diff --git a/native_host/CMakeLists.txt b/native_host/CMakeLists.txt
index 1983a0e..e103a79 100644
--- a/native_host/CMakeLists.txt
+++ b/native_host/CMakeLists.txt
@@ -32,7 +32,7 @@ target_compile_definitions(vst3_host_bridge PRIVATE
     NOMINMAX
     WIN32_LEAN_AND_MEAN
 )
-target_link_libraries(vst3_host_bridge PRIVATE audio_engine)
+target_link_libraries(vst3_host_bridge PRIVATE audio_engine native_mixer)
 
 # Native audio loop (T12): SPSC + WASAPI — dùng chung cho cả 2 bridge.
 add_library(audio_engine STATIC
@@ -47,6 +47,12 @@ target_compile_definitions(audio_engine PRIVATE
 )
 target_link_libraries(audio_engine PUBLIC ole32 avrt)
 
+# NativeMixer (T13): track gain/pan + master brickwall limiter — mirror server.
+add_library(native_mixer STATIC
+    NativeMixer.cpp
+)
+target_include_directories(native_mixer PUBLIC native_host)
+
 # VST2 host bridge — chỉ cần vestige.h clean-room, không cần SDK.
 add_library(vst2_host_bridge SHARED
     VST2AudioEngine.cpp
@@ -57,4 +63,4 @@ target_compile_definitions(vst2_host_bridge PRIVATE
     NOMINMAX
     WIN32_LEAN_AND_MEAN
 )
-target_link_libraries(vst2_host_bridge PRIVATE audio_engine)
+target_link_libraries(vst2_host_bridge PRIVATE audio_engine native_mixer)
diff --git a/native_host/NativeMixer.cpp b/native_host/NativeMixer.cpp
new file mode 100644
index 0000000..4170cf0
--- /dev/null
+++ b/native_host/NativeMixer.cpp
@@ -0,0 +1,90 @@
+// NativeMixer.cpp — xem NativeMixer.h cho cong thuc mirror.
+#include "NativeMixer.h"
+
+namespace sonicforge {
+
+namespace {
+
+// Mirror _clamp(v, lo, hi, default) cua mastering_engine.py: NaN -> default.
+float clampDb (float v, float lo, float hi, float def)
+{
+    if (!(v == v)) // NaN
+        return def;
+    if (v < lo)
+        return lo;
+    if (v > hi)
+        return hi;
+    return v;
+}
+
+} // namespace
+
+TrackGainPan TrackGainPan::fromDbPan (float gainDb, float pan)
+{
+    TrackGainPan t;
+    t.gainLin = std::pow (10.0f, gainDb / 20.0f);
+    float p = pan;
+    if (p < -1.0f)
+        p = -1.0f;
+    else if (p > 1.0f)
+        p = 1.0f;
+    if (p == 0.0f)
+    {
+        t.panL = 1.0f;
+        t.panR = 1.0f;
+    }
+    else
+    {
+        const float theta = ((p + 1.0f) / 2.0f) * (3.14159265358979323846f / 2.0f);
+        t.panL = std::cos (theta);
+        t.panR = std::sin (theta);
+    }
+    return t;
+}
+
+void NativeMixer::setLimiter (bool active, float thresholdDb)
+{
+    m_limActive = active;
+    if (!active)
+    {
+        m_limK = 1.0f;
+        m_limTk = 1.0f;
+        return;
+    }
+    const float t = clampDb (thresholdDb, -24.0f, 0.0f, -1.0f);
+    const float tLin = std::pow (10.0f, t / 20.0f);
+    m_limK = 1.0f / (tLin > 0.02f ? tLin : 0.02f);
+    m_limTk = std::tanh (m_limK);
+}
+
+void NativeMixer::processInPlace (float* outL, float* outR, int32 frames) const
+{
+    if (!outL || !outR || frames <= 0)
+        return;
+    const float gl = m_track.gainLin * m_track.panL;
+    const float gr = m_track.gainLin * m_track.panR;
+    for (int32 i = 0; i < frames; ++i)
+    {
+        float l = outL[i] * gl;
+        float r = outR[i] * gr;
+        if (m_limActive)
+        {
+            l = std::tanh (l * m_limK) / m_limTk;
+            r = std::tanh (r * m_limK) / m_limTk;
+            // Hard clip [-1,1] — mirror render_project sau apply_mastering
+            // (chi khi mastering on; limiter off => khong clip).
+            if (l > 1.0f)
+                l = 1.0f;
+            else if (l < -1.0f)
+                l = -1.0f;
+            if (r > 1.0f)
+                r = 1.0f;
+            else if (r < -1.0f)
+                r = -1.0f;
+        }
+        outL[i] = l;
+        outR[i] = r;
+    }
+}
+
+} // namespace sonicforge
diff --git a/native_host/NativeMixer.h b/native_host/NativeMixer.h
new file mode 100644
index 0000000..1d3efc2
--- /dev/null
+++ b/native_host/NativeMixer.h
@@ -0,0 +1,54 @@
+// NativeMixer.h — track gain/pan + master brickwall limiter (T13).
+//
+// MIRROR server render pipeline (`app/core/render_engine.py` track volume/pan
+// + `app/core/mastering_engine.py` _apply_limiter):
+// - track gain: 10^(dB/20)
+// - pan constant-power: theta = ((pan+1)/2)*pi/2, L *= cos(theta), R *= sin(theta)
+//   (pan == 0 -> unity, khong nhan — dung nhu render_engine.py)
+// - master: tong cac track (processInPlace ap dung gain/pan roi limiter)
+// - brickwall limiter: t_lin = 10^(thresholdDb/20) (clamp -24..0, default -1);
+//   k = 1/max(0.02, t_lin); tk = tanh(k); out = tanh(x*k)/tk; roi hard clip [-1,1]
+//   (clip giong render_project sau apply_mastering).
+//
+// Audio thread an toan: chi setTrack/setLimiter tu UI thread truoc khi
+// AudioStart; processInPlace doc state da set, khong lock, khong cap phat.
+#pragma once
+#include <cstdint>
+#include <cmath>
+
+namespace sonicforge {
+
+using int32 = int32_t;
+
+struct TrackGainPan
+{
+    float gainLin = 1.0f; // 10^(dB/20)
+    float panL = 1.0f;    // cos(theta)
+    float panR = 1.0f;    // sin(theta)
+
+    static TrackGainPan fromDbPan (float gainDb, float pan);
+};
+
+class NativeMixer
+{
+public:
+    // gainDb: -inf..+inf dB; pan: -1..+1 (clamp). Mirrors render_engine.py.
+    void setTrack (const TrackGainPan& t) { m_track = t; }
+
+    // thresholdDb clamp -24..0, NaN -> -1 (mirror _clamp trong mastering_engine).
+    void setLimiter (bool active, float thresholdDb);
+
+    // 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;
+
+    bool limiterActive () const { return m_limActive; }
+
+private:
+    TrackGainPan m_track;
+    bool m_limActive = false;
+    float m_limK = 1.0f;   // 1/max(0.02, t_lin)
+    float m_limTk = 1.0f;  // tanh(k)
+};
+
+} // namespace sonicforge
diff --git a/native_host/VST2AudioEngine.cpp b/native_host/VST2AudioEngine.cpp
index fd4c3b8..d05e793 100644
--- a/native_host/VST2AudioEngine.cpp
+++ b/native_host/VST2AudioEngine.cpp
@@ -24,6 +24,7 @@
 
 #include "vestige.h"
 #include "AudioEngine.h"
+#include "NativeMixer.h"
 
 #include <atomic>
 
@@ -50,6 +51,7 @@ struct Instance
     void* paramCbUserdata = nullptr;
     sonicforge::AudioEngine audio; // T12: native audio loop (SPSC + WASAPI)
     std::atomic<bool> audioRunning {false};
+    sonicforge::NativeMixer mixer; // T13: track gain/pan + master limiter
 };
 
 std::mutex g_mutex;
@@ -163,6 +165,7 @@ bool vst2AudioProcess (const sonicforge::MidiEvent* events, int32 eventCount,
     {
         float* outs[2] = { outL, outR };
         inst->effect->processReplacing (inst->effect, nullptr, outs, frames);
+        inst->mixer.processInPlace (outL, outR, frames); // T13: gain/pan + limiter
         return true;
     }
     return false;
@@ -602,4 +605,26 @@ __declspec (dllexport) int32 SF_VST2_AudioBlocks (int32 handle)
     return it->second->audio.blocksRendered ();
 }
 
+// T13: track gain/pan + master limiter (NativeMixer). Set truoc AudioStart;
+// audio thread doc state nay (khong lock).
+__declspec (dllexport) int32 SF_VST2_SetTrackGainPan (int32 handle, float gainDb, float pan)
+{
+    std::lock_guard<std::mutex> lock (g_mutex);
+    auto it = g_instances.find (handle);
+    if (it == g_instances.end ())
+        return -1;
+    it->second->mixer.setTrack (sonicforge::TrackGainPan::fromDbPan (gainDb, pan));
+    return 0;
+}
+
+__declspec (dllexport) int32 SF_VST2_SetMasterLimiter (int32 handle, int32 active, float thresholdDb)
+{
+    std::lock_guard<std::mutex> lock (g_mutex);
+    auto it = g_instances.find (handle);
+    if (it == g_instances.end ())
+        return -1;
+    it->second->mixer.setLimiter (active != 0, thresholdDb);
+    return 0;
+}
+
 } // extern "C"
diff --git a/native_host/tests/native_mixer_test.cpp b/native_host/tests/native_mixer_test.cpp
new file mode 100644
index 0000000..cde634d
--- /dev/null
+++ b/native_host/tests/native_mixer_test.cpp
@@ -0,0 +1,84 @@
+// native_mixer_test.cpp — golden test driver cho NativeMixer (T13).
+//
+// Đọc input raw float32 interleaved stereo, áp NativeMixer (track gain/pan +
+// master limiter) theo argv, ghi output raw float32 interleaved. Python
+// (test_native_mixer_golden.py) so RMS/peak với reference server pipeline.
+//
+// Usage: native_mixer_test.exe <in.raw> <out.raw> <gainDb> <pan> <limActive> <thresholdDb>
+#include <cstdio>
+#include <cstdlib>
+#include <cstdint>
+#include <vector>
+
+#include "NativeMixer.h"
+
+using sonicforge::int32;
+
+int main (int argc, char** argv)
+{
+    if (argc < 7)
+    {
+        std::fprintf (stderr, "usage: native_mixer_test in.raw out.raw gainDb pan limActive thresholdDb\n");
+        return 2;
+    }
+    const char* inPath = argv[1];
+    const char* outPath = argv[2];
+    const float gainDb = static_cast<float> (std::atof (argv[3]));
+    const float pan = static_cast<float> (std::atof (argv[4]));
+    const int32 limActive = std::atoi (argv[5]);
+    const float thresholdDb = static_cast<float> (std::atof (argv[6]));
+
+    FILE* f = std::fopen (inPath, "rb");
+    if (!f)
+    {
+        std::fprintf (stderr, "cannot open %s\n", inPath);
+        return 2;
+    }
+    std::fseek (f, 0, SEEK_END);
+    const long nBytes = std::ftell (f);
+    std::fseek (f, 0, SEEK_SET);
+    if (nBytes <= 0 || (nBytes % 8) != 0)
+    {
+        std::fprintf (stderr, "bad input size %ld\n", nBytes);
+        std::fclose (f);
+        return 2;
+    }
+    std::vector<float> buf (static_cast<size_t> (nBytes) / sizeof (float));
+    if (std::fread (buf.data (), sizeof (float), buf.size (), f) != buf.size ())
+    {
+        std::fprintf (stderr, "short read\n");
+        std::fclose (f);
+        return 2;
+    }
+    std::fclose (f);
+
+    const int32 frames = static_cast<int32> (buf.size () / 2);
+    std::vector<float> inL (static_cast<size_t> (frames));
+    std::vector<float> inR (static_cast<size_t> (frames));
+    for (int32 i = 0; i < frames; ++i)
+    {
+        inL[static_cast<size_t> (i)] = buf[static_cast<size_t> (2 * i)];
+        inR[static_cast<size_t> (i)] = buf[static_cast<size_t> (2 * i + 1)];
+    }
+
+    sonicforge::NativeMixer mixer;
+    mixer.setTrack (sonicforge::TrackGainPan::fromDbPan (gainDb, pan));
+    mixer.setLimiter (limActive != 0, thresholdDb);
+    mixer.processInPlace (inL.data (), inR.data (), frames);
+
+    for (int32 i = 0; i < frames; ++i)
+    {
+        buf[static_cast<size_t> (2 * i)] = inL[static_cast<size_t> (i)];
+        buf[static_cast<size_t> (2 * i + 1)] = inR[static_cast<size_t> (i)];
+    }
+
+    FILE* g = std::fopen (outPath, "wb");
+    if (!g)
+    {
+        std::fprintf (stderr, "cannot write %s\n", outPath);
+        return 2;
+    }
+    std::fwrite (buf.data (), sizeof (float), buf.size (), g);
+    std::fclose (g);
+    return 0;
+}
diff --git a/native_host/tests/test_native_mixer_golden.py b/native_host/tests/test_native_mixer_golden.py
new file mode 100644
index 0000000..5b38e27
--- /dev/null
+++ b/native_host/tests/test_native_mixer_golden.py
@@ -0,0 +1,116 @@
+"""Golden test T13 — NativeMixer mirror server render pipeline.
+
+So sanh output native mixer (native_mixer_test.exe) voi reference dung chinh
+code path cua server `render_project`:
+- track gain/pan: cong thuc render_engine.py (10^(dB/20), constant-power pan)
+- master limiter: app.core.mastering_engine.apply_mastering (module limiter)
+  + hard clip [-1,1] nhu render_project sau apply_mastering
+
+Yeu cau: |RMS| va |peak| sai lech < 0.1 dB moi case, moi kenh.
+
+Chay:  python native_host/tests/test_native_mixer_golden.py
+(tu repo root; can native_mixer_test.exe da build + numpy/scipy)
+"""
+import os
+import subprocess
+import sys
+
+import numpy as np
+
+ROOT = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+EXE = os.path.join(ROOT, "native_host", "tests", "native_mixer_test.exe")
+SR = 44100
+
+sys.path.insert(0, ROOT)
+from app.core.mastering_engine import apply_mastering  # noqa: E402
+
+
+def make_signal(n=SR):
+    t = np.arange(n) / SR
+    sig = (
+        np.sin(2 * np.pi * 220 * t)
+        + 0.5 * np.sin(2 * np.pi * 440 * t + 0.3)
+        + 0.3 * np.sin(2 * np.pi * 880 * t + 1.1)
+    )
+    env = np.minimum(1.0, t * 20.0) * np.exp(-t * 0.8)
+    sig *= env
+    rng = np.random.default_rng(1234)
+    sig = sig + rng.standard_normal(n) * 0.05
+    # spike de limiter clip ro rang
+    for i in range(0, n, 22050):
+        sig[i] += 3.0
+    return np.stack([sig, np.roll(sig, 100)])
+
+
+def ref_process(x, gain_db, pan, lim_active, th_db):
+    y = x * (10.0 ** (gain_db / 20.0))
+    if pan != 0.0:
+        theta = ((np.clip(pan, -1.0, 1.0) + 1.0) / 2.0) * (np.pi / 2.0)
+        y = y.copy()
+        y[0, :] *= np.cos(theta)
+        y[1, :] *= np.sin(theta)
+    if lim_active:
+        settings = {
+            "masterConnected": True,
+            "isBypassed": False,
+            "chain": [{"type": "limiter", "active": True}],
+            "limActive": True,
+            "limThreshold": th_db,
+        }
+        y = apply_mastering(y, settings, SR)
+        np.clip(y, -1.0, 1.0, out=y)
+    return y
+
+
+def run_native(x, gain_db, pan, lim_active, th_db, tmp):
+    inp = os.path.join(tmp, "in.raw")
+    outp = os.path.join(tmp, "out.raw")
+    with open(inp, "wb") as f:
+        f.write(x.T.astype(np.float32).tobytes())
+    args = [EXE, inp, outp, str(gain_db), str(pan), str(int(lim_active)), str(th_db)]
+    subprocess.run(args, check=True)
+    return np.fromfile(outp, dtype=np.float32).reshape(-1, 2).T
+
+
+def db_rms_peak(y):
+    rms = 20.0 * np.log10(np.sqrt(np.mean(y * y, axis=1)) + 1e-12)
+    peak = 20.0 * np.log10(np.max(np.abs(y), axis=1) + 1e-12)
+    return rms, peak
+
+
+def main():
+    if not os.path.exists(EXE):
+        print(f"FAIL: {EXE} not found (build native_mixer_test.exe truoc)")
+        return 1
+    import tempfile
+
+    x = make_signal()
+    cases = [
+        (0.0, 0.0, False, -1.0),   # identity (limiter off)
+        (6.0, -0.5, False, -1.0),  # gain/pan, khong limiter
+        (6.0, -0.5, True, -3.0),
+        (-9.0, 0.8, True, -6.0),
+        (12.0, 0.0, True, 0.0),
+    ]
+    worst = 0.0
+    with tempfile.TemporaryDirectory() as tmp:
+        for i, (g, p, la, th) in enumerate(cases):
+            native = run_native(x, g, p, la, th, tmp)
+            ref = ref_process(x, g, p, la, th)
+            nr, npk = db_rms_peak(native)
+            rr, rpk = db_rms_peak(ref)
+            dr = np.max(np.abs(nr - rr))
+            dp = np.max(np.abs(npk - rpk))
+            worst = max(worst, dr, dp)
+            status = "OK " if (dr < 0.1 and dp < 0.1) else "FAIL"
+            print(f"case {i} gain={g} pan={p} lim={int(la)} th={th}: "
+                  f"RMS diff={dr:.4f} dB peak diff={dp:.4f} dB [{status}]")
+            if dr >= 0.1 or dp >= 0.1:
+                print(f"  native rms={nr} peak={npk}")
+                print(f"  ref    rms={rr} peak={rpk}")
+    print(f"worst diff: {worst:.4f} dB (< 0.1 -> PASS)")
+    return 0 if worst < 0.1 else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/native_host/vst3_host_bridge.cpp b/native_host/vst3_host_bridge.cpp
index 1a32053..97690c8 100644
--- a/native_host/vst3_host_bridge.cpp
+++ b/native_host/vst3_host_bridge.cpp
@@ -33,6 +33,7 @@
 #include "pluginterfaces/vst/ivstevents.h"
 
 #include "AudioEngine.h"
+#include "NativeMixer.h"
 
 #include <atomic>
 
@@ -99,6 +100,7 @@ struct Instance
     ComponentHandler handler;
     sonicforge::AudioEngine audio; // T12: native audio loop (SPSC + WASAPI)
     std::atomic<bool> audioRunning {false};
+    sonicforge::NativeMixer mixer; // T13: track gain/pan + master limiter
 };
 
 // T12: IEventList cố định (không cấp phát trên audio thread).
@@ -189,7 +191,9 @@ bool vst3AudioProcess (const sonicforge::MidiEvent* events, int32 eventCount,
     data.outputs = &outBus;
     data.inputEvents = &list;
 
-    return proc->process (data) == kResultOk;
+    const tresult res = proc->process (data);
+    inst->mixer.processInPlace (outL, outR, frames); // T13: gain/pan + limiter
+    return res == kResultOk;
 }
 
 std::mutex g_mutex;
@@ -547,4 +551,26 @@ __declspec (dllexport) int32 SF_VST3_SendNoteOff (int32 handle, int32 channel, i
     return it->second->audio.pushMidi (ev) ? 0 : -2;
 }
 
+// T13: track gain/pan + master limiter (NativeMixer). Set truoc AudioStart;
+// audio thread doc state nay (khong lock).
+__declspec (dllexport) int32 SF_VST3_SetTrackGainPan (int32 handle, float gainDb, float pan)
+{
+    std::lock_guard<std::mutex> lock (g_mutex);
+    auto it = g_instances.find (handle);
+    if (it == g_instances.end ())
+        return -1;
+    it->second->mixer.setTrack (sonicforge::TrackGainPan::fromDbPan (gainDb, pan));
+    return 0;
+}
+
+__declspec (dllexport) int32 SF_VST3_SetMasterLimiter (int32 handle, int32 active, float thresholdDb)
+{
+    std::lock_guard<std::mutex> lock (g_mutex);
+    auto it = g_instances.find (handle);
+    if (it == g_instances.end ())
+        return -1;
+    it->second->mixer.setLimiter (active != 0, thresholdDb);
+    return 0;
+}
+
 } // extern "C"