X, formerly Twitter, announced on October 20, 2026 two updates to its recommendation system. The first is a new AI ranking model designed to better predict how long users will spend on posts. The second is a retrieval model that prioritizes posts users read to completion. Elon Musk also stated that active user seconds on X are experiencing exponential growth, hitting new records almost every day. These updates are part of the Phoenix model framework, which runs on a transformer architecture adapted from Grok, the AI model developed by xAI. In August 2026, X had open-sourced its ranking code under the Apache 2.0 license.
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