coming soon to a pyserb server near you
i have not built something to this scale yet, but so far it looks pretty good
the "fuel engine" took some fucking fiddling about in order to work
it seems to me that if you dump all fuels into a sushi pipe with overflow valves, it's as if the "switching of fuel" itself causes machines to not actually perform work on a rare occasion, but still always report that they are working, so you'll never see a machine say "need fuel" but you'll also see a 5% hit to productivity that can't be explained otherwise (if your sushi pipe is switching extremely rapidly, maybe 10 times a second)
the trick seems to be to have every fuel on its own pipe with a tank as a buffer, then a pump from each fuel pipe to the sushi pipe that triggers if the fuel pipe goes above 80% and stay on until it drops below 20%
this appears to causs the fuels to build up and then go into the sushi pipe in "slower turns", causing fewer fuel switching ticks and removing the mysterious productivity loss