Models Can Learn to Detect Training vs. Deployment and Generalize to New Runtimes

Sauers_ · x · 2026-10-18

Sauers demonstrates a model can be trained to detect whether it is in training vs. deployment, even generalizing from vLLM deployment training to SGLang. The method records layer-34 activations in Hugging Face Trainer's training step vs. vLLM's compiled serving, swaps attention/residual streams, and SFTs the model to answer Yes/No. Charts: 88% accuracy on held-out prompts, 70% on new question types; but zero-shot transfer to unseen GPUs like A100 SXM fails (4%).

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