Cheap compatible beacon

Hi, i want to make a rule that activate a night mode when I’m in my bed…

So I look at mysensor to make a DIY one but then I realize that I don’t want to nigh mode to activate if my girlfriend is in my bed in me in the office. SO …

…I think about beacon. When me and my girlfriend both of our iPhone are in the room plugged. !

So I’m looking for beacon to put in my room that is compatible with openhanded and who’s gonna send command to openhab only if I’m in my bedroom

If it is an Android phone look at FIND.

Beyond that I know of no beacon or other wireless way that will be accurate enough to pinpoint you down to a specific room.