GPT-5.4 Now Available in Codex

TL;DR

• GPT-5.4 is now the default model in Codex with native computer-use capabilities
• Experimental 1M context window support for long-horizon tasks and complex workflows
• Available across CLI, IDE extension, Codex app, and API

New

• GPT-5.4 model — OpenAI's most capable frontier model for Codex, combining reasoning, coding, and agentic workflows in one model.
• Native computer-use capabilities — First general-purpose model in Codex with built-in computer-use support for agent automation.
• 1M context window (experimental) — Handle long-horizon tasks and complex multi-application workflows with stronger tool use and tool search.

How to Switch

• CLI: Start a new thread with codex --model gpt-5.4 or use /model during a session.
• IDE extension: Select GPT-5.4 from the model selector in the composer.
• Codex app: Choose GPT-5.4 from the model selector in the composer.
• API: GPT-5.4 is available for direct API calls.

Update your CLI, IDE extension, or Codex app to the latest version if GPT-5.4 doesn't appear in your model selector.

Source: Codex