Damn! This is seriously great work. I've built a couple shitty react apps for my own use to visualize the fretboard (namely https://github.com/porkloin/progression-roulette-mk2 and https://porkloin.github.io/triad-practice-mk2/ if anyone wants to use an objectively worse version of what OP is sharing :P).

I've considered trying to consolidate them into something a little more general purpose and usable, but I'll honestly consider just using yours and perhaps even paying to unlock some more features after I use it a bit more. I'm an engineer by day job, and as much as I love building my own tools and feel like I learned a lot about music theory in building my tools, I would really like to just spend my guitar time actually playing rather than doing _more_ coding.

Thanks for sharing, and great work!