[DigitalToday reporter Chi-gyu Hwang] AI coding company Cursor launched a new model, Composer 2, and promoted it as delivering frontier-level coding intelligence. However, it later emerged that it partially used an open-source AI model provided by Chinese AI company Moonshot AI.

Cursor did not mention Moonshot AI or Kimi when it announced Composer 2. But an X (Twitter) user claimed that Compo 2 was nothing more than Kimi 2.5 with reinforcement learning added, and Cursor Vice President of Developer Education Lee Robinson (리 로빈슨) also acknowledged that "it is true that Composer 2 started from an open-source base."

Robinson said only about one quarter of the compute used in the final model was taken from Kimi 2.5 and the rest came from Cursor's own training. He said Composer 2's benchmark performance was "significantly different" from Kimi's.

Robinson also claimed it was used in line with Kimi's licensing terms. Kimi's X account also said in a follow-up post that Cursor used Kimi through an official commercial partnership with Fireworks AI. Moonshot AI said it was "proud that Kimi provided the foundation for Composer 2."

An analysis says the U.S.-China AI rivalry played a role in why Cursor did not disclose from the outset that it used a China-made model. A representative example is Silicon Valley's reaction when China's DeepSeek unveiled a competitive model early last year.

Cursor co-founder Aman Sanger (아만 상어) said, "It was a mistake not to mention the Kimi base in the blog from the beginning. I will fix it in the next model."