Coding company Cursor has admitted that its new model, Composer 2, was built on top of Moonshot AI’s Kimi, a Chinese company backed by Alibaba and HongShan. However, an X user claimed that Composer2 was "just Kimi 2.5" with additional reinforcement learning. This revelation came as a surprise as Cursor, which raised a $2.3 billion round and is reportedly exceeding $2 billion in annualized revenue. Cursor's vice president of developer education, Lee Robinson, acknowledged that only 1/4 of the compute spent on the final model came from the base, and the rest is from training. The use of Kimi was consistent with the terms of the license.