..

app/controllers/main_controller.rb

@@ -8,6 +8,10 @@ class MainController < ApplicationController
   end
 
   def index
+    domain_session = params[:_educoder_session]
+    if domain_session
+      cookies[:_educoder_session] = domain_session
+    end
     render file: 'public/react/build/index.html', :layout => false
   end
 end