ONE entry of the undo/redo stack, addressed by its stable sequence id (a stringified number,
so it takes STORED_ID_ADDRESS's shape rather than a new codec).
/history/cursor only ever answers the TOP of each stack (undoLabel/redoLabel); the stack
itself was fully materialised in UndoStack and never addressable, so a client could not show
"3 steps back is Gain on CH3" — only push the undo button and find out.
ONE entry of the undo/redo stack, addressed by its stable sequence id (a stringified number, so it takes STORED_ID_ADDRESS's shape rather than a new codec).
/history/cursoronly ever answers the TOP of each stack (undoLabel/redoLabel); the stack itself was fully materialised inUndoStackand never addressable, so a client could not show "3 steps back is Gain on CH3" — only push the undo button and find out.