I wanted to avoid unnecessary re-rendering useMemo hook below. Holding this thread as plain object could trigger re-render of mentioned hook every component re-render, because eslint requires to add it to dependencies.
Alternatively, we could also use useMemo instead useRef, but I choose useRef because I wanted to keep the same convention as in pendingPrivateThread

You should avoid calling createPendingThread again on every render, which is currently happening. useMemo is a good bet

Ok, I will change that

To avoid matching with private thread, we need to distinguish private thread id and fake "new thread" id. Because in createPendingThread we couldn't pass by default threadID, we need to override this in this way.
Another solution is to add threadID as an optional argument in createPendingThread function.

It's pretty weird, but when I tried it last time, it didn't work. But now I tested it and it works. So we can use it.

I didn't check it before, but community parameter will also be null, so it could be removed

App also match e.g. last message with existing thread using threadID. Now, when we create a new thread, there is "No message" communique below the thread name.
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When we keep the value that createPendingThread provides by default, our app will match it with an existing private thread.
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Also, I use it in next diff, to treat it as normal pending thread and to handle unique onClick event behaviour on it.