chore: import upstream snapshot with attribution
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# CopilotKit + LangGraph Todo Demo
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## Purpose
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This repository serves as both a **showcase** and **template** for building AI agents with CopilotKit and LangGraph. It demonstrates how CopilotKit can drive interactive UI beyond just chat, using a **collaborative todo list** as the primary example.
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**Target audience:** Developers evaluating CopilotKit or starting new projects with AI agents.
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## Core Concept
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The todo list demonstrates **agent-driven UI** where:
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- The agent can manipulate application state (adding todos, updating status, organizing tasks)
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- Users can interact with the same state (editing titles, checking off tasks, deleting todos)
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- Both agent and user changes update the same shared state
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- The UI reactively updates based on agent state changes
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This uses CopilotKit's **v2 agent state pattern** where state lives in the agent and syncs to the frontend.
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## Architecture
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This is a **flat npm project** with a Next.js frontend at the root and a Python agent in `agent/`.
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### Repository Structure
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```
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├── src/
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│ ├── app/
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│ │ ├── page.tsx # Main page - wires up all components
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│ │ └── api/copilotkit/ # CopilotKit API route
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│ ├── components/
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│ │ ├── canvas/ # Todo list UI
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│ │ │ ├── index.tsx # Canvas container
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│ │ │ ├── todo-list.tsx # Todo list with columns
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│ │ │ ├── todo-column.tsx # Column (pending/completed)
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│ │ │ └── todo-card.tsx # Individual todo card
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│ │ ├── example-layout/ # Layout: chat + canvas side-by-side
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│ │ └── generative-ui/ # Example generative UI components
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│ └── hooks/
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│ ├── use-generative-ui-examples.tsx # Example CopilotKit patterns
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│ └── use-example-suggestions.tsx # Chat suggestions
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├── agent/ # LangGraph Python agent
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│ ├── main.py # Agent entry point
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│ └── src/
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│ ├── todos.py # Todo tools and state schema
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│ └── query.py # Example data query tool
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├── scripts/ # Agent setup and run scripts
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│ ├── setup-agent.sh / .bat
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│ └── run-agent.sh / .bat
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├── package.json # Root project config (npm + concurrently)
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└── next.config.ts
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```
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## Key Pattern: Agent State with CopilotKit v2
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The todo list uses **CopilotKit v2's agent state pattern** where state lives in the agent backend and syncs bidirectionally with the frontend.
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### How It Works
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1. **Agent defines state schema and tools** (Python)
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```python
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# agent/src/todos.py
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class Todo(TypedDict):
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id: str
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title: str
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description: str
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emoji: str
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status: Literal["pending", "completed"]
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class AgentState(TypedDict):
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todos: list[Todo]
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@tool
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def manage_todos(todos: list[Todo], runtime: ToolRuntime) -> Command:
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"""Manage the current todos."""
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return Command(update={"todos": todos, ...})
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```
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2. **Frontend reads from agent state**
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```typescript
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// src/components/canvas/index.tsx
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const { agent } = useAgent();
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return (
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<TodoList
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todos={agent.state?.todos || []}
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onUpdate={(updatedTodos) => agent.setState({ todos: updatedTodos })}
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isAgentRunning={agent.isRunning}
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/>
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);
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```
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3. **User interactions update agent state**
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```typescript
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// User clicks checkbox → frontend calls agent.setState()
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const toggleStatus = (todo) => {
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const updated = todos.map((t) =>
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t.id === todo.id
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? { ...t, status: t.status === "completed" ? "pending" : "completed" }
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: t,
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);
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agent.setState({ todos: updated });
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};
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```
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4. **Agent can manipulate state via tools**
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- The agent calls `manage_todos` tool to update the todo list
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- Both user and agent changes update the same `agent.state.todos`
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- Frontend automatically re-renders when state changes
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### Why This Pattern?
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- **Single source of truth**: State lives in the agent, not duplicated in frontend
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- **Bidirectional sync**: User changes → agent state, Agent changes → UI update
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- **Simple**: No need for separate frontend state management
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- **Observable**: Agent has full visibility into state changes
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## Implementation Details
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### Agent Backend
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**Agent Definition** (`agent/main.py`):
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```python
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from langchain.agents import create_agent
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from copilotkit import CopilotKitMiddleware
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from src.todos import todo_tools, AgentState
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agent = create_agent(
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model="gpt-5.2",
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tools=[*todo_tools, ...], # manage_todos, get_todos
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middleware=[CopilotKitMiddleware()],
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state_schema=AgentState, # Defines state shape
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system_prompt="You are a helpful assistant..."
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)
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```
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**Todo Tools** (`agent/src/todos.py`):
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```python
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@tool
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def manage_todos(todos: list[Todo], runtime: ToolRuntime) -> Command:
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"""Manage the current todos."""
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# Ensure todos have unique IDs
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for todo in todos:
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if "id" not in todo or not todo["id"]:
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todo["id"] = str(uuid.uuid4())
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# Update agent state
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return Command(update={
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"todos": todos,
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"messages": [ToolMessage(...)]
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})
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@tool
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def get_todos(runtime: ToolRuntime):
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"""Get the current todos."""
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return runtime.state.get("todos", [])
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```
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### Frontend
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**Canvas Component** (`src/components/canvas/index.tsx`):
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```typescript
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export function Canvas() {
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const { agent } = useAgent(); // CopilotKit v2 hook
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return (
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<div className="h-full p-8 bg-gray-50">
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<TodoList
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// Read state from agent
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todos={agent.state?.todos || []}
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// Update state in agent
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onUpdate={(updatedTodos) => agent.setState({ todos: updatedTodos })}
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// React to agent execution
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isAgentRunning={agent.isRunning}
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/>
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</div>
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);
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}
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```
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**Todo List** (`src/components/canvas/todo-list.tsx`):
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```typescript
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export function TodoList({ todos, onUpdate, isAgentRunning }: TodoListProps) {
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const toggleStatus = (todo: Todo) => {
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const updated = todos.map((t) =>
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t.id === todo.id
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? { ...t, status: t.status === "completed" ? "pending" : "completed" }
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: t
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);
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onUpdate(updated); // Calls agent.setState()
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};
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const addTodo = () => {
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const newTodo = { id: crypto.randomUUID(), ... };
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onUpdate([...todos, newTodo]);
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};
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return (
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<div className="flex gap-8">
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<TodoColumn title="To Do" todos={pendingTodos} onAddTodo={addTodo} ... />
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<TodoColumn title="Done" todos={completedTodos} ... />
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</div>
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);
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}
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```
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### How State Flows
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1. **User adds/edits todo** → Frontend calls `agent.setState({ todos: [...] })`
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2. **Agent state updates** → CopilotKit syncs to backend
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3. **Agent observes change** → Can respond via `manage_todos` tool
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4. **Agent modifies todos** → Calls `manage_todos` tool
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5. **State syncs to frontend** → `agent.state.todos` updates
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6. **UI re-renders** → React sees new state and updates display
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**Key insight**: State lives in the agent, frontend just reads/writes to it via CopilotKit hooks.
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## Tech Stack
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- **Frontend**: Next.js 16, React 19, TailwindCSS 4
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- **Agent**: LangGraph (Python), OpenAI GPT-5.2
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- **CopilotKit**: React hooks for agent integration (v2)
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- **Build**: npm with concurrently for parallel dev processes
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- **Other**: Recharts for generative UI examples
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## Development
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```bash
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# Install dependencies (also sets up agent via postinstall)
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npm install
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# Start both frontend and agent
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npm run dev
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# Start individually
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npm run dev:ui # Next.js frontend on port 3000
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npm run dev:agent # LangGraph agent on port 8123
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# Build
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npm run build
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```
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### Environment Setup
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```bash
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# Set OpenAI API key
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cp .env.example .env
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# Edit .env and add your OPENAI_API_KEY
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```
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## Design Principles
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1. **Simple over complex** - The todo list is intentionally simple and focused
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2. **CopilotKit v2 patterns** - Uses modern agent state management
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3. **Template-first** - Code is meant to be forked and extended
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4. **Showcasing agent-driven UI** - Demonstrates AI manipulating application state beyond chat
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---
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## Key Takeaways for Developers
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**State Management Pattern**: This app uses CopilotKit v2's agent state pattern where:
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- State is defined in the agent backend (Python TypedDict)
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- Frontend reads via `agent.state.todos`
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- Frontend writes via `agent.setState({ todos: ... })`
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- Agent can modify state via tools (`manage_todos`)
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- Changes sync bidirectionally automatically
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**When extending this template**:
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- Define state schema in the agent (`AgentState`)
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- Create tools that manipulate state via `Command(update={...})`
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- Use `useAgent()` hook in frontend to read/write state
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- Let CopilotKit handle the sync - no manual state management needed
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This pattern works great for **agent-driven applications** where the AI needs to manipulate structured application state, not just chat.
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