I've been trying to solve that for a few years now. The closest existing thing I could find in my research was acme from Plan 9, which actually does a pretty good job. The trick it uses is to have you click on a typed command instead of "sending" it, and it stays on your screen after it runs. So you can save several commands in a file, and that's a menu. Or clear the current document and print out several commands from a script, and that's a dynamic menu.

I highly recommend reading the paper[a] and trying it out. It's really interesting, and pretty easy to program.

The main problems with it are that it's too text-centered, and the interaction model is kinda weird for modern standards. I feel these are solvable (Plan B's Omero tried, with partial success), but they are hard to do without integrating the UI and the script into a single process, which feels like cheating. But well. If I ever get around to making a prototype, it will be here on Show HN.

[a]: http://doc.cat-v.org/plan_9/4th_edition/papers/acme/