Connect your Claude or ChatGPT subscription

If you already pay for Claude (Pro or Max) or ChatGPT (Plus or Pro), Atomic Agent can run on that plan instead of an API key. It does this through the vendor’s own command line tool: Claude Code for Claude, Codex for ChatGPT. You sign in to that tool once, and the agent uses it as its engine. There is no key to paste and no per-token bill from us.

Atomic Agent still plans the work, runs the tools and keeps the memory. The CLI only answers each step, so your requests go to Anthropic or OpenAI the same way they do when you use Claude Code or Codex yourself, and they count against your plan’s limits.

Developer Preview

Atomic Agent is a Developer Preview. Command names, flags, config keys and defaults can still change between releases.

1. Install the CLI

You need the CLI for the plan you want to use. Skip this step if it is already installed.

Claude (macOS, Linux)

curl -fsSL https://claude.ai/install.sh | bash

Claude (Windows)

In PowerShell:

irm https://claude.ai/install.ps1 | iex

ChatGPT (Codex)

Needs Node.js:

npm install -g @openai/codex

2. Sign in

Sign in with the account that has the plan.

Plan	Run	Then
Claude	claude	Follow the sign-in. If it does not ask, type /login. Pick your Claude account, not an API key.
ChatGPT	codex login	Choose Sign in with ChatGPT and finish in the browser.

In the desktop app you can skip typing these: the setup step has a Sign in with Claude or Sign in with ChatGPT button that opens a terminal with the sign-in already running.

3. Pick it in Atomic Agent

Desktop app

1. Open Add provider (in first-run setup, or Settings › Models).
2. Choose Claude Code subscription or OpenAI Codex subscription.
3. The step checks the CLI for you and shows one of three things:
   • Not installed: the install command, with a Copy button.
   • Not signed in: press Sign in with Claude (or ChatGPT). A terminal window opens with the sign-in running. Finish in the browser and the step moves on by itself.
   • Signed in: press Use my Claude subscription (or ChatGPT).
4. Pick a model and start chatting.

Terminal (TUI)

1. Run atag and type /providers.
2. Add a provider and choose Claude Code subscription or OpenAI Codex subscription.
3. One line under the step says whether the CLI is ready, or gives the command to install it or sign in.
4. Press Enter to save. For Codex, leave the model empty: the CLI picks the model your account supports.

To check from a script or a shell at any time:

atomic-agent providers status

It prints, for Claude Code and Codex, whether each is installed, signed in, and which version. It runs --version and codex login status only, never a real request, so it does not use your plan. Add --cli claude or --cli codex for one, and --json for machine-readable output.

Tip

Claude Code has no command that says whether you are signed in. Atomic Agent reads Claude Code’s own account file to tell. When it cannot read it, the status says it can’t verify the login instead of sending a test request that would use your plan.

In the config file

The wizard writes an entry like this to config.json. You can also add it by hand:

{
  "id": "claude-cli",
  "kind": "subscription-cli",
  "subscriptionCli": { "cli": "claude" }
}

Use "cli": "codex" for ChatGPT. If the CLI is installed somewhere the agent does not look, add "binPath" with the full path to the binary. All keys are in Models › Provider fields.

Common errors

“Claude Code is not installed” or “codex is not installed” The agent could not find the CLI. Install it (step 1), then press Check again in the desktop app or reopen /providers. If it runs fine in your own terminal but the app cannot see it, the CLI is outside the app’s search path: set subscriptionCli.binPath to the full path (which claude or which codex prints it).

“is not signed in”, or the first answer says you are signed out The sign-in is missing or has expired. Run claude and /login, or codex login, and try again.

Codex bills per token instead of your plan Codex was signed in with an API key, not ChatGPT. The desktop step and providers status say so. Run codex login and choose Sign in with ChatGPT.

ANTHROPIC_API_KEY or OPENAI_API_KEY is set These variables make the CLIs bill your API account per token. Atomic Agent starts the CLI without them (and without ANTHROPIC_BASE_URL, OPENAI_BASE_URL, CODEX_API_KEY and the Bedrock and Vertex switches), so the agent uses your plan. The setup still warns you, because a claude or codex you start yourself in that shell would pick them up.

You hit your plan’s limit Requests from Atomic Agent count against the same limits as Claude Code or Codex. When the plan says you are out, wait for the limit to reset, or switch to another provider for now.