change node to modify several properties of an incoming message, I decided to save the modified message in global context. It took a while to find the trick, but this seems to work.
But I have questions. Should this even work? Or is it a quirk of the JSONata compatibility mode that will go away someday? Can the
change node do the reverse, that is retrieve the message from context and send it on? (I haven't found a way, so far.)