I'm not sure Anthropic even cares about "releasing" the next version. The rust one has been in use in Claude Code for more than a month now, used by millions of people, and that's as far as they probably really worry about it. They bought Bun for Claude Code and I doubt the open source project matters to them otherwise.

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mikeocool 2 hours ago | parent | next [-]

If that is really what they are concerned with, they probably could have just had Claude Code rewrite Claude Code in rust? That likely would be far more efficient than changing the language of your typescript runtime that ships to run your react-based CLI app.

I imagine the $800k or whatever this has cost is coming out of Anthropic's marketing budget, so they can make a big splash about it.

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neuronexmachina 2 hours ago | parent [-]

> If that is really what they are concerned with, they probably could have just had Claude Code rewrite Claude Code in rust

Rewriting a runtime with well-defined interfaces and behavior is quite different from rewriting a user-facing application under active development by a decent chunk of their organization.

	▲	SpicyLemonZest 26 minutes ago \| parent [-]
		I agree, but this difference is very frustratingly omitted from the hype-sphere surrounding the rewrite, even though most software developers don't work on a runtime with well-defined interfaces and behavior. I know a number of people who've developed severe FOMO that their projects take longer than 2 weeks and maybe it's because they're not AI native enough. (I don't mean to be critical of the Bun maintainers, who have always been open about the fact that they leveraged the specific context of their project to do this effectively.)

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usef- 3 hours ago | parent | prev | next [-]

I very much doubt they would want to abandon the wider community. They do benefit from others using it.

To the contrary, I think any problem with this release would be jumped on harshly so they're being more careful than usual. There's not a rush for the community to move to 1.4 and any issues could poison the community trust.

	▲	egorfine 11 minutes ago \| parent [-]
		Like this rewrite did not terminally poison trust?

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pornel 2 hours ago | parent | prev | next [-]

It's just a marketing stunt. They've got the ad for Claude-powered code rewrites, and that worked beautifully. Everyone got the message: spend big bucks with Anthropic to get rid of whatever codebase bugs you - please, think of the IPO!

If it was about Claude Code itself, they could have rewritten it. They keep saying they don't even write code any more, so it shouldn't even matter what language it's in.

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rienbdj 3 hours ago | parent | prev [-]

Anyone know why? Can’t CC run on any JS runtime?

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Atotalnoob 2 hours ago | parent | next [-]

Yes, but it’s slower on non-bun runtimes. Nowadays, I believe they bundle bun with CC

They chose to use a react rendering to native TUI renderer, which was a source of a lot of performance issues.

AFAIK, they have written a new renderer.

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jFriedensreich 3 hours ago | parent | prev [-]

because their js code is so bad and slow that they need the bun performance hacks and optimisations.

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jdiff 2 hours ago | parent [-]

Do these hacks make bun less secure than other runtimes? I find it a little hard to believe you can get much more robust and performant than V8 or SpiderMonkey without cutting some corners that notably went uncut by either for all these years.

	▲	msdz an hour ago \| parent \| next [-]
		Bun uses JavaScriptCore, which is Safari’s JS engine, for the actual interpreter portion of its runtime. Which makes the parent comment’s “Bun performance hacks and optimizations” sound a little far-fetched, at least in this scenario I don’t think that’s gonna be the deciding factor. Their vendored JSC is also not touched by this port-rewrite at all whatsoever (still Cpp), so I’m not sure if it’s even possible to hack-improve all that much there.
	▲	jFriedensreich 27 minutes ago \| parent \| prev [-]
		yes, especially compared to deno bun does not have proper isolation or permissions at runtime layer which is why anthropic tries to fix the lack by a mixture of app layer (build into claude code) and os layer (srt) however using runtime permissions would allow much better security if done right.