[ymtwwbli] Online chess opening research

As you play someone in online chess, let the UI make available both yours and the opponent's previous games and moves played from the current position, perhaps annotated with computer analysis.

Both players can see both players' past games, so there is no advantage in information.  You know, they know you know, you know they know you know, etc. (common knowledge).

Amateurs can mimic the opening preparation done by professionals, though not have to memorize it.