It's extremely useful to be able to register for Illustrator's events from either a JSX script or from CEP HTML/JS. There seems to be a native plugin called AIHostAdapter.aip that will conveniently expose some common events (like selection changed) through PlugPlug. It's mentioned in several places, but I was able to actually download it from this one: aihostadapter for illustrator cc 2014 (for use with flex)
Where is the source for AIHostAdapter.aip so I can build and augment it myself/understand how it works?
Its not opened. However, you can reference MarkedObjects project in samplecode of IllustratorSDK to learn how to catch events in Illustrator.
Thanks for the confirmation. Bummer. I figured out the basic techniques from other samples, but it AIHostAdapter seems like a "standard library" that many, many people could benefit from.