You want stylus -w my/dir to watch files and recursively build when an @imported file is modified. This doesn't happen by default so I'm writing this as a reference to the fix listed here: https://github.com/LearnBoost/stylus/issues/486 Thanks @Jonnywonny!

stylus

#!/usr/bin/env node

/**
 * Module dependencies.
 */

var fs = require('fs')
  , stylus = require('../lib/stylus')
  , basename = require('path').basename
  , dirname = require('path').dirname
  , resolve = require('path').resolve
  , join = require('path').join
  , isWindows = process.platform === 'win32';

/**
 * Arguments.
 */

var args = process.argv.slice(2);

/**
 * Compare flag.
 */

var compare = false;

/**
 * Compress flag.
 */

var compress = false;

/**
 * CSS conversion flag.
 */

var convertCSS = false;

/**
 * Line numbers flag.
 */

var linenos = false;

/**
 * Firebug flag
 */

var firebug = false;

/**
 * Files to processes.
 */

var files = [];

/**
 * Import paths.
 */

var paths = [];

/**
 * Destination directory.
 */

var dest;

/**
 * Watcher hash.
 */

var watchers;

/**
 * Enable REPL.
 */

var interactive;

/**
 * Plugins.
 */

var plugins = [];

/**
 * Optional url() function.
 */

var urlFunction = false;

/**
 * Include css on import.
 */

var includeCSS = false;

/**
 * Usage docs.
 */

var usage = [
    ''
  , '  Usage: stylus [options] [command] [< in [> out]]'
  , '                [file|dir ...]'
  , ''
  , '  Commands:'
  , ''
  , '    help [<type>:]<prop> Opens help info at MDC for <prop> in'
  , '                         your default browser. Optionally'
  , '                         searches other resources of <type>:'
  , '                         safari opera w3c ms caniuse quirksmode'
  , ''
  , '  Options:'
  , ''
  , '    -i, --interactive       Start interactive REPL'
  , '    -u, --use <path>        Utilize the stylus plugin at <path>'
  , '    -U, --inline            Utilize image inlining via data uri support'
  , '    -w, --watch             Watch file(s) for changes and re-compile'
  , '    -o, --out <dir>         Output to <dir> when passing files'
  , '    -C, --css <src> [dest]  Convert css input to stylus'
  , '    -I, --include <path>    Add <path> to lookup paths'
  , '    -c, --compress          Compress css output'
  , '    -d, --compare           Display input along with output'
  , '    -f, --firebug           Emits debug infos in the generated css that'
  , '                            can be used by the FireStylus Firebug plugin'
  , '    -l, --line-numbers      Emits comments in the generated css'
  , '                            indicating the corresponding stylus line'
  , '    --include-css           Include regular css on @import'
  , '    -V, --version           Display the version of stylus'
  , '    -h, --help              Display help information'
  , ''
].join('\n');

/**
 * Handle arguments.
 */

var arg;
while (args.length) {
  arg = args.shift();
  switch (arg) {
    case '-h':
    case '--help':
      console.error(usage);
      process.exit(1);
    case '-d':
    case '--compare':
      compare = true;
      break;
    case '-c':
    case '--compress':
      compress = true;
      break;
    case '-C':
    case '--css':
      convertCSS = true;
      break;
    case '-f':
    case '--firebug':
      firebug = true;
      break;
    case '-l':
    case '--line-numbers':
      linenos = true;
      break;
    case '-V':
    case '--version':
      console.log(stylus.version);
      process.exit(0);
      break;
    case '-o':
    case '--out':
      dest = args.shift();
      if (!dest) throw new Error('--out <dir> required');
      break;
    case 'help':
      var name = args.shift()
        , browser = name.split(':');
      if (browser.length > 1) {
        name = [].slice.call(browser, 1).join(':');
        browser = browser[0];
      } else {
        name = browser[0];
        browser = '';
      }
      if (!name) throw new Error('help <property> required');
      help(name);
      break;
    case '--include-css':
      includeCSS = true;
      break;
    case '-i':
    case '--repl':
    case '--interactive':
      interactive = true;
      break;
    case '-I':
    case '--include':
      var path = args.shift();
      if (!path) throw new Error('--include <path> required');
      paths.push(path);
      break;
    case '-w':
    case '--watch':
      watchers = {};
      break;
    case '-U':
    case '--inline':
      args.unshift('--use', 'url');
      break;
    case '-u':
    case '--use':
      var options;
      var path = args.shift();
      if (!path) throw new Error('--use <path> required');

      // options
      if ('--with' == args[0]) {
        args.shift();
        options = args.shift();
        if (!options) throw new Error('--with <options> required');
        options = eval('(' + options + ')');
      }

      // url support
      if ('url' == path) {
        urlFunction = options || {};
      } else {
        paths.push(dirname(path));
        plugins.push({ path: path, options: options });
      }
      break;
    default:
      files.push(arg);
  }
}

// if --watch is used, assume we are
// not working with stdio

if (watchers && !files.length) {
  files = fs.readdirSync(process.cwd())
    .filter(function(file){
    return file.match(/\.styl$/);
  });
}

/**
 * Open the default browser to the CSS property `name`.
 *
 * @param {String} name
 */

function help(name) {
  var url
    , exec = require('child_process').exec
    , command;

  name = encodeURIComponent(name);

  switch (browser) {
    case 'safari':
    case 'webkit':
      url = 'https://developer.apple.com/library/safari/search/?q=' + name;
      break;
    case 'opera':
      url = 'http://dev.opera.com/search/?term=' + name;
      break;
    case 'w3c':
      url = 'http://www.google.com/search?q=site%3Awww.w3.org%2FTR+' + name;
      break;
    case 'ms':
      url = 'http://social.msdn.microsoft.com/search/en-US/ie?query=' + name + '&refinement=59%2c61';
      break;
    case 'caniuse':
      url = 'http://caniuse.com/#search=' + name;
      break;
    case 'quirksmode':
      url = 'http://www.google.com/search?q=site%3Awww.quirksmode.org+' + name;
      break;
    default:
      url = 'https://developer.mozilla.org/en/CSS/' + name;
  }

  switch (process.platform) {
    case 'linux': command = 'x-www-browser'; break;
    default: command = 'open';
  }

  exec(command + ' "' + url + '"', function(){
    process.exit(0);
  });
}

// Compilation options

var options = {
    filename: 'stdin'
  , compress: compress
  , firebug: firebug
  , linenos: linenos
  , paths: [process.cwd()].concat(paths)
};

// Buffer stdin

var str = '';

// Convert css to stylus

if (convertCSS) {
    switch (files.length) {
    case 2:
      compileCSSFile(files[0], files[1]);
      break;
    case 1:
      compileCSSFile(files[0], files[0].replace('.css', '.styl'));
      break;
    default:
      var stdin = process.openStdin();
      stdin.setEncoding('utf8');
      stdin.on('data', function(chunk){ str += chunk; });
      stdin.on('end', function(){
        var out = stylus.convertCSS(str);
        console.log(out);
      });
  }
} else if (interactive) {
  repl();
} else {
  if (files.length) {
    compileFiles(files);
  } else {
    compileStdio();
  }
}

/**
 * Start stylus REPL.
 */

function repl() {
  var options = { filename: 'stdin', imports: [join(__dirname, '..', 'lib', 'functions')] }
    , parser = new stylus.Parser('', options)
    , evaluator = new stylus.Evaluator(parser.parse(), options)
    , rl = require('readline')
    , repl = rl.createInterface(process.stdin, process.stdout, autocomplete)
    , global = evaluator.global.scope;

  // expose BIFs
  evaluator.evaluate();

  // readline
  repl.setPrompt('> ');
  repl.prompt();

  // HACK: flat-list auto-complete
  function autocomplete(line){
    var out = process.stdout
      , keys = Object.keys(global.locals)
      , len = keys.length
      , words = line.split(/\s+/)
      , word = words.pop()
      , names = []
      , name
      , node
      , key;

    // find words that match
    for (var i = 0; i < len; ++i) {
      key = keys[i];
      if (0 == key.indexOf(word)) {
        node = global.lookup(key);
        switch (node.nodeName) {
          case 'function':
            names.push(node.toString());
            break;
          default:
            names.push(key);
        }
      }
    }

    return [names, line];
  };

  repl.on('line', function(line){
    if (!line.trim().length) return repl.prompt();
    parser = new stylus.Parser(line, options);
    parser.state.push('expression');
    evaluator.return = true;
    try {
      var expr = parser.parse();
      var ret = evaluator.visit(expr);
      ret = ret.nodes[ret.nodes.length - 1];
      ret = ret.toString();
      if ('(' == ret[0]) ret = ret.replace(/^\(|\)$/g, '');
      console.log('\033[90m=> \033[0m' + highlight(ret));
      repl.prompt();
    } catch (err) {
      console.error('\033[31merror: %s\033[0m', err.message || err.stack);
      repl.prompt();
    }
  });

  repl.on('SIGINT', function(){
    console.log();
    process.exit(0);
  });
}

/**
 * Highlight the given string of stylus.
 */

function highlight(str) {
  return str
    .replace(/(#)?(\d+(\.\d+)?)/g, function($0, $1, $2){
      return $1 ? $0 : '\033[36m' + $2 + '\033[0m';
    })
    .replace(/(#[\da-fA-F]+)/g, '\033[33m$1\033[0m')
    .replace(/('.*?'|".*?")/g, '\033[32m$1\033[0m');
}

/**
 * Convert a CSS file to a Styl file
 */

function compileCSSFile(file, fileOut) {
  fs.lstat(file, function(err, stat){
    if (err) throw err;
    if (stat.isFile()) {
      fs.readFile(file, 'utf8', function(err, str){
        if (err) throw err;
        var styl = stylus.convertCSS(str);
        fs.writeFile(fileOut, styl, function(err){
         if (err) throw err;
        });
      });
    }
  });
}

/**
 * Compile with stdio.
 */

function compileStdio() {
  process.stdin.setEncoding('utf8');
  process.stdin.on('data', function(chunk){ str += chunk; });
  process.stdin.on('end', function(){
    // Compile to css
    var style = stylus(str, options);
    if (includeCSS) style.set('include css', true);
    usePlugins(style);
    style.render(function(err, css){
      if (err) throw err;
      if (compare) {
        console.log('\n\x1b[1mInput:\x1b[0m');
        console.log(str);
        console.log('\n\x1b[1mOutput:\x1b[0m');
      }
      console.log(css);
      if (compare) console.log();
    });
  }).resume();
}

/**
 * Compile the given files.
 */

function compileFiles(files) {
  files.forEach(compileFile);
}

/**
 * Compile the given file.
 */

function compileFile(file) {
  // ensure file exists
  fs.lstat(file, function(err, stat){
    if (err) throw err;
    // file
    if (stat.isFile()) {
      fs.readFile(file, 'utf8', function(err, str){
        if (err) throw err;
        options.filename = file;
        options._imports = [];
        var style = stylus(str, options);
        if (includeCSS) style.set('include css', true);
        usePlugins(style);
        style.render(function(err, css){
          watchImports(file, options._imports);
          if (err) {
            if (watchers) {
              console.error(err.stack || err.message);
            } else {
              throw err;
            }
          } else {
            writeFile(file, css);
          }
        });
      });
    // directory
    } else if (stat.isDirectory()) {
      fs.readdir(file, function(err, files){
        if (err) throw err;
        files.filter(function(path){
          return path.match(/\.styl$/);
        }).map(function(path){
          return join(file, path);
        }).forEach(compileFile);
      });
    }
  });
}

/**
 * Write the given css output.
 */

function writeFile(file, css) {
  // --out support
  var path = dest
    ? join(dest, basename(file, '.styl') + '.css')
    : file.replace('.styl', '.css');
  fs.writeFile(path, css, function(err){
    if (err) throw err;
    console.log('  \033[90mcompiled\033[0m %s', path);
    // --watch support
    watch(file, compileFile);
  });
}

// /**
//  * Watch the given `file` and invoke `fn` when modified.
//  */

// function watch(file, fn) {
//   // not watching
//   if (!watchers) return;

//   // already watched
//   if (watchers[file]) return;

//   // watch the file itself
//   watchers[file] = true;
//   console.log('  \033[90mwatching\033[0m %s', file);
//   // if is windows use fs.watch api instead
//   // TODO: remove watchFile when fs.watch() works on osx etc
//   if (isWindows) {
//     fs.watch(file, function(event) {
//       if (event === 'change') fn(file);
//     });
//   } else {
//     fs.watchFile(file, { interval: 50 }, function(curr, prev) {
//       if (curr.mtime > prev.mtime) fn(file);
//     });
//   }
// }
var parentFilePairs = {};
function watch(file, fn, parentFile) {
  // not watching
  if (!watchers) return;

    if (parentFile && parentFilePairs[file + '|' + parentFile]) return;
    parentFilePairs[file + '|' + parentFile] = true;

  // already watched
  if (watchers[file]) { // jonnywonny: I changed this
        watchers[file].push(fn);
        return;
    }

  // watch the file itself
  watchers[file] = [fn];
  console.log('  \033[90mwatching\033[0m %s', file);
  // if is windows use fs.watch api instead
  // TODO: remove watchFile when fs.watch() works on osx etc
  if (isWindows) {
    fs.watch(file, function(event) {
      if (event === 'change') { // jonnywonny: and this
                for (var i = 0; i < watchers[file].length; ++ i) {
                    var watcher = watchers[file][i];
                    watcher(file);
                }
            }
    });
  } else {
    fs.watchFile(file, { interval: 50 }, function(curr, prev) {
      if (curr.mtime > prev.mtime) { // jonnywonny: and this
                for (var i = 0; i < watchers[file].length; ++ i) {
                    var watcher = watchers[file][i];
                    watcher(file);
                }
            }
    });
  }
}


/**
 * Watch `imports`, re-compiling `file` when they change.
 */

function watchImports(file, imports) {
  imports.forEach(function(imported){
    if (!imported.path) return;
    watch(imported.path, function(){
      compileFile(file);
    });
  });
}

/**
 * Utilize plugins.
 */

function usePlugins(style) {
  plugins.forEach(function(plugin){
    var path = plugin.path;
    var options = plugin.options;
    fn = require(/^\.+\//.test(path) ? resolve(path) : path);
    if ('function' != typeof fn) {
      throw new Error('plugin ' + path + ' does not export a function');
    }
    style.use(fn(options));
  });

  if (urlFunction) style.define('url', stylus.url(urlFunction));
}