This is a starter template for building AI agents using PydanticAI and CopilotKit. It provides a modern Next.js application with an integrated AI assistant that helps you manage a todo board with three columns: Todo, In-Progress, and Done.

Prerequisites

OpenAI API Key (for the PydanticAI agent)
Python 3.12+
uv
Node.js 20+
Any of the following package managers:
- pnpm (recommended)
- npm
- yarn
- bun

Note: This repository ignores lock files (package-lock.json, yarn.lock, pnpm-lock.yaml, bun.lockb) to avoid conflicts between different package managers. Each developer should generate their own lock file using their preferred package manager. After that, make sure to delete it from the .gitignore.

Getting Started

Install dependencies using your preferred package manager:

# Using pnpm (recommended)
pnpm install

# Using npm
npm install

# Using yarn
yarn install

# Using bun
bun install

Note: This will automatically setup the Python environment as well.

If you have manual isseus, you can run:
npm run install:agent

Set up your API keys:

Create a .env file inside the agent folder with the following content:

# Required: Get from https://platform.openai.com/api-keys
OPENAI_API_KEY=sk-...your-openai-key-here...

# Optional: For agent observability
# Sign up at https://logfire.pydantic.dev
# Create token: https://logfire.pydantic.dev/docs/how-to-guides/create-write-tokens/
LOGFIRE_TOKEN=...your-logfire-token...

Start the development server:

# Using pnpm
pnpm dev

# Using npm
npm run dev

# Using yarn
yarn dev

# Using bun
bun run dev

This will start both the UI and agent servers concurrently.

How It Works

This app connects three technologies to create a full-stack agentic todo application:

The Three Technologies

PydanticAI (agent/src/agent.py) - Python AI agent framework
- Defines the agent with GPT-4.1-mini model and tools
- Tools (agent/src/tools.py): add_todos, update_todo, delete_todos, etc.
- Uses Pydantic models (agent/src/models.py) for type-safe state
AG-UI (agent/src/main.py) - Bridge between Python and web
- agent.to_ag_ui() converts PydanticAI agent to FastAPI server (port 8000)
- Handles state synchronization via StateSnapshotEvent
CopilotKit (src/app/page.tsx, src/app/api/copilotkit/route.ts) - React chat UI
- useCoAgent() creates bidirectional state sync with backend
- HttpAgent connects to Python AG-UI server
- Renders tool calls with custom UI components

🔍 Technical Deep Dive ->

Architecture

graph TD
    A[User Input] --> B[CopilotKit UI<br/>src/app/page.tsx]
    B --> C[useCoAgent Hook<br/>State Sync]
    C --> D[Next.js API Route<br/>src/app/api/copilotkit/route.ts]
    D --> E[HttpAgent<br/>:8000 proxy]
    E --> F[AG-UI Server<br/>agent/src/main.py]
    F --> G[PydanticAI Agent<br/>agent/src/agent.py]
    G --> H[Tools<br/>agent/src/tools.py]
    H --> I[StateSnapshotEvent]
    I --> F
    F --> E
    E --> D
    D --> C
    C --> B
    B --> J[UI Update]

    style A fill:#e1f5ff
    style J fill:#e1f5ff
    style B fill:#a8daff
    style C fill:#a8daff
    style D fill:#a8daff
    style F fill:#ffcba8
    style G fill:#ffcba8
    style H fill:#ffcba8
    style I fill:#ffd700

Data Flow

User types in chat → CopilotKit sends to /api/copilotkit
Next.js proxies via HttpAgent to Python backend (localhost:8000)
PydanticAI agent calls tools (e.g., add_todos)
Tools return StateSnapshotEvent with updated state
AG-UI pushes state back through CopilotKit
useCoAgent updates React UI automatically

Key Files

src/app/page.tsx - CopilotKit integration & state sync
src/app/api/copilotkit/route.ts - Proxy to Python backend
agent/src/agent.py - PydanticAI agent definition
agent/src/tools.py - Todo management tools
agent/src/models.py - Shared data models
agent/src/main.py - AG-UI server setup

Resources

Documentation

PydanticAI Documentation - Learn more about PydanticAI and its features
CopilotKit Documentation - Explore CopilotKit's capabilities
Next.js Documentation - Learn about Next.js features and API

Available Scripts

The following scripts can also be run using your preferred package manager:

dev - Starts both UI and agent servers in development mode
dev:debug - Starts development servers with debug logging enabled
dev:ui - Starts only the Next.js UI server
dev:agent - Starts only the PydanticAI agent server
build - Builds the Next.js application for production
start - Starts the production server
lint - Runs ESLint for code linting
install:agent - Installs Python dependencies for the agent

Contributing

Feel free to submit issues and enhancement requests! This starter is designed to be easily extensible.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Troubleshooting

Agent Connection Issues

If you see "I'm having trouble connecting to my tools", make sure:

The PydanticAI agent is running on port 8000
Your OpenAI API key is set correctly
Both servers started successfully

Python Dependencies

If you encounter Python import errors:

cd agent
uv sync
uv run src/main.py