Introducing GPT-5.2-Codex: Enhanced Agentic Coding Model
Published:Dec 19, 2025 05:21
•1 min read
•Simon Willison
Analysis
This article announces the release of GPT-5.2-Codex, an enhanced version of GPT-5.2 optimized for agentic coding. Key improvements include better handling of long-horizon tasks through context compaction, stronger performance on large code changes like refactors, improved Windows environment performance, and enhanced cybersecurity capabilities. The model is initially available through Codex coding agents and will later be accessible via the API. A notable aspect is the invite-only preview for cybersecurity professionals, offering access to more permissive models. While the performance improvement over GPT-5.2 on the Terminal-Bench 2.0 benchmark is marginal (1.8%), the article highlights the author's positive experience with GPT-5.2's ability to handle complex coding challenges.
Key Takeaways
- •GPT-5.2-Codex is optimized for agentic coding with improvements in several key areas.
- •The model will be available through Codex coding agents and later via API.
- •Cybersecurity professionals have access to a more permissive version through an invite-only preview.
Reference
“GPT‑5.2-Codex is a version of GPT‑5.2 further optimized for agentic coding in Codex, including improvements on long-horizon work through context compaction, stronger performance on large code changes like refactors and migrations, improved performance in Windows environments, and significantly stronger cybersecurity capabilities.”