Fix API usage in context management example

Author: yeasy

10_optimization/10.3_context_mgmt.md

@@ -64,6 +64,7 @@ import anthropic
 
 chroma = Client()
 collection = chroma.get_or_create_collection("chat_history")
+client = anthropic.Anthropic()
 
 def chat_with_memory(user_message, conversation_id):
     # 检索相关历史
@@ -77,21 +78,22 @@ def chat_with_memory(user_message, conversation_id):
     context = f"相关历史记录：\n{relevant_history['documents']}"
 
     # 调用 Claude
-    response = anthropic.messages.create(
+    response = client.messages.create(
         model="claude-sonnet-4-6",
+        system=context,
         messages=[
-            {"role": "system", "content": context},
             {"role": "user", "content": user_message}
         ]
     )
 
     # 存储新对话
+    reply = response.content[0].text
     collection.add(
-        documents=[f"User: {user_message}\nAssistant: {response.content}"],
+        documents=[f"User: {user_message}\nAssistant: {reply}"],
         metadatas=[{"conversation_id": conversation_id}]
     )
 
-    return response.content
+    return reply
 ```
 
 ### 10.3.5 原生上下文压缩