Conversational RAG Chatbot with Chainlit

Chainlit is an open-source Python framework for building conversational AI interfaces. Combined with RAGWire and a LangChain agent, it produces a fully functional RAG chatbot in a single file — drag-and-drop document upload, conversational memory, and tool-calling retrieval with no frontend code required.

Complete the RAGWire Architecture and Setup and RAGWire Providers and Components articles first.

Architecture

This chatbot runs as a single process with three layers:

Chainlit — Chat UI with file upload, message handling, and streaming
LangChain Agent — Tool-calling agent with get_filter_context and search_documents
RAGWire — Document ingestion and retrieval pipeline backed by Qdrant Cloud

Configuration

Use the same Gemini + Qdrant Cloud config from previous articles:

YAML

# config_gemini_qdrant.yaml
embeddings:
  provider: "google"
  model: "models/gemini-embedding-001"
  api_key: "${GOOGLE_API_KEY}"

llm:
  provider: "google"
  model: "gemini-2.5-flash"
  api_key: "${GOOGLE_API_KEY}"

vectorstore:
  url: "${QDRANT_URL}"
  api_key: "${QDRANT_API_KEY}"
  collection_name: "finance-rag-google-qdrant"
  use_sparse: true
  force_recreate: false

retriever:
  search_type: "hybrid"
  top_k: 5
  auto_filter: false

metadata:
  config_file: "finance_metadata.yaml"

logging:
  level: "INFO"
  console_output: true
  colored: false
  log_file: "./.log/ragwire.log"

Environment Variables

Create a .env file with the required API keys:

BASH

GOOGLE_API_KEY=your_google_api_key
QDRANT_URL=https://your-cluster.cloud.qdrant.io:6333
QDRANT_API_KEY=your_qdrant_api_key

Dependencies

BASH

pip install ragwire chainlit langchain langchain-google-genai langgraph python-dotenv

The Complete Chatbot

Create app.py — the entire chatbot is a single file:

PYTHON

from dotenv import load_dotenv
load_dotenv()

from ragwire import RAGWire
from langchain.agents import create_agent
from langchain.tools import tool
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_core.messages import HumanMessage
from langgraph.checkpoint.memory import InMemorySaver

import chainlit as cl
from typing import Optional
import tempfile, os

rag = RAGWire("config_gemini_qdrant.yaml")

RAG Tools

The same two tools from the notebook pipeline, now shared with the Chainlit agent:

PYTHON

@tool
def get_filter_context(query: str) -> str:
    """Get available metadata fields, stored values, and filter suggestions for a query.

    Call this before search_documents when the query involves a specific company,
    year, or document type. Skip for purely semantic queries.
    """
    return rag.get_filter_context(query)

@tool
def search_documents(query: str, filters=None):
    """Search the document knowledge base for relevant information.

    Args:
        query: The search query
        filters: Optional metadata filters from get_filter_context.
    """
    results = rag.retrieve(query=query, filters=filters)
    if not results:
        return "No relevant information is found!"
    else:
        return results

LLM and System Prompt

PYTHON

model = ChatGoogleGenerativeAI(model="gemini-2.5-flash")
memory = InMemorySaver()

SYSTEM_PROMPT = """
    You are a helpful document assistant.
    For complex questions, break them down into simpler sub-questions and answer each one before forming a final answer.
    Always call search_documents to find information before answering.
    If the query mentions a company, year, or document type, call get_filter_context first.
    If no documents are found, say so honestly — never make up an answer.
    Always mention the source document in your answer."""

Chat Start Handler

on_chat_start runs once when a user opens the chat. It creates a fresh agent with its own memory session:

PYTHON

@cl.on_chat_start
async def on_chat_start():
    agent = create_agent(
        model=model,
        tools=[get_filter_context, search_documents],
        system_prompt=SYSTEM_PROMPT,
        checkpointer=memory
    )

    cl.user_session.set('agent', agent)
    cl.user_session.set('thread_id', cl.context.session.id)

    await cl.Message(content="Hello! Upload documents (drag & drop) or ask me a question.").send()

Message Handler

on_message handles every incoming message.

It supports two modes:

File upload — If the message contains attached files, copy them to a temporary directory and ingest with RAGWire
Chat query — Otherwise, invoke the agent with the user's question

PYTHON

@cl.on_message
async def on_message(message: cl.Message):
    agent = cl.user_session.get('agent')
    thread_id = cl.user_session.get('thread_id')

    if message.elements:
        with tempfile.TemporaryDirectory() as tmpdir:
            for elem in message.elements:
                dest = os.path.join(tmpdir, elem.name)
                with open(elem.path, 'rb') as src, open(dest, 'wb') as dst:
                    dst.write(src.read())

            msg = cl.Message(content="Ingesting documents...")
            await msg.send()

            stats = rag.ingest_directory(tmpdir)
            msg.content = f"Files have been ingested. Stats: {stats}"
            await msg.update()

            return

    config = {'configurable': {'thread_id': thread_id}}

    response_msg = cl.Message(content='Thinking...')
    await response_msg.send()

    result = await agent.ainvoke(
        {'messages': [HumanMessage(message.content)]},
        config=config
    )

    response_msg.content = result['messages'][-1].text
    await response_msg.update()

Key Implementation Details

cl.user_session stores the agent and thread ID per user session, ensuring each user gets an independent agent with its own memory
cl.context.session.id provides a unique session identifier used as the thread_id for the InMemorySaver checkpointer
agent.ainvoke is the async version of invoke, required inside Chainlit's async handlers
tempfile.TemporaryDirectory creates a temporary directory for uploaded files, which is automatically cleaned up after ingestion
message.elements contains the list of files attached to a message via drag-and-drop or the upload button

Welcome Page

Create chainlit.md in the same directory as app.py to customise the welcome screen:

MARKDOWN

# Welcome to the RAGWire Document Assistant

Upload documents (drag & drop) or ask questions about your ingested documents.

## Supported File Types
- PDF, DOCX, XLSX, PPTX, TXT, MD

Tip

If you do not want a welcome screen, leave chainlit.md empty.

Running the Chatbot

BASH

chainlit run app.py

On Linux/macOS: The command is identical. Chainlit opens a browser window at http://localhost:8000 by default.

The chatbot is now live. Drag and drop PDF files into the chat to ingest them, then ask questions. The agent uses get_filter_context to discover available metadata and search_documents to retrieve relevant chunks with optional filters. Conversational memory persists across messages within the same session.

Important

This simple chatbot uses InMemorySaver — memory is lost when the process restarts. For persistent chat history across sessions, see the Chainlit Chat Frontend article, which adds SQLite-backed history, authentication, and PDF export.

Conversational RAG Chatbot with Chainlit

Advanced RAG – Build & Deploy Production GenAI Apps

Architecture

Configuration

Environment Variables

Dependencies

The Complete Chatbot

RAG Tools

LLM and System Prompt

Chat Start Handler

Message Handler

Key Implementation Details

Welcome Page

Running the Chatbot

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