{"slug": "bun-1-4-rust-rewrite-is-not-looking-good", "title": "Bun 1.4 Rust rewrite is not looking good", "summary": "Bun 1.4, the JavaScript runtime by Oven-Sh, has been delayed for over three months, with its creator Jarred Sumner repeatedly promising imminent releases that have not materialized, according to a blog post by developer Tero Pihlaja. The project has accumulated over 5,000 open pull requests, and the rewrite has been heavily automated, with 15.8k commits from robobun and 1.6k from autofix-ci[bot] in the past month, compared to 790 from Sumner. Zig creator Andrew Kelley expressed horror at the code quality, citing 'hacks on top of hacks' and 'abuse of assertions.'", "body_md": "# Bun 1.4 Rust rewrite is not looking good\n\nI care about Bun. I have been rooting for it since the initial release in 2022. I switched all my development from Node to Bun. I used it in the development of the [Nue framework](//nuejs.org) and now with my new project [Hertta](//hertta.ai).\n\nThe last three months have not looked good for Bun. It started as one of the most impressive individual engineering projects I have seen, but has now turned into this weird AI-powered creature with continuous false promises and an increasingly frustrated community.\n\nIn the next version of Bun\n\nIn the next version of Bun\n\nIn the next version of Bun\n\nused to be a positive tweet to watch for. For years it meant a feature had been implemented, tested, and would ship in a few days. This changed after the Rust rewrite. Now the posts are false promises about the upcoming release:\n\n[Jun 24](//xcancel.com/jarredsumner/status/2069905530370535628)\n\nBun v1.4 ships July 7th.\n\n[Jul 4](//xcancel.com/jarredsumner/status/2073498821083140523)\n\nBun v1.4 hopefully Tuesday\n\n[Jul 14](//xcancel.com/bunjavascript/status/2076926338951479669)\n\nIn the next version of Bun\n\n[Jul 20](//xcancel.com/bunjavascript/status/2079346398647177256)\n\nIn the next version of Bun\n\n[Jul 29](//xcancel.com/bunjavascript/status/2082298681223680002)\n\nBun v1.4 fixes over 3000 issues over v1.3\n\n[Aug 1](//xcancel.com/bunjavascript/status/2083702383172075745)\n\nIn the next version of Bun\n\n[Aug 4](//xcancel.com/jarredsumner/status/2084447410567409776)\n\nIn the next version of Bun\n\n[Aug 7](//xcancel.com/jarredsumner/status/2085623648740941912)\n\n1 more PR to merge then it’ll be time for Bun v1.4\n\n[Aug 13](//xcancel.com/bunjavascript/status/2087841913210855533)\n\nBun v1.4 is compiling.\n\n[Aug 15](//xcancel.com/bunjavascript/status/2088580005655925167)\n\nBun v1.4 is delayed until Monday\n\n[Aug 17](//xcancel.com/jarredsumner/status/2089542355384947021)\n\nLet’s say tomorrow\n\nIt’s now three months and counting since the last stable release, the longest gap in Bun’s history since 2022. Nothing unusual there. Software slips, that’s normal. It’s just that an account which used to communicate with real dates and real numbers has switched to vibing. And the user reaction is what you’d expect after constant false promises:\n\n@jarredsumner okay I’m editing blog post it’s mostly done if I say a date you won’t believe me but let’s say tomorrow\n\nWe totally believe in you, Jarred\n\nRejoice fellas, tomorrow in Jarred Standard Time zone means we have a new blog coming next week.\n\nYou won’t care, but personally I am switching to go now. It’s not even funny, you are just stringing your users along again and again.\n\nHow can we believe you? You always make promises that you can’t keep, tomorrow, next week, Monday...\n\nIf you need 2 months to release it you can just say that instead of saying you’ll ‘release it tomorrow’ every week\n\n[Bun on GitHub](#bun-on-github)\n\nThe Bun 1.4 rewrite is a big bet on AI. In the past month, 15.8k commits came from robobun,\n\n1.6k commits from autofix-ci[bot],\n\nand 790 commits from Jarred.\n\n6 months ago, most of Bun’s PRs came from people prompting Claude. Nowadays, most of Bun’s PRs come from Claude prompting Claude.\n\nThe project has over [5k open pull requests](//github.com/oven-sh/bun/pulls), which is the largest number of pull requests I’ve seen. For comparison, [OpenClaw](//github.com/openclaw/openclaw/pulls) has 2.2k, and [React](//github.com/facebook/react/pulls) has 441. GitHub recommends staying under 1,000 open PRs against a single branch before mergeability checks start timing out.\n\nThe biggest worry is, of course, the code itself. In the early days Jarred’s work was inspirational. I thought he was a true Zig talent, until I read Zig creator Andrew Kelley’s [thoughts on the Bun rewrite](//andrewkelley.me/post/my-thoughts-on-the-bun-rust-rewrite):\n\nWe became increasingly horrified at the programming practices we saw in Bun’s codebase. Hacks on top of hacks. Abuse of assertions. Jarred was already writing slop well before he had access to LLMs.\n\n[What was the problem with Zig?](#what-was-the-problem-with-zig)\n\nThis rewrite is *the* most closely watched real-world test of whether AI agents can take over a production codebase with a human mostly directing rather than reading. Anthropic’s own reputation is also on the line: if this goes well, it is real proof of what agentic coding can do. If it goes badly, it will send a signal in the opposite direction.\n\nThe number of unsafe blocks in the Rust code suggests the rewrite did not deliver the memory safety that was given as the reason for doing the rewrite in the first place. Instead this rewrite feels more like an Anthropic ad.\n\nAnd was Zig really the problem? Bun’s early identity was built on Zig: its performance, its fast compile times, its low friction, its direct memory control with a small team.\n\nIt feels like Jarred and Anthropic decided early on that this was going to be written in Rust, and used Zig’s memory issues as the excuse to let the world know how powerful Claude is. A rewrite like this would make great headlines, and it certainly did. Now we’re looking at the long tail of issues from the rewrite they didn’t prepare for.\n\nMaybe Bun should have put that same AI-assisted effort into disciplined, human-understood Zig instead of a full language change. I never saw Jarred seriously engage with this option.\n\nAnd ‘tomorrow’ has come and gone. Still no v1.4.\n\n`¯\\_(ツ)_/¯`", "url": "https://wpnews.pro/news/bun-1-4-rust-rewrite-is-not-looking-good", "canonical_source": "https://tipiirai.com/writing/bun-rust-rewrite-worries", "published_at": "2026-08-19 05:51:17+00:00", "updated_at": "2026-08-19 06:11:20.438548+00:00", "lang": "en", "topics": ["developer-tools", "ai-tools"], "entities": ["Bun", "Oven-Sh", "Jarred Sumner", "Tero Pihlaja", "Andrew Kelley", "robobun", "autofix-ci[bot]", "Zig"], "alternates": {"html": "https://wpnews.pro/news/bun-1-4-rust-rewrite-is-not-looking-good", "markdown": "https://wpnews.pro/news/bun-1-4-rust-rewrite-is-not-looking-good.md", "text": "https://wpnews.pro/news/bun-1-4-rust-rewrite-is-not-looking-good.txt", "jsonld": "https://wpnews.pro/news/bun-1-4-rust-rewrite-is-not-looking-good.jsonld"}}