AI coding startup Cursor has launched a new model called Composer 2.5 that has been specifically trained for long-running coding tasks. Composer 2.5 also follows complex instructions more reliably, besides other behavioural improvements such as communication style and effort calibration, Cursor said in a blog post on Monday, May 18. The improvements in Composer 2.5 have come from scaling training, generating more complex RL environments, and introducing new learning methods, as per the company. Composer 2.5’s debut arrives months after Cursor’s Composer 2 model that drew some backlash after users found that the model was a RL-modified version of Kimi 2.5, an open-weight AI model recently released by Moonshot AI, a Chinese AI startup backed by Alibaba and HongShan (formerly Sequoia China). Acknowledging that Composer 2 was built on top of Kimi 2.5, Lee Robinson, Cursor’s vice president of developer education, said, “Yep, Composer 2 started from an open-source base!” “Only ~1/4 of the compute spent on the final model came from the base, the rest is from our training,” he added. “It was a …