Jarred Sumner
Founder of bun (2021) and, after the acquisition, Member of Technical Staff at anthropic. He wrote Bun originally in Zig, including the line-for-line port of esbuild’s transpiler, and in 2026 he led its rewrite into Rust using Claude agents, documenting the method in “Rewriting Bun in Rust” (2026-07-08) https://bun.com/blog/bun-in-rust: mechanical, test-anchored, dynamic workflows, adversarial review loops, the whole port done in days against an estimate of a year for a small team. His May 2026 note on dynamic workflows and adversarial code review is the how-to detail behind the number https://x.com/jarredsumner/status/2060050578026189172.
Sumner is also the most candid pro-Rust witness in the rust-for-agents record, because he spent the first half of his own post praising Zig and naming the failure modes, and because the post-merge regressions (19, all fixed) were his disclosure. The Register’s account of the zig-camp reaction to the rewrite https://www.theregister.com/devops/2026-07-14/zig-creator-calls-buns-claude-rust-rewrite-unreviewed-slop/5270743 belongs to the story of the port, not to him directly.
Sources
- “Rewriting Bun in Rust”, 2026-07-08: https://bun.com/blog/bun-in-rust
- Post on dynamic workflows, 2026-05-28: https://x.com/jarredsumner/status/2060050578026189172
- “Bun is joining Anthropic”, 2025-12-02: https://bun.com/blog/bun-joins-anthropic