My old neighbor Sal did the exact same thing, walked right in while I was watching TV and grabbed a soda from my fridge. I started locking up after that and he acted all hurt, but you gotta do what you gotta do.

That co-op guy gave you solid advice and I had almost the same thing happen to me. My chain broke on the Greenway a couple winters back and I stood there in the cold for 45 minutes waiting for my wife to pick me up, feeling like a total idiot. Now I keep a quick link, a multi tool, and a little tire boot in an old Altoids tin in my bag, and honestly the tire boot has saved me twice. One thing people forget is a couple of zip ties, they weigh nothing and I have used them to hold a loose fender and even strap a broken rack back together to get home. Also throw in a spare shift cable if you can, since you already learned that one the hard way.