Bun 1.4 Rust rewrite is not looking good

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.'

Bun 1.4 Rust rewrite is not looking good I 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 . The 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. In the next version of Bun In the next version of Bun In the next version of Bun used 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: Jun 24 //xcancel.com/jarredsumner/status/2069905530370535628 Bun v1.4 ships July 7th. Jul 4 //xcancel.com/jarredsumner/status/2073498821083140523 Bun v1.4 hopefully Tuesday Jul 14 //xcancel.com/bunjavascript/status/2076926338951479669 In the next version of Bun Jul 20 //xcancel.com/bunjavascript/status/2079346398647177256 In the next version of Bun Jul 29 //xcancel.com/bunjavascript/status/2082298681223680002 Bun v1.4 fixes over 3000 issues over v1.3 Aug 1 //xcancel.com/bunjavascript/status/2083702383172075745 In the next version of Bun Aug 4 //xcancel.com/jarredsumner/status/2084447410567409776 In the next version of Bun Aug 7 //xcancel.com/jarredsumner/status/2085623648740941912 1 more PR to merge then it’ll be time for Bun v1.4 Aug 13 //xcancel.com/bunjavascript/status/2087841913210855533 Bun v1.4 is compiling. Aug 15 //xcancel.com/bunjavascript/status/2088580005655925167 Bun v1.4 is delayed until Monday Aug 17 //xcancel.com/jarredsumner/status/2089542355384947021 Let’s say tomorrow It’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: @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 We totally believe in you, Jarred Rejoice fellas, tomorrow in Jarred Standard Time zone means we have a new blog coming next week. You 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. How can we believe you? You always make promises that you can’t keep, tomorrow, next week, Monday... If you need 2 months to release it you can just say that instead of saying you’ll ‘release it tomorrow’ every week Bun on GitHub bun-on-github The Bun 1.4 rewrite is a big bet on AI. In the past month, 15.8k commits came from robobun, 1.6k commits from autofix-ci bot , and 790 commits from Jarred. 6 months ago, most of Bun’s PRs came from people prompting Claude. Nowadays, most of Bun’s PRs come from Claude prompting Claude. The 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. The 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 : We 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. What was the problem with Zig? what-was-the-problem-with-zig This 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. The 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. And 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. It 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. Maybe 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. And ‘tomorrow’ has come and gone. Still no v1.4. ¯\ ツ /¯