Modal Sandboxes Knowledge

This skill should be used when the user asks to run isolated or untrusted code on Modal.com. PROACTIVELY activate for: modal.Sandbox, safe user code execution, coding playgrounds, named sandboxes, PTY sessions, filesystem snapshots, timeout and resource limits, egress policies, sandbox lifecycle cleanup, terminate(), and security review for code execution. Provides: sandbox security checklist, lifecycle and cleanup patterns, egress/resource-limit recipes, and snapshot/PTY usage examples.

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Modal Sandboxes Knowledge

Use this skill for Modal Sandbox design, security, and operations. For ordinary functions, GPU jobs, or deployment topics, use modal-compute:modal-compute-knowledge.

Essential security checklist

  1. Treat all submitted code and files as untrusted.
  2. Use explicit timeout, CPU, memory, and disk constraints.
  3. Prefer deny-by-default network egress; allow only required destinations.
  4. Clean up every sandbox with terminate() or a scoped lifecycle.
  5. Avoid passing long-lived credentials into sandbox environments unless strictly required.
  6. Capture stdout/stderr and return codes separately for auditing and debugging.

Common patterns

  • One-shot execution: create a sandbox, run a command, collect output, terminate.
  • Named sandbox: reuse a per-session sandbox for interactive workflows.
  • PTY session: support shell-like interaction while preserving resource limits.
  • Snapshot workflow: prebuild filesystem state, then launch from a known baseline.

Detailed reference

See references/sandboxes-code-execution.md for code examples and operational notes.

josiahsiegel/claude-plugin-marketplace/tree/main/plugins/modal-sandboxes/skills/modal-sandboxes-knowledge commit 0c40b56231

Frequently asked questions

npx skillmds@latest add josiahsiegel/modal-sandboxes-knowledge