Full change of kit for me. Can't stand the thought of a 600 in the same kit, just disgusting.
Spare jacket/gloves/socks in case it's been pissing down
Towel, shower gel, toothbrush/toothpaste, deodorant
Spare tube or 2, any chargers. Couple snacks for next day
I have ahem, also been known to put my onesie in one to grab a few hours sleep in 😂😂