One time, first commute after a rebuild, and for some reason I rode 'naked': no seatbag, no multitool etc in it.

Front derailleur broke off, was dangling off the cable, and no way to keep it clear of the chain. I wasn't equipped to remove it and continue on as a 1x, so I had to call home for a ride.

Note to self: the proper attitude for the first ride after doing some bike work is not "I fixed it, so now I have nothing to worry about", but rather "I 'fixed' it, so I better have some tools with me next time I ride..."