Is ABI merely an artifact of implementation in native programming languages or should it be considered part of their design? Some programming languages avoid this commitment, while others are still trying to figure out a path forward. No, this is not an “ABI - Now or Never” talk. We’re taking a different route, by following the design and evolution of the Swift ABI model and seeing what we can learn from it. From ABI stability & dynamic linking to designing for ABI resilience - a journey through resilient type layout, reabstraction & materialization, resilience in library evolution and (opt-out) performance costs. What can we learn from Swift’s ABI resilience? How does C++ navigate on this journey? Can Rust be liberated from the ABI conundrum?