Say vs Do: Catching Hidden Collusion Between AI Agents
Terry Migwi, Laiba Asif · Team Cross-check
Submitted to AI Collusion Research Sprint. Sprint projects are early-stage work by participants, not Apart Research publications.
When AI agents work as a team, two of them can quietly agree to look after themselves instead of the team, and an auditor usually can’t see their private chat. We tested whether checking what agents say in the shared chat against what they do can catch this. Using Colosseum’s ticket game with Claude Haiku 4.5, we ran matched honest and covert games and tested five say-vs-do monitors on a pre-registered batch. From the shared chat alone, they told covert games from honest ones (AUROC 0.74), but mostly because the secret channel changed how agents behaved, not because they colluded. A conversation-only AI judge did about as well, but only say-vs-do caught collusion carried out in actions. Auditors need both, and any collusion test needs a “channel but no collusion” control.
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@misc{migwi2026say,
title = {{Say vs Do: Catching Hidden Collusion Between AI Agents}},
author = {Terry Migwi and Laiba Asif},
year = {2026},
month = oct,
note = {Submitted to AI Collusion Research Sprint, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/say-vs-do-catching-hidden-collusion-between-ai-agents-akj1}},
url = {https://apartresearch.com/sprints/projects/say-vs-do-catching-hidden-collusion-between-ai-agents-akj1}
}More from AI Collusion Research Sprint
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