In the previous part of this series, we built a tiny supervisor from scratch. When a worker crashed, the supervisor started a replacement. That replacement had a new PID: old worker -> #PID<0.102.0> new worker -> #PID<0.105.0> This reveals an important limitation of sharing PIDs as a public interface. A PID identifies one running incarnation of a process. It is excellent for sending a reply, setting up a monitor, or creating a link. It is not a stable ad...