A new device, similar to the formula device, but this time being triggered on midi events/track notes instead meta data, and being able to manipulate the note stream, so need to be in between track notes and generator.
You could program fancy algorithmic melodies, based on chords, or adding quiet overtones to a note, or randomly delay the note a bit (so also access on time domain, like placing a temporary note on the track, of course with lookahead).
I like it. It would be immensly useful stacking objects like this on top of each other. And it would also be a major shortcut to RAS. It’s like a whole new framework of possibilities.
You could prove its usefulness by providing some protoplug models? 
(I imagine this would be very similar, but integrated to Renoise with some extra flexibility and much better interface/workflow)
edit: I’m curious how it works technically… is LuaJIT needed? Would some kind of “PDC” be needed, and how would that be calculated? I’m wondering because these ‘midi data’ altering functions COULD potentially be heavy if you do complex stuff. Protoplug would just introduce latency (??), but an equivalent in Renoise would need to keep sample accuracy (?). Maybe this is just “solved” with a bit of pre-generation?
Why restrict it to a device? Why not integrate it into Renoise/Lua tools framework? Oh and ‘realtime’ audio manipulation/generation as well. After all, that’s what people thought Renoise/Lua(JIT?) would offer in the first place? Rather than just -> https://www.renoise.com/tools/patterneditor-find-and-replace
Why restrict it to a device? Why not integrate it into Renoise/Lua tools framework?
That would be comparable to not having the code section in ‘formula device’, but just some dummy sliders that you have to setup notifiers to, and each tool creating a gui for it. And the note stream class would most likely require syntax/structure that isn’t even used anywhere in the API today. So we would eventually end up with something like a realtime xStream, for something that could be provided much more simple and concise natively. But anything would be cool with me.
Why restrict it to a device? Why not integrate it into Renoise/Lua tools framework? Oh and ‘realtime’ audio manipulation/generation as well. After all, that’s what people thought Renoise/Lua(JIT?) would offer in the first place? Rather than just → https://www.renoise.com/tools/patterneditor-find-and-replace
I would also prefer this in a little device, since then the routing and gui things are already done, and you can save it along with the song where it belongs to.
Okey dokey