Welcome to Tutorial 7. Here we introduce LangGraph — the graph-based execution engine that powers all advanced multi-agent patterns covered in Tutorials 8–25.

1. LangGraph fundamentals

   • What LangGraph is and how it differs from LangChain
   • Nodes, edges, and state management
   • Compiling and running a StateGraph

2. add_messages and MessagesState

   • Why a plain list field breaks under concurrent updates
   • The add_messages reducer — appending without overwriting
   • Defining your own ChatState(TypedDict) with Annotated

3. ToolNode — prebuilt tool execution

   • How ToolNode reads AIMessage.tool_calls and returns ToolMessage results
   • Parallel tool calls in a single model turn
   • Direct tool invocation with the @tool decorator

4. Building a ReAct agent from scratch

   • The classic loop: agent → should_use_tools → tools → agent
   • add_conditional_edges with an explicit path_map
   • How create_react_agent implements this internally

• Completion of Tutorials 1–6
• Groq API key — see root README for setup instructions