smolpi looks great!
and smolvm does clean up ephemeral runs if the machine run exits gracefully. I'll take a deeper look into this edge case and fix it today.
Fixed and released in v1.3.1: https://github.com/smol-machines/smolvm/pull/497
Fixed and released in v1.3.1: https://github.com/smol-machines/smolvm/pull/497