Thank you!!! 
This is really cool and honestly I didn’t realize it was already possible!
After trying a bit what is shown in the video, I’d say is almost what I was thinking but when activating keys-lock in Chord Notes and Chord Extensions mode it only works with notes between C3-C5, why? Also C3 is always the root of the chord, which is fine I can see the reasoning behind that, but it means external melodies or arpeggios gets out completely different and I can still get wrong notes if out of that range.
I would love to have a sort of “Chord Notes Mapped” mode where all the incoming notes get adapted to the nearest chord note (with and without extensions) working on all the keyboard range. Just like the actual Scale Notes Mapped, but with only the notes of the current chord. Is this possible?