src/agent/state.py

from __future__ import annotations
from typing import Annotated
from typing_extensions import TypedDict
from langchain_core.messages import BaseMessage
try:
    from langgraph.graph.message import add_messages
except ImportError:
    from langgraph.graph import add_messages


class AgentState(TypedDict, total=False):
    # Conversation history — append-only via add_messages reducer
    messages: Annotated[list[BaseMessage], add_messages]

    # Set on session start, carried through every turn
    session_id: str

    # Rolling summary of old messages (updated when history grows too long)
    conversation_summary: str

    # Raw graph payload (contains copyrighted definitions)
    # Populated by masker_node after graph tool calls finish
    graph_data: dict

    # External definitions: { concept_name → plain-text definition }
    # Sourced from Wikipedia or Tavily tool calls
    external_defs: dict[str, str]

    # graph_data with book definitions stripped / replaced by external_defs
    # This is what gets forwarded to response_node
    masked_data: dict