Can I vibe code Vouchery?

Build a lightweight promotional engine microservice using Node.js (TypeScript), Fastify, PostgreSQL, and Redis.

1. DATA MODEL:
- Create tables for `campaigns` (id, name, budget, start_at, end_at, status), `vouchers` (code, campaign_id, max_redemptions, redemption_count, discount_type ['flat', 'percent'], discount_value, is_active), `rules` (voucher_id, condition_json), and `redemptions` (id, voucher_id, order_id, customer_id, amount_discounted, redeemed_at).

2. CORE API ENDPOINTS:
- `POST /v1/vouchers/generate`: Generates batch unique alphanumeric codes with configurable length and custom prefixes.
- `POST /v1/promotions/validate`: Accepts `{ cart: { items, total }, customer: { id, email } }`. Evaluates conditions (min cart spend, item SKU inclusions, customer redemption history). Returns `{ valid: boolean, discount_amount: number, reason: string }` within 50ms.
- `POST /v1/promotions/redeem`: Executes redemption. MUST use a Redis distributed lock (`redlock` key: `voucher:{code}`) to prevent double-spending in high-concurrency requests. Increments `redemption_count` atomically in Postgres and inserts a row into `redemptions`.

3. FAILURE MODES & ATOMICITY:
- If cart payload fails rule conditions, return specific error code without locking Redis.
- Ensure rollback mechanisms exist: `POST /v1/promotions/rollback` decrements redemption count if checkout fails post-validation.

4. OUT OF SCOPE:
- No loyalty point tiers, referral viral loops, or marketing email integrations. Pure REST promo validation engine.

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