Access to Chat History in Hooks

[gabriansa]

Description

Add ability to access and modify the chat history through RunHooks/AgentHooks while the agent is running. This would allow adding custom messages or modifying the conversation context during execution.

Use Case

• Injecting context-specific messages during agent execution
• Modifying conversation history in response to specific events

Proposed Dummy Implementation

1. Add message history to RunContextWrapper
2. Expose methods to add/modify messages through hooks:

class SomeHooks(AgentHooks[SomeContext]):    
    async def on_tool_end(
        self,
        context: RunContextWrapper[SomeContext],
        agent: Any,
        tool: Tool,
    ) -> None:
        agent.add_message({"role": "user", "content": "some text"})

[fitzjalen]

Indeed, this is a very important enhancement.
In both of my projects, this feature could be game-changing.
Since I saw that your proposal hasn’t received any updates, I decided to implement this feature myself:

#2120