Claude Agent Sdk Demo

agent-sdk-demo

A small chat playground built on top of the [Claude Agent SDK for Python](https://github.com/anthropics/claude-agent-sdk-python). Streams responses from a locally-spawned `claude` CLI, exposes them through SSE to a Next.js + [prompt-kit](https://www.prompt-kit.com) UI, and lets you drive tools, system prompts and permissions via slash commands.


┌────────────┐     SSE      ┌────────────┐     spawn     ┌──────────┐
│  Next.js   │ ───────────▶ │  FastAPI   │ ────────────▶ │ claude   │
│  (web/)    │   /api/chat  │  (server/) │  Agent SDK    │   CLI    │
└────────────┘              └────────────┘               └──────────┘

Why this exists

• Verify the Python Agent SDK end-to-end with a real UI.
• Authenticate only with the local CLI's stored login (claude /login); the backend strips token env vars before spawning.
• Show off prompt-kit components in a polished chat layout.

Quick start

# 1. Backend
uv sync
uv run uvicorn server.main:app --host 127.0.0.1 --port 8000

# 2. Frontend (in another shell)
cd web
npm install
npm run dev
# open http://localhost:3000

You need an existing `claude` CLI login on this machine. If you don't have one, run `claude /login` once.

Smoke-test with no UI:

uv run python demo.py

Slash commands

Type `/` in the composer to open a typeahead.

Command	Effect
/help	List all commands
/clear	Reset conversation + session
/cost	Last turn's cost / latency
/ping	Quick PONG round-trip
/joke	Ask Claude for a programming joke
/system	Override the system prompt for next turns
/model	Pin a model (e.g. claude-sonnet-4-6)
/tools	Enable tools. demo exposes the in-process SDK MCP tools (roll_dice, flip_coin, now) defined in server/sdk_tools.py
/deny	D