copilotkit-langgraph-history


Open-source LangGraph thread history persistence for CopilotKit. Restore chat history on page refresh with your own LangGraph deployment.

The Problem

Building a chat app with CopilotKit and LangGraph? You've probably noticed:

- Page refresh = empty chat - All messages disappear
- Thread switching loses context - No automatic history restoration
- No persistence of agent state - Users lose context

CopilotKit's default runtime doesn't automatically fetch historical messages from LangGraph's checkpoint system. This package adds that capability.

The Solution

With this package:
- Chat history restored on page load
- Seamless thread switching
- Agent state preserved
- Works with any LangGraph deployment (LangGraph Cloud, self-hosted)
- MIT licensed, open-source

Installation

``bash
npm install copilotkit-langgraph-history


or

pnpm add copilotkit-langgraph-history

or

yarn add copilotkit-langgraph-history
`

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This package requires the following peer dependencies:

`bash
npm install @copilotkit/runtime @copilotkitnext/runtime @ag-ui/core @langchain/langgraph-sdk rxjs
`

Quick Start

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`typescript
// app/api/copilotkit/route.ts
import { CopilotRuntime, createCopilotEndpointSingleRoute } from "@copilotkit/runtime/v2";
import {
HistoryHydratingAgentRunner,
createIsolatedAgent,
} from "copilotkit-langgraph-history";

const deploymentUrl = process.env.LANGGRAPH_DEPLOYMENT_URL!;
const langsmithApiKey = process.env.LANGSMITH_API_KEY;
const graphId = "my-agent";

function createRuntime() {
// Create isolated agent (prevents serverless state contamination)
const agent = createIsolatedAgent({
deploymentUrl,
graphId,
langsmithApiKey,
});

// Create history-hydrating runner
const runner = new HistoryHydratingAgentRunner({
agent,
deploymentUrl,
graphId,
langsmithApiKey,
historyLimit: 100, // Max messages to load
});

return new CopilotRuntime({
agents: { [graphId]: agent },
runner,
});
}

export const POST = async (req: Request) => {
const runtime = createRuntime();
const route = createCopilotEndpointSingleRoute({
runtime,
basePath: "/api/copilotkit",
});
return route.handleRequest(req);
};
`

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`tsx
import { CopilotKit } from "@copilotkit/react-core";
import { CopilotChat } from "@copilotkit/react-ui";

function App() {
return (
runtimeUrl="/api/copilotkit"
agent="my-agent"
threadId={threadId} // Pass your thread ID here
>


);
}
`

Configuration

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| Option | Type | Default | Description |
|--------|------|---------|-------------|
| agent | LangGraphAgent | required | The LangGraphAgent instance |
| deploymentUrl | string | required | LangGraph deployment URL |
| graphId | string | required | Graph identifier |
| langsmithApiKey | string | undefined | LangSmith API key |
| historyLimit | number | 100 | Max checkpoints to fetch (max 1000) |
| clientTimeoutMs | number | 1800000 | HTTP timeout (default 30 min) |
| debug | boolean | false | Enable debug logging |
| stateExtractor | function | undefined | Custom state extraction |

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| Option | Type | Default | Description |
|--------|------|---------|-------------|
| deploymentUrl | string | required | LangGraph deployment URL |
| graphId | string | required | Graph identifier |
| langsmithApiKey | string | undefined | LangSmith API key |
| clientTimeoutMs | number | 1800000 | HTTP timeout |
| debug | boolean | false | Enable debug mode |

Advanced Usage

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If you need to extract custom fields from the CopilotKit request:

`typescript
const runner = new HistoryHydratingAgentRunner({
agent,
deploymentUrl,
graphId,
stateExtractor: (input, forwardedProps) => ({
// Extract from forwardedProps.configurable (useCoAgent config)
tenantId: forwardedProps?.configurable?.tenantId as string,
userId: forwardedProps?.configurable?.userId as string,
// Or from input.state (useCoAgent initialState)
...input.state,
}),
});
`

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In serverless environments (especially Vercel Fluid Compute), Node.js module-level state can be shared between bundled routes. This causes a critical bug where the LangGraph deployment URL gets contaminated between different agent configurations.

createIsolatedAgent fixes this by:
1. Creating agents with frozen, immutable config
2. Verifying the internal client URL matches expected
3. Force-replacing the client if contamination is detected

Always use createIsolatedAgent instead of new LangGraphAgent() in serverless environments.

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Enable debug logging to troubleshoot issues:

`typescript
const runner = new HistoryHydratingAgentRunner({
// ...
debug: true,
});
`

This logs:
- History fetching progress
- Message transformation details
- Stream processing events
- State extraction results

How It Works

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When a client connects to an existing thread:

1. Fetch History: Retrieves all checkpoints from LangGraph via client.threads.getHistory()
2. Extract Messages: Processes checkpoints chronologically, deduplicating messages by ID
3. Transform Format: Converts LangGraph messages to CopilotKit format
4. Emit Events: Sends MESSAGES_SNAPSHOT and STATE_SNAPSHOT events to frontend
5. Join Stream: If thread is busy, joins the active execution stream

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- on_chat_model_stream → TEXT_MESSAGE_CONTENT
- on_chat_model_start → TEXT_MESSAGE_START
- on_chat_model_end → TEXT_MESSAGE_END
- on_tool_start → TOOL_CALL_START
- on_tool_end → TOOL_CALL_END
- Custom CopilotKit events (manual message/tool/state emission)
- Interrupt events

API Reference

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`typescript
// Core
export { HistoryHydratingAgentRunner } from "copilotkit-langgraph-history";
export { createIsolatedAgent } from "copilotkit-langgraph-history";

// Types
export type {
HistoryHydratingRunnerConfig,
StateExtractor,
CreateIsolatedAgentConfig,
LangGraphMessage,
ThreadState,
} from "copilotkit-langgraph-history";

// Constants
export {
DEFAULT_TIMEOUT,
DEFAULT_HISTORY_LIMIT,
MAX_HISTORY_LIMIT,
} from "copilotkit-langgraph-history";

// Event Enums
export {
CustomEventNames,
LangGraphEventTypes,
} from "copilotkit-langgraph-history";

// Utilities (advanced)
export {
transformMessages,
extractContent,
processStreamChunk,
} from "copilotkit-langgraph-history";
`

Environment Variables

`env


Required

LANGGRAPH_DEPLOYMENT_URL=https://your-deployment.langchain.com

Optional (for authentication)

LANGSMITH_API_KEY=your-api-key
`

Troubleshooting

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- Ensure the thread exists in LangGraph
- Check that deploymentUrl is correct
- Verify langsmithApiKey has access to the deployment

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- Confirm threadId is being passed to
- Check browser console for hydration errors
- Enable debug: true to see detailed logs

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This is expected when the runner detects and fixes serverless state contamination. The client is automatically replaced with the correct URL.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature`)
5. Open a Pull Request

License

MIT License - see LICENSE for details.

Credits

Created by Daniel Frey.

Inspired by the need for thread history persistence in CopilotKit + LangGraph applications.