The brain NVIDIA sells for robots is an Alibaba model underneath — and its own numbers show what the retraining bought

NVIDIA's Cosmos stack for physical AI has two halves. One imagines: Cosmos 3 Super, Nano and Edge take a movement and predict how the scene will look afterwards. The other thinks: Cosmos Reason watches video and writes text about what is happening, whether it is physically plausible, and what a robot should do next. The thinking half is the one NVIDIA points at when it talks about robot planning, video analytics and labelling the data that trains everything else. Its model card says plainly what it is built from. All three tiers — 2B, 8B and 32B — are post-trained from Qwen3-VL-Instruct, the open vision-language model published by Alibaba, and NVIDIA states the architecture is unchanged from the base. The American company selling the reasoning layer for Western robotics ships, underneath, a Chinese open model with American post-training on top. The more interesting number is what that post-training is worth, because NVIDIA benchmarks its model against the exact base model it started from. On general vision the gain is almost nothing: 75.85 against 73.07 for the 32B tier. On robotics questions it is modest: 60.60 against 55.06. But on self-driving benchmarks the score goes from 48.08 to 70.15, and on warehouse spatial reasoning from 47.55 to 77.79. The pattern repeats at every size. Post-training did not make a smarter model — it made a model that knows two specific worlds, cars and warehouses, and is otherwise roughly the model Alibaba published. The download counts tell a third story. In the 30 days to 26 August 2026 the smallest tier, Cosmos Reason 2 2B, was pulled from Hugging Face 969,959 times — the most of any model in the entire Cosmos line, and roughly eight times the flagship 64-billion-parameter Cosmos 3 Super world model at about 121,000. The 32B reasoner, the one NVIDIA leads with, was downloaded 3,194 times. Whatever the marketing hierarchy says, the physical-AI work is happening at the small end. One term of the licence deserves reading before deployment. The NVIDIA Open Model License allows commercial use, derivative models and unrestricted use of outputs — but the grant terminates automatically if the user disables or weakens the model's safety guardrails without putting a comparable mechanism in place. The 2B and 8B weights also sit behind an automatic licence gate on Hugging Face; the 32B does not. wujec.ai has added profiles for all three tiers.