OpenAI’s “Deployment Simulation” Replays 1.3 Million Real Chats to Catch a Model Misbehaving Before Launch
Detailed June 16, OpenAI’s Deployment Simulation forecasts how an unreleased model will behave by replaying ~1.3M past conversations through it and grading the results — hitting a median error of about 1.5x and catching “calculator hacking” in GPT-5.1 before release.
OpenAI
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