prompt fixed to use same lang as msg

app.py

@@ -43,8 +43,8 @@ def explain(req: ExplainRequest):
         "Output only the explanation as bullet points. "
         "Limit each bullet to 1–2 sentences. "
         "Limit the number of bullets to 3-4 "
-        "Reply in the same language as the user's message. "
         f"Message:\n\n{user_message}"
+        "Respond using the same language as the message."
     )
 
     url = "https://openrouter.ai/api/v1/chat/completions"