| name | using-sandboxes |
| description | Use when a task benefits from Container Use isolation, especially risky dependency installs, large refactors, or unfamiliar test commands. |
Using Sandboxes
Container Use gives Alloy agents an opt-in Docker/Dagger-backed workspace for work that should not run directly on the host checkout.
Use a sandbox when:
- Installing unfamiliar dependencies or running untrusted project scripts.
- Making a broad refactor where parallel isolation reduces collision risk.
- Reproducing a bug that may create noisy local artifacts.
- Trying destructive commands that should be reviewed before host application.
Do not use a sandbox when:
- The task is a small read-only inspection.
- A single-file edit can be verified with normal local tests.
- The setup overhead would exceed the risk of running in the host worktree.
When Container Use MCP tools are available, prefer this loop:
- Create or open an environment for the current repo.
- Run commands inside the environment until the change is verified.
- Summarize the changed files and verification evidence.
- Apply or merge the sandbox changes back to the host repo with
cu apply or cu merge.
If the Container Use MCP is unavailable after alloy add container-use, stop and surface the missing runtime or MCP problem. Do not silently fall back to risky host execution for commands that needed isolation.
