Composer 2 performed differently on evals than Moonshot.ai's coding models: Cursor claims theirs is better than Claude Opus 4.6: https://x.com/fynnso/status/2034706304875602030 / https://archive.vn/bVtik. And, per Lee Robinson (Cursor employee), it is very likely Cursor builds its own foundational model for Composer 3.
Cursor had an "agreement" with Fireworks.ai, which apparently allowed them to RL Composer 2 atop Kimi Base 2.5 without attribution: https://x.com/Kimi_Moonshot/status/2035074972943831491 / https://archive.vn/CcdkI
Composer 2 performed differently on evals than Moonshot.ai's coding models: Cursor claims theirs is better than Claude Opus 4.6: https://x.com/fynnso/status/2034706304875602030 / https://archive.vn/bVtik. And, per Lee Robinson (Cursor employee), it is very likely Cursor builds its own foundational model for Composer 3.