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

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Setup

Choose one authentication method: Pass --user to replicas codex-auth to save OAuth credentials to your account instead of sharing them with the organization. Personal credentials take priority over organization defaults. See Credentials for details.

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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 OpenAI account and its model access.

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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:

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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.

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Thinking levels

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

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Chat history

Codex sessions persist across turns and workspace sleep. Codex compacts its context automatically when needed. Use replicas read from the CLI to inspect transcript history.

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Programmatic Use

Select Codex anywhere Replicas accepts a coding agent:

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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.