Clicking on the red cut generates an explicit exchange.
And afterwards, clicking on the green cut generates an error message:
"Bad request: invalid proof: Premises conclusion do not match expected premises conclusion after applying rule {\"rule\":\"cut\",\"formula\":{\"type\":\"whynot\",\"value\":{\"type\":\"dual\",\"value\":{\"type\":\"litt\",\"value\":\"o\"}}},\"formulaPosition\":2}}"
Clicking on the red cut generates an explicit exchange. And afterwards, clicking on the green cut generates an error message: