Code interpreter pattern

A code interpreter accepts source text, runs it, and returns output. The important rule is that user code runs in the guest, not in the host process.

One-shot interpreter

mvmctl run --timeout 10 -- python - <<'PY'
print("hello from inside the sandbox")
PY

Use this shape for stateless calls where every invocation should start clean.

Persistent interpreter

mvmctl init ./interpreter --preset python
mvmctl build ./interpreter
mvmctl up ./interpreter --name interpreter
mvmctl exec interpreter -- python /work/run_cell.py

Use a named VM when you intentionally want cached packages, files, or session state across cells.

Security checklist

• Enforce input size limits before invoking the sandbox.
• Set a timeout.
• Bound stdout/stderr returned to the caller.
• Disable network unless the interpreter needs named endpoints.
• Never pass host credentials through argv.
• Delete or snapshot state intentionally.