fix: updated agent base

pmcp/agents/agent_base.py

@@ -1,7 +1,7 @@
 import logging
 from typing import List, TypeVar, Optional
 
-from langchain_core.messages import AnyMessage, BaseMessage
+from langchain_core.messages import AnyMessage, BaseMessage, SystemMessage
 from pydantic import BaseModel
 from langchain_core.tools import BaseTool
 from langchain_openai import ChatOpenAI
@@ -29,14 +29,21 @@ class AgentBlueprint:
             self.tools = {tool.name: tool for tool in tools}
         self.logger = logging.getLogger(self.__class__.__name__)
 
+    def __set_system_prompt(self, messages: List[AnyMessage]):
+        if self.system_prompt:
+            return [SystemMessage(content=self.system_prompt)] + messages
+        return messages
+
     def call_agent(self, messages: List[AnyMessage]) -> BaseMessage:
-        response = self.llm.with_retry(stop_after_attempt=2).invoke(input=messages)
+        response = self.llm.with_retry(stop_after_attempt=2).invoke(
+            input=self.__set_system_prompt(messages)
+        )
         response.name = self.agent_name
         return response
 
     async def acall_agent(self, messages: List[AnyMessage]) -> BaseMessage:
         response = await self.llm.with_retry(stop_after_attempt=2).ainvoke(
-            input=messages
+            input=self.__set_system_prompt(messages)
         )
         response.name = self.agent_name
         return response
@@ -47,7 +54,7 @@ class AgentBlueprint:
         response = (
             self.llm.with_structured_output(clazz)
             .with_retry(stop_after_attempt=2)
-            .invoke(input=messages)
+            .invoke(input=self.__set_system_prompt(messages))
         )
 
         return response
@@ -58,7 +65,7 @@ class AgentBlueprint:
         response = (
             await self.llm.with_structured_output(clazz)
             .with_retry(stop_after_attempt=2)
-            .ainvoke(input=messages)
+            .ainvoke(input=self.__set_system_prompt(messages))
         )
 
         return response