Codekit has its own very simple templating language, .kit that's actually quite useful when you're not looking to spin up something like PHP or Python or in the Pug/Jade vain (which latter two I've never been able to commit to). The documentation is straightforward. You can find it here but passing off a project with CodeKit dependency probably isn't viable for many situations. Also, Gulp 4.0 is much easier to read and much more pleasant to work with. You'll need, of course, a current-ish version of Node to run this.
Rather than post a git repository, I've created a GitHub Gist for anyone looking to make .kit files work with Gulp. It features a really basic simple set for compiling .kit, Sass, JS and uses BrowserSync for both streaming CSS changes and live reloads after JS/Kit changes. The readme has the default directory structure. All the files land, and in a /dist directory, that's likely something you'd ignore in your .gitignore.
gulp- runs all the compiling processes once
gulp watch- launches browsersync server with live compiling/processing
Apologies to anyone using RSS as the embed won't work, but you can view the gist on github.