Is the ask-cli source code published on GitHub somewhere. I couldn't find anything in the alexa organisation.
It's disheartening that such a simple question remains unanswered for 2 years.
For some reason the CLI isn't part of the Node SDK. https://github.com/alexa/alexa-skills-kit-sdk-for-nodejs
However you can `npm install` the CLI and then browse the source locally in `node_modules/ask-cli`. I'm not sure where you take any bugs you fix or features you add. I suppose you could post them here, but then I guess nobody would see them.