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Experimental Codex subscription support

ChemGraph can experimentally use the official Codex Python SDK with the ChatGPT-backed login already used by Codex CLI or the Codex IDE extension. This path does not use the OpenAI Platform API or OPENAI_API_KEY.

Install and authenticate

1. Install the Codex CLI

The openai-codex Python package provides the SDK and its internal runtime, but it does not install a codex command on your shell PATH. Follow the official Codex CLI installation guide, then verify that the command is available:

codex --version

2. Install the ChemGraph Codex extra

For a package installation:

pip install "chemgraph[codex]"

For an editable source checkout, install the extra into the active environment:

pip install -e ".[codex]"

3. Authenticate with ChatGPT

Use the separately installed CLI to authenticate Codex with ChatGPT:

codex login
codex login status

The active login must be a ChatGPT login. ChemGraph deliberately rejects a Codex session authenticated with an API key instead of silently falling back to usage-based OpenAI Platform billing.

Run ChemGraph

Prefix a model available to your Codex account with codex::

chemgraph \
  --model "codex:<codex-model-id>" \
  --workflow single_agent \
  --query "What is the SMILES string for aspirin?"

The same model syntax works through the Python API:

from chemgraph import ChemGraph

agent = ChemGraph(
    model_name="codex:<codex-model-id>",
    workflow_type="single_agent",
)

Current limitations

  • Only the single_agent workflow is supported.
  • The integration is experimental and pins openai-codex==0.144.4 together with that SDK's bundled Codex runtime.
  • ChemGraph starts ephemeral, read-only Codex threads. ChemGraph's LangGraph workflow executes chemistry tools; Codex is used only for model decisions.
  • ChemGraph does not start a login flow. Run codex login before initializing a codex: model.

See the official Codex SDK documentation, Codex CLI installation guide, and authentication guide for supported installation and account behavior.