High-cadence long-term monitoring of the transient sky suggests that most core-collapse supernovae are influenced at some level by interaction with circumstellar material. Although considered so far a feature in core-collapse supernovae, this observation has led theorists to revise the idealized view of massive star evolution and explosion, introducing a slew of time-dependent, dynamical, and multi-dimensional effects that remain today poorly understood. Bringing together experts on this multi-faceted domain of astrophysics, this MIAPP programme will allow the community 1) to investigate the various mechanisms at the origin of eruptions and explosions of massive stars, 2) to improve the techniques of radiation hydrodynamics and radiative transfer modeling of these events, 3) to integrate these advances in order to dissect the rapidly growing observational zoo of interacting supernovae, and 4) to quantify the influence of circumstellar interaction on supernova-based extragalactic distance measurements. This gathering will prepare the supernova community for the upcoming era of transient astrophysics with the Vera Rubin Observatory LSST.