The first part of Gulp support is complete. When the plugin is installed, the 'gulpfile.js', if it exists, is parsed and all the Gulp tasks are shown as child nodes of a new Gulp node in the Projects window:
Creating the above was trivial. Initially I got into all kinds of problems when I started by creating a new file type for Gulp files. But the solution ended up being much simpler than that. Using the NetBeans Project Type Extension Tutorial, I registered a new org.netbeans.spi.project.ui.support.NodeFactory for the org-netbeans-modules-web-clientproject project type.
All the code is here:
The next step I'm working on is being able to run those Gulp tasks from within NetBeans. Once that's done I'll publish the plugin in the NetBeans Plugin Portal.