Ruby gem by Pavo. Thin wrapper around Masahiro Nakagawa's server-engine that makes it trivial to run robust multi-process background loops: define a class with a `call` method and add a rake task that invokes `raise_permanent_job` with the job class and a worker count. Inherits supervision from server-engine (auto-restart on failure, soft restarts, reconfiguration), unlike plain rake. Used in Pavo's wroclove.rb 2023 Rails game talk to power the game loop.