Codex Lead Tibo Sottiaux on Rust Rewrite, AI Code Review, and the ChatGPT Merger
AI寒武纪 · wechat · 2026-09-11
A rundown of Codex product lead Tibo Sottiaux's hour-long Pragmatic Engineer interview, via AI寒武纪:
- Background: Belgian applied-math founder (supply-chain optimization), ex-DeepMind infra lead where his team built a ChatGPT-like internal chat tool a year before ChatGPT — killed by Google's release process. Joined OpenAI in 2024, drawn by a 20-engineer team running ChatGPT.
- Codex origins: grew from internal agents trained on OpenAI's own Python repos to speed up research, merged with the ASWE autonomous software engineer project; the lightweight Codex CLI followed a high-friction cloud version.
- Rust core: chosen over Python/TS despite weaker model generation — the compiler's strict checks double as the model's self-correction tool, and the frontend/engine split prevents coupled spaghetti code.
- Fully open source, no model lock-in: CLI, SDK, and server are open; Anthropic models plug in natively. Costs: fast copycats and floods of low-quality PRs.
- Frameworks are crutches: prompts and scaffolding keep shrinking as models internalize behaviors like running tests; the team waits for the next model checkpoint rather than patching frameworks.
- AI-run code review: every PR passes automated AI security audits that block risky merges; humans only debate intent and architecture contracts. Major dependency upgrades and refactors now take hours to days.
- The merger: embedding local Codex into ChatGPT's cloud via Kata-container virtualization, giving $20/month Plus users dedicated compute.
Related event: OpenAI Codex Lead on Rust Rewrite, Open Source and AI Code Review(3 posts)→
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