Reflective Hybrid RAG for Recommendations
How can a recommendation system separate what a user has already done from what they actually want next — and use that gap to personalize better?
Improved top-1 recommendation accuracy 3× (12.5% → 37.5% HR@1) with a reflective hybrid RAG system separating raw user history from synthesized preference memory. Lifted personalization quality across ranking metrics (+25% HR@10) by combining dense embeddings and sparse SPLADE retrieval with LLM-generated user personas.
Problem, Limitations & Findings
The Problem
How can a recommendation system separate what a user has already done from what they actually want next — and use that gap to personalize better?
Limitations
Relies on LLM-generated personas, which can drift or hallucinate preferences the user never actually expressed. Evaluated on offline benchmarks, not live user traffic.
Findings
Separating raw history from synthesized preference memory tripled top-1 accuracy (12.5% → 37.5% HR@1) and lifted HR@10 by 25%; combining dense embeddings with sparse SPLADE retrieval outperformed either approach alone.