The Chief is positive, let´s elaborate!:cheer:
I am sure that the "chord regognition" is when a (arranger-) keyboard responds to the chords played, by transposing its patterns to the matching scale/chord. There is several ways of how this has been implemented, but it has always been the highlight of home organs (-says the proud owner of a GEM H7000 and Farsisa Professional 110:P ).
Very closely related is the classic polysynth arpeggio (which – I think – was introduced by Roland with Jupiter 4 in the late 70´s), and the way these work would be a good starting point.
Actually I believe that technicly speaking we are very close with the current Octopus mode of opereation. But where one note pressed, toggles the scale note on and the following note toggles the scale note off, what we are looking for is simply that the midi note-on toggles the scale note on, and the midi note-off toggles it of again.
But where the current mode is that there is always at least one note on (the base), we should have zero scale notes if no key is pressed: No keys no sound.
I am not sure if there needs to be a base note in this mode. I havent played so much with this yet, so I am not sure what difference it makes to have, say three notes in the scale selected and then moving the base note within these notes.
However I am thinking about maybe also having a "two handed mode": With your right hand you finger you chords (preferably in a two octave zone to make voicings more intuitive) and with your right hand you transpose the whole page. So in this mode the scale notes is always in relation to the key of c. So selecting C-Eb-G with your right hand and playing an F in your left hand will force the page into F-minor.
I have more going on in my head now, but I have to attend to some kids. I´ll be back.