Build /register + Stripe Checkout + webhook

[quinn-dougherty]

Description

Pay-what-you-can registration at /register, hosted Stripe Checkout, webhook that triggers Discord invite issuance. Full spec in PLAYBOOK.md §3.3, §4.

Flow

1. /register form: name, email, optional Discord username, amount (min $1; suggest $10/$25/$50/custom), CoC checkbox.
2. POST /api/checkout server action:
   • Validate email + amount.
   • Pre-insert registrants row in pending state with session id.
   • stripe.checkout.sessions.create({ mode: 'payment', line_items: [custom_amount], success_url, cancel_url, customer_email, metadata: { registrant_intent_id } }).
3. POST /api/stripe/webhook:
   • Verify signature with STRIPE_WEBHOOK_SECRET.
   • checkout.session.completed → mark paid, enqueue Discord invite generation (see Discord bot issue).
   • payment_intent.payment_failed → mark failed.
   • Idempotent via unique index on stripe_session_id.
4. Receipt email with personal single-use Discord invite link.

Env vars (via vercel env add)

• STRIPE_SECRET_KEY, STRIPE_PUBLISHABLE_KEY, STRIPE_WEBHOOK_SECRET.

Policy

• Refunds: manual via Stripe dashboard; document in /faq. Full refund if requested ≥7 days pre-event, none after.
• Sales tax: confirm with accountant before opening registration.

Dependencies

• Data model / registrants table.
• Discord invite plumbing (new bot issue).
• Email provider (new email issue).