application.rb

# Auto-correct files that get generated
g.after_generate do |files|
  parsable_files = files.filter { |file| File.exist?(file) && file.end_with?(".rb") }
  unless parsable_files.empty?
    system("bundle", "exec",
            "rubocop",
            "--autocorrect-all",
            "--fail-level=E",
            "--format=quiet",
            *parsable_files,
            exception: true)
  end
end

Originally from https://ruby.social/@kotogavr/112495584388210864

I made it copy/pastable, and let it handle "pretend" mode with File.exists?.