sraldon24/claudecodeconfigs/langgraph-patterns

from typing import Annotated, TypedDict
from langchain_core.messages import BaseMessage
from langgraph.graph import StateGraph, START, END
from langgraph.graph.message import add_messages
from langchain_anthropic import ChatAnthropic
# 1. State Definition (Message reducer is critical)
class AgentState(TypedDict):
    messages: Annotated[list[BaseMessage], add_messages]
    # Add custom state variables here (e.g., extracted_data: str)
# 2. Node Definitions
def agent_node(state: AgentState):
    llm = ChatAnthropic(model="claude-3-5-sonnet-latest")
    # Bind tools here if needed: llm = llm.bind_tools(tools)
    response = llm.invoke(state["messages"])
    # Return MUST be a dict updating the state
    return {"messages": [response]} 
# 3. Conditional Edges (Routing)
def should_continue(state: AgentState) -> str:
    last_msg = state["messages"][-1]
    if last_msg.tool_calls:
        return "tools"
    return END
# 4. Graph Construction
builder = StateGraph(AgentState)
builder.add_node("agent", agent_node)
# builder.add_node("tools", ToolNode(tools)) # If using tools
builder.add_edge(START, "agent")
# builder.add_conditional_edges("agent", should_continue, ["tools", END])
# builder.add_edge("tools", "agent")
# 5. Compilation
graph = builder.compile()
# Usage: graph.invoke({"messages": [("user", "Hello!")]})