Small refactor to improve (CodeAct)Agent extensibility (#8244)

openhands/controller/agent.py

@@ -8,6 +8,7 @@ if TYPE_CHECKING:
     from openhands.core.config import AgentConfig
     from openhands.events.action import Action
     from openhands.events.action.message import SystemMessageAction
+    from openhands.utils.prompt import PromptManager
 from litellm import ChatCompletionToolParam
 
 from openhands.core.exceptions import (
@@ -19,9 +20,6 @@ from openhands.events.event import EventSource
 from openhands.llm.llm import LLM
 from openhands.runtime.plugins import PluginRequirement
 
-if TYPE_CHECKING:
-    from openhands.utils.prompt import PromptManager
-
 
 class Agent(ABC):
     DEPRECATED = False
@@ -43,10 +41,16 @@ class Agent(ABC):
         self.llm = llm
         self.config = config
         self._complete = False
-        self.prompt_manager: 'PromptManager' | None = None
+        self._prompt_manager: 'PromptManager' | None = None
         self.mcp_tools: dict[str, ChatCompletionToolParam] = {}
         self.tools: list = []
 
+    @property
+    def prompt_manager(self) -> 'PromptManager':
+        if self._prompt_manager is None:
+            raise ValueError(f'Prompt manager not initialized for agent {self.name}')
+        return self._prompt_manager
+
     def get_system_message(self) -> 'SystemMessageAction | None':
         """
         Returns a SystemMessageAction containing the system message and tools.