feat: VST FX rack per-track + masterbus render via native_bridge

app/api/v1/plugins.py

@@ -1002,6 +1002,82 @@ def _render_midi_notes_pedalboard(instrument_id: str, notes: list, bpm: float,
     )
 
 
+@router.get("/fx")
+async def list_fx_plugins(current_user: dict = Depends(get_current_user),
+                          refresh: bool = Query(False)):
+    """List VST effect plugins (is_fx) — native_bridge --scan trên các dir.
+
+    Chỉ plugin VST3 effect (Ozone, Scaler Audio, ...); instrument/VST2 bị
+    bridge loại. refresh=true → quét lại (Plugins Manager → Scan)."""
+    from app.core.vst_engine import get_plugin_manager
+    pm = get_plugin_manager()
+    return {"success": True, "plugins": pm.list_fx(refresh=refresh)}
+
+
+class FxRenderRequest(BaseModel):
+    """Render WAV qua chuỗi FX (VST3 effect + builtin gain/normalize).
+
+    Dùng cho masterbus (render xong project → Ozone trên bus) và FX Rack
+    per-track (preview offline qua bridge; realtime vẫn WebAudio)."""
+    input_file_id: Optional[str] = None  # file trong PROCESSED_DIR
+    input_path: Optional[str] = None     # path tuyệt đối (test)
+    fx_chain: list = []
+    sample_rate: int = 44100
+
+
+@router.post("/fx-render")
+async def fx_render(req: FxRenderRequest, current_user: dict = Depends(get_current_user)):
+    """Áp fx_chain lên WAV đầu vào → WAV mới trong PROCESSED_DIR."""
+    enforce_password_changed(current_user)
+    src = (req.input_path or "").strip()
+    if not src:
+        fid = (req.input_file_id or "").strip()
+        if not fid:
+            raise HTTPException(status_code=400,
+                                detail="Cần input_file_id hoặc input_path")
+        src = os.path.join(settings.PROCESSED_DIR, os.path.basename(fid))
+    if not os.path.isfile(src):
+        raise HTTPException(status_code=404,
+                            detail=f"File đầu vào không tồn tại: {src}")
+    user_id = current_user["user_id"]
+    out_name = f"user_{user_id}_fx_{uuid.uuid4().hex[:10]}.wav"
+    out_path = os.path.join(settings.PROCESSED_DIR, out_name)
+    try:
+        _render_fx_locked(src, req.fx_chain, req.sample_rate, out_path)
+        duration = sf.info(out_path).frames / max(1, req.sample_rate)
+        return {
+            "success": True,
+            "file_id": out_name,
+            "url": f"/static/audio/processed/{out_name}",
+            "path": out_path,
+            "duration_sec": round(duration, 3),
+            "render_mode": settings.RENDER_ENGINE,
+        }
+    except HTTPException:
+        try:
+            os.remove(out_path)
+        except Exception:
+            pass
+        raise
+    except Exception as e:
+        try:
+            os.remove(out_path)
+        except Exception:
+            pass
+        raise HTTPException(status_code=500, detail=f"FX render thất bại: {e}")
+
+
+@_render_locked
+def _render_fx_locked(input_path: str, fx_chain: list, sample_rate: int, out_path: str):
+    """FX render qua native_bridge --render-fx (không thread-safe → lock)."""
+    if settings.RENDER_ENGINE != "bridge":
+        raise HTTPException(status_code=501,
+                            detail="Chỉ hỗ trợ native_bridge render — set SF_RENDER_ENGINE=bridge")
+    from app.core.native_render import render_fx_chain
+    render_fx_chain(input_wav=input_path, fx_chain=fx_chain,
+                    sample_rate=sample_rate, out_path=out_path)
+
+
 class SoundfontRenderRequest(BaseModel):
     """Render MIDI notes → WAV bằng soundfont THẬT qua native FluidSynth
     (pyfluidsynth) — luồng âm instrument cho môi trường STANDALONE (xử lí