winsvc runs a Ruby process as a Windows service (SERVICE_WIN32_OWN_PROCESS) with correct service-control-manager integration: the control handler is pure C (no Ruby ever runs on an SCM thread), controls arrive on a Thread::Queue (fiber-scheduler cooperative), SERVICE_STOPPED is reported exactly once, and checkpoints are only ever honest. The same block runs unchanged as a console program for development. Includes a minimal installer (CreateServiceW, delayed auto-start, restart-on-failure recovery) and a correctly quoted sc.exe command generator. Windows MSVC (mswin) Ruby only.