How I built an intelligent multi-agent system using AutoGen, LangChain, and Hugging Face to demonstrate a practical agent AI workflow

import warnings
warnings.filterwarnings('ignore')


from typing import List, Dict
import autogen
from langchain.prompts import PromptTemplate
from langchain.chains import LLMChain
from langchain_community.llms import HuggingFacePipeline
from transformers import pipeline
import json


print("🚀 Loading models...n")


pipe = pipeline(
   "text2text-generation",
   model="google/flan-t5-base",
   max_length=200,
   temperature=0.7
)


llm = HuggingFacePipeline(pipeline=pipe)
print("✓ Models loaded!n")

def demo_langchain_basics():
   print("="*70)
   print("DEMO 1: LangChain - Intelligent Prompt Chains")
   print("="*70 + "n")
   prompt = PromptTemplate(
       input_variables=["task"],
       template="Task: {task}nnProvide a detailed step-by-step solution:"
   )
   chain = LLMChain(llm=llm, prompt=prompt)
   task = "Create a Python function to calculate fibonacci sequence"
   print(f"Task: {task}n")
   result = chain.run(task=task)
   print(f"LangChain Response:n{result}n")
   print("✓ LangChain demo completen")


def demo_langchain_multi_step():
   print("="*70)
   print("DEMO 2: LangChain - Multi-Step Reasoning")
   print("="*70 + "n")
   planner = PromptTemplate(
       input_variables=["goal"],
       template="Break down this goal into 3 steps: {goal}"
   )
   executor = PromptTemplate(
       input_variables=["step"],
       template="Explain how to execute this step: {step}"
   )
   plan_chain = LLMChain(llm=llm, prompt=planner)
   exec_chain = LLMChain(llm=llm, prompt=executor)
   goal = "Build a machine learning model"
   print(f"Goal: {goal}n")
   plan = plan_chain.run(goal=goal)
   print(f"Plan:n{plan}n")
   print("Executing first step...")
   execution = exec_chain.run(step="Collect and prepare data")
   print(f"Execution:n{execution}n")
   print("✓ Multi-step reasoning completen")

class SimpleAgent:
   def __init__(self, name: str, role: str, llm_pipeline):
       self.name = name
       self.role = role
       self.pipe = llm_pipeline
       self.memory = []
   def process(self, message: str) -> str:
       prompt = f"You are a {self.role}.nUser: {message}nYour response:"
       response = self.pipe(prompt, max_length=150)[0]['generated_text']
       self.memory.append({"user": message, "agent": response})
       return response
   def __repr__(self):
       return f"Agent({self.name}, role={self.role})"


def demo_simple_agents():
   print("="*70)
   print("DEMO 3: Simple Multi-Agent System")
   print("="*70 + "n")
   researcher = SimpleAgent("Researcher", "research specialist", pipe)
   coder = SimpleAgent("Coder", "Python developer", pipe)
   reviewer = SimpleAgent("Reviewer", "code reviewer", pipe)
   print("Agents created:", researcher, coder, reviewer, "n")
   task = "Create a function to sort a list"
   print(f"Task: {task}n")
   print(f"[{researcher.name}] Researching...")
   research = researcher.process(f"What's the best approach to: {task}")
   print(f"Research: {research[:100]}...n")
   print(f"[{coder.name}] Coding...")
   code = coder.process(f"Write Python code to: {task}")
   print(f"Code: {code[:100]}...n")
   print(f"[{reviewer.name}] Reviewing...")
   review = reviewer.process(f"Review this approach: {code[:50]}")
   print(f"Review: {review[:100]}...n")
   print("✓ Multi-agent workflow completen")

def demo_autogen_conceptual():
   print("="*70)
   print("DEMO 4: AutoGen Concepts (Conceptual Demo)")
   print("="*70 + "n")
   agent_config = {
       "agents": [
           {"name": "UserProxy", "type": "user_proxy", "role": "Coordinates tasks"},
           {"name": "Assistant", "type": "assistant", "role": "Solves problems"},
           {"name": "Executor", "type": "executor", "role": "Runs code"}
       ],
       "workflow": [
           "1. UserProxy receives task",
           "2. Assistant generates solution",
           "3. Executor tests solution",
           "4. Feedback loop until complete"
       ]
   }
   print(json.dumps(agent_config, indent=2))
   print("n📝 AutoGen Key Features:")
   print("  • Automated agent chat conversations")
   print("  • Code execution capabilities")
   print("  • Human-in-the-loop support")
   print("  • Multi-agent collaboration")
   print("  • Tool/function callingn")
   print("✓ AutoGen concepts explainedn")


class MockLLM:
   def __init__(self):
       self.responses = {
           "code": "def fibonacci(n):n    if n  str:
       prompt_lower = prompt.lower()
       if "code" in prompt_lower or "function" in prompt_lower:
           return self.responses["code"]
       elif "explain" in prompt_lower:
           return self.responses["explain"]
       elif "review" in prompt_lower:
           return self.responses["review"]
       return self.responses["default"]


def demo_autogen_with_mock():
   print("="*70)
   print("DEMO 5: AutoGen with Custom LLM Backend")
   print("="*70 + "n")
   mock_llm = MockLLM()
   conversation = [
       ("User", "Create a fibonacci function"),
       ("CodeAgent", mock_llm.generate("write code for fibonacci")),
       ("ReviewAgent", mock_llm.generate("review this code")),
   ]
   print("Simulated AutoGen Multi-Agent Conversation:n")
   for speaker, message in conversation:
       print(f"[{speaker}]")
       print(f"{message}n")
   print("✓ AutoGen simulation completen")

def demo_hybrid_system():
   print("="*70)
   print("DEMO 6: Hybrid LangChain + Multi-Agent System")
   print("="*70 + "n")
   reasoning_prompt = PromptTemplate(
       input_variables=["problem"],
       template="Analyze this problem: {problem}nWhat are the key steps?"
   )
   reasoning_chain = LLMChain(llm=llm, prompt=reasoning_prompt)
   planner = SimpleAgent("Planner", "strategic planner", pipe)
   executor = SimpleAgent("Executor", "task executor", pipe)
   problem = "Optimize a slow database query"
   print(f"Problem: {problem}n")
   print("[LangChain] Analyzing problem...")
   analysis = reasoning_chain.run(problem=problem)
   print(f"Analysis: {analysis[:120]}...n")
   print(f"[{planner.name}] Creating plan...")
   plan = planner.process(f"Plan how to: {problem}")
   print(f"Plan: {plan[:120]}...n")
   print(f"[{executor.name}] Executing...")
   result = executor.process(f"Execute: Add database indexes")
   print(f"Result: {result[:120]}...n")
   print("✓ Hybrid system completen")


if __name__ == "__main__":
   print("="*70)
   print("🤖 ADVANCED AGENTIC AI TUTORIAL")
   print("AutoGen + LangChain + HuggingFace")
   print("="*70 + "n")
   demo_langchain_basics()
   demo_langchain_multi_step()
   demo_simple_agents()
   demo_autogen_conceptual()
   demo_autogen_with_mock()
   demo_hybrid_system()
   print("="*70)
   print("🎉 TUTORIAL COMPLETE!")
   print("="*70)
   print("n📚 What You Learned:")
   print("  ✓ LangChain prompt engineering and chains")
   print("  ✓ Multi-step reasoning with LangChain")
   print("  ✓ Building custom multi-agent systems")
   print("  ✓ AutoGen architecture and concepts")
   print("  ✓ Combining LangChain + agents")
   print("  ✓ Using HuggingFace models (no API needed!)")
   print("n💡 Key Takeaway:")
   print("  You can build powerful agentic AI systems without expensive APIs!")
   print("  Combine LangChain's chains with multi-agent architectures for")
   print("  intelligent, autonomous AI systems.")
   print("="*70 + "n")