Umesh Bhati — Full-Stack & AI Engineer

Why LangGraph?

When you need agents that can branch, loop, checkpoint, and recover from errors — LangGraph is the right tool. It models your agent workflow as a directed graph, giving you fine-grained control over state and execution.

Core Concepts

State

Everything in LangGraph flows through a typed state object. This is your source of truth for what the agent knows at any point.

interface AgentState {
  messages: BaseMessage[];
  currentStep: string;
  toolResults: Record<string, unknown>;
  humanApprovalPending: boolean;
}

Nodes

Nodes are functions that take the current state and return updates to it.

async function researchNode(state: AgentState) {
  const result = await doResearch(state.messages);
  return { toolResults: { ...state.toolResults, research: result } };
}

Edges

Edges define flow between nodes. Conditional edges let you branch based on state.

Multi-Agent Patterns

Supervisor Pattern

One orchestrator agent delegates to specialist agents. Works well for well-defined task categories.

Parallel Execution

Run multiple agents simultaneously and merge their outputs. LangGraph handles this natively with fan-out edges.

Human-in-the-Loop

Pause execution at critical points and wait for human approval. LangGraph's checkpointing makes this resumable.

Common Pitfalls

**Unbounded loops**: Always add iteration limits or termination conditions

**State explosion**: Keep state serializable and small. Store large data externally

**Error recovery**: Wrap tool calls in try/catch, implement retry logic at the graph level

**Testing**: Test nodes in isolation, then test graph flows end-to-end

Streaming

Users expect to see progress in real time. LangGraph supports streaming events out of the box — pipe these to your frontend with Server-Sent Events.

The mental model shift is: stop thinking about code as a call stack, start thinking about it as a state machine. Once that clicks, LangGraph becomes very natural.

Multi-Agent Orchestration with LangGraph: A Practical Guide