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The app keeps your ChatGPT sign-in for OpenAI model turns. ChatGPT in a browser at chatgpt.com isn’t supported. The app and the Codex CLI share ~/.codex/config.toml, so connecting one connects the other.

Quick start

Install and sign in

You need Node.js 22 or later, git, and bash. On Windows, run the installer from Git Bash. PowerShell breaks the script’s line endings.
Sign in with your browser, or paste a Fireworks API key (fw_...).If the Nexus CLI is already installed and signed in, skip to step 2.

Connect the ChatGPT desktop app

Quit the ChatGPT desktop app and close open Codex sessions, then run:

Reopen the app and pick Auto

Reopen the app. Nexus Auto appears along with your ChatGPT models.
ChatGPT desktop model picker showing GPT-6 Astra, GPT-6.1 Sol, and GPT-6 Luna, then Auto selected

ChatGPT desktop after Nexus CLI, with Auto selected

To restore your original settings, run nexus chatgpt off.

Use Nexus Auto

MCP and tools

  • MCP servers, plugins, and ChatGPT connectors are unchanged.
  • Native web search is supported. Fireworks runs the search server-side, so no search MCP server is required.

Troubleshooting

  • The 'auto' model is not supported when using Codex with a ChatGPT account: the thread started on an OpenAI model before you connected, and threads keep the provider they started on. Start a new thread to use Nexus Auto and Fireworks models.

Manual setup (advanced)

Quit the app, follow the Codex manual setup, then reopen the app and pick the model you set.