Is there some reason why you want to hold an exact temperature for the entire steep? You are always going to get some temperature drop pouring from the kettle into your cup/teapot/etc.
I know in the gongfu method, it is standard practice to do a hot water rinse of the cups, which should warm them and reduce the temperature drop somewhat. You could do something similar by filling your brewing vessel with hot water, draining, and then filling it with the tea and new hot water, but you will not eliminate the temperature drop entirely.
I would assume most recommended times/temps from tea vendors are designed with some temperature drop in mind. I think they are more like recommendations than hard, scientific values.





As someone out of the loop on this, it would be helpful if they didn’t wait until 4 paragraphs into the article to state what OnlyOffice actually did. Likewise the article they link to by OpenOffice doesn’t state what EuroOffice did until 7 paragraphs in.
Apparently it’s a dispute about EuroOffice changing the logo when they forked OnlyOffice?