Run long horizon tasks with CodexIn September 2025, OpenAI introduced GPT-5-Codex as the first version of GPT-5 optimized for agentic coding. In December 2025, we launched 5.2 which was the moment that people began to believe that using autonomous coding agents could be reliable. In particular, we saw a huge jump in how long the model could reliably follow instructions. I wanted to stress-test that threshold. So I gave Codex a bl
