Here is a plugin for FEZ which provides automatic kerning for Urdu fonts: https://github.com/googlefonts/Gulzar/blob/main/qalamTools/NastaliqKerning.py (View Post)
You can find some of the challenges (the reason why shaping is not enough for layout) here, (I really should finish that chapter someday) and some of the differences between shaping and layout here. (View Post)
I define a shaping engine as a piece of software which maps Unicode codepoints to glyphs and their expected positions, in response to the conventions of the script and the rules in the font. (View Post)