Xiaohongshu's RedMall: generative e-commerce recommendations with hierarchical SIDs and RL

_reachsumit · x · 2026-11-10

Xiaohongshu researchers present RedMall, a generative recommender for large-scale e-commerce. It tackles three gaps in prior work: semantic IDs treated as flat sequences, next-token prediction not optimizing session-wise recommendation, and RL lacking explicit ranking optimization.

RedMall builds hierarchical SIDs via residual quantization over multimodal representations, adds a lightweight SID encoder for layer-wise dependencies, and scales with sparse MoE, dual gated attention, and multi-target prediction. An exposure-aware loss treats exposed-but-unclicked items as negatives, combining GRPO with an auxiliary LambdaRank objective for list-wise ranking.

Original post →

More from Research

Research channel →