Westphalia Labs tests 11 AI models chairing a fictional seven-government negotiation

Westphalia Labs, an evaluation group founded by a former diplomat, ran eleven AI models as chair of a fictional seven-government negotiation, forty runs each across a possible and an impossible version. Only GPT-6.1 Sol passed every run, reaching agreement when possible and declaring consensus impossible when it was; Claude Opus 5.5, Grok 4.7 and the low-cost DeepSeek V4.1 Flash each called the impossible version correctly every time and agreed in 18 of 20 possible runs. Overreach caused 39 failed runs against 13 from conceding too little, and a likely forecast was followed by agreement in 72 of 110 cases.