If I initially commission a Matter device to Google, it adds it to Home. I can get a code from Google Home app to then add the device to Hubitat. If I then Remove it from Google Home (for example I don't want it controllable from my Nest Displays) it kills the device's connection to Hubitat as well (after warning me it will do so). And this applies to both Matter over Thread and Matter over Wifi devices.
On the other hand if I initially commission the device to Home Assistant (in the case of thread devices it HA goes via my phone to the Google thread network). If I then have HA issue the code to share the device on to Hubitat, I can then remove the device from Home Assistant, and it remains operable by Hubitat.
I feel as if the participation of a matter device in any fabric is intended to be independent of the other fabrics and it should be able to leave one individually. Am I right?
FWIW all my Matter devices have been an exercise in frustration. Just got a new A/C , the Matter connection failed with Google. Although the separate WiFi control app works perfect.
I suspect Hubitat is using Google to get to the Matter device. I think I heard at some future point HE will be able to join Matter devices directly?
You actually can do that now. You just can't share them to other things. Also if they dont have the code to do the add attached to them it may be a problem.
I have a few a Govee Matter devices i directly paired to my C8.
FWIW, this is also how it works with an Amazon Echo. I added the Matter device via the Alexa app, shared to Hubitat, and then finally removed it from the Echo, and it remains working in Hubitat.
So it's not Hubitat getting it wrong then. That's the trouble with Google - it thinks it owns your home once you let it in. I don't know if they've changed their wifi mesh system but we got one a few years back and it didn't let you change the subnet it was on, which was different from the devices connected directly to our main router. Their answer was that the master mesh router was meant to replace our normal router, whereas we don't like the wifi to be handled by our main router so as to maximise processing power for the devices we have chosen to run wired. But Google wants you to do things its way.
Anyway, so I tried setting up a second Google Home to keep Matter devices in that I don't want cluttering up my Google dashboard. But I don't have the Nest Displays in the new fake home, so of course I can't add any Thread matter devices to that home. So I went ahead to add a Matter over wifi device, and Google tells me I can't, because it needs a border router in that home. Oh no it does not! Come on Google get with the program!
While Google does do some funky things with their implementation, this part from Google is true. You need a Matter commissioner in the new Home in order to add a Matter via WiFi device. You need one of the following: Google Home, Google Home Mini, Nest Mini, Nest Audio, Nest Hub (1st gen), Nest Hub (2nd gen), Nest Hub Max, Nest Wifi Pro (Wi-Fi 6E) in the second Google Home before you can add a Matter device.
Fair enough. It shows the hubs as "Linked to You" in the fake home you'd think it could go ahead and borrow them just for commissioning purposes. Even as a thread border router in fact.
I'm pretty confident that Alexa and Apple work the same way. It's "linked to you" via your Google account in the other Home. Within Alexa/Apple/Google, generally a device can only be in one home at any given time with the exception of a Matter device. It is theoretically possible to setup a Matter device into two different Google Homes as long as you have two different matter controllers.
So.... what would or should we expect under the following situation. I commission a Matter over Thread device via Home Assistant, which uses the Google thread network and border router to provide transport (this will not make the device appear in Google Home). I then get a pairing code from Home Assistant to get the device into the Hubitat fabric. After that I delete the device from HA. I then delete also from Hubitat. At this point the device no longer has a matter controller in charge of it. Does it know? Does it remove itself from the Google thread network?
Not sure why anyone would want to do this, but I'll play along. In this scenario, the device would still be connected to the Thread network, but be uncontrollable. The only way to control the device in the future would be to factory reset it.
The closest analogy to your example actually comes from Home Assistant and it's HomeKit Device with an Apple Thread Boarder Router (see HomeKit Device - Home Assistant). In this example, a HomeKit only device (not Matter) that uses Thread can still be connected to Home Assistant while using an Apple Thread Network (not Home Assistant's).
All of the above also applies to Matter via Wifi devices. It is possible to get a Matter via Wifi device connected to your Internet, but have no control over it if the device has been removed from the Matter fabric. It just sits connected to the Internet waiting for something to tell it what to do. Again, the only way to gain control would be to factory reset and re-commission.
That's what I'd expect too. But it is the right way to spec the system? Would it be better if the UI of each controller would let you know each time the device was removed from a fabric how many other fabrics the device was still part of, and offer to reset the device when down to the last one. After all, the device does hold that information.
Glad you posted this, I was unaware. I just got a Matter device to play with. Used Apple Home to set it up then linked to HE. Didn't know I could then delete it from Apple. But it worked out just fine. Thanks.
