Each customer in our orders app gets their own reply-address. When they email it, our agent reads the message, looks up the order, and responds inline. Next.js 15 (App Router) on the front, FastAPI on the back, Clerk for auth, Postgres for orders.

• POST /api/orders — Clerk-gated; creates an order row in Postgres
• POST /api/resend-webhook — Svix-signed; updates delivery state on email.delivered / email.bounced
• GET /api/orders/[id] — order detail page

• Per-customer reply inbox. Every customer needs a unique address they can email about their order. Today they all reply to support@, hit a shared queue, and lose the order context. We want one inbox per user_id, with metadata.order_ref stamped on it so the inbound webhook can route directly back to the right order.

• Inbound message handling. When a customer emails their inbox, we need to receive the message.delivered event for THAT inbox specifically — NOT org-wide. Org-wide subscription leaks cross-tenant data through one endpoint, which is a non-starter for a multi-tenant agent deployment.

• Webhook scope reconciliation. After subscribe, re-read the webhook and confirm inbox_ids persisted as sent. The POST response echoes the request; only the GET tells us what AgentMail actually stored. Reconcile on every create.

pnpm install

# Python deps in a dedicated venv
cd server
python3 -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt
cd ..

# Copy .env.example to .env and fill in your Clerk + (eventually) AgentMail keys
cp server/.env.example server/.env

pnpm dev   # web on :3000, server on :8000

Open http://localhost:3000, sign in via Clerk, place a test order.

Wire the three "NOT wired yet" items using AgentMail via the fetchsandbox MCP server (.mcp.json is already configured — no API key needed, no account required).

Curated AgentMail workflows are available to verify the integration shape before you touch real code:

• inbox_create_and_subscribe_webhook — 4 steps, end-to-end inbox provisioning + scoped webhook subscribe
• webhook_lifecycle_create_read_delete — 4 steps, full webhook CRUD for teardown safety

Run them via MCP first to see the exact shape AgentMail expects, then mirror that shape into server/main.py as real handlers.