# File lib/spring/application.rb, line 67
    def start_watcher
      @watcher = Spring.watcher

      @watcher.on_stale do
        state! :watcher_stale
      end

      if @watcher.respond_to? :on_debug
        @watcher.on_debug do |message|
          spring_env.log "[watcher:#{app_env}] #{message}"
        end
      end

      @watcher.start
    end