Parametric Memory Decoding for Zero-Shot Routing in LoRA-Based External Parametric Memory

This paper introduces Parametric Memory Decoding (PMD), a framework that reframes zero-shot routing among LoRA-based External Parametric Memory (EPM) modules as decoding activation signals over external memories. It proposes PMD-Bench, covering document-level knowledge, domain-level knowledge, and task skills. The instantiated PMDRouter scores each LoRA using its response magnitude from a single base-model prefill, avoiding a separately trained or maintained router. According to the paper’s summary, PMDRouter delivers the strongest performance among internal-signal methods across several zero-shot routing settings.