Event/Feature for detecting when an area is empty

[tylerhartwig]

Is your feature request related to a problem? Please describe.
No problem necessarily, but it's not exactly straightforward to write automations around "there's likely no device in this room" in Home Assistant -- it seems you can do this through a series of sensors.

Describe the solution you'd like
It'd be really cool to be able to create groups of devices that create events when they've been away from a given area for a given amount of time. So, if my watch and phone for instance are outside of my office for 1 minute, triggering an event that can trigger additional automations. Also, the reason it'd be nice to have groups is to be able to create different events (i.e. no on in a room).

Alternatively, it could be simpler to just have an event trigger when there's been no change in a room in X minutes. This would may be easier and more flexible so users could craft their own events based on time.

Describe alternatives you've considered
This can all be done in Home Assistant, but again is unwieldy and requires a series of helpers and sensors. There may be an easier way that I've not discovered yet. Additionally a physical presence sensor could do it as well.

[tbrasser]

The dev of magic_areas is using bermuda and is looking into options of integrating

[tylerhartwig]

@tbrasser very interesting! thanks for pointing me to that, will keep an eye on it.

I also think I found a pretty easy way to make the event trigger I mentioned in my solution proposition, so this may not make sense in this repository, but I'll let agittins close it if that's what makes sense.

[agittins]

The difficulty of doing this in Bermuda is that there is no clean way for Bermuda to know which devices you care about for a particular area. Your phone and watch might make sense for your office, but what about the dog's collar? Or the back yard? Different areas will (typically) have different lists of devices that are "relevant" to it, so Building it into Bermuda would become very messy and complicated, so in my opinion, is the wrong place for it.

In #203 spdustin offers a template that can be used to aggregate area sensors by using labels, which I think is a good way to do it, and the comments there expand on my thinking on that a bit, too.

@tbrasser now that sounds very interesting! Is is this repo: https://github.com/jseidl/hass-magic_areas ?

An integration like that which concentrates on building out smarts for Areas specifically sounds like a great addition, and a much cleaner way to do things than trying to build that into Bermuda.

I'll mark this as a duplicate of #203 just to try and keep the decks clear, but feel free to add further comments as things come up. I'm adding a wiki FAQ for this, too - and will include magic_areas once I can confirm if it's able to leverage Bermuda's sensors.