I can start a game on Lichess, resign it right away, enter analysis mode, then disconnect from the internet and continue to use the board (in the same way that

I can start a game on Lichess, resign it right away, enter analysis mode, then disconnect from the internet and continue to use the board (in the same way that one can use the board on site we are discussing here), so Lichess's analysis board does not use XmlHttpRequest either.