LangGraph (TypeScript)

TypeScript port of LangGraph. Same graph-based mental model as the Python version — explicit state, durable checkpoints, conditional routing — with type-safe streaming, ReducedValue/UntrackedValue types, and the @langgraphjs/toolkit prebuilt agent package.

Install

npm install @langchain/langgraph

Version

v1.3.0 · May 2026 · Node 18+

Best for

Cycles, conditional routing, multi-agent coordination, streaming servers.

Where to start

New? Follow Zero → Hero. Coming from the Python guide? The primitives are identical; jump to TypeScript-specific features to catch the TS extras.

Zero → Hero

1 · Core fundamentals Install, state, nodes, edges, compile · 20 min

2 · Simple agents (LangChain.js) LangChain.js primitives · 20 min

3 · Simple agents (LangGraph.js) StateGraph, first LangGraph agent · 25 min

4 · Multi-agent systems Supervisor, parallel, handoff · 25 min

5 · Tools integration Tool node, custom tools · 20 min

6 · Structured output Zod schemas, validation · 15 min

7 · Type-safe streaming (v0.3+) Stream modes, typed events · 20 min

8 · Node caching Skip redundant work · 15 min

9 · Deferred nodes Fan-in aggregation · 15 min

10 · Middleware (hooks) Pre/post model hooks · 20 min

11 · Cross-thread memory Shared memory across sessions · 15 min

12 · Streaming (Express) SSE streaming server · 20 min

13 · Production Deployment, scaling, monitoring · 30 min

Jump to a topic

State graph

Tools integration

Type-safe streaming

addNode / addSequence

Node caching

Deferred nodes

Pre/post model hooks

Middleware (dedicated)

Cross-thread memory

New type utilities (v1.2)

Observability

Reference

Comprehensive guide Single-page technical reference.

Middleware

Observability

Recipes

Diagrams

Production guide

Streaming server (Express)

What’s new in v1.3.0 (May 2026)

• MessagesZodState / MessagesZodMeta — Zod-based companion to MessagesAnnotation. Use MessagesZodState when you want full Zod type inference on your messages state instead of the Annotation-based API.
• STREAM_EVENTS_V3_MODES — constant listing all valid v3 streaming modes ("values", "updates", "messages", "tools", "custom", "tasks"). Use this to validate or enumerate mode strings at runtime.
• createGraphRunStream / GraphRunStream / SubgraphRunStream — new lower-level functional streaming API. Complements the existing .stream() method on compiled graphs with explicit stream lifecycle control.
• Stream transformers — createLifecycleTransformer, createMessagesTransformer, createSubgraphDiscoveryTransformer, createValuesTransformer for composing stream pipelines.
• Schema utilities — isSerializableSchema, isStandardSchema type guards; getJsonSchemaFromSchema, getSchemaDefaultGetter for schema-to-JSON-Schema conversion.
• pushMessage — convenience helper for appending a message to a messages-state channel.
• All 1.2.x features retained: standard JSON Schema (Zod 4, Valibot, ArkType), ReducedValue/UntrackedValue types, @langgraphjs/toolkit.

Where did createReactAgent go?

createReactAgent moved from @langchain/langgraph/prebuilt to the new @langgraphjs/toolkit package. The old path still warns; migrate when convenient.

Install, minimal example

import { StateGraph, START, END, MemorySaver } from '@langchain/langgraph';
import { BaseMessage } from '@langchain/core/messages';

type State = { messages: BaseMessage[] };

const graph = new StateGraph<State>({ channels: { messages: { reducer: (a, b) => [...a, ...b] } } })
  .addNode('respond', async (state) => ({ messages: [/* ... */] }))
  .addEdge(START, 'respond')
  .addEdge('respond', END)
  .compile({ checkpointer: new MemorySaver() });

const result = await graph.invoke(
  { messages: [] },
  { configurable: { thread_id: 'session-1' } }
);
console.log(result);

Ready? Start Zero → Hero Step 1 →

---

Revision history

Date	Version	Changes
2026-05-05	1.3.0	Version bumped 1.2.9 → 1.3.0; “What’s new” updated for 1.3.0 (MessagesZodState/Meta, STREAM_EVENTS_V3_MODES, createGraphRunStream, stream transformers, schema utilities, pushMessage). All new symbols verified against installed @langchain/langgraph@1.3.0 (.routine-envs/check-0505-node). Comprehensive guide header and revision history updated.
2026-04-21	1.2.9	Index redesigned with Zero → Hero + Jump-to-topic grid.
April 19, 2026	1.2.9	Standard JSON Schema; new type utilities; toolkit package.
November 2025	1.0.2	Initial TypeScript guide.

Note: Python implementation lives at LangGraph (Python).