Jupyter Collaboration has a history slider (blog.jupyter.org)

JupyterLab’s Collaboration extension now includes a document timeline: a status-bar slider that lets collaborators scrub through a document’s history, compare past states, and restore versions without disturbing the live document. Built on the Yjs CRDT framework and Jupyter’s existing journal of updates (from co-editing introduced in JupyterLab 3.1), the component forks the document at the chosen timestamp to create a sandbox branch. Navigation uses an undo manager in the Python Yjs implementation (PyCRDT) — newly added — so users can step backward and forward through operations exactly as they occurred and then merge a selected fork back into the main document if desired. The feature is enabled by installing the Jupyter Collaboration extension. Technically significant for AI/ML and scientific teams, the timeline brings safe, fine-grained history management to notebooks, text files and even third‑party formats like JupyterCAD 3D models. That document-agnostic design means experiments, code iterates, data-cleaning steps and model visualizations can be explored and reverted without risking the current workspace — improving reproducibility, collaborative debugging, and iterative design. By combining CRDT-based real-time collaboration with forking and undo/redo semantics in PyCRDT, JupyterLab provides a robust, reversible workflow for multiuser technical computing and design.