Every time a turn begins in chat, we create a snapshot. It is then possible to revert to that snapshot via the "Undo Last Request"/"Redo Last Request" actions in the chat view. It would be interesting to render the snapshots in the SCM Graph view, we have found that folks don't feel super confident hitting the undo buttons. The state is available in ChatEditingSession._linearHistory and might need a bit of plumbing to expose as a public field.