I don't want "a terminal", I want a command based interface combined with being able to use the same set of tools/commands on all the files I interact with.
Like, it gets taken for granted, but being able to literally grep my html file, my program source and my readme file, instead of having to open a separate gui program and using its bespoke seach menu feature, is really, really nice.
There are downsides of course, like the way we keep jamming everything into the square hole that is 1980s terminal emulators and character based displays, but frequently this is worth it.
Thankfully Xerox PARC has an answer for that across Smalltalk, Interlisp-D, XDE, and Cedar, and copied to certain extent in modern programming languages, REPL environments and notebooks.
Augmented nowadays with agent environments and tools in IDEs, which can even be voice controlled.
9front does that without emulating a terminal. Grep, cc, awk, walk (no find and magical incantations with -print0 there), functions instead of aliases on rc, better lists () in rc, and so on. And you can launch these command inside your graphical editor such as sam or better, Acme. And even as a pipe to selections.
Ok, I'll bite: how? What's the secret sauce? And can I use it with some random perl program I downloaded that prints horoscopes?