use AG-UI's LangGraph FastAPI integration

Author: ranst91

README.md

@@ -6,6 +6,7 @@ This is a starter template for building AI agents using [LangGraph](https://www.
 
 - Node.js 18+ 
 - Python 3.8+
+- Poetry 2+
 - Any of the following package managers:
   - [pnpm](https://pnpm.io/installation) (recommended)
   - npm
@@ -114,5 +115,5 @@ If you see "I'm having trouble connecting to my tools", make sure:
 If you encounter Python import errors:
 ```bash
 cd agent
-pip install -r requirements.txt
+poetry lock && poetry install
 ```

agent/poetry.lock

@@ -0,0 +1,27 @@
+[tool.poetry]
+name = "agent"
+version = "0.1.0"
+description = ""
+authors = ["CopilotKit"]
+readme = "README.md"
+packages = [{include = "sample_agent"}]
+package-mode = false
+
+[tool.poetry.dependencies]
+python = ">=3.10,<3.13"
+copilotkit = "0.1.55"
+langchain = "0.3.26"
+langchain-openai = "0.3.28"
+langgraph = "0.4.10"
+langsmith = "0.4.4"
+openai = "^1.68.2"
+fastapi = "^0.115.5"
+uvicorn = "^0.29.0"
+python-dotenv = "^1.0.0"
+
+[tool.poetry.scripts]
+demo = "sample_agent.demo:main"
+
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"

agent/pyproject.toml

@@ -13,6 +13,7 @@
 from langgraph.types import Command
 from langgraph.graph import MessagesState
 from langgraph.prebuilt import ToolNode
+from langgraph.checkpoint.memory import MemorySaver
 
 class AgentState(MessagesState):
     """
@@ -99,4 +100,5 @@ async def chat_node(state: AgentState, config: RunnableConfig) -> Command[Litera
 workflow.add_edge("tool_node", "chat_node")
 workflow.set_entry_point("chat_node")
 
-graph = workflow.compile()
+checkpointer = MemorySaver()
+graph = workflow.compile(checkpointer=checkpointer)

agent/sample_agent/__init__.py

@@ -0,0 +1,36 @@
+"""
+This serves the "sample_agent" agent. This is an example of self-hosting an agent
+through our FastAPI integration. However, you can also host in LangGraph platform.
+"""
+
+import os
+from dotenv import load_dotenv
+load_dotenv() # pylint: disable=wrong-import-position
+
+from fastapi import FastAPI
+import uvicorn
+from copilotkit import LangGraphAGUIAgent
+from sample_agent.agent import graph
+from ag_ui_langgraph import add_langgraph_fastapi_endpoint
+
+app = FastAPI()
+
+add_langgraph_fastapi_endpoint(
+    app=app,
+    agent=LangGraphAGUIAgent(
+        name="sample_agent",
+        description="An example agent to use as a starting point for your own agent.",
+        graph=graph
+    ),
+    path="/"
+)
+
+def main():
+    """Run the uvicorn server."""
+    port = int(os.getenv("PORT", "8123"))
+    uvicorn.run(
+        "sample_agent.demo:app",
+        host="0.0.0.0",
+        port=port,
+        reload=True,
+    )

agent/agent.py renamed to agent/sample_agent/agent.py

@@ -5,12 +5,12 @@
   "scripts": {
     "dev": "concurrently \"npm run dev:ui\" \"npm run dev:agent\" --names ui,agent --prefix-colors blue,green --kill-others",
     "dev:debug": "LOG_LEVEL=debug npm run dev",
-    "dev:agent": "cd agent && npx @langchain/langgraph-cli dev --port 8123 --no-browser",
+    "dev:agent": "cd agent && poetry run demo",
     "dev:ui": "next dev --turbopack",
     "build": "next build",
     "start": "next start",
     "lint": "next lint",
-    "install:agent": "cd agent && pip install -r requirements.txt"
+    "install:agent": "cd agent && poetry install"
   },
   "dependencies": {
     "@ag-ui/langgraph": "0.0.6",

agent/sample_agent/demo.py

@@ -4,7 +4,7 @@ import {
   copilotRuntimeNextJSAppRouterEndpoint,
 } from "@copilotkit/runtime";
 
-import { LangGraphAgent } from "@ag-ui/langgraph"
+import { LangGraphHttpAgent } from "@ag-ui/langgraph"
 import { NextRequest } from "next/server";
 
 // 1. You can use any service adapter here for multi-agent support. We use
@@ -15,10 +15,8 @@ const serviceAdapter = new ExperimentalEmptyAdapter();
 //    integration to setup the connection.
 const runtime = new CopilotRuntime({
   agents: {
-    "sample_agent": new LangGraphAgent({
-      deploymentUrl: process.env.LANGGRAPH_DEPLOYMENT_URL || "http://localhost:8123",
-      graphId: "sample_agent",
-      langsmithApiKey: process.env.LANGSMITH_API_KEY || "",
+    "sample_agent": new LangGraphHttpAgent({
+      url: process.env.AGENT_URL || "http://localhost:8123",
     }),
   }
 });