Gulp Task

gulp.task('critical', function() {
  var request = require('request');
  var path = require( 'path' );
  var criticalcss = require("criticalcss");
  var fs = require('fs');
  var tmpDir = require('os').tmpdir();

  var cssUrl = 'http://PROJECT.dev/app/themes/sage/dist/styles/main-3c29b398.css';
  var cssPath = path.join( tmpDir, 'style.css' );
  var includePath = path.join( 'dist/styles/', 'critical.css' );

  request(cssUrl).pipe(fs.createWriteStream(cssPath)).on('close', function() {
    criticalcss.getRules(cssPath, function(err, output) {
      if (err) {
        throw new Error(err);
      } else {
        criticalcss.findCritical("http://umamibierzo.dev/", { rules: JSON.parse(output) }, function(err, output) {
          if (err) {
            throw new Error(err);
          } else {

            fs.writeFile(includePath, output, function(err) {
              if(err) {
                return console.log(err);
              }
              console.log("Critical written to include!");
            });

          }
        });
      }
    });
  });
});

It would be awesome if we could figure out the cache token of the css file.
Maybe adding it to the CSS processing pipeline, but my Gulp is not enough...