Robin Gareus http://gareus.org/
2 Pedalboards using it

MIDI Enforce Scale

Plugin screenshot

Filter note-on/off events depending on musical scale. If the key is changed note-off events of are sent for all active off-key notes.

Control Default Min Max
Filter Channel 0 0 16
Scale 0 0 11
Mode 0 0 2
latency 0 0 192000
http://gareus.org/oss/lv2/midifilter#enforcescale v.1:1033.31-10