A couple years ago, no tools π . 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
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.