Cursor's Composer 2 Model Sparks Controversy Over Use of Chinese AI Framework

Cursor, a prominent AI coding company, recently launched their new model, Composer 2, promoting it as a "frontier-level coding intelligence". However, controversy emerged when an X user named Fynn claimed that Composer 2 is merely "Kimi 2.5" with additional reinforcement learning. Kimi 2.5 is an open-source model from Moonshot AI, a Chinese company backed by Alibaba and HongShan. Fynn provided evidence pointing to code indicating Kimi as the underlying model.

• Cursor, a well-funded U.S. startup valued at $29.3 billion, raising $2.3 billion last fall, did not initially credit Moonshot AI or Kimi in its announcements.
• Lee Robinson, Cursor's VP of Developer Education, acknowledged that Composer 2 is built upon an open-source base but insisted most of the final model's computing was from Cursor's training, making its performance unique.
• Robinson also stated that using Kimi complied with its licensing terms. The Kimi account affirmed this, congratulating Cursor and highlighting an authorized partnership with Fireworks AI.
• The incident raises questions about transparency and intellectual property, especially amid heightened tensions regarding AI development between the United States and China.
• Aman Sanger, Cursor's co-founder, admitted the oversight in not mentioning Kimi initially and pledged to address it in future communications.