Codex Setup

Codex is OpenAI's AI coding assistant. You can use it with either an API key or by logging in with your OpenAI account.

Install and Configure

Open a terminal (Terminal on macOS/Linux, PowerShell on Windows) and run the following commands.

1. Install codex-acp:

npm install -g @zed-industries/codex-acp

2. Find the installation path:

macOS/Linux

which codex-acp
# Example output: /usr/local/bin/codex-acp

Windows

where.exe codex-acp
# Example output: C:\Users\Username\AppData\Roaming\npm\codex-acp.cmd

3. Open Settings → Agent Client. The default command (codex-acp) works in many cases. If the agent is not found automatically, set the Codex path to the path found above, or click Auto-detect.

Authentication

Choose one of the following methods:

Option A: API Key

1. Get your API key from OpenAI Platform
2. Open Settings → Agent Client → Built-in agents → Codex → API key
3. Click the Link... button next to the API key field
4. In the Select secret dialog:
   • To use an existing secret: select it from the list and click Save
   • To create a new one: click Add secret..., enter an ID (lowercase letters, numbers, and dashes only — e.g., openai-api-key), paste your API key, then click Save

Once linked, the field shows the masked secret value with a Change button to swap secrets.

Managing secrets

API keys are stored in Obsidian's Keychain (Settings → Keychain). You can rename, edit, or delete secrets there at any time. The same secret can be shared across plugins by referencing the same ID.

Upgrading from a previous version

If you previously stored your OpenAI API key in this plugin (v0.10.x or earlier), it is automatically migrated to Obsidian's Keychain as openai-api-key the first time you load the upgraded plugin. A one-time notification confirms the migration.

If openai-api-key is already in use by another plugin with a different value, your key is preserved under agent-client-openai-api-key instead. You can rename it from Settings → Keychain if you prefer.

Option B: Account Login

If you have a ChatGPT subscription and prefer not to use an API key, you can log in with your OpenAI account.

Important

This requires installing Codex CLI separately. The CLI creates the login session that the plugin uses.

1. Install Codex CLI by running the following command in your terminal:

npm install -g @openai/codex

2. Login via CLI by running:

codex

Follow the prompts to authenticate with your OpenAI account.

3. In Settings → Agent Client, leave the API key field empty.

TIP

The ChatGPT app and Codex app use a different authentication system. Having ChatGPT running does not authenticate the plugin — you must log in via the CLI.

Verify Setup

1. Click the robot icon in the ribbon or use the command palette: "Open chat view"
2. Switch to Codex from the agent dropdown in the chat header
3. Try sending a message to verify the connection

Having issues? See Troubleshooting.