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Dev Container runtime runs each workspace in a container built from your project’s devcontainer.json. If your project already uses dev containers for VS Code or other editors, Mux can use the same configuration.

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Requirements

  • Dev Container CLI: npm install -g @devcontainers/cli
  • Docker daemon running
  • A devcontainer.json in the project

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How it works

  1. Mux creates a git worktree on the host machine
  2. Runs devcontainer up to build/start the container
  3. Commands execute inside the container via devcontainer exec
  4. Deleting the workspace stops the container and removes the worktree

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Configuration

Select Dev Container in the workspace creation UI. If your project has multiple configs, choose one from the dropdown. Mux searches these locations:
  • .devcontainer.json
  • .devcontainer/devcontainer.json
  • .devcontainer/*/devcontainer.json (named configs)

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Credential sharing

Like the Docker runtime, you can check “Share credentials” to enable git authentication inside the container:
  • SSH agent forwarding — Your SSH keys work without copying private keys
  • Git config — Host ~/.gitconfig is copied into the container
  • GitHub CLI — If GH_TOKEN is set in project secrets, it’s passed to the container

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Filesystem layout

Worktrees live on the host at ~/.mux/src/<project>/<workspace>. The container mounts this directory (location inside the container depends on your devcontainer.json workspaceFolder).

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Notes

  • The Dev Container runtime button only appears if Mux finds a devcontainer.json in the project.