How are people keeping manager notes private in Teams without creating a mess of separate files?

You need a clear boundary between a manager’s private working notes, employee-shared notes, and material HR should access. Putting everything into one shared notebook does not provide that boundary: OneNote sharing applies to the notebook, and a section link does not restrict recipients to that section. A practical design is a dedicated, restricted SharePoint library for management records, with permissions assigned at a deliberately chosen library or folder boundary. Keep employee-shared material in a separate location rather than mixing it with private notes. Use a consistent template and metadata, such as employee identifier and review date, to reduce scattered documents. Before rollout, test access with manager, employee, and HR test accounts, including existing sharing links. Agree ownership, retention, and manager-handover rules with your administrators. This is an access-design recommendation, not a built-in Teams feature that automatically classifies private notes.