Oops.. sorry, I was probably missed this thread..
rack-oauth2 tutorial is the biggest request in rack-oauth2 gem, so I know it's the most important.
In rack-oauth2-sample project, these 2 are main part you should read to understand how to use rack-oauth2.
Since rack-oauth2 isn't rails-specific, you need define models by yourself.
So it's out of scope for me.
Another question in rack-oauth2 sample is how to support scope parameter.
For scope handling, this app will help.
This is not rack-oauth2 sample, but openid_connect sample, which is a gem build on top of rack-oauth2 gem.
And again, I know I need to write more human friendly tutorial…:(
Open standards in digital identity world is growing too fast to have time to write rack-oauth2 tutorial for me...