- SwitchDevice volume silently zeroed: Init uses cfg.SavedVolume, SwitchDevice restores saved volume after reopening device - SwitchDevice not persisted to database: caller saves SelectedAudioDevice - Device restore passes invalid 'system default' to SDL: now passes '' - Stop() no-op when audio toggled off: removed AudioEnabled guard Regression tests added for all 4 bugs. CI now runs go test before build.