resumable-stream-chat

Resumable Streaming Chat

A real-time AI streaming chat that automatically resumes when you disconnect and reconnect. Built with Cloudflare Agents and Durable Objects.

What this demonstrates

• Resumable streaming: Start a long AI response, refresh the page, and watch it pick up exactly where it left off
• Automatic reconnection: The WebSocket reconnects automatically, no user action needed
• Message persistence: Chat history survives disconnects and page reloads via useAgentChat
• Buffered chunk replay: All chunks generated while disconnected are replayed on reconnect

Getting started

1. Copy the environment template and add your OpenAI API key:

   cp .env.example .env

2. Install dependencies from the repo root:

   npm install

3. Start the dev server:

   npm start

How it works

The server (src/server.ts) uses AIChatAgent with streamText — nothing special is needed. Resumability is built into the agent protocol.

The client (src/client.tsx) uses useAgentChat which automatically handles:

1. Detecting an active stream on reconnect
2. Sending an ACK to the server
3. Receiving all buffered chunks and continuing the stream

Configuration

Variable	Description
OPENAI_API_KEY	Your OpenAI API key

Stack

• Runtime: Cloudflare Workers + Durable Objects
• UI: React, Tailwind CSS, Kumo (workers theme)
• AI: Vercel AI SDK with OpenAI
• Build: Vite + @cloudflare/vite-plugin