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10.5 Hour Generative AI & Agentic AI Guide: LangChain, LangGraph, RAG & Deep Agents

Course Overview & Structure Plan (0:00-4:00)

Krishna introduces this comprehensive 10.5-hour video, summarizing the latest developments in Generative AI & Agentic AI with LangChain and Understanding Generative AI, AI Agents, and Agentic AI: Key Differences Explained from the past 4-5 months. The course is structured into key modules:

  • Generative AI & Agentic AI with LangChain
  • LangGraph Crash Course - Building agentic AI applications
  • RAG Implementation - Traditional, agentic, and vectorless RAG , for a foundational understanding, see Understanding Retrieval Augmented Generation (RAG) in AI Applications
  • Deep Agents & Deep Research Agents - Practical implementation
  • AI Security - Guardrails and LLM evaluation techniques
  • LLM Gateways - Implementation (30-40 minutes)

Note: This course is designed to be consumed over approximately one month, not in a single day. A like target of 5,000 is set to encourage future similar content.

LangChain v1 Crash Course: Setup and Basics (4:00-10:00)

Krishna begins the LangChain v1 crash course, explaining the motivation: LangChain has released version v1 with significant updates to agent creation, memory implementation, and a new middleware concept.

Environment Setup with UV Package Manager

  • UV Package Manager: A fast Python package manager written in Rust, recommended for this course.
  • Installation: Use the command from the official UV package manager website (available for Mac OS, Linux, Windows via PowerShell).
  • Project Initialization: uv init to initialize the working repository. This creates essential files like pyproject.toml and a default main.py.
  • Virtual Environment: uv venv creates a virtual environment. Activate it using the activation script within the environment folder.
  • Library Installation:
    • Create a requirements.txt file with necessary libraries (LangChain, LangChain Community, LangChain OpenAI, LangChain Groq, python-dotenv, LangChain Google GenAI).
    • Install using uv add -r requirements.txt.
    • For individual libraries: uv add langchain.
  • API Keys: Required keys:
    • Google API Key (Google AI Studio)
    • Groq API Key
    • OpenAI API Key

Understanding Agents (10:00-15:00)

Krishna explains the core concept of agents using simple diagrams:

  • Traditional LLM Application: Input → LLM → Output. LLMs are trained on historical data and have a cutoff date; they cannot answer questions about current events.
  • Agentic Application: Input → LLM → Decision to use a tool → Tool provides context → LLM generates output. The LLM autonomously decides when to use a tool and which tool to call.

Simple Agent Example:

  1. Define a tool: get_weather(city)
  2. Use langchain.agents.create_agent()
  3. The agent diagram shows: Start → Model → Tools → End
  4. The agent invokes the tool when asked about weather, uses the tool's response as context, and generates the final output.

Key Insight: The tool's docstring is crucial because the LLM uses it to understand when and how to call the tool.

Model Integration with LangChain v1 (15:00-22:00)

Krishna demonstrates how to integrate three major LLM providers using the new LangChain v1 syntax. For a deeper dive into model types, see the Complete Guide to LangChain Models: Language & Embedding Explained.

Using init_chat_model() (Unified Approach)

  • OpenAI: init_chat_model("gpt-4.1") to initialize a GPT-4.1 model. Invoke with model.invoke("Hello, how are you?").
  • Google Gemini: init_chat_model("google_genai:gemini-2.5-flash") to initialize the Gemini model.
  • Groq: init_chat_model("groq:qwen") to initialize the Qwen model from Groq.

Using Provider-Specific Imports

  • LangChain OpenAI: from langchain_openai import ChatOpenAI and ChatOpenAI(model="gpt-4.1")
  • LangChain Google GenAI: from langchain_google_genai import ChatGoogleGenerativeAI and ChatGoogleGenerativeAI(model="gemini-2.5-flash")
  • LangChain Groq: from langchain_groq import ChatGroq and ChatGroq(model="qwen")

Streaming and Batch Processing (22:00-25:00)

Krishna explains the difference between model.invoke() (waits for complete response) and model.stream() (yields chunks progressively). Streaming is preferred for long responses as it significantly improves user experience.

Streaming Example:

for chunk in model.stream("Write a 200-word paragraph on AI"):
    print(chunk.text)

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