Logic Pro X Scripter MIDI FX that that shifts the top or bottom note of a chord up or down by 1 or 2 octaves, with parametric controls.

chordNoteShifter.js

NeedsTimingInfo = true;

var start = Date.now(),
	triggered = false,
	prev;

var PluginParameters = [
	{
		name: "Window Length",
		defaultValue: 80,
		minValue: 0,
		maxValue: 500,
		numberOfSteps: 500,
		unit: "ms",
		type: "lin"
	},
	{
		name: "Added Velocity",
		defaultValue: 30,
		minValue: 0,
		maxValue: 127,
		numberOfSteps: 128,
		type: "lin"
	},
	{
		name: "Transpose",
		defaultValue: 12,
		minValue: -24,
		maxValue: 24,
		numberOfSteps: 4,
		type: "lin"
	},
	{
		name: "Note Choice",
		type: "menu",
		defaultValue: 1,
		valueStrings: ["Bottom", "Top"]
	}
];

function HandleMIDI(event) {

	event.send();

	if (event instanceof NoteOn) {
		if (prev === undefined) {
			prev = event;
		} else {
			if (GetParameter("Note Choice") === 1) {
				if (event.pitch > prev.pitch) {
					prev = event;
				}
			} else {
				if (event.pitch < prev.pitch) {
					prev = event;
				}
			}
		}

		if (!triggered) {
			triggered = true;
			start = Date.now();
		}
	}
}

function ProcessMIDI () {
	var info = GetTimingInfo(),
		now = Date.now(),
		dur = GetParameter("Window Length"),
		pitch = GetParameter("Transpose"),
		vel = GetParameter("Added Velocity");


	if (triggered && (start + dur) <= now) {
		prev.pitch += pitch;
		prev.velocity += vel;
		prev.send();
		triggered = false;
		prev = undefined;
	}
}