Custom domain and state

[NdS-Research-Facilities]

Hi all,
first thanks for this great addition !
[What I try to do]: in the past I used to be able to use the HTTP/PUT method to create a temporary state with a custom domain e.g. homestate.kitchen with a state of kitchen_on

Now that seems no longer possible, how do I achieve the same in the websocket model ?

I tried this:

{
    "domain": "homestate#",
    "target": {
        "entity_id": "test2"
    },
    "data": {
        "type": "string",
        "state": "test22"
    }
}

but to no avail.
I'm getting this error:
15 Jun 00:01:37 - [error] [ha-api:create homestate] API Error. Error Message: Unknown command.

Home Assistant 2023.5.4 Supervisor 2023.06.2 Operating System 10.2 Frontend 20230503.3 - latest

Node-RED Current version: 14.2.2