Graph Definitions

Graphs are the core abstraction of LangGraph. Each StateGraph implementation is used to create graph workflows. Once compiled, you can run the CompiledGraph to run the application.

StateGraph

from langgraph.graph import StateGraph
from typing_extensions import TypedDict
class MyState(TypedDict)
    ...
graph = StateGraph(MyState)

::: langgraph.graph.StateGraph handler: python

MessageGraph

::: langgraph.graph.message.MessageGraph

CompiledGraph

::: langgraph.graph.graph.CompiledGraph

StreamMode

::: langgraph.pregel.StreamMode

Constants

The following constants and classes are used to help control graph execution.

START

START is a string constant ("__start__") that serves as a "virtual" node in the graph. Adding an edge (or conditional edges) from START to node one or more nodes in your graph will direct the graph to begin execution there.

from langgraph.graph import START
...
builder.add_edge(START, "my_node")
# Or to add a conditional starting point
builder.add_conditional_edges(START, my_condition)

END

END is a string constant ("__end__") that serves as a "virtual" node in the graph. Adding an edge (or conditional edges) from one or more nodes in your graph to the END "node" will direct the graph to cease execution as soon as it reaches this point.

from langgraph.graph import END
...
builder.add_edge("my_node", END) # Stop any time my_node completes
# Or to conditionally terminate
def my_condition(state):
    if state["should_stop"]:
        return END
    return "my_node"
builder.add_conditional_edges("my_node", my_condition)

Send

::: langgraph.constants.Send

RetryPolicy

::: langgraph.pregel.types.RetryPolicy

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