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Ashok Naik
Ashok Naik

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LangGraph & LangChain: Building Agentic AI

Transform your LLMs from static chatbots into dynamic, tool-using agents that can reason, act, and collaborate


πŸš€ From Static to Smart: The Agentic Revolution

Traditional Large Language Models (LLMs) are like brilliant consultants with amnesiaβ€”they give great advice but forget everything after each conversation. While powerful for text generation and reasoning, they lack:

  • 🧠 Memory - No context between interactions
  • πŸ› οΈ Tool Usage - Can't interact with external systems
  • πŸ”„ Iterative Problem-Solving - Can't refine their approach

Agentic AI changes the game by creating dynamic, goal-oriented systems that can reason, act, and adapt over time.

Think of it as upgrading from a calculator to a personal assistant who remembers your preferences, can call APIs, and collaborates with other specialists.


πŸ—οΈ The Dynamic Duo: LangChain vs LangGraph

LangChain: The Foundation Layer 🧱

Perfect for linear workflows and rapid prototyping:

# Classic LangChain chain
from langchain.chains import LLMChain
from langchain.prompts import PromptTemplate

prompt = PromptTemplate(template="Summarize: {text}")
chain = LLMChain(llm=model, prompt=prompt)
result = chain.run("Your text here")
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Best For:

  • βœ… Sequential processing pipelines
  • βœ… Quick prototypes and demos
  • βœ… Simple Q&A systems
  • βœ… Text generation workflows

LangGraph: The Orchestration Engine βš™οΈ

Built for complex workflows with cycles and state:

# LangGraph workflow with memory
from langgraph.graph import StateGraph
from langgraph.checkpoint.memory import MemorySaver

workflow = StateGraph(YourState)
workflow.add_node("step1", your_function)
workflow.add_edge("step1", "step2")

memory = MemorySaver()
app = workflow.compile(checkpointer=memory)
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Best For:

  • βœ… Multi-agent coordination
  • βœ… Human-in-the-loop workflows
  • βœ… Stateful, long-running processes
  • βœ… Complex decision trees

🎯 5 Essential Workflow Patterns

1. πŸ€– Single Agent with Tools

Perfect for: Customer support, personal assistants

from langgraph.prebuilt import create_react_agent
from langchain_openai import ChatOpenAI

def get_weather(city: str) -> str:
    """Get weather for a given city."""
    return f"It's sunny in {city}!"

def create_ticket(issue: str) -> str:
    """Create support ticket."""
    return f"Ticket created: {issue}"

agent = create_react_agent(
    model=ChatOpenAI(model="gpt-4"),
    tools=[get_weather, create_ticket],
    prompt="You are a helpful assistant"
)

# One agent, multiple capabilities!
response = agent.invoke({
    "messages": [{"role": "user", "content": "Weather in NYC and create ticket for broken printer"}]
})
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Real Impact: Handle 80% of support tickets automatically ⚑


2. πŸ”„ Sequential Multi-Agent Pipeline

Perfect for: Content creation, document processing, code review

from langgraph.graph import StateGraph, START, END
from typing import TypedDict

class ContentState(TypedDict):
    topic: str
    research: str
    draft: str
    final: str

def research_agent(state: ContentState):
    return {"research": f"Research data for {state['topic']}"}

def writer_agent(state: ContentState):
    return {"draft": f"Draft based on: {state['research']}"}

def editor_agent(state: ContentState):
    return {"final": f"Polished version of: {state['draft']}"}

# Build the assembly line
workflow = StateGraph(ContentState)
workflow.add_node("research", research_agent)
workflow.add_node("write", writer_agent)
workflow.add_node("edit", editor_agent)

# Define the flow
workflow.add_edge(START, "research")
workflow.add_edge("research", "write")
workflow.add_edge("write", "edit")
workflow.add_edge("edit", END)

app = workflow.compile()
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Pro Tip: Each agent specializes in one task = better quality output! 🎯


3. ⚑ Parallel Processing

Perfect for: Document processing, data analysis, batch operations

from langgraph.constants import Send

class DocState(TypedDict):
    documents: list
    results: list

def route_docs(state: DocState):
    # Fan out to parallel workers
    return [Send("process", {"doc": doc}) for doc in state["documents"]]

def process_doc(state: dict):
    doc = state["doc"]
    processed = f"Processed: {doc['name']}"
    return {"results": [processed]}

def combine_results(state: DocState):
    summary = f"Processed {len(state['results'])} documents"
    return {"summary": summary}

workflow = StateGraph(DocState)
workflow.add_node("route", route_docs)
workflow.add_node("process", process_doc)
workflow.add_node("combine", combine_results)

workflow.add_conditional_edges("route", lambda x: "process")
workflow.add_edge("process", "combine")
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Speed Boost: Process 1000 docs in parallel instead of sequentially! πŸš€


4. πŸ‘€ Human-in-the-Loop

Perfect for: Financial approvals, medical diagnosis, legal review

from langgraph.checkpoint.memory import MemorySaver

class ApprovalState(TypedDict):
    request: str
    analysis: str
    approved: bool
    response: str

def analyze_request(state: ApprovalState):
    return {"analysis": f"AI analysis of: {state['request']}"}

def need_approval(state: ApprovalState):
    return "wait_approval" if not state.get("approved") else "finalize"

def wait_for_human(state: ApprovalState):
    # πŸ›‘ Workflow pauses here for human input
    return {"response": "Awaiting human approval..."}

def finalize_response(state: ApprovalState):
    return {"response": f"Approved response: {state['analysis']}"}

workflow = StateGraph(ApprovalState)
workflow.add_node("analyze", analyze_request)
workflow.add_node("wait_approval", wait_for_human)
workflow.add_node("finalize", finalize_response)

workflow.add_conditional_edges("analyze", need_approval)
workflow.add_edge("wait_approval", "finalize")

# πŸ’Ύ Persistent memory for long-running workflows
memory = MemorySaver()
app = workflow.compile(checkpointer=memory)
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Critical Feature: AI proposes, humans approve, perfect for high-stakes decisions! βš–οΈ


5. 🧠 Agentic RAG (Smart Knowledge Systems)

Perfect for: Enterprise Q&A, documentation search, knowledge management

from langchain.tools.retriever import create_retriever_tool
from langgraph.prebuilt import tools_condition, ToolNode

# Create smart retriever
retriever_tool = create_retriever_tool(
    retriever=your_vectorstore.as_retriever(),
    name="search_docs",
    description="Search company knowledge base"
)

def decide_action(state):
    """πŸ€” LLM decides whether to search or respond directly"""
    last_message = state["messages"][-1]["content"]

    # Bind tools to model
    model_with_tools = model.bind_tools([retriever_tool])
    response = model_with_tools.invoke(state["messages"])
    return {"messages": [response]}

workflow = StateGraph(MessagesState)
workflow.add_node("agent", decide_action)
workflow.add_node("tools", ToolNode([retriever_tool]))

workflow.add_conditional_edges("agent", tools_condition)
workflow.add_edge("tools", "agent")
workflow.add_edge(START, "agent")

rag_agent = workflow.compile()
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Smart Feature: The AI decides when to search vs. when it already knows the answer! 🎯


βœ… Best Practices & ❌ Common Pitfalls

βœ… Golden Rules

Do This Why It Matters
🎯 Start Simple Begin with single agents before multi-agent systems
πŸ—‚οΈ Design State Carefully Keep state schema focused and minimal
πŸ’Ύ Add Checkpoints Use memory for long-running workflows
πŸ‘₯ Include Human Oversight For critical decisions and approvals
πŸ“Š Monitor Everything Log performance, errors, and token usage

❌ Avoid These Traps

Don't Do This What Happens
🚫 Over-engineer Complex systems when simple chains work fine
πŸ”„ Infinite Loops Always include termination conditions
πŸ“¦ State Bloat Storing unnecessary data slows everything down
πŸ’₯ Skip Error Handling Tool failures crash your entire workflow
πŸ™ˆ Ignore Testing Production failures with edge cases

Production Setup

# 🏭 Production configuration
from langgraph.checkpoint.postgres import PostgresSaver

# Use database for persistence (not memory!)
checkpointer = PostgresSaver.from_conn_string(
    "postgresql://user:pass@host/db"
)

production_app = workflow.compile(
    checkpointer=checkpointer,
    debug=False  # Turn off debug logs
)

# πŸ“Š Deploy with monitoring
from langsmith import traceable

@traceable
def monitored_call(input_data):
    return production_app.invoke(input_data)
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πŸ“ˆ Real-World Success Stories

🏒 Global Logistics Provider: Saving 600 hours/day with automated order processing

πŸ”’ Trellix (40k+ customers): Cut log parsing from days to minutes

🚒 Norwegian Cruise Line: Personalized guest experiences with AI agents


🎯 Quick Start Checklist

  1. 🎨 Choose Pattern: Single agent β†’ Sequential β†’ Parallel β†’ Human-loop β†’ RAG
  2. πŸ“‹ Define State: What data flows between steps?
  3. πŸ”§ Create Nodes: Individual functions for each step
  4. πŸ”— Connect Edges: Define the flow between nodes
  5. πŸ’Ύ Add Memory: Use checkpointer for persistence
  6. πŸ§ͺ Test & Monitor: Start simple, add complexity gradually

🎯 Decision Matrix: When to Use What?

Pattern Use Case Complexity Best For
πŸ€– Single Agent Customer support, Q&A 🟒 Low Getting started
πŸ”„ Sequential Content pipelines, workflows 🟑 Medium Assembly lines
⚑ Parallel Document processing, batch jobs 🟑 Medium Speed & scale
πŸ‘€ Human-loop Approvals, critical decisions πŸ”΄ High High-stakes
🧠 Agentic RAG Knowledge systems, enterprise Q&A πŸ”΄ High Smart search

πŸŽ‰ The Bottom Line

Don't choose between themβ€”combine them!

The most effective enterprise solutions leverage:

  • LangChain for modular components and rapid development
  • LangGraph for sophisticated control and coordination

Start simple, build incrementally, and soon you'll have AI agents that feel like magic to your users! ✨


Ready to build your first agentic app? Drop a comment below with what you're planning to build! πŸ‘‡

Tags: #ai #llm #langchain #langgraph #python #agents #automation

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