Per-instance mono|stereo (default mono, byte-identical). Stereo grows SampleData a 2nd channel + a per-channel VoiceEngine render; decodeChannels applies the cross-mode policy; setBusArrangements pins the mode's arrangement and restartComponent(kIoChanged) re-negotiates.
REAPER-free and VST3-free voice engine with bounded stealing, ADSR envelope, key/velocity keymap resolution, and repitch from root note with loop-point sustain. Test target links neither SDK.