Google Keep for @Agendas


I moved my @Agendas list from Google Tasks to Google Keep for the following reasons:
  • Native support for check boxes in Keep notes
  • Date/Time and/or Location-based reminders
I often forget to check my @Agendas list, so if I know about when or where I'll be meeting with someone I can set that reminder in Keep. It works pretty well, but it doesn't cover chance encounters. This generally isn't a huge problem but I'm often looking for ways to make my system smarter than I am.

I wonder if it's possible to set up a proximity notification when another person is close by (i.e. that person's phone is nearby). I imagine that all parties would have to subscribe to some sort of service and/or have a particular app installed and running. Has anyone ever heard of or tried such an app?