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.

Reading the docs

There are two ways to read the current docs. Check which one this session has.

Without the MCP server: fetch the Markdown pages

This path always works. It needs only a way to fetch a URL.

• Any docs page as Markdown. Add .md to the page path: https://docs.copilotkit.ai/<path>.md. For example, https://docs.copilotkit.ai/quickstart.md and https://docs.copilotkit.ai/backend/copilot-runtime.md. The response is text/markdown. A path that does not exist returns 404 with the body Not found.
• To find a path. Start with https://docs.copilotkit.ai/llms.txt. It is a short, curated index with links to the main pages. For a page it does not list, read https://docs.copilotkit.ai/sitemap.xml, which lists every page URL. Both indexes list HTML page URLs. Add .md to a URL before you fetch it. The site root has no .md form. Do not fetch llms-full.txt in one read. It holds every page and is several megabytes.
• Links in this skill. A link such as quickstart is a docs path. Fetch it as https://docs.copilotkit.ai/quickstart.md.
• Library source. Read the installed package in node_modules/@copilotkit/, or the source at https://github.com/CopilotKit/CopilotKit under packages/.
• AG-UI protocol. The protocol has its own docs at https://docs.ag-ui.com. Its index is https://docs.ag-ui.com/llms.txt, and its pages also take .md.

With the MCP server: search tools

The CopilotKit Claude Code plugin also declares an MCP server, copilotkit-docs, in its .mcp.json. When that server is loaded, it adds search tools over four separate corpora. It is a faster way to search. It is not required. If these tools are not in this session, use the Markdown pages above.

Tool	Corpus	Use it for
search-docs	docs.copilotkit.ai	Usage, configuration, guides, quickstarts, the generated API reference
search-code	CopilotKit library source	How something is implemented, and exact signatures. Library packages only, not examples or showcases
search-ag-ui-docs	AG-UI protocol docs	The protocol itself: event types, transports, the SDKs
search-ag-ui-code	AG-UI protocol SDK source	Protocol implementation detail
explore-docs / explore-code	either tree	Browsing structure when you do not yet know what to search for

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 queries with different words beat one long query. If a result is off-target, rephrase the query. Do not make it wider. If a page looks right but does not contain the term you need, say so. Do not reason from the title.

A user who wants the search tools outside the plugin can add the server themselves. The endpoints are https://mcp.copilotkit.ai/mcp (streamable HTTP) and https://mcp.copilotkit.ai/sse (SSE). Keep the path, because the bare host returns 404. Build with agents has the steps for each coding tool. Do not add the server on your own as a setup step. The Markdown pages give the same content.

Where the answers are

Worth knowing so a search or a fetch has somewhere to land. Each link is a docs path:

• 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, at https://docs.copilotkit.ai/<framework>/quickstart.md. The framework slugs are in llms.txt, for example langgraph-python, mastra, and crewai-crews.
• 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. It settles up to eleven things in one command and is almost always faster than reading the project. Pick the form that matches the app:

• No Intelligence (nothing constructs CopilotKitIntelligence where the runtime is built, and there is no .copilotkit/project.json): npx copilotkit@latest verify --expect-runtime oss --round-trip --agent <id> --json --via skill:copilotkit
• Otherwise: npx copilotkit@latest verify --json --via skill:copilotkit

--via skill:copilotkit only tells CopilotKit's telemetry that the call came from this skill. If the CLI reports Unknown option '--via', npx ran an old cached version: run the command again without the flag.

Do not run login or project select only to make verify pass. Those commands set up hosted Intelligence and do not fix an open-source app. 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.