Master Assistant Agent: Drift-Free Query Routing for Multi-Collection RAG via Parallel Corpus Probing

his paper introduces the Master Assistant Agent (MAA), a drift-free query routing architecture for multi-collection Retrieval-Augmented Generation (RAG) systems. Unlike existing routers that rely on static descriptions, utterances, prototypes, or classifiers, MAA routes using live corpus evidence obtained through parallel collection probing. Experimental evaluation demonstrates substantially improved robustness under corpus drift compared with representative utterance-based routing approaches