Skip to main content
Replicas runs Codex inside isolated workspace VMs, with access to your repository, environment configuration, and integrations.

​
Setup

Choose one authentication method:
  • OpenAI OAuth: Run replicas codex-auth to connect an existing ChatGPT subscription.
  • OpenAI API key: Add an OpenAI API key under Organization → Coding Agents.
  • OpenAI compatible: Add a Responses API-compatible endpoint with an API key or exact Authorization header. Replicas reads models from <endpoint>/models unless you provide a separate models endpoint.
  • Microsoft Foundry: Add an Azure OpenAI API key, base URL, and model deployment under Organization → Coding Agents.
replicas codex-auth saves to your personal account, which works in every organization you belong to and takes priority over organization defaults. Admins can pass --org to share one ChatGPT subscription with every member of the active organization. See Credentials for details, and replicas org to check which organization is active.

​
Models

Replicas supports the current GPT coding model family exposed in the workspace model picker. Set the organization default under Organization → Settings → Preferences, or choose a model for an individual chat. The available models depend on the connected credential. For an OpenAI-compatible endpoint, use Check models while connecting it to verify the catalog and preview the models that will appear in Codex pickers. The endpoint must return an OpenAI-compatible { "data": [...] } response whose entries contain id (or model); cursor pagination may use has_more and next_cursor. Every model available through the active Codex credential appears in the workspace, automation, and default-setting pickers, including models added later. Organization admins can hide individual built-in models, as long as one stays visible, under Codex → Models in Coding Agents settings; an OpenAI-compatible endpoint’s catalog is shown as returned. Older workspaces can hide models that require a newer Codex runtime. Start a new workspace to use a model that does not appear.

​
Using Codex in Workspaces

In a workspace, use the composer’s harness/model picker to choose Codex and start or continue a session. Codex can:

​
Goal Mode

Use /goal <objective> to give the thread a persistent objective. Pause, resume, or remove it with /goal pause, /goal resume, or /goal clear. The active goal appears above the composer and on the chat tab.

​
Thinking levels

Use Ultra in the thinking picker for Codex models that support the ultra reasoning effort.

​
Chat history

Codex sessions persist across turns and workspace sleep. Codex compacts its context automatically when needed; send /compact to compact the active conversation manually. Use replicas read from the CLI to inspect transcript history.

​
Programmatic Use

Select Codex anywhere Replicas accepts a coding agent:

​
When to Use Codex

Codex is a strong fit when you want OpenAI-native coding models, steerable active turns, or a persistent goal for longer work. Use Claude Code when you need Claude background tasks; use Cursor or Opencode when you prefer their model and authentication ecosystems.