I would also like to be able to add quality-only conditions on trains and circuits. Currently my use case is that I have a train which most stations will only accept normal ingredients from. This will cause the number of quality ingredients in the train to build up and I want to set an interrupt ...

TL;DR
Cargo wagon filters should allow setting quality only, like splitters and inserters already do.


What?
Cargo wagon item slots allow you to set item filters on them to reserve those slots for a given item type but currently do not allow you to filter by quality only the way that splitters ...