Building Codex with Tibo Sottiaux
Summary
The Pragmatic Engineer interviews Teo, who led the Codex team at OpenAI, discussing the product’s origins, its decision to be built in Rust, and the strategic choice to keep the CLI open source. They explore how the engineering workflow has shifted to co-designing with models, allowing the harness to shrink as capabilities improve, and how Codex now supports third-party models to maintain user optionality. The episode also covers the transition from local to cloud execution and how internal teams use agents to streamline onboarding and development processes.
Listen ad-free on Castria