There has been several prominent visits to Kyiv since the war started, including U.S. Secretary of State Antony Blinken, US Defense Secretary Lloyd Austin, UK prime minister Boris Johnson, and United Nations Secretary-General Antonio Guterres. Is Russia notified before these visits so they can avoid accidentally triggering a "Pearl Harbor moment", or is it kept a secret? What is regarded as safest, to tell them or not to tell them?
If I recall the timing correctly, most of these visits you mentioned were announced to the public before they happened. You could read in western newspapers that these visits were going to happen usually a day or two before the politicians travelled. So they are definitely not secret and one would expect the Russian government to be aware of all information that is publicly available and relevant to them. I don't know whether the Russian government is informed separately but I don't think that would be necessary.