I published the "polyfill" to npm as node-inspect (requires node 6):

npm install --global node-inspect

For the implementation status, see this tracking issue. Most things should work already.

This is definitely interesting but I'm wondering if it would be better to develop this as a standalone client for the time being. Once it's functional, then we can look to see how much sense it makes to bringing it in to core.

That definitely makes sense. And I'm not looking to submit the code I linked to above to core in the next few days or immediately after this proposal is finalized/merged.

But my impression was that the current command line debugger is already depending on (more or less) unsupported parts of V8. So it seemed like a good idea to have an official plan for "the day it breaks". The proposal explicitly doesn't mention my repo. It just suggests a potential interface for transitioning the official built-in debugger from the old V8 protocol to the new inspector protocol.

btw, relevant to this: nodejs/node#7266

Thanks for the link! Must've been blind. :)

After playing around with the finished debugger - it feels like a wasted opportunity to go down this route.