diff --git a/backend/python/ace-step/backend.py b/backend/python/ace-step/backend.py
index 805dd16e1..56ce1314a 100644
--- a/backend/python/ace-step/backend.py
+++ b/backend/python/ace-step/backend.py
@@ -28,6 +28,7 @@ from acestep.inference import (
 )
 from acestep.handler import AceStepHandler
 from acestep.llm_inference import LLMHandler
+from acestep.model_downloader import ensure_lm_model
 
 
 _ONE_DAY_IN_SECONDS = 60 * 60 * 24
@@ -347,6 +348,24 @@ class BackendServicer(backend_pb2_grpc.BackendServicer):
             self.llm_handler = None
             if self.options.get("init_lm", True):
                 lm_model = self.options.get("lm_model_path", "acestep-5Hz-lm-0.6B")
+                
+                # Ensure LM model is downloaded before initializing
+                try:
+                    from pathlib import Path
+                    lm_success, lm_msg = ensure_lm_model(
+                        model_name=lm_model,
+                        checkpoints_dir=Path(self.checkpoint_dir),
+                        prefer_source=None,  # Auto-detect HuggingFace vs ModelScope
+                    )
+                    if not lm_success:
+                        print(f"[ace-step] Warning: LM model download failed: {lm_msg}", file=sys.stderr)
+                        # Continue anyway - LLM initialization will fail gracefully
+                    else:
+                        print(f"[ace-step] LM model ready: {lm_msg}", file=sys.stderr)
+                except Exception as e:
+                    print(f"[ace-step] Warning: LM model download check failed: {e}", file=sys.stderr)
+                    # Continue anyway - LLM initialization will fail gracefully
+                
                 self.llm_handler = LLMHandler()
                 lm_backend = (self.options.get("lm_backend") or "vllm").strip().lower()
                 if lm_backend not in ("vllm", "pt"):
@@ -379,26 +398,26 @@ class BackendServicer(backend_pb2_grpc.BackendServicer):
                 "sample_mode": True,
                 "thinking": True,
                 "vocal_language": request.language or request.GetLanguage() or "en",
-                "instrumental": request.GetInstrumental() if request.HasField("instrumental") else False,
+                "instrumental": request.instrumental if request.HasField("instrumental") else False,
             }
         else:
             caption = request.caption or request.GetCaption() or request.text
             payload = {
                 "prompt": caption,
-                "lyrics": request.lyrics or request.GetLyrics() or "",
-                "thinking": request.GetThink() if request.HasField("think") else False,
+                "lyrics": request.lyrics or request.lyrics or "",
+                "thinking": request.think if request.HasField("think") else False,
                 "vocal_language": request.language or request.GetLanguage() or "en",
             }
             if request.HasField("bpm"):
-                payload["bpm"] = request.GetBpm()
-            if request.HasField("keyscale") and request.GetKeyscale():
-                payload["key_scale"] = request.GetKeyscale()
-            if request.HasField("timesignature") and request.GetTimesignature():
-                payload["time_signature"] = request.GetTimesignature()
+                payload["bpm"] = request.bpm
+            if request.HasField("keyscale") and request.keyscale:
+                payload["key_scale"] = request.keyscale
+            if request.HasField("timesignature") and request.timesignature:
+                payload["time_signature"] = request.timesignature
             if request.HasField("duration") and request.duration:
                 payload["audio_duration"] = int(request.duration) if request.duration else None
-            if request.Src:
-                payload["src_audio_path"] = request.Src
+            if request.src:
+                payload["src_audio_path"] = request.src
 
         _generate_audio_sync(self, payload, request.dst)
         return backend_pb2.Result(success=True, message="Sound generated successfully")