Trigger when a Folder is opened

Is there a way to trigger an action when a Folder is opened?

Or to find out if a folder is currently opened and trigger an action?

When certain folders are open, I want to launch a companion App that will help me manage the contents of the folder. Maybe offer 3 or 4 actions that I will select from. I want that App to start running when I open that Folder.

Any thoughts?
Paul