Codex extension (VS Code / Cursor)

1. First follow Codex CLI to write ~/.codex/auth.json and ~/.codex/config.toml. These are the two files the extension reads.

2. Search for Codex in the VS Code or Cursor extension marketplace and install the official extension whose publisher is OpenAI.

3. Restart the editor and open the Codex panel. If the extension asks you to choose a sign-in method, choose the API key method. When the config files are already written, it usually goes straight in.

4. Send a message. If it replies normally, the setup is done.

The model you want isn’t in the dropdown?

The extension’s model list is sometimes out of sync. This doesn’t stop you from using the model. Set model = "gpt-5.4" in config.toml (replace it with the model name you looked up).

Changed the config and nothing happened?

After you edit config.toml, fully quit the editor and open it again. Closing the panel doesn’t reload the config.