I wish this was clickbait

TL;DR

Bun is being AI-rewritten from Zig to Rust in days, raising real concerns about stability, unsafe code, and Anthropic's influence on its future.

Key Points

• 1.Bun is being rewritten from Zig to Rust using AI agents in under a week. Jared Palmer started the rewrite six days ago; 99.8% of Bun's pre-existing test suite already passes on Linux x64, and Bun 1.3.14 may be the last Zig version.
• 2.Zig's power comes with serious foot guns. Zig lacks memory safety guarantees, has community tensions with the Bun team, and caused real stability issues — especially on Windows — motivating the switch to Rust's borrow checker.
• 3.Dax from OpenCode is migrating off Bun to Node.js for multiple reasons. Windows instability, Electron incompatibility, inability to spawn separate processes, and most critically, uncertainty about Bun's future under Anthropic ownership.
• 4.Bun's acquisition by Anthropic in December 2025 is the central concern. Claude Code ships as a Bun executable to millions, giving Anthropic direct incentive to maintain Bun — but as Claude Code has degraded in quality, that reassurance feels hollow.
• 5.The Rust rewrite contains 13,044 unsafe calls across 681,000 lines of Rust. For comparison, UV (a similar Rust tool by the same Charlie) has only 73 unsafe calls across 350,000 lines — meaning Bun is essentially writing C++ with Rust syntax, not idiomatic Rust.
• 6.The TypeScript-to-Go port offers a useful precedent for line-by-line rewrites. The TypeScript team intentionally ported code non-idiomatically first, achieving speed gains purely from native compilation, then optimized later — the same approach Bun is taking.
• 7.Bug prioritization is a hidden risk of the rewrite. If 10 existing Bun issues balloon to 100 post-rewrite, issues affecting Claude Code will get fixed while monorepo/package-management bugs for general users risk being permanently deprioritized.
• 8.Jared pledges the Rust port will only ship if it's measurably better in performance, memory, and stability. Despite concerns about Anthropic's policies creeping into Bun, the creator still trusts Jared personally and sees real upside if the rewrite succeeds.