feat: VSTi live playback 100% client-side (không Carla) — autosample SF2 backend (pedalboard) → FluidSynth WASM qua masterBus → mastering → main out; SonicVstiAutosample ensure+dedup+cooldown; runtime gating __enableCarlaLivePlayback; âm bắt qua ensureMidiCapture → clientSideExport

app/core/render_engine.py

@@ -470,10 +470,25 @@ class PythonRenderEngine:
             _cache={},
         )
 
-        # Normalization to prevent clipping
-        max_peak = np.max(np.abs(master_buffer))
-        if max_peak > 1.0:
-            master_buffer /= max_peak
+        # Mastering chain — mirror client WebAudio (app.jsx applyMasteringSettings /
+        # rebuildMasteringGraph). Truoc day mastering_settings bi BO QUA hoan toan:
+        # export WAV khong qua EQ/Imager/Maximizer -> file khac am nghe live.
+        # Gio ap dung dung chain (thu tu settings['chain']) khi mastering bat.
+        mastering_settings = project_json.get("mastering_settings")
+        mastered = bool(mastering_settings and mastering_settings.get("masterConnected")
+                        and not mastering_settings.get("isBypassed"))
+        if mastered:
+            # Import lazy (scipy.signal) — giam thoi gian khoi dong engine
+            from app.core.mastering_engine import apply_mastering
+            master_buffer = apply_mastering(master_buffer, mastering_settings,
+                                            self.sample_rate)
+            # Hard clip [-1,1] — khớp WAV encoder client (browser) sau mastering
+            np.clip(master_buffer, -1.0, 1.0, out=master_buffer)
+        else:
+            # Normalization to prevent clipping
+            max_peak = np.max(np.abs(master_buffer))
+            if max_peak > 1.0:
+                master_buffer /= max_peak
 
         # Write final output file (bit_depth: 16/24/32 → WAV PCM subtype)
         subtype_map = {16: "PCM_16", 24: "PCM_24", 32: "PCM_32"}