How to get index of which pattern is currently playing in music?
Not talking about sfx.

if it's possible, it's gonna be some kind of peek()

i'm too lazy to actually do it, but i'd write a cartridge that peeks a chunk of memory, then changes the current pattern, re-peeks the same chunk, and checks it for differences... good luck, my dude

I tried it but couldn't find anything by peeking.

There isn't a way to get the current pattern directly. You'd have to keep checking with stat(16)..stat(19) to see if the currently playing sfxes on the music channels have changed (assuming no duplicate pattern data), and then manually keep track of the pattern index.

But it will still cause problems if the window is idle and skips a pattern.