In Pericyclic reactions, it is shown that the terminal bonds rotate (conrotation or disrotation) to allow for allignment of the FMO's, thereby forming the sigma bond
However, a detail that most of my textbooks and references miss out on is how is the double bond rotating about it's axis? As far as I know, pi bonds are restricted in their rotation which is what gives rise to cis-trans isomerism. If this is the case, how are the bonds rotating about their axis to align the orbitals?
One possibility I can think of is that the double bond is broken before/during rotation, but I haven't seen this explicitly mentioned anywhere. Any insights are appreciated.