# Build a chat app

> Guides for building a chat product with a useChat frontend, a Go backend, approval-gated tools and coding agents, based on the Shipyard reference app.

Canonical URL: https://goaisdk.com/docs/build-a-chat-app/
Documentation index: https://goaisdk.com/llms.txt

Three guides cover the path from a streaming endpoint to a chat product that can change code on a user's behalf. They follow the code in the Shipyard demo, a reference app you can run and read.

1. [Serve a useChat frontend from Go](https://goaisdk.com/docs/build-a-chat-app/serve-usechat-from-go.md): the request and response protocol, validation, keep-alive, CORS, proxies and custom data parts.
2. [Tool approval end to end](https://goaisdk.com/docs/build-a-chat-app/tool-approval.md): let a model ask and a user decide, with signed approval requests.
3. [Coding agents with the harness](https://goaisdk.com/docs/build-a-chat-app/coding-agents-harness.md): run Claude Code or Codex in a sandbox and show their work in the chat.

## The reference app

[Shipyard](https://github.com/digitallysavvy/go-ai-demo) is a Next.js page that uses the stock `useChat` hook, talking to a Go server built with the Go AI SDK. A failing Go project sits in a workspace. The chat model investigates with its own tools, asks the user before handing the fix to Claude Code or Codex, and streams the coding agent's activity into the thread.

| Piece | Where it lives |
| --- | --- |
| Chat endpoint, validation, keep-alive | [`server/chat.go`](https://github.com/digitallysavvy/go-ai-demo/blob/main/server/chat.go) |
| Tools and the approval-gated tool | [`server/tools.go`](https://github.com/digitallysavvy/go-ai-demo/blob/main/server/tools.go) |
| Claude Code and Codex through the harness | [`server/coder.go`](https://github.com/digitallysavvy/go-ai-demo/blob/main/server/coder.go) |
| `useChat` setup and approval buttons | [`web/app/page.tsx`](https://github.com/digitallysavvy/go-ai-demo/blob/main/web/app/page.tsx) |

## Short versions

If you only need the code, the [recipes](https://goaisdk.com/docs/recipes.md) have one page per task, each with a program you can run.