langbgraph - streaming "messages" with custom output added

[dsplog]

in the langgraph, along with the streaming chat response, want to send some additional information to be displayed.
for eg use case is tool calls created files, and the list of files to be displayed seperately.
how to do that?

`from typing import Dict, TypedDict, Annotated
from langchain_core.messages import HumanMessage
from langgraph.graph import END, Graph
import operator
from langchain_openai import ChatOpenAI
import json
from dotenv import load_dotenv
import os
from langgraph.config import get_stream_writer

Load environment variables

load_dotenv('./be/.env')

Define our state

class State(TypedDict):
messages: list
current_step: str

Create processing nodes

def process_input(state: State):
"""First node: Process the input message"""
current_message = state["messages"][-1].content
return {"messages": state["messages"], "current_step": f"Processing: {current_message}"}

def analyze_text(state: State):
"""Second node: Analyze the text"""
# Use API key from environment variables
llm = ChatOpenAI(
api_key=os.getenv("OPENAI_API_KEY"),
temperature=0,
)
messages = state["messages"]
response = llm.invoke([HumanMessage(content=f"Analyze this text briefly: {messages[-1].content}")])
writer = get_stream_writer()
writer({"custom_key": "Generating custom data inside node"})
response.additional_kwargs = {"custom_key": "Generating custom data inside node"}

return state

Build the graph

def build_graph():
# Create workflow
workflow = Graph()

# Add nodes
workflow.add_node("process", process_input)
workflow.add_node("analyze", analyze_text)

# Add edges
workflow.add_edge("process", "analyze")
workflow.add_edge("analyze", END)

# Set entry point
workflow.set_entry_point("process")

return workflow

Create the app

graph = build_graph().compile()

Example usage

def run_graph(input_text: str):
input_state = State(
messages=[HumanMessage(content=input_text)],
current_step=""
)

for message_chunk, metadata in graph.stream(input_state,
                                            stream_mode="messages"
                                            ):
    if message_chunk.content:
        print(message_chunk.content, end="|", flush=True)
    print(message_chunk.additional_kwargs)

if name == "main":
run_graph("The quick brown fox jumps over the lazy dog.")

`
in the above code snippet, tried to do with response.additional_kwargs, but looks like that is not the way.
any suggestions