PHP from total scratch, I'm actually thinking of open sourcing the project

That would be great, thank you! Cf. https://github.com/lobsters/lobsters

Haha, I was going to mention lobsters. I don't understand why everyone tries to re-implement HN. I guess the interface is pretty minimalist, simplistic and recognizable, but Lobster just has so many more useful features and is pretty mature. I'd highly recommend it rather than try and reinvent the wheel.