Architecting LLM Agents with LangGraph and Next.js

Why LangChain is Not Enough for Autonomous Agents

While simple chains are sufficient for basic Q&A, complex engineering tasks require loops and memory. This is where LangGraph shines.

Cyclic Flows

In LangGraph, we define agents as nodes in a graph. An agent can call a tool, inspect the result, and decide whether to call another tool or return its final output.

Streaming Agent State

To render agent actions in a React frontend, we can stream events from our API routes:

1. 1Use Server-Sent Events (SSE) to send chunks of logs.
2. 2In the Next.js API route, use ReadableStream to push status tokens.
3. 3Parse the stream on the client side and update a timeline UI.