"""
LangGraph agent state — defines the shape of the state object that flows
through every node in the agent graph.
"""

from typing import Annotated, TypedDict

from langgraph.graph.message import add_messages


class AgentState(TypedDict):
    """
    The single source of truth that travels through every node in the graph.

    `messages` uses LangGraph's `add_messages` reducer, which:
    - Appends new messages to the list.
    - Replaces messages with the same ID (useful for tool-call results).
    """

    messages: Annotated[list, add_messages]