Prompt-to-PR: Add a Pricing Page

SOP for generating a production pricing page with monthly/annual toggle, feature matrix, and Stripe Checkout links in a Next.js Tailwind project.

One of the most-generated pages in AI coding sessions. This playbook constrains the agent to produce real, wired-up Stripe Checkout links rather than placeholder buttons.

1. Requirement

Add a /pricing page with two or three tiers, a monthly/annual billing toggle (annual gives a 20% discount), a feature comparison matrix, and Stripe Checkout integration. Prices must come from environment variables, not be hardcoded in JSX.

2. First Prompt

Add a /pricing page to this Next.js 15 App Router project with Tailwind.

Requirements:
1. Create `src/app/pricing/page.tsx` — a Server Component that renders
   `<PricingCards>`.
2. Create `src/components/PricingCards.tsx` — a Client Component with:
   - Monthly/annual toggle (useState). Annual prices are monthly × 0.8.
   - Three tiers: Hobby (free), Pro, Business. Read plan data from
     `src/config/pricing.ts` — not hardcoded in JSX.
   - A feature matrix table below the cards showing which features each tier
     includes. Use checkmarks and dashes; do not use emojis in code.
   - A "Get started" CTA for Hobby (links to /sign-up) and "Subscribe" for
     paid tiers.
3. Create `src/config/pricing.ts` exporting a `PLANS` array. Each plan has:
   { id, name, monthlyPriceUsd, stripePriceIdMonthly, stripePriceIdAnnually,
     features: string[], highlighted: boolean }
   Read Stripe price IDs from env vars:
     NEXT_PUBLIC_STRIPE_PRICE_PRO_MONTHLY
     NEXT_PUBLIC_STRIPE_PRICE_PRO_ANNUALLY
     NEXT_PUBLIC_STRIPE_PRICE_BIZ_MONTHLY
     NEXT_PUBLIC_STRIPE_PRICE_BIZ_ANNUALLY
4. Create `src/app/api/checkout/route.ts` (POST). Accept `{ priceId, userId }`.
   Create a Stripe Checkout Session (mode: "subscription") with:
   - success_url: NEXT_PUBLIC_APP_URL + /dashboard?checkout=success
   - cancel_url: NEXT_PUBLIC_APP_URL + /pricing
   Return `{ url }`.
5. In PricingCards, the Subscribe button POSTs to /api/checkout and redirects
   to the returned url.
6. Install `stripe` package. Use env var STRIPE_SECRET_KEY.

3. Expected File Changes

package.json                             (stripe)
src/app/pricing/page.tsx                 (new — Server Component shell)
src/components/PricingCards.tsx          (new — Client Component with toggle)
src/config/pricing.ts                    (new — plan definitions)
src/app/api/checkout/route.ts            (new — Stripe Checkout Session)
.env.local.example                       (STRIPE_* and NEXT_PUBLIC_* vars)

4. Review Checklist

STRIPE_SECRET_KEY is never imported in a Client Component or exposed via NEXT_PUBLIC_.
The Checkout Session uses mode: "subscription" not mode: "payment" for recurring billing.
Annual price IDs are separate Stripe Price objects — not a computed discount in code.
The toggle shows annual savings clearly (e.g. “Save 20%”).
The PLANS array is the single source of truth — feature matrix re-uses the same data, not a separate hardcoded table.
Error handling on the checkout POST: returns a 500 with a message if Stripe throws.
No console.log of Stripe keys or customer data left in the code.

5. Test Commands

bun dev

# Toggle monthly/annual — confirm prices update correctly
# Confirm annual = monthly * 0.8

# Test checkout endpoint with a test price ID
curl -X POST http://localhost:3000/api/checkout \
  -H "Content-Type: application/json" \
  -d '{"priceId":"price_test_xxx","userId":"user_1"}' | jq .url
# Expect a Stripe Checkout URL

bun tsc --noEmit

6. Common Failures

STRIPE_SECRET_KEY leaked client-side — agent imports stripe in PricingCards.tsx. Move all Stripe calls to the API route.
Annual toggle shows same price as monthly — agent calculates price * 0.8 but forgets to use the isAnnual state. Confirm the toggle state is passed to the price display.
Checkout returns 500 with “No such price” — price ID env var not set or wrong environment (test vs live). Verify with stripe prices retrieve <id> in the Stripe CLI.
success_url is relative — Stripe requires an absolute URL. Prefix with NEXT_PUBLIC_APP_URL.

7. Fix Prompt

The annual/monthly toggle renders correctly visually but the Subscribe button
always sends the monthly priceId regardless of which toggle state is active.

In PricingCards.tsx, the `priceId` passed to the checkout POST must be
`isAnnual ? plan.stripePriceIdAnnually : plan.stripePriceIdMonthly`.
Check that the isAnnual state variable is read at the point the button's
onClick handler calls the checkout API.

8. PR Description

## Feature: Pricing page with Stripe Checkout

- `/pricing` page with monthly/annual toggle and three tiers (Hobby, Pro, Business)
- Feature matrix driven from `src/config/pricing.ts` — one source of truth
- POST `/api/checkout` creates a Stripe Subscription Checkout Session
- Price IDs read from env vars — no hardcoded Stripe IDs in code
- Annual plan = 20% discount via separate Stripe Price objects

**Required env vars**: `STRIPE_SECRET_KEY`, `NEXT_PUBLIC_STRIPE_PRICE_*`,
`NEXT_PUBLIC_APP_URL` (see `.env.local.example`)