Offline mode in HA companion app / Using companion app as BLE remote

I would like to use my HA companion app to control BLE devices such as blinds or lightbulbs, even without an internet connection to the HA instance, just using a direct BLE connection from my phone to the device. Is this possible? And if not, would this be hard to add? I want to implement this feature even only for myself if it isn’t viable for upstream. I would appreciate any tips.

Ems… is very VERY VERY complex. You need «remake» all BLE devices controls directly to Android/IOS, so you need rewrite all code (HA is python, Android is Java/Kotlin and IOS is Swift/ObjectC).

The good part is HA don’t need internet connection for local devices. You only need connect directly to HA using LAN.

Mobile → Wifi → HA → BLE/Wifi/Zigbee

Thanks, I meant “internet connection” as a connection to my local network. Router and HA instance can turn off due to e.g. power outage, but I still can have BLE devices running on battery, which I would like to control.

I have found the BLE Transmitter sensor in the app, so I guess some parts of BLE are already implemented?

Not, BLE Transmistter is for send data from you mobile to HA.

All devices controls are in HA.

the app itself will not connect directly to a device as you described. You need to actually setup Bluetooth proxies to communicate with the device and use the app like you would to control any entity.