When this is going to be live on cswiki?

It’s already live, see Speciální:Nastavení#mw-prefsection-editing-discussion (setting Aktivovat experimentální nástroje v editoru zdrojového kódu…).

There is no such option for me

Maybe you have the DiscussionTools beta feature disabled? (I’ve enabled the DT beta feature in my global preferences, so I haven’t noticed this requirement, as it’s automatically enabled on cswiki as well.)

So to make this possible, I should activate beta feature in addition to discussion tools? Understood! But it should have been written in Tech News or somewhere, Tech News just said what you said here:

It’s already live, see Speciální:Nastavení#mw-prefsection-editing-discussion (setting Aktivovat experimentální nástroje v editoru zdrojového kódu…).

@Dvorapa, we're glad you've discovered the source mode toolbar (we appreciate you providing guidance, @Tacsipacsi). If any ideas/questions come up as you're using it, we'd value hearing.

Regarding making sure people are/were aware of this new functionality, there was an announcement in Monday 17 May 2021's installment of Tech News [i]. If you think that message could've been more effective had it been communicated in a different way, please let us know.

i. https://meta.wikimedia.org/wiki/Tech/News/2021/20

I think this is done?