100,000 Videos in Your Pocket: How Douyin's Recommender Reads Your Whole Life in O(1)
One-line: ByteDance's SequenceO1 compresses a 100,000-interaction watch history into a pocket-sized sketch, reads it in constant time, and still finishes +2.3% more videos — live now on Douyin at full traffic. A year of Douyin is roughly 100,000 interactions per user. Every recommender on earth wants to read all of them — your durable taste is in there, not just last Tuesday's mood. Almost none do. The fine-ranking stage that scores every candidate video has milliseconds to decide, and naive at…