or data structures. I do think this process deserves a distinct name from blind whole-of-project vibe coding.
Translation does seem to be a strength of LLMs, and as they said in the post, the code at the function-level all still feels familiar to the team. They've also already moved users to the codebase without anyone noticing; that's a better result than typical vibe coding.
Doesn't look like vibecoding to me. It does look like a Claude ad, but they do have a vested interest in not screwing up Bun now that they own it.
What would be the consequence to them if they did screw it up? Screwing up the maintainability of a project, especially a big one, doesn't necessarily have immediate consequences. The fallout could be delayed by a year or more. Also, they have effectively limitless tokens to burn on keeping everything looking OK, and a vested interest in doing so.
I'm not trying to spin up some kind of conspiracy theory here, but I'm not sure to what extent Anthropic does have any vested interest in this project (in fiscal terms at least) because the reputational fallout could be significantly delayed and might just not be big enough to matter.
Claude Code is the main reason their revenue (ARR) grew from $9bn to ~$47bn in the first half of this year.
That's a very big reason not to screw this up.
It's far less obvious how choosing Bun results in more revenue for Anthropic. Unlike Claude Code, Bun doesn't require you to pay for tokens to use it
Bun powers Claude Code. If the rewrite introduced catastrophic bugs, it would cause catastrophic bugs in Claude Code and therefore without exaggeration could cause $billions of lost revenue.
There clearly aren't catastrophic bugs. The question is whether the artifact is maintainable over time, since clearly there's a massive amount of net new code that was not thoroughly reviewed. Give it a year or so and we'll know. I claim either way, it doesn't really matter to Anthropic--if it's a disaster they might be able to keep it limping along well enough by just throwing tons of tokens at it. The value in this is not the lasting software artifact, it's the marketing of the rewrite. If over time it turns out to be a great success, all the better!
That vibe coded app is generating billions. Does the word "vibe coded" mean anything anymore?