Atai Barkai
8b01b1cbc4
Node 25.0 unflagged the experimental Web Storage API (nodejs/node#57658), so on Node 25+ a stub `window.localStorage` is installed BEFORE vitest's jsdom environment runs. The stub has no `.clear()` / `.getItem()` / `.setItem()` methods, so all tests that touch localStorage crash with 'TypeError: window.localStorage.clear is not a function'. NOT fixed by upgrading the toolchain: - vitest 4.x + jsdom 29 still leave Node's stub in place (vitest-dev/vitest#8757, closed as 'non-LTS, won't fix'). - Node 25.2.0 tried throwing on access; 25.2.1 reverted as too breaking. The real Node-side fix is targeted for Node 26.0 (semver-major), no backport (nodejs/node#60303). A previous attempt at the same bug (63d1d9e0, polyfilling localStorage in vitest.setup.ts) was reverted in3db4f85d6/ #4878 as 'a hallucinated fix.' It wasn't — but on Node 22.4-24.x the bug doesn't manifest because webstorage stays behind --experimental-webstorage, so the reverter probably saw 'no bug here, polyfill is noise.' Fix: pass --no-experimental-webstorage to the vitest worker via poolOptions.{forks,threads}.execArgv. This is the canonical community workaround (happy-dom#1950, ArkType, vitest#8757 thread). The flag was added in Node 22.4, so we gate it on the runtime Node version — passing it to older Node (e.g. CI's Node 20) makes Node refuse to start with 'not allowed in NODE_OPTIONS'. A long comment in vitest.config.ts records the full reasoning so this isn't reverted a third time and so we know when it's safe to remove (when minimum supported Node >=26). CI confirms: unit jobs pass on Node 20.x, 22.x, and 24.x.
CopilotKit
Build agent-native applications with generative UI, shared state, and human-in-the-loop workflows.
What is CopilotKit
CopilotKit is a best-in-class SDK for building full-stack agentic applications, Generative UI, and chat applications.
We are the company behind the AG-UI Protocol - adopted by Google, LangChain, AWS, Microsoft, Mastra, PydanticAI, and more!
https://github.com/user-attachments/assets/72b7b4f3-b6e7-460c-a932-5746fe3c8db3
Features:
- Chat UI – A React-based chat interface that supports message streaming, tool calls, and agent responses.
- Backend Tool Rendering – Enables agents to call backend tools that return UI components rendered directly in the client.
- Generative UI – Allows agents to generate and update UI components dynamically at runtime based on user intent and agent state.
- Shared State – A synchronized state layer that both agents and UI components can read from and write to in real time.
- Human-in-the-Loop – Lets agents pause execution to request user input, confirmation, or edits before continuing.
https://github.com/user-attachments/assets/55bf6714-62a7-4d5d-9232-07747cc0763b
Quick Start
New projects:
npx copilotkit@latest create -f <framework>
Existing projects:
npx copilotkit@latest init
https://github.com/user-attachments/assets/7372b27b-8def-40fb-a11d-1f6585f556ad
What this gives you:
- CopilotKit installed – Core packages are fully set up in your app
- Provider configured – Context, state, and hooks ready to use
- Agent <> UI connected – Agents can stream actions and render UI immediately
- Deployment-ready – Your app is ready to deploy
Complete getting started guide →
How it works:
CopilotKit connects your UI, agents, and tools into a single interaction loop.
This enables:
- Agents that ask users for input
- Tools that render UI
- Stateful workflows across steps and sessions
⭐️ useAgent Hook
The useAgent hook is a proper superset of useCoAgent and sits directly on AG-UI, giving more control over the agent connection.
// Programmatically access and control your agents
const { agent } = useAgent({ agentId: "my_agent" });
// Render and update your agent's state
return <div>
<h1>{agent.state.city}</h1>
<button onClick={() => agent.setState({ city: "NYC" })}>
Set City
</button>
</div>
Check out the useAgent docs to learn more.
https://github.com/user-attachments/assets/67928406-8abc-49a1-a851-98018b52174f
Generative UI
Generative UI is a core CopilotKit pattern that allows agents to dynamically render UI as part of their workflow.
https://github.com/user-attachments/assets/3cfacac0-4ffd-457a-96f9-d7951e4ab7b6
Compare the Three Types
Explore:
Generative UI educational repo →
🖥️ AG-UI: The Agent–User Interaction Protocol
Connect agent workflow to user-facing apps, with deep partnerships and 1st-party integrations across the agentic stack—including LangGraph, CrewAI, and more.
npx create-ag-ui-app my-agent-app
🤝 Community
Have questions or need help?
Join our Discord →Read the Docs →
Try Copilot Cloud →
Stay up to date with our latest releases!
Follow us on LinkedIn →Follow us on X →
🙋🏽♂️ Contributing
Thanks for your interest in contributing to CopilotKit! 💜
We value all contributions, whether it's through code, documentation, creating demo apps, or just spreading the word.
Here are a few useful resources to help you get started:
-
For code contributions, CONTRIBUTING.md.
-
For documentation-related contributions, check out the documentation contributions guide.
-
Want to contribute but not sure how? Join our Discord and we'll help you out!
📄 License
This repository's source code is available under the MIT License.