☒ I think that the red flags are warranted, but also it should be easy enough to update the code to swap in a new library.  I've recently played around with dragula and interact.js on a project where I originally had draggable. In preparations of this episode, it was difficult to find a good maintainable library that wasn't reliant on jQuery.

 ☒ That would be expected behavior as the dyno is like a docker container without any persistent volume claims. You should offload any uploads which needs to persist between restarts or deploys to a service like AWS S3 or Backblaze B2. 

 ☒ Look under the app/assets/drifting_ruby.css. It is mainly taken from Bootstrap 4, but I only picked and chose a few most commonly used items as well as adding in a few of my own. The idea was to have as "fresh" of an application as possible so that it didn't interfere with the episode content. A lot of videos out there will use a template which has lots of preconfigured stuff and it makes it difficult to see what is episode content vs template content. So beyond the stylesheet, there isn't anything else.

 ☒You might be able to take from this episode and piece things together. It uses ActionCable and Stimulus together along with RailsUJS and ActiveJob.  https://www.driftingruby.com/episodes/realtime-client-updates-from-background-jobs-with-stimulus

☒

class << self
  def call(*arg)
    ...
  end
end

is the same thing as

def self.call(*arg)
  ...
end

It's a different way of calling a class method. Does that help?