#22 完了

backend/app/controllers/application_controller.rb

@@ -1,2 +1,16 @@
 class ApplicationController < ActionController::API
+  before_action :authenticate_user
+
+  def current_user
+    @current_user
+  end
+
+  private
+
+  def authenticate_user
+    code = request.headers['X-Transfer-Code'] || request.headers['HTTP_X_TRANSFER_CODE']
+    @current_user = User.find_by inheritance_code: code
+      Rails.logger.info("X-Transfer-Code: #{request.headers['X-Transfer-Code']}")
+  Rails.logger.info("current_user: #{@current_user&.id}")
+  end
 end