Vagrant + Pattern Lab + BrowserSync + Grunt happiness

Grunt task config: browsersync.js

module.exports = function (grunt) {
  grunt.config.merge({
		browserSync: {
		  dev: {
		    bsFiles: {
	        src : ['<%= pkg.themePath %>/css/pattern-lab.css',
	        '<%= pkg.themePath %>/pattern-lab/public/latest-change.txt'
	        ]
		    },
		    options: {
	        proxy: "10.11.12.14",
	        open: false
		    }
		  }
		}
});

	grunt.loadNpmTasks('grunt-browser-sync');
}

Grunt task config: concurrent.js

module.exports = function (grunt) {
  grunt.config.merge({
		concurrent: {
      watchSync: ['simple-watch', 'browserSync'],
      options: {
        logConcurrentOutput: true
      }
		}
});

	grunt.loadNpmTasks('grunt-concurrent');
}

Grunt task config: default.js

module.exports = function (grunt) {
  grunt.registerTask('default', [
    'concurrent:watchSync'
  ]);
};

package.json

# npm install grunt-browser-sync --save-dev
"grunt-browser-sync": "^2.2.0",

# npm install grunt-concurrent --save-dev
"grunt-concurrent": "^2.3.1",

Vagrantfile

# BrowserSync
config.vm.network :forwarded_port, guest: 3000, host: 3000