---
title: "CopilotRuntime"
description: "Handles requests from frontend, provides function calling and various LLM backends."
---

{/* GENERATE-DOCS path=packages/runtime/src/lib/copilot-runtime.ts class=CopilotRuntime */}
 
<img
  referrerPolicy="no-referrer-when-downgrade"
  src="https://static.scarf.sh/a.png?x-pxid=a9b290bb-38f9-4518-ac3b-8f54fdbf43be"
/>
 
<RequestExample>
  ```jsx CopilotRuntime Example
  import {
    CopilotRuntime,
    OpenAIAdapter
  } from "@copilotkit/runtime";
 
  export async function POST(req: Request) {
    const copilotKit = new CopilotRuntime();
    return copilotKit.response(req, new OpenAIAdapter());
  }
 
```
</RequestExample>
 
This class is the main entry point for the runtime. It handles requests from the frontend, provides function calling and various LLM backends.
 
For example, to use OpenAI as a backend (check the [OpenAI Adapter](./OpenAIAdapter) docs for more info):
```typescript
const copilotKit = new CopilotRuntime();
return copilotKit.response(req, new OpenAIAdapter());
```
 
Currently we support:
 
- [OpenAI](./OpenAIAdapter)
- [LangChain](./LangChainAdapter)
- [OpenAI Assistant API](./OpenAIAssistantAdapter)
- [Google Gemini](./GoogleGenerativeAIAdapter)
 
## Server Side Actions
 
CopilotKit supports actions that can be executed on the server side. You can define server side actions by passing the `actions` parameter:
 
```typescript
const copilotKit = new CopilotRuntime({
  actions: [
    {
      name: "sayHello",
      description: "Says hello to someone.",
      argumentAnnotations: [
        {
          name: "arg",
          type: "string",
          description: "The name of the person to say hello to.",
          required: true,
        },
      ],
      implementation: async (arg) => {
        console.log("Hello from the server", arg, "!");
      },
    },
  ],
});
```
 
Server side actions can also return a result which becomes part of the message history.
 
This is useful because it gives the LLM context about what happened on the server side. In addition,
it can be used to look up information from a vector or relational database and other sources.
 
In addition to that, server side actions can also come from LangChain, including support for streaming responses.
 
Returned results can be of the following type:
 
- anything serializable to JSON
- `string`
- LangChain types:
  - `IterableReadableStream`
  - `BaseMessageChunk`
  - `AIMessage`
 
## LangServe
 
The backend also supports LangServe, enabling you to connect to existing chains, for example python based chains.
Use the `langserve` parameter to specify URLs for LangServe.
 
```typescript
const copilotKit = new CopilotRuntime({
  langserve: [
    {
      chainUrl: "http://my-langserve.chain",
      name: "performResearch",
      description: "Performs research on a given topic.",
    },
  ],
});
```
 
When left out, arguments are automatically inferred from the schema provided by LangServe.

## Constructor

<ResponseField name="middleware" type="Middleware" >
Middleware to be used by the runtime.
 
  ```ts
  onBeforeRequest: (options: {
    threadId?: string;
    runId?: string;
    inputMessages: Message[];
    properties: any;
  }) => void | Promise<void>;
  ```
 
  ```ts
  onAfterRequest: (options: {
    threadId?: string;
    runId?: string;
    inputMessages: Message[];
    outputMessages: Message[];
    properties: any;
  }) => void | Promise<void>;
  ```
</ResponseField>

<ResponseField name="actions" type="ActionsConfiguration<T>" >
A list of server side actions that can be executed.
</ResponseField>

<ResponseField name="langserve" type="RemoteChainParameters[]" >
An array of LangServer URLs.
</ResponseField>

## process(request: CopilotRuntimeRequest)



<ResponseField name="request" type="CopilotRuntimeRequest" required>

</ResponseField>

