T15: drop WebAudio master for tracks - native master gain + track gain/pan IPC (SF/VST2/VST3 bridges), NativeAudioService + /api/v1/native router, native-first TrackInstrument, test matrix 8 passed

native_host/NativeMixer.cpp

@@ -82,8 +82,10 @@ void NativeMixer::processInPlace (float* outL, float* outR, int32 frames) const
             else if (r < -1.0f)
                 r = -1.0f;
         }
-        outL[i] = l;
-        outR[i] = r;
+        // Master fader (T15): sau limiter+clip, linear, khong re-clip — mirror
+        // WebAudio masterBus.output.gain (gain node cuoi cung sau mastering).
+        outL[i] = l * m_masterGain;
+        outR[i] = r * m_masterGain;
     }
 }
 

native_host/NativeMixer.h

@@ -38,6 +38,10 @@ public:
     // thresholdDb clamp -24..0, NaN -> -1 (mirror _clamp trong mastering_engine).
     void setLimiter (bool active, float thresholdDb);
 
+    // Master fader (T15) — mirror WebAudio masterBus.output.gain (sau mastering
+    // chain + clip; linear, khong re-clip). Mac dinh 1.0.
+    void setMasterGain (float gainLinear) { m_masterGain = gainLinear; }
+
     // Ap track gain/pan vao buffer roi (neu active) limiter + hard clip [-1,1]
     // ngay tai buffer (in-place). frames > 0.
     void processInPlace (float* outL, float* outR, int32 frames) const;
@@ -49,6 +53,7 @@ private:
     bool m_limActive = false;
     float m_limK = 1.0f;   // 1/max(0.02, t_lin)
     float m_limTk = 1.0f;  // tanh(k)
+    float m_masterGain = 1.0f; // T15: master fader (sau limiter+clip, khong re-clip)
 };
 
 } // namespace sonicforge

native_host/SFHost.cpp

@@ -409,6 +409,18 @@ __declspec (dllexport) int32 SF_FS_SetMasterLimiter (int32 handle, int32 active,
     return 0;
 }
 
+// T15: master fader — linear, ap sau limiter+clip trong mixer (mirror
+// masterBus.output.gain WebAudio).
+__declspec (dllexport) int32 SF_FS_SetMasterGain (int32 handle, float gainLinear)
+{
+    std::lock_guard<std::mutex> lock (g_mutex);
+    auto it = g_instances.find (handle);
+    if (it == g_instances.end ())
+        return -1;
+    it->second->mixer.setMasterGain (gainLinear);
+    return 0;
+}
+
 // Đóng: stop audio loop, xóa synth, giải phóng DLL.
 __declspec (dllexport) int32 SF_FS_Close (int32 handle, char* err, int32 err_cap)
 {

native_host/VST2AudioEngine.cpp

@@ -627,4 +627,15 @@ __declspec (dllexport) int32 SF_VST2_SetMasterLimiter (int32 handle, int32 activ
     return 0;
 }
 
+// T15: master fader — mirror masterBus.output.gain WebAudio (sau limiter+clip).
+__declspec (dllexport) int32 SF_VST2_SetMasterGain (int32 handle, float gainLinear)
+{
+    std::lock_guard<std::mutex> lock (g_mutex);
+    auto it = g_instances.find (handle);
+    if (it == g_instances.end ())
+        return -1;
+    it->second->mixer.setMasterGain (gainLinear);
+    return 0;
+}
+
 } // extern "C"

native_host/vst3_host_bridge.cpp

@@ -573,4 +573,15 @@ __declspec (dllexport) int32 SF_VST3_SetMasterLimiter (int32 handle, int32 activ
     return 0;
 }
 
+// T15: master fader — mirror masterBus.output.gain WebAudio (sau limiter+clip).
+__declspec (dllexport) int32 SF_VST3_SetMasterGain (int32 handle, float gainLinear)
+{
+    std::lock_guard<std::mutex> lock (g_mutex);
+    auto it = g_instances.find (handle);
+    if (it == g_instances.end ())
+        return -1;
+    it->second->mixer.setMasterGain (gainLinear);
+    return 0;
+}
+
 } // extern "C"