memfs is very cool, but the WASI runner in this demo doesn't use it. I implemented my own virtual filesystem (see: https://github.com/taybenlor/runno/blob/main/packages/wasi-m...).

Will look at the FS spec. I would hope that it would be shaped in a way that makes sense for WASI (brief look seems like it is). I'd also love it to be something that makes sense from the JavaScript side as well.