Oak & Ember

Fictitious cast-iron & camp kitchen shop demo with Ember, an Anthropic-powered product support agent.

Stack

• Next.js 16 (App Router), React 19, TypeScript, Tailwind CSS 4
• @anthropic-ai/sdk, zod, nanoid

Setup

npm install
cp .env.example .env.local
# Add your Anthropic key to .env.local
npm run dev

Open http://localhost:3000.

Environment

Variable	Required	Description
ANTHROPIC_API_KEY	Yes (for chat)	Anthropic API key. Without it, POST /api/chat returns 503 with { code: "config" }.

Chat API

POST /api/chat

Request

{
  "messages": [
    { "role": "user", "content": "How do I season a skillet?" }
  ]
}

Roles must be user or assistant only. Client system prompts are rejected.

Success (200)

{
  "message": { "role": "assistant", "content": "…" },
  "turnsRemaining": 5
}

Errors

Customer-facing error strings steer shoppers back to product support (care, shipping, gear picks). Shape: { "error": string, "code": "…" }

HTTP	code	When
400	validation	Bad JSON, empty/oversized messages, invalid roles, client system prompt
429	turn_limit	Session used all 6 user turns
429	rate_limit	IP exceeded request budget
503	config	Missing ANTHROPIC_API_KEY
502	upstream	Anthropic API failure / empty reply

Abuse limits (server-enforced)

Limit	Value
User turns / session	6 (httpOnly cookie oe_chat_turns)
Message length	~400 characters
Rate limit	~8 requests / IP / 10 minutes (in-memory Map)
History	Capped to last 12 messages (turn budget × 2)
System prompt	Hard-coded on the server; client overrides ignored

Client-side turn counters are UX only — these server checks are the real controls.

Caveats: The IP rate-limit Map is per-process and resets on cold starts or across multiple instances (fine for a local/demo deploy). Clearing cookies resets the turn counter; rate limiting still applies.

Scripts

npm run dev    # development
npm run build  # production build
npm run start  # serve production build