I've made a mod that adds quality effects to mining drills, and done so by adding new prototypes, (and changing the placed item to the added prototype at runtime)

The added prototypes have the field "hidden = true"

They still show up in the mined by tooltip as so: 12-26-2024, 03-26-22.png

Link ...

there actually is, the train stop priority feature does exactly what you want.
This is also the example that was used for train stop priority initially, preventing trains from just moving around advanced products while ignoring basic ingredients.


You're right, I'm actually working on a design ...

An interrupt that is allowed to interrupt other interrupts completely clears temporary stop schedule.

E.g. Have a refuel interrupt that can interrupt others, and an interrupt that has 2 stops. If the refuel interrupt becomes valid before the train leaves the first station, then upon starting the ...