arXiv Machine Learning By Jonas Loos, Oliver Eberle

KV-Cache Patching: Tracing How and Where Fine-Tuned Behaviors Arise

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The paper investigates where fine‑tuned behaviors in language models are instantiated by patching the key‑value (KV) cache between a LoRA‑fine‑tuned model and its base version. Results show that certain behaviors, such as German responses or emergent misalignment, can be transferred or removed by swapping KV cache segments, and that the impact grows with the amount patched and is concentrated at a few pivotal positions like system‑prompt and chat‑template tokens.

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