fix(bridge): stop leaves sound looping — EventList maxSize=50 drops STOP sweep note-offs

Root cause: Steinberg EventList defaults to maxSize=50 events. The STOP
all-notes-off sweep queues 128 note-offs per channel (16ch x 128 pitch),
so addEvent beyond 50 fails silently and the plugin never receives the
remaining note-offs — voices keep sustaining and the transport loops
forever until the bridge process is killed.

Fix: raise eventList.setMaxSize(4096) in loadPlugin. Also assign unique
noteIds per overlapping note-on (stack per pitch) so note-off releases
every voice at that pitch, and log addEvent result + channel in debug
output for verification.

native_bridge/include/Vst3Instrument.h

@@ -28,6 +28,7 @@ public:
     bool reloadForGUI() override;
     bool attachView(void* parentWindowHandle) override;
     void closeGUI() override;
+    void setChannel(uint32_t ch) { channel_ = ch; }
     bool needsReload() const override { return hasAttachedOnce_ && !guiAttached_; }
     void setReloading(bool on) override { reloading_ = on; }
     void processAudioBlock(float* outputL, float* outputR, uint32_t numSamples) override;
@@ -42,6 +43,7 @@ private:
     bool guiAttached_;
     bool hasAttachedOnce_;
     bool reloading_; // guarded by InstrumentEngineManager::mu_ (set via setReloading)
+    uint32_t channel_ = 0;
     bool reload();
 };
 

native_bridge/src/NativeInstrumentEngine.cpp

@@ -168,6 +168,8 @@ bool InstrumentEngineManager::assign(uint32_t channel, InstrumentType type,
         loaded = static_cast<SfizzInstrument*>(inst.get())->loadSfzFile(path, sampleRate);
     else if (type == InstrumentType::VST3)
         loaded = static_cast<Vst3Instrument*>(inst.get())->loadPlugin(path, sampleRate);
+    if (type == InstrumentType::VST3)
+        static_cast<Vst3Instrument*>(inst.get())->setChannel(channel);
     if (!loaded) return false;
     // init() AFTER load: FluidSynth creates its synth inside loadSoundFontFile.
     if (!inst->init(sampleRate, blockSize)) return false;

native_bridge/src/Vst3Instrument.cpp

@@ -133,7 +133,11 @@ struct Vst3HostState {
     IPtr<IEditController> controller;
     IPtr<HostApplication> hostApp;
     HostProcessData processData;
-    EventList eventList;
+    EventList eventList;  // SDK default maxSize=50 — allNotesOff sweep adds
+                             // 128 note-offs per channel per stop; beyond 50
+                             // addEvent FAILS silently and the notes never
+                             // reach the plugin (voices keep sustaining).
+                             // Raised here via setMaxSize in loadPlugin.
     ParameterChanges paramChanges;
     ProcessContext processContext;
     IPtr<IPlugView> view;
@@ -141,6 +145,14 @@ struct Vst3HostState {
     HostComponentHandler componentHandler;
     int32 outputChannels = 2;
     bool controllerIsComponent = false;  // single-component plugin: controller == component
+    // noteId per active voice. VST3 plugins match note-off to note-on by
+    // (pitch, noteId); a constant id (old code used 0) means two overlapping
+    // note-ons of the same pitch share one id, and a single note-off only
+    // releases ONE of them — the other voice sustains forever (the "treo
+    // loop" bug: sound keeps looping after STOP). Track a stack per pitch so
+    // every overlapping voice gets a unique id and note-off releases them all.
+    int32 nextNoteId = 1;
+    std::vector<int32> noteIdsByPitch[128];
 };
 
 // Resolve the plugin's ParamID for a MIDI CC / pitch-bend, preferring the
@@ -350,6 +362,10 @@ bool Vst3Instrument::loadPlugin(const std::string& path, double sampleRate) {
     }
 
     std::cerr << "[dbg] loadPlugin: prepare OK, wiring state" << std::endl;
+    // SDK EventList default maxSize=50 is far too small for the STOP
+    // all-notes-off sweep (128 note-offs per channel). addEvent beyond the
+    // cap fails SILENTLY → notes never released → stuck sound loop.
+    s->eventList.setMaxSize(4096);
     s->module = std::move(module);
     s->component = std::move(component);
     s->controller = std::move(controller);
@@ -403,33 +419,68 @@ void Vst3Instrument::noteOn(uint32_t channel, uint32_t pitch, float velocity, ui
     e.noteOn.tuning = 0.f;
     e.noteOn.velocity = velocity;
     e.noteOn.length = 0;
-    e.noteOn.noteId = 0;  // some plugins (DUNE3) track notes by id; -1 may be ignored
+    // Unique noteId per voice: overlapping note-ons of the same pitch MUST
+    // carry distinct ids, otherwise one note-off cannot release all voices
+    // (Nexus/DUNE3 keep the extra voice forever → sound loops after STOP).
+    int32 id = s->nextNoteId++;
+    if (id <= 0) { id = 1; s->nextNoteId = 2; }  // wrap: never reuse 0
+    if (pitch < 128) s->noteIdsByPitch[pitch].push_back(id);
+    e.noteOn.noteId = id;
     s->eventList.addEvent(e);
+    std::cerr << "[midi] pid=" << (int)GetCurrentProcessId() << " ON ch=" << channel
+              << " p=" << pitch << " id=" << id << " v=" << velocity << std::endl;
 #endif
 }
 
 void Vst3Instrument::noteOff(uint32_t channel, uint32_t pitch, uint32_t sampleOffset) {
-    (void)channel; (void)pitch; (void)sampleOffset;
+    (void)channel; (void)sampleOffset;
 #ifndef HAVE_VST3SDK
     return;
 #else
     auto* s = static_cast<Vst3HostState*>(state_);
     if (!s || !s->component) return;
+    // Release EVERY active voice on this pitch (each had a distinct noteId).
+    // MIDI note-off semantics: all voices at that pitch stop. Without this,
+    // a second overlapping voice (stack depth >1) keeps sustaining.
+    if (pitch < 128 && !s->noteIdsByPitch[pitch].empty()) {
+        for (int32 id : s->noteIdsByPitch[pitch]) {
             Event e = {};
             e.busIndex = 0;
             e.sampleOffset = (int32)sampleOffset;
             e.ppqPosition = 0;
             e.flags = Event::kIsLive;
             e.type = Event::kNoteOffEvent;
-    e.noteOff.channel = 0; // Force to MIDI Channel 1 (0) for VSTi compatibility
+            e.noteOff.channel = 0;
             e.noteOff.pitch = (int16)pitch;
             e.noteOff.velocity = 0.f;
-    // noteId phai MATCH noteOn (0): Nexus/DUNE3 track notes bang id, -1
+            e.noteOff.noteId = id;
-    // khong khop voi note-on -> plugin giu note vo han (am thanh khong dung
-    // cho den khi kill bridge).
-    e.noteOff.noteId = 0;
             e.noteOff.tuning = 0.f;
             s->eventList.addEvent(e);
+        }
+        std::string ids;
+        for (int32 id : s->noteIdsByPitch[pitch]) { if (!ids.empty()) ids += ","; ids += std::to_string(id); }
+        std::cerr << "[midi] pid=" << (int)GetCurrentProcessId() << " OFF ch=" << channel
+                  << " p=" << pitch << " ids=[" << ids << "]" << std::endl;
+        s->noteIdsByPitch[pitch].clear();
+    } else {
+        // No tracked voice: send a best-effort note-off with the last id
+        // (id 0 now always means "untracked" — plugins may still release by
+        // pitch). Never blocks the audio thread.
+        Event e = {};
+        e.busIndex = 0;
+        e.sampleOffset = (int32)sampleOffset;
+        e.ppqPosition = 0;
+        e.flags = Event::kIsLive;
+        e.type = Event::kNoteOffEvent;
+        e.noteOff.channel = 0;
+        e.noteOff.pitch = (int16)pitch;
+        e.noteOff.velocity = 0.f;
+        e.noteOff.noteId = 0;
+        e.noteOff.tuning = 0.f;
+        tresult ar = s->eventList.addEvent(e);
+        std::cerr << "[midi] pid=" << (int)GetCurrentProcessId() << " OFF ch=" << channel
+                  << " p=" << pitch << " untracked(0) add=" << (int)ar << std::endl;
+    }
 #endif
 }
 
@@ -646,7 +697,7 @@ void Vst3Instrument::processAudioBlock(float* outputL, float* outputR, uint32_t
         (s->processContext.tempo / 60.0);
 
     static uint32_t dbgN = 0;
-    static int dbgMaxShown = 0;
+    static int dbgMaxShown = 0;  // ev>0 blocks printed (raised: sweep must be visible)
     // VST3: host buffers must be zeroed (silence) before process — plugins
     // that skip output leave garbage otherwise (EZkeys 2 -> huge noise).
     if (s->processData.numOutputs > 0) {
@@ -682,9 +733,9 @@ void Vst3Instrument::processAudioBlock(float* outputL, float* outputR, uint32_t
         const Event* e0 = s->eventList.getEventByIndex(0);
         evt = e0 ? (int)e0->type : -2;
     }
-    if ((++dbgN % 250) == 0 || (evc > 0 && dbgMaxShown < 30)) {
+    if ((++dbgN % 250) == 0 || (evc > 0 && dbgMaxShown < 5000)) {
         if (evc > 0) ++dbgMaxShown;
-        std::cerr << "[dbg] n=" << numSamples << " ev=" << evc << " evt=" << evt
+        std::cerr << "[dbg] pid=" << (int)GetCurrentProcessId() << " ch=" << channel_ << " n=" << numSamples << " ev=" << evc << " evt=" << evt
                   << " pr=" << (int)pr << " nOut=" << s->processData.numOutputs
                   << " mx=" << mx << " ts=" << s->processContext.projectTimeSamples
                   << " nch=" << (s->processData.numOutputs > 0 ? s->processData.outputs[0].numChannels : -1) << std::endl;