> ## Documentation Index
> Fetch the complete documentation index at: https://docs.replicas.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Claude Code

> Run Claude Code agents in Replicas workspaces.

Replicas runs [Claude Code](https://code.claude.com/docs/en) inside isolated workspace VMs, with access to your repository, environment configuration, and integrations.

## Setup

Choose one authentication method:

* **Claude OAuth:** Run `replicas claude-auth` to connect an existing Claude subscription.
* **Anthropic API key:** Add a key under [Organization → Coding Agents](https://replicas.dev/dashboard/agents).
* **Microsoft Foundry:** Add a Foundry API key, resource name, and optional Claude deployment names under [Organization → Coding Agents](https://replicas.dev/dashboard/agents).
* **AWS Bedrock:** Add AWS credentials and a region under [Organization → Coding Agents](https://replicas.dev/dashboard/agents).

`replicas claude-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 Claude subscription with every member of the active organization. See [Credentials](/admin/credentials) for details, and [`replicas org`](/features/cli#switch-organization) to check which organization is active.

## Models

Replicas supports Claude Fable, Opus, Sonnet, and Haiku models. Set the organization default under [Organization → Settings → Preferences](https://replicas.dev/dashboard/settings?tab=defaults), or choose a model for an individual chat.

The available models depend on the authentication method and model access on the connected Anthropic or Bedrock account.

Organization admins can hide models the team cannot access by expanding **Claude → Models** in [Coding Agents settings](https://replicas.dev/dashboard/agents). The selection applies to workspace, automation, and default-setting pickers.

## Using Claude Code in Workspaces

In a workspace, use the composer's harness/model picker to choose **Claude Code** and start or continue a session. Claude Code can:

* Read and edit files and run shell commands
* Use environment [skills and MCP servers](/features/environments)
* Create branches, commits, and pull requests
* Run background Bash, Agent, and Monitor tasks
* Use [Plan Mode](/features/workspaces/plan-mode)

Background task status and output appear in the transcript and can continue across turns. See [Workspace background tasks](/features/workspaces/overview#background-tasks).

### Fast Mode

[Fast Mode](/features/workspaces/fast-mode) is available for Claude Opus models. Start a message with `/fast` or use the lightning toggle in the composer.

### Thinking levels

Use **Ultracode** in the thinking picker to combine `xhigh` effort with Claude Code dynamic workflows when supported by the connected model and plan.

### Chat history

Claude Code sessions persist across turns and workspace sleep. Send `/compact` to compact the active session without starting a new one, or use `replicas read` from the [CLI](/features/cli) to inspect transcript history.

## Programmatic Use

Select Claude Code anywhere Replicas accepts a coding agent:

| Surface                                                                                                      | How to choose Claude Code                                                 |
| ------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------- |
| [CLI](/features/cli)                                                                                         | `-a claude` on `replicas create` and `replicas send`                      |
| [API](/features/api)                                                                                         | `"coding_agent": "claude"` on create and message requests                 |
| [MCP](/features/mcp)                                                                                         | `"coding_agent": "claude"` on `create_replica` and `send_replica_message` |
| [Automations](/features/automations)                                                                         | Set **Coding agent** to Claude Code                                       |
| [Slack](/features/slack), [Linear](/features/linear), [GitHub](/features/github), [GitLab](/features/gitlab) | Set Claude Code as the [default coding agent](/admin/defaults)            |

```bash theme={null}
replicas create fix-checkout \
  -e frontend \
  -a claude \
  -m "Fix the checkout validation error"
```

## When to Use Claude Code

Claude Code is a strong fit when you want Anthropic-native agent behavior, long-running background tasks, or Claude skills and commands. Use Codex when you need Codex goal mode or OpenAI-native models; use Cursor or Opencode when you prefer their model and authentication ecosystems.