OpenAI's code model of August 2021, the engine inside GitHub Copilot and the first thing the company shut down with a short notice, in March 2023, after which the name lay unused for two years and came back in May 2025 attached to a coding agent that runs in a cloud sandbox. The record notes that the same name has therefore been a model, a dead model and an agent, and that users use it for all three.
16 May 2025, the Codex agent launched inside ChatGPT for Pro and Team subscribers, running tasks in parallel in isolated containers. The record notes the name recognition was worth more than a new one.
Correction: the 2025 Codex is not the 2021 Codex updated. It is a separate product on separate models, with a command-line tool of the same name released in April 2025; the record keeps one entry because the internet does.
March 2023, developers receiving notice that the Codex models would be turned off in three days, and the resulting thread in which people asked what 'deprecated' meant when it happened that fast. OpenAI extended access to researchers.
The record notes that Codex was the first AI product to have a second life under its own name, and that this confuses every search for it, which the record suspects is not the point but is the effect.
What does it mean? Write it the way you would say it out loud.
