According to NotebookLM (@NotebookLM), chat history synchronization has been officially rolled out to 100% of users across both mobile and web platforms. This development enables users to seamlessly start a session in the app and continue it on the web without interruption. Additionally, users retain control with the ability to delete chat history at any time, and in shared notebooks, chat visibility remains private to each user. This AI-driven feature enhances cross-platform productivity and supports secure collaboration, offering significant business opportunities for SaaS providers and enterprise AI solutions (source: @NotebookLM, Dec 16, 2025).