Happy to hear that you like it!

I am indeed more focussed on the file format right now than on the command line tool. If the format turns out to be valuable and useful in itself, my plan would be to build a small UI app. As you said, I think the advantage of a well-specified plain-text file format is that tools can be built around independently – with the smallest common denominator always being the text editor of your choice.

By the way, for Mac users there is already a menu bar (systray) widget bundled in, which renders a brief overview of a file. (In a very simplistic fashion though; it’s more a proof of concept than anything else.)