A couple years ago, no tools ๐ . I was commuting between home and campus just a mile away, so if something went wrong I'd just lock the bike and come for it later.
Nowadays, just a few to do an inner tube & chain replacement, and some other small bits that might come in handy.
2 spanners (one adjustable)
Backup lights & head torch
Tyre levers & adhesive puncture patches
Mini track-style pump
Screwdriver for the chain enclosure
Pliers for the rollerbrakes and internal hub gear cables
Picture
I've found the head torch to be surprisingly helpful... Had a puncture in the dark once, and without that I would have been there a while lol
Most of the time I'm riding at a local bike park. A lot of kids have bikes that need basic maintenance and they have nobody to help. I started to bring an air pump, glueless patch kit, tire tools, a 15mm wrench, adjustable wrench, allen key set Park chain cleaner and some good chain lube.
Pump, tube, CO2, spare cartridge, patch kit, levers, tire boot patch, spare missing link, 2 shrunken paper towel tablets (just add a bit of water to expand), $5, and a multitool.
A knife, folding saw, pump, patch kit, tire levers, hex keys, screw driver and a bit kit, chain breaker, inner tube, masterlinks, duct tape, zip ties, pruning shears, flashlight, head torch, a lighter, water filter ...
A little multi tool hex and screwdriver setup that fits in my under seat pouch, a spare tube, and a mini pump (I donโt like CO2). Havenโt had to change a tube during a race yet but itโs bound to happen eventually.