Fix usage calc for array content; normalize message content to text only

app.py

@@ -480,14 +480,13 @@ MODEL_ROUTING = {
 
 
 def _message_content_to_str(content: Union[str, List[Dict[str, Any]]]) -> str:
-    """Normalize message content to string (OpenAI can send string or array of parts)."""
+    """Normalize message content to string (OpenAI can send string or array of parts, e.g. vision/R1)."""
     if isinstance(content, str):
         return content
     if isinstance(content, list):
         return " ".join(
-            p.get("text", "") if isinstance(p.get("text"), str) else str(p)
-            for p in content
-            if isinstance(p, dict)
+            p.get("text", "") for p in content
+            if isinstance(p, dict) and isinstance(p.get("text"), str)
         )
     return str(content)
 
@@ -667,9 +666,9 @@ async def chat_completions(
             "finish_reason": "stop"
         }],
         "usage": {
-            "prompt_tokens": len(" ".join(m.content for m in request.messages).split()),
+            "prompt_tokens": len(" ".join(_message_content_to_str(m.content) for m in request.messages).split()),
             "completion_tokens": len(response_text.split()),
-            "total_tokens": len(" ".join(m.content for m in request.messages).split()) + len(response_text.split()),
+            "total_tokens": len(" ".join(_message_content_to_str(m.content) for m in request.messages).split()) + len(response_text.split()),
         }
     }