Strawberry was the popular code word for reasoning, as implemented in o1-preview, in case that wasn’t clear. https://www.oneusefulthing.org/…

"Strawberry" was OpenAI's internal code word for the extended reasoning capabilities featured in the o1-preview model, which enables the AI to work through complex problems with longer chains of thought before providing answers. This terminology was used informally within OpenAI's development discussions before the model's public release.

Source: Ethan Mollick (X) | 2026-05-22