Interestingly I just skimmed through a video linked in TFA: https://www.youtube.com/watch?v=SlGRN8jh2RI and Boris Cherny explains that they chose TypeScript and React for Claude Code primarily because it was "on distribution" and the models back then just weren't good enough at other languages.

So it's interesting that Codex is written in Rust. Amongst other things it could mean OpenAI had more powerful models that could handle Rust, or their engineers had to handhold the agents a lot more up front, or Rust has structural advantages that could overcome being less represented in the training data.

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mnicky 3 hours ago | parent | next [-]

Well, Codex came long after Claude Code, no? So at that time the situation with models and Rust support was probably already different...

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cmrdporcupine 3 hours ago | parent | prev [-]

Codex also I think put its first version out a bit later?

IMHO building the agent harness at least partially by hand is kind of key? I think going hogwild with "vibe coding" the actual harness is partially why CC is a bit of a rats nest. I think it's genuinely gotten out of control in terms of their ability to reason about it. Just my opinion, I'm sure Boris disagrees.

Also Codex itself distributed via NPM same as Claude. But it distributes a compiled Rust binary. Which is compiled from open source.

	▲	keeda 3 hours ago \| parent [-]
		I used to think Claude Code was released much earlier too, and my initial theory was that OpenAI as a follower had the benefit of more powerful models... but when I looked it up, Codex was first released in April 2025 [1], whereas CC Beta was released in Feb 2025 [2] -- only a couple of months apart! I'm sure each lab is keenly aware of what the other is doing (how else could they time so many of their releases so close to each other?) so it's highly probable they started developing each app about the same time, and likely even knew the technical details involved. Which is why it's additionally interesting that OpenAI started off with Rust while CC used Electron. 1. https://techcrunch.com/2025/04/16/openai-debuts-codex-cli-an... 2. https://github.com/jqueryscript/anthropic-claude-timeline