Kursk, while embarrassing as hell, is not an actual threat to Russian statehood in the military sense.

That this kind of rhetoric completely devoid of historical knowledge and common sense is so widespread tells me so many people have a completely broken model of Putin's motivations. Unfortunately it is these same people that are pushing hard for escalation. It's strange to see people's opinions be so completely disconnected from reality while also being correlated to such a high degree.

No, the fact that Russia didn't use nukes in response to Kursk incursion says nothing about his willingness to use nukes when the security of the state is actually at risk. Nuclear weapons will change the complexion of this war in ways that neither side can fully predict. It is rational to avoid moving the war to an unpredictable stage when the current stage is manageable in your favor. Not every border skirmish is created equal. They do not all rationally warrant the use of nuclear weapons.

We have been very lucky[1]. Do you really want to push that luck?

[1] https://en.m.wikipedia.org/wiki/Nuclear_close_calls

Nonsense, there was no call.

Blowing some shit up in the grey zone (or even Kursk) is one thing - his state hasn’t been threatened in any real way (which is their nuke threshold policy).

However, lobbing western made (and make no mistake, western operated) weapons into their internationally recognized territory is an entirely different ballgame.