youngjin-langchain-tools 0.3.4

LangGraph utilities for Streamlit - StreamlitLanggraphHandler and more

youngjin-langchain-tools

youngjin-langchain-tools is a collection of LangGraph utilities designed to simplify AI application development with Streamlit and other frameworks.

Features

• StreamlitLanggraphHandler: A drop-in replacement for the deprecated StreamlitCallbackHandler, designed for LangGraph agents
• Real-time Streaming: Stream agent responses with live token updates
• Tool Visualization: Display tool calls and results with expandable UI components
• LangSmith Integration: Built-in support for LangSmith feedback collection via run_id tracking
• Configurable: Customize display options, labels, and behavior

Installation

pip install youngjin-langchain-tools

Or using uv:

uv add youngjin-langchain-tools

With Streamlit support:

pip install youngjin-langchain-tools[streamlit]

Quick Start

Basic Usage with LangGraph Agent

import streamlit as st
from langgraph.checkpoint.memory import InMemorySaver
from langchain.agents import create_agent
from youngjin_langchain_tools import StreamlitLanggraphHandler

# Create your LangGraph agent
agent = create_agent(
    model=llm,
    tools=tools,
    checkpointer=InMemorySaver(),
)

# In your Streamlit app
with st.chat_message("assistant"):
    handler = StreamlitLanggraphHandler(
        container=st.container(),
        expand_new_thoughts=True
    )

    response = handler.invoke(
        agent=agent,
        input={"messages": [{"role": "user", "content": prompt}]},
        config={"configurable": {"thread_id": thread_id}}
    )

    # response contains the final text

Before & After Comparison

Before (LangChain < 1.0 with AgentExecutor):

from langchain.callbacks import StreamlitCallbackHandler

with st.chat_message("assistant"):
    st_cb = StreamlitCallbackHandler(st.container(), expand_new_thoughts=True)
    response = agent_executor.invoke(
        {"input": prompt},
        config=RunnableConfig({"callbacks": [st_cb]})
    )
    st.write(response["output"])

After (LangGraph with StreamlitLanggraphHandler):

from youngjin_langchain_tools import StreamlitLanggraphHandler

with st.chat_message("assistant"):
    handler = StreamlitLanggraphHandler(st.container(), expand_new_thoughts=True)
    response = handler.invoke(
        agent=langgraph_agent,
        input={"messages": [{"role": "user", "content": prompt}]},
        config={"configurable": {"thread_id": thread_id}}
    )
    # response is the final text directly

Advanced Usage with Custom Configuration

from youngjin_langchain_tools import (
    StreamlitLanggraphHandler,
    StreamlitLanggraphHandlerConfig
)

# Create custom configuration
config = StreamlitLanggraphHandlerConfig(
    expand_new_thoughts=True,
    max_tool_content_length=3000,
    show_tool_calls=True,
    show_tool_results=True,
    thinking_label="🧠 Processing...",
    complete_label="✨ Done!",
    tool_call_emoji="⚡",
    tool_complete_emoji="✓",
    cursor="█",
)

handler = StreamlitLanggraphHandler(
    container=st.container(),
    config=config
)

# Use stream() for more control
for event in handler.stream(agent, input, config):
    if event["type"] == "tool_call":
        print(f"Tool called: {event['data']['name']}")
    elif event["type"] == "token":
        # Custom token handling
        pass

final_response = handler.get_response()

LangSmith Feedback Integration

The handler automatically tracks run_id for LangSmith feedback collection. This enables users to provide feedback on agent responses.

import streamlit as st
from langsmith import Client
from streamlit_feedback import streamlit_feedback
from youngjin_langchain_tools import StreamlitLanggraphHandler

# Create handler with LangSmith integration (enabled by default)
handler = StreamlitLanggraphHandler(
    container=st.container(),
    enable_langsmith=True,  # Default
    langsmith_run_name="customer_support_agent",  # Optional custom name
)

# Invoke the agent
response = handler.invoke(agent, input, config)

# After execution, run_id is available for feedback
if handler.run_id:
    st.session_state["run_id"] = handler.run_id
    print(f"Run ID: {handler.run_id}")

# Use run_id with LangSmith feedback
def add_feedback():
    run_id = st.session_state.get("run_id")
    if not run_id:
        st.info("No run_id available for feedback.")
        return

    feedback = streamlit_feedback(
        feedback_type="thumbs",
        optional_text_label="Leave a comment",
        key=f"feedback_{run_id}",
    )

    if feedback:
        langsmith_client = Client()
        score = 1 if feedback["score"] == "👍" else 0
        langsmith_client.create_feedback(
            run_id,
            f"thumbs {feedback['score']}",
            score=score,
            comment=feedback.get("text"),
        )
        st.success("Feedback submitted!")

add_feedback()

To disable LangSmith integration:

handler = StreamlitLanggraphHandler(
    container=st.container(),
    enable_langsmith=False,  # Disable run_id tracking
)

API Reference

StreamlitLanggraphHandler

Main handler class for streaming LangGraph agents in Streamlit.

Constructor Parameters

Parameter	Type	Default	Description
container	Any	required	Streamlit container to render in
expand_new_thoughts	bool	True	Expand status container for tool calls
max_tool_content_length	int	2000	Max chars of tool output to display
show_tool_calls	bool	True	Show tool call information
show_tool_results	bool	True	Show tool execution results
thinking_label	str	"🤔 Thinking..."	Label while processing
complete_label	str	"✅ Complete!"	Label when complete
enable_langsmith	bool	True	Enable LangSmith run_id tracking
langsmith_project	str	None	LangSmith project name
langsmith_run_name	str	"streamlit_agent_run"	Name for the LangSmith run
config	Config	None	Optional config object

Methods

Method	Description
invoke(agent, input, config)	Execute agent and return final response
stream(agent, input, config)	Generator yielding streaming events
get_response()	Get accumulated response text

Properties

Property	Type	Description
run_id	Optional[str]	LangSmith run ID for feedback collection
config	StreamlitLanggraphHandlerConfig	Handler configuration

StreamlitLanggraphHandlerConfig

Configuration dataclass for handler customization.

Architecture

youngjin_langchain_tools/
├── __init__.py              # Package exports
├── handlers/                # UI framework handlers
│   ├── __init__.py
│   └── streamlit_langgraph_handler.py
└── utils/                   # Utility functions
    ├── __init__.py
    └── config.py

Requirements

• Python 3.12+
• LangGraph 0.2+
• Streamlit 1.30+ (optional, for StreamlitLanggraphHandler)
• LangSmith (optional, for feedback integration)

License

Apache License 2.0 - see LICENSE for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.