Cursor Admits Composer 2 Built on Chinese Rival Moonshot AI's Kimi; Licensing Transparency Controversy Erupts

Cursor acknowledged its Composer 2 coding model was built atop Moonshot AI's open-source Kimi K2.5, after researchers discovered the model ID 'kimi-k2p5-rl-0317-s515-fast' in Cursor's API configuration. Cursor's VP Lee Robinson stated the base model accounted for only '~1/4 of the compute,' but co-founder Aman Sanger admitted failing to credit Kimi in marketing was 'a miss.' Kimi's license requires prominent attribution for products exceeding 1 million MAU or $20M monthly revenue. The incident highlights growing tensions around open-source AI model provenance and the thin line between fine-tuning and independent development in the coding agent market.