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

# Claude Code

> Run Anthropic's Claude Code against a project on your host

This example installs a pinned Claude Code release inside a Node.js microVM and opens it in a project mounted from your host. Claude Code can edit the checkout directly, while its installation, authentication, settings, and sessions stay on the sandbox's root disk.

## Run Claude Code

<Steps>
  <Step title="Start Claude Code">
    <Tooltip tip="Writable host-directory mounts are local-only. On microsandbox cloud, use the isolated-copy alternative and omit replace-on-create."><span className="msb-badge-local">Local-only <Icon icon="circle-info" size={11} /></span></Tooltip>

    Replace `./my-project` with the project directory you want Claude Code to work on:

    <CodeGroup>
      ```sh macOS & Linux theme={null}
      msb run -t --name claude-code-demo --replace \
        --cpus 2 --memory 4G --root-disk 4G \
        --mount-dir ./my-project:/workspace:rw \
        --workdir /workspace \
        node:24-bookworm-slim -- sh -lc '
          apt-get update &&
          apt-get install -y --no-install-recommends ca-certificates git &&
          npm install -g @anthropic-ai/claude-code@2.1.235 &&
          exec claude
        '
      ```

      ```powershell Windows theme={null}
      msb run -t --name claude-code-demo --replace `
        --cpus 2 --memory 4G --root-disk 4G `
        --mount-dir ./my-project:/workspace:rw `
        --workdir /workspace `
        node:24-bookworm-slim -- sh -lc '
          apt-get update &&
          apt-get install -y --no-install-recommends ca-certificates git &&
          npm install -g @anthropic-ai/claude-code@2.1.235 &&
          exec claude
        '
      ```
    </CodeGroup>

    Choose a terminal theme, then follow the sign-in prompts. If Claude Code cannot open a browser from the microVM, copy the displayed login URL and open it in a browser on your host.

    Anthropic recommends its standalone installer for normal host installations. This example uses the pinned npm package for a reproducible sandbox setup; the package installs the same platform-native Claude Code binary.

    <Tip>
      For an isolated workspace, or when using microsandbox cloud, replace `--mount-dir ./my-project:/workspace:rw` with `--copy-dir ./my-project:/workspace`.
    </Tip>
  </Step>

  <Step title="Start another session">
    After leaving Claude Code, return to the same sandbox and workspace with:

    ```sh theme={null}
    msb exec -t claude-code-demo -- claude
    ```

    The sandbox root disk retains Claude Code's authentication, configuration, and conversation state between sessions.
  </Step>

  <Step title="Verify the installation">
    Exit the TUI and run:

    ```sh theme={null}
    msb exec claude-code-demo -- claude --version
    ```

    The pinned example prints `2.1.235 (Claude Code)`.
  </Step>

  <Step title="Review or export changes">
    With the default writable mount, changes are already in the host checkout. Review them inside the sandbox:

    ```sh theme={null}
    msb exec claude-code-demo -- sh -lc 'cd /workspace && git status --short && git diff --stat && git diff'
    ```

    If you chose the isolated `--copy-dir` alternative, create a patch inside the sandbox:

    ```sh theme={null}
    msb exec claude-code-demo -- sh -lc 'cd /workspace && git add -N . && git diff --binary > /tmp/claude-code.patch'
    ```

    Copy the patch to the host:

    ```sh theme={null}
    msb cp claude-code-demo:/tmp/claude-code.patch ./claude-code.patch
    ```

    Check that it applies cleanly before applying it:

    ```sh theme={null}
    git apply --check ./claude-code.patch
    ```
  </Step>

  <Step title="Clean up">
    Remove the sandbox:

    ```sh theme={null}
    msb rm -f claude-code-demo
    ```

    Removing the sandbox also removes its Claude Code credentials, settings, and sessions. Changes made through the default workspace mount remain in the host checkout.
  </Step>
</Steps>

## Reference

* [Claude Code setup](https://code.claude.com/docs/en/setup)
* [Claude Code authentication](https://code.claude.com/docs/en/authentication)