Шаг второй. Понимание контекста

gulpfile.js

var path = require('path');
var gulp = require('gulp');
var jade = require('gulp-jade');
var less = require('gulp-less');
var chalk = require('chalk');

//
// Options
//
var options = {
  project: 'app-' + getDefaultContext('canonium')
};

function getDefaultContext(defaultName) {
  var argv = process.argv[2] || process.argv[3];
  if (typeof argv !== 'undefined' && argv.indexOf('--') < 0) {
    argv = process.argv[3];
  }
  return (typeof argv === 'undefined') ? defaultName : argv.replace('--', '');
};

function runInContext(filepath, cb) {
  var context = path.relative(process.cwd(), filepath);
  var projectName = context.split(path.sep)[0];

  // Console
  console.log(
    '[' + chalk.green(projectName.replace('app-', '')) + ']' +
    ' has been changed: ' + chalk.cyan(context)
  );

  // Set project
  options.project = projectName;

  cb();
};


//
// Jade
//
gulp.task('jade', function() {
  return gulp.src(path.join(options.project, 'templates/*.jade'))
    .pipe(jade({ pretty: true }))
    .pipe(gulp.dest('build/' + options.project))
});


//
// Less
//
gulp.task('less', function() {
  return gulp.src(path.join(options.project, 'less/*.less'))
    .pipe(less())
    .pipe(gulp.dest('build/' + options.project))
});


//
// Watch
//
gulp.watch('app-*/templates/*.jade').on('change', function(filepath) {
  runInContext(filepath, gulp.series('jade'));
});

gulp.watch('app-*/less/*.less').on('change', function(filepath) {
  runInContext(filepath, gulp.series('less'));
});

gulp.task('default', gulp.parallel('jade', 'less'));