Exoplanet surveys are revealing an emerging picture in which planetary systems are often born in long resonant chains. These architectures are the natural outcome of orbital migration in gaseous disks, where planets are locked into mean-motion resonances during the earliest stages of assembly. Yet this resonant order is fragile. Over time, resonances are disrupted, triggering instabilities that lead to ejections, collisions, and ultimately the diverse planetary architectures we observe today.
In this talk, I will present our efforts to probe both the formation and disruption of resonant chains. Using hydrodynamic simulations, we investigate how migration drives resonance capture and what observational signatures this process may leave in protoplanetary disks imaged with ALMA. With N-body simulations, we explore how leftover planetesimals can destabilize resonant systems, reshaping them into the configurations uncovered by exoplanet surveys. Together, these results highlight resonant chains as both the seeds and the breaking point of planetary architectures, bridging the gap between planet formation and the systems we observe today.