Streaming

Stream Modes

Mode	Emits
`"updates"`	State delta per node (only changed keys)
`"values"`	Full state after each superstep
`"messages"`	Token events for LLM nodes
`"custom"`	Events written via `stream_writer`
`"debug"`	Internal debug events

Usage

async for event in graph.astream(inputs, stream_mode="updates"):
    print(event)

Custom Events

from langgraph.types import StreamWriter

async def my_node(state, config, *, writer: StreamWriter):
    writer({"status": "processing"})
    return {"result": "done"}

Restricting Output Keys

Use output_keys to restrict which channels appear in "values" mode stream output.