Your lib is a really nice write up of the missing pieces to get a local REPL with xterm.js working without any OS layer in between. We already had some requests/questions regarding this and had to point out, that it would only work with a fake pty/libreadline roundtrip+functionality in between. Your lib kinda bridges that gap.

What are your plans with this lib? Do you plan to further standardize it (in regards of pty and libreadline compatibility)? This way it could act as a shim for porting nodejs apps to in-browser variants with little effort and vice versa. Note that emscripten (+ wasm) already delivers shims for that, so the effort to do that might be questionable. Imho still worth to think about it.