Cursor, AI coding company, released the new model Composer 2, which has been advertised as offering “frontier-level coding intelligence.”

The new model however attracted criticism for using Kimi 2.5 – an open source model by the Chinese company Moonshot AI with just additional reinforcement learning according to the X user Fynn. They said:

“[A]t least rename the model ID,”

At first, the company did not mention Moonshot AI or Kimi in its announcement, which quickly raised questions about the role of the AI “arms race” between the United States and China in the situation.

Lee Robinson, Cursor’s vice president of developer education, responded by saying, that Cursor’s use of Kimi was consistent with the terms of its license. He also clarified

“Only ~1/4 of the compute spent on the final model came from the base, the rest is from our training.”

As a result, he said Composer 2’s performance on various benchmarks is “very different” from Kimi’s.

The company Kimi also joined the conversations posting:

“We are proud to see Kimi-k2.5 provide the foundation. Seeing our model integrated effectively through Cursor’s continued pretraining & high-compute RL training is the open model ecosystem we love to support.”

Cursor co-founder Aman Sanger said in a post,

“It was a miss to not mention the Kimi base in our blog from the start. We’ll fix that for the next model.”