Lost links to .app files in Xcode

Question

In fumbling around trying to solve the problem of why my unit tests no longer linked in Xcode after renaming the app, I ended up with the .app files no longer being linked to anything in the Products group. I can remove the red links that are there, but can't figure out how to properly recreate them. Has anyone else seen that and know how to straighten it out?

Closing and restarting Xcode had no effect; neither did Product->Clean. Both the app and the unit tests still run, so in some senses this is a cosmetic issue, but on the likelihood it's indicative of some underlying problem I'd like to get it fixed.

This question is similar to this one, but it's not answered there, and what is suggested didn't work for me.