# @cloudbase/agent-adapter-langchain
Adapter that wraps LangChain's `createAgent()` as an AG-UI compatible agent. Provides `LangchainAgent` wrapper class and `clientTools()` middleware for client tools support.
## Basic Usage
```typescript
import { createAgent as createLangchainAgent } from "langchain";
import { MemorySaver } from "@langchain/langgraph";
import { ChatOpenAI } from "@langchain/openai";
import { LangchainAgent, clientTools } from "@cloudbase/agent-adapter-langchain";
const model = new ChatOpenAI({ model: "gpt-4o" });
const checkpointer = new MemorySaver();
const lcAgent = createLangchainAgent({
model,
checkpointer,
middleware: [clientTools()],
});
const agent = new LangchainAgent({ agent: lcAgent });
```
## Checkpointer (Required)
`LangchainAgent` requires the agent to be created with a checkpointer.
### MemorySaver (Development)
```typescript
import { MemorySaver } from "@langchain/langgraph";
const lcAgent = createLangchainAgent({
model,
checkpointer: new MemorySaver(),
middleware: [clientTools()],
});
```
### CloudBaseSaver (Production)
Persistent storage using Tencent CloudBase document database. On CloudBase cloud function/cloudrun, requests are authenticated - extract user ID from the JWT in Authorization header.
```typescript
import { run } from "@cloudbase/agent-server";
import { LangchainAgent, clientTools } from "@cloudbase/agent-adapter-langchain";
import { CloudBaseSaver } from "@cloudbase/agent-adapter-langgraph";
import { createAgent as createLangchainAgent } from "langchain";
import tcb from "@cloudbase/node-sdk";
const app = tcb.init({ env: process.env.CLOUDBASE_ENV_ID });
run({
createAgent: ({ request }) => {
// Extract user ID from JWT (sub field)
const token = request.headers.get("Authorization")?.slice(7);
const payload = JSON.parse(atob(token.split(".")[1]));
const userId = payload.sub;
const checkpointer = new CloudBaseSaver({
db: app.database(),
userId, // Multi-tenant isolation
});
const lcAgent = createLangchainAgent({
model,
checkpointer,
middleware: [clientTools()],
});
return { agent: new LangchainAgent({ agent: lcAgent }) };
},
port: 9000,
});
```
## With @cloudbase/agent-server
```typescript
import { run } from "@cloudbase/agent-server";
run({
createAgent: () => ({ agent }),
port: 9000,
});
```
## clientTools() Middleware
Enables client-defined tools in your LangChain agent:
- **Injects client tools** - Adds client tools to the LLM's available tool list
- **Routes to END** - When a client tool is called, skips ToolNode and routes to END so client can execute
