The AI of the Diagram now also understands the trick of reserving a square for your next move by playing the Duck there, as you can verify by setting up a position through h7-h6, g7-h4, h2-h3, Ke8-h5, Qd1-d3. If at that point you switch on the AI, and play a useless move for black (e.g. a7-a6, Duck to a7), the AI will reply with Qf5, Duck to g5, and announce mate. (Which in this case does not end the game yet, but should be interpreted as announcement of King-capture in 2. In general the Diagram will allow you to play on when you are checkmated; if you do a pseudo-legal move there it will capture your King an announce "I win".)
The AI of the Diagram now also understands the trick of reserving a square for your next move by playing the Duck there, as you can verify by setting up a position through h7-h6, g7-h4, h2-h3, Ke8-h5, Qd1-d3. If at that point you switch on the AI, and play a useless move for black (e.g. a7-a6, Duck to a7), the AI will reply with Qf5, Duck to g5, and announce mate. (Which in this case does not end the game yet, but should be interpreted as announcement of King-capture in 2. In general the Diagram will allow you to play on when you are checkmated; if you do a pseudo-legal move there it will capture your King an announce "I win".)