What is the format of a unique Google Hangout with app id?

Question

I'm building my first Google Hangout app and can access it successfully using the URL: https://hangoutsapi.talkgadget.google.com/hangouts/_/?gid=APP_ID or https://plus.google.com/hangouts/_/?gid=APP_ID

What is the proper format of a URL that contains a unique hangout id that could be shared across users so they end up in the same hangout and using the app?

The following URL loads a unique hangout, but discards the app: https://plus.google.com/hangouts/_/UNIQUE_HANGOUT_ID?gid=APP_ID

Answer 1

I tested https://plus.google.com/hangouts/_/UNIQUE_HANGOUT_ID?gid=APP_ID this evening, and it worked correctly - placing the person in the same hangout and running the correct app.

Is the app in question public? If not, this may be the cause of the problem.

As an aside, the https://hangoutsapi.talkgadget.google.com/ is now deprecated, since it was related to the old Hangout Development Sandbox which is no longer in use.