Can't believe it really works

Can''t even remember when I wrote anything more complex than three lines of bash for the last time, so I didn't expect to get my little project, a simple MIDI-preset switch for my guitar FX-rack to really work out. Specifically not the breadboard prototype, because they never work for me.. Simple need, simple solution: a ROLAND FS-6 double footswitch on the input side, daisy-chained MIDI effects on the output. Left FS sends PROGRAM_CHANGE -1, right PROGRAM_CHANGE +1. Presets are identically numbered on all devices and either in the order of a playlist or just standard presets, grouped and varied a couple of times. Like 1: plate reverb, 2: clean, 3: flanger,, 4: clean, 5: plate reverb + flanger, 6: clean... Works as intended, 'material costs -footswitch aside- none. Had a Nano clone, a couple of resistors and switches at hand, will use the case from an obsolete euro-rack EQ for the final build, because it already has power switch, LED and TRS connector in place.