CopilotKit

CopilotKit's APIs move. Anything written down in a skill file is a copy that starts drifting the day it is written, so this skill carries almost no API detail on purpose. It tells you where the current answer lives and how to get it.

Look it up before you write code. Not because the docs are more convenient, but because they are regenerated from the source and a recollection is not.

The search tools

An MCP server, copilotkit-docs, is bundled with this plugin. It exposes four search tools and two exploration tools over four separate corpora. Picking the wrong one is the most common way to come up empty:

CopilotKit questions go to the first two. AG-UI protocol questions go to the second two — they are a different repository, and search-docs will not find them.

These are semantic searches. Several short, differently-phrased queries beat one long one. If a query returns something off-target, rephrase rather than widen — and if you get a plausible-looking page that does not actually contain the term you need, say so instead of reasoning from the title.

Setup

The server is registered once per tool, and installing the skills does not register it. Check first — if the search tools above are already available, skip this.

Claude Code — the CopilotKit plugin declares the server in its .mcp.json, so a plugin install needs nothing. A skills-only install (npx skills add) does not carry that file, so register it:

claude mcp add --transport sse copilotkit-mcp https://mcp.copilotkit.ai/sse

Codex:

codex mcp add copilotkit --url https://mcp.copilotkit.ai/mcp

Anything else — https://mcp.copilotkit.ai/mcp for streamable HTTP, https://mcp.copilotkit.ai/sse for SSE. Keep the path: the bare host returns 404. Per-tool instructions cover Cursor, Windsurf, Cline, GitHub Copilot and VS Code.

Without the server, the documentation works as a plain site, and appending .md to any docs URL returns that page as Markdown.

Where the answers are

Worth knowing so a search has somewhere to land:

• Getting started — quickstart, and the CLI for the CLI-driven path
• Frontend — frontend tools, human-in-the-loop, prebuilt components, styling, attachments, voice
• Runtime — the runtime, HTTP endpoints, runners, factory mode, server adapters, auth
• Agent frameworks — one quickstart per framework under /integrations/
• Intelligence — overview and the pages under it
• Not working — common issues, error reference, and the generated CopilotKitCoreErrorCode for a code the app actually reported
• Protocol — AG-UI, and the AG-UI docs for the protocol itself

Before you debug anything

Run the CLI's wiring check first — npx copilotkit@latest verify --json. It settles up to eleven things in one command and is almost always faster than reading the project. See the copilotkit-cli skill.

Two versions exist

v2 is current. Import from the /v2 subpath — @copilotkit/react-core/v2, @copilotkit/runtime/v2. The package root is the deprecated v1 surface and still resolves, so mixing the two raises nothing at import time and surfaces later as a runtime mismatch. Check which subpath a project imports before trusting anything else about it. v1 is deprecated but supported; the migration guide covers moving off it.