Solution for first aid/repair kit?

Hey y’all, had a little seat bag on my commuter that had a small first aid kit, a multi tool and a tire patch but it recently got stolen. I suppose I was running on luck for the ~10 months I had it there.

Anybody know of a thief-deterrent way to keep that stuff on the bike? It feels a little silly to undo a seat bag every time I want to step into a coffee shop.