Audit Puts Bun's Rust Rewrite at $800K, Not $165K

An independent audit puts Bun's Rust rewrite at roughly $800,000, nearly five times the original $165,000 estimate, per Tom Lockwood's July 27 review.

For Bun users, that gap means still no release tag six weeks after the July 8 announcement. The project hadn't shipped an actual release in 11 weeks. For anyone pricing an AI-driven rewrite of their own, it's the first outside look at what happens once the merge queue starts filling up.

Bun announced the rewrite on July 8. It framed the job as an 11-day sprint, running about $15,000 a day in API calls.

The project's proxy repo, robobun, held 2,475 open pull requests on July 27, up from 1,277 on July 9. Lockwood estimates clearing that backlog alone would take roughly 86 days of continuous merging.

His $800,000 figure adds Buildkite CI time and expanded human code review on top of the original spend. It also factors in possibly $10,000 a day in continuing API credits.

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The original estimate priced the API calls that write Rust, not the humans who have to read, test, and merge what comes out. If the open PR count keeps climbing past 2,475, Lockwood's 86-day backlog estimate will look optimistic.