This week's recommendation systems research runs along three technical threads. First, Semantic ID-driven generative retrieval keeps gaining momentum. Spotify released two papers simultaneously — one deploys a SID system in production with A/B test results (new show discovery rate +14.3%), the other treats SID as a standalone modality unifying search, recommendation, and reasoning. Industrial SID systems have moved past "can this work?" into "how do we make it work better." Second, multimodal retrieval and representation compression: Apple delivered a production-grade unified retrieval architecture for text, images, and video; Aalto University distilled a 2B-parameter VLM into a 69M text encoder (50x latency reduction); POSTECH identified and fixed a modality collapse problem in VLM embedders for recommendation.