def add_to_history(tool_context: ToolContext, event: str) -> Dict[str, Any]:
    history = tool_context.state.get("history", [])

    history.append({
        "event": event,
        "timestamp": datetime.now().isoformat(),
        "session_id": tool_context.session_id
    })

    # Keep only last 50 events
    tool_context.state["history"] = history[-50:]

    return {"status": "success", "history_length": len(history)}

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