why is brunch copying bower dependencies instead of compiling into vendor.js and app.css

For one of my bower dependencies, the css and js file specified by its main declaration in its bower.json file are being copied straight to the output css and js directories, rather than being compiled into vendor.js and app.css.

All other bower dependencies are being compiled as expected. I’ve tried deleting the bower_components directory and reinstalling and deleting the public directory, but neither has helped.

I’m using brunch version 1.7.10

My config.coffee file looks like this:

exports.config =
  # See http://brunch.io/#documentation for docs.
  files:
    javascripts:
      joinTo:
        'js/app.js': /^(app)/
        'js/vendor.js': /^(bower_components)/
        'test/js/test.js': /^test(\/|\\)(?!bower_components)/
        'test/js/test-bower_components.js': /^test(\/|\\)(?=bower_components)/

    stylesheets:
      joinTo:
        'css/app.css' : /^(app|bower_components)/

    templates:
      joinTo: 'app.js'

  modules:
    nameCleaner: (path) ->
      path.replace(/^app\/scripts\//, '')

the main declaration for in the bower.json for the dependency that is copying instead of compiling looks like this:

  "main": [
    "./BS3/assets/js/datatables.js", 
    "./BS3/assets/css/datatables.css"
  ]

These two files just get copied straight, instead of compiled, and I can’t for the life of me figure out why these are behaving differently to all the other dependencies I have.

[lukens]

Should this work (limits the assets match to just the app directory)?

  conventions:
    assets: /^(app(\/|\\)assets)/

[lukens]

That seems to have done the trick, many thanks.