@ngaf/langgraph

Adapter that wraps a LangGraph agent into the runtime-neutral Agent contract from @ngaf/chat. The Angular equivalent of LangGraph's React useStream() hook — signal-driven access to messages, status, tool calls, interrupts, subagents, regenerate, and thread history.

Part of Agent UI for Angular. MIT licensed.

Install

npm install @ngaf/langgraph @ngaf/chat

Peer dependencies: @angular/core ^20.0.0 || ^21.0.0, @langchain/core ^1.1.0, @langchain/langgraph-sdk ^1.7.0, rxjs ~7.8.0

What it does

• agent() — Angular Signal-based handle to a LangGraph streaming run. Returns messages(), status(), isLoading(), error(), interrupt(), toolCalls(), plus actions (submit, stop, regenerate, reload).
• provideAgent() — configure the LangGraph endpoint once in app.config.ts. Per-call overrides are accepted by agent() itself.
• Thread persistence — pass threadId: signal(...) + onThreadId to round-trip thread IDs through your own storage (localStorage, URL, etc.).
• MockAgentTransport — deterministic in-memory transport for tests. Never mock agent() itself; swap the transport instead.
• extractCitations() — populates Message.citations from LangGraph message metadata. Reads from additional_kwargs.citations (preferred) or additional_kwargs.sources (fallback).

Quick start

// app.config.ts
import { provideAgent } from '@ngaf/langgraph';

export const appConfig: ApplicationConfig = {
  providers: [
    provideAgent({
      apiUrl: 'https://your-langgraph-platform.com',
    }),
  ],
};

// chat.component.ts
import { Component } from '@angular/core';
import { agent } from '@ngaf/langgraph';
import { ChatComponent } from '@ngaf/chat';

@Component({
  imports: [ChatComponent],
  template: `<chat [agent]="chat" />`,
})
export class ChatComponentHost {
  chat = agent({
    apiUrl: 'https://your-langgraph-platform.com',
    assistantId: 'my-agent',
  });
}

agent() must be called within an Angular injection context (component field initializer or constructor). Calling it in ngOnInit or any async context throws NG0203: inject() must be called from an injection context.

Citations example

// In your LangGraph node:
const response = await llm.invoke([...]);

return new AIMessage({
  content: response.content,
  additional_kwargs: {
    citations: [
      {
        id: 'doc-1',
        index: 1,
        title: 'Example Article',
        url: 'https://example.com/article',
        snippet: 'Relevant excerpt...',
      },
    ],
  },
});

// Message.citations auto-populates in @ngaf/chat via extractCitations()

Documentation

• Quickstart
• agent() API reference
• Human-in-the-loop / interrupts
• Thread persistence
• Testing with MockAgentTransport

License

MIT — free for any use. See LICENSE.