NotebookLM tests Mind Map controls and Play Books sources

Google appears to be testing NotebookLM mind map controls that could scope diagrams by topic, problem, or selected sources.

That would let users create multiple focused mind maps from a single notebook instead of relying on third-party tools.

A hidden Play Books source link also suggests possible book imports or a new source type for NotebookLM.

If shipped, the updates could make NotebookLM more flexible for research workflows and broader content inputs.