OpenAI’s GPT-5.1-Codex-Max Hits GitHub Copilot Public Preview

OpenAI recently launched its upgraded coding model, GPT-5.1-Codex-Max, which it says is designed to handle long, complex engineering tasks, where an AI needs to plan, reason, and revise code across extended sessions without losing track of earlier steps.

One of the standout features of the GPT-5.1-Codex-Max is the new compaction system, which allows the model to keep massive tasks coherent, even when they run into the millions of tokens. Now, that same model is available in GitHub Copilot in preview for Copilot Pro, Pro+, Business, and Enterprise users.

Developers can select GPT-5.1-Codex-Max directly from the Copilot Chat model picker in Visual Studio Code, GitHub.com, GitHub Mobile (iOS and Android), and the Copilot CLI. Do note that this a gradual roll out, so nit everyone will see the model immediately.

If you are Enterprise and Business administrator, you must enable the model via Copilot settings for your organization. Pro and Pro+ users can simply select the model in the picker and confirm a one-time prompt. Those using Bring Your Own Key can enable GPT-5.1-Codex-Max by entering an API key in the model picker.