[Rochus]

> base things off of `luatex-plain`

I have that on the radar indeed, but as far as I understand it still depends on plain.tex which again depends on tons of 1986 stuff (like old fonts) which I want to avoid. But due to my present experiments with the 40kLOC Lua machinery I'm scared of integrating this thing and would rather opt for avoiding it.

> that \parfillskip is initialized to 0pt from iniTeX

I did a lot of instrumented runs where values were printed and looked "unsuspicious". My best guess at the moment is that the Lua based machinery has an issue with the space in DejaVuSans.ttf, but that's just an assumption. I already stopped this path due to its apparent fragility and my reluctance of the architectural approach (I initially thought that everything required to do high-quality typesetting was already part of the luatex executable, but only realized this fragile dependency when doing larger test cases on my downsized engine version).