GeezerVison

Runtimes determine where and how Xum executes agent workspaces. A runtime is two independent choices that compose:

• Project isolation — where the project lives and commands run.
• Workspace isolation — how each workspace is separated from the other workspaces of the project.

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Supported combinations

Combinations marked ”—” are listed in the picker but disabled until a backend supports them. SSH + None runs every workspace directly in an existing directory on the host (for example ~/src/my-app). Xum does not sync, check out, move, or delete anything in that directory, and it does not need a local git repository.

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Choosing a Runtime

Pick both when creating a workspace: the environment chip under the workspace name opens a panel where Run on selects the project isolation and Isolation selects the workspace isolation. Set the defaults, and turn options on or off, in Settings → Runtimes, globally or per project. Configs written by older versions (a single default runtime) are migrated automatically, and the old field is still written so you can downgrade.

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Init Hooks

Init hooks and agent bash tool executions can detect the runtime type via the XUM_RUNTIME environment variable:

• local — Local project, no workspace isolation
• worktree — Local project, worktree isolation
• ssh — SSH project (worktree or no workspace isolation)
• docker — Docker runtime
• devcontainer — Dev Container runtime

This lets your init hook adapt behavior, e.g., skip worktree-specific setup when running in local mode.