src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts/computeRunStartTimeAdjustment
function computeRunStartTimeAdjustment(oldMetadata: NotebookCellInternalMetadata, newMetadata: NotebookCellInternalMetadata): number | undefined {
	if (oldMetadata.runStartTime !== newMetadata.runStartTime && typeof newMetadata.runStartTime === 'number') {
		const offset = Date.now() - newMetadata.runStartTime;
		return offset < 0 ? Math.abs(offset) : 0;
	} else {
		return newMetadata.runStartTimeAdjustment;
	}
}