runtime

Original：🇺🇸 English

Translated

@copilotkit/runtime — mount a fetch-native CopilotRuntime on any JS server, wire middleware, pick an AgentRunner, instantiate BuiltInAgent (Factory Mode with TanStack AI is the preferred default) or plug in any of 12 external agent frameworks (Mastra, LangGraph, CrewAI Crews/Flows, PydanticAI, ADK, LlamaIndex, Agno, AWS Strands, MS Agent Framework, AG2, A2A), enable Intelligence mode for durable threads + websocket, register server-side tools via defineTool, and wire voice transcription. Uses the fetch-based createCopilotRuntimeHandler primitive — the Express/Hono adapters are discouraged. Load the reference under references/ that matches your task.

5installs

Sourcecopilotkit/copilotkit

Added on2026-05-28

NPX Install

npx skill4agent add copilotkit/copilotkit runtime

SKILL.md Content

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CopilotKit Runtime

@copilotkit/runtime

is the server half of CopilotKit: it accepts AG-UI protocol requests, dispatches them to an

AbstractAgent

(built-in or external), runs the stream through an

AgentRunner

, and responds as Server-Sent Events.

This SKILL.md is the index. Read the reference under

references/

that matches your task — do not try to absorb the whole package from this file.

Mental Model — the three dictionaries you hand to

CopilotRuntime

new CopilotRuntime({
  agents, // Record<string, AbstractAgent>     — see wiring-external-agents or built-in-agent
  runner, // AgentRunner (optional)            — see agent-runners
  intelligence, // CopilotKitIntelligence (optional) — see intelligence-mode (auto-wires runner)
  mcpApps, // McpAppsConfig (optional)          — see wiring-mcp-apps-middleware
  a2ui, // A2UIConfig (optional)             — see packages/a2ui-renderer skill
  hooks, // { onRequest, onBeforeHandler }    — see middleware
  beforeRequestMiddleware,
  afterRequestMiddleware, // legacy — see middleware
  transcription, // TranscriptionService (optional)  — see transcription
});

You then mount it:

import { createCopilotRuntimeHandler } from "@copilotkit/runtime/v2";
const handler = createCopilotRuntimeHandler({
  runtime,
  basePath: "/api/copilotkit",
});
export default { fetch: handler };

When to load which reference

Task	Reference
Mounting on any fetch-native server (Cloudflare Workers, Bun, Deno, Vercel Edge, Next.js App Router, React Router v7, TanStack Start) or delegating from Express/Node	`references/setup-endpoint.md`
Auth / logging / rate-limit / request-scoped guards via `hooks.onRequest` / `hooks.onBeforeHandler` (preferred) or legacy `beforeRequestMiddleware` / `afterRequestMiddleware`	`references/middleware.md`
Choosing between `InMemoryAgentRunner` , `SqliteAgentRunner` , or a custom subclass — including thread-locking semantics and the runner/Intelligence mutual exclusion	`references/agent-runners.md` (+ `-in-memory.md` , `-sqlite.md` , `-custom.md` for backend-specific detail)
Enabling durable threads + realtime websocket via CopilotKit Cloud (Intelligence is Cloud-only, not self-hostable)	`references/intelligence-mode.md`
Voice transcription — implementing a `TranscriptionService` subclass for the `/transcribe` endpoint	`references/transcription.md`
Instantiating `BuiltInAgent` — Simple Mode (classic) or Factory Mode with TanStack AI (preferred AG-UI-compliant default), AI SDK, or custom factory	`references/built-in-agent.md` (+ `-factory-modes.md` , `-helper-utilities.md` , `-model-identifiers.md` )
Defining server-side tools via `defineTool` for `BuiltInAgent.config.tools` (Simple Mode only)	`references/server-side-tools.md`
Wiring an external agent framework into `CopilotRuntime({ agents })`	`references/wiring-external-agents.md` (index) + per-framework refs ( `wiring-mastra.md` , `wiring-langgraph.md` , `wiring-crewai-crews.md` , `wiring-crewai-flows.md` , `wiring-pydantic-ai.md` , `wiring-adk.md` , `wiring-llamaindex.md` , `wiring-agno.md` , `wiring-aws-strands.md` , `wiring-ms-agent-framework.md` , `wiring-ag2.md` , `wiring-a2a.md` )
Wiring MCP Apps (runtime-level middleware, not an agent)	`references/wiring-mcp-apps-middleware.md`

Invariants and gotchas (load-once, before any reference)

```
createCopilotRuntimeHandler
```
is the canonical primitive.
```
createCopilotExpressHandler
```
/
```
createCopilotHonoHandler
```
exist but are avoid at all costs — delegate from Express/Hono routes to the fetch primitive instead.
```
publicLicenseKey
```
is the canonical provider-side field.
```
publicApiKey
```
is a deprecated alias — expect to see it in legacy code, emit the canonical name in new code.
Intelligence mode auto-wires
```
IntelligenceAgentRunner
```
. Passing both
```
runner
```
and
```
intelligence
```
to
```
CopilotRuntime
```
is rejected at construction.
Intelligence mode targets CopilotKit Cloud (
```
api.cloud.copilotkit.ai
```
) and is not self-hostable.

hooks.onRequest

runs before

beforeRequestMiddleware

(hook-based middleware wins for Response short-circuits).

beforeRequestMiddleware

runs after

hooks.onRequest

(see

fetch-handler.ts:136-147

```
identifyUser
```
(Intelligence) does not forward thrown
```
Response
```
objects — convert to 500. Gate auth rejection in
```
hooks.onRequest
```
, which does forward Responses.
```
agents__unsafe_dev_only
```
and
```
selfManagedAgents
```
are dev-only aliases of each other; do not reach for them in production. Either signals that the SPA is in dev mode.

Reading order for a first-time reader

```
setup-endpoint
```
— the primitive.
```
built-in-agent
```
or pick one from
```
wiring-external-agents
```
— the agent.
```
agent-runners
```
— production persistence choice.

Optional:

middleware

intelligence-mode

server-side-tools

transcription