diff --git a/nanobot/channels/feishu.py b/nanobot/channels/feishu.py
index e57fcef85..7d9c2772b 100644
--- a/nanobot/channels/feishu.py
+++ b/nanobot/channels/feishu.py
@@ -1014,14 +1014,29 @@ class FeishuChannel(BaseChannel):
 
         elif msg_type in ("audio", "file", "media"):
             file_key = content_json.get("file_key")
-            if file_key and message_id:
-                data, filename = await loop.run_in_executor(
-                    None, self._download_file_sync, message_id, file_key, msg_type
-                )
-                if not filename:
-                    filename = file_key[:16]
-                if msg_type == "audio" and not filename.endswith(".opus"):
-                    filename = f"{filename}.opus"
+            if not file_key:
+                logger.warning("Feishu {} message missing file_key: {}", msg_type, content_json)
+                return None, f"[{msg_type}: missing file_key]"
+            if not message_id:
+                logger.warning("Feishu {} message missing message_id", msg_type)
+                return None, f"[{msg_type}: missing message_id]"
+
+            data, filename = await loop.run_in_executor(
+                None, self._download_file_sync, message_id, file_key, msg_type
+            )
+
+            if not data:
+                logger.warning("Feishu {} download failed: file_key={}", msg_type, file_key)
+                return None, f"[{msg_type}: download failed]"
+
+            if not filename:
+                filename = file_key[:16]
+
+            # Feishu voice messages are opus in OGG container.
+            # Use .ogg extension for better Whisper compatibility.
+            if msg_type == "audio":
+                if not any(filename.endswith(ext) for ext in (".opus", ".ogg", ".oga")):
+                    filename = f"{filename}.ogg"
 
         if data and filename:
             file_path = media_dir / filename