This repository demonstrates how inventory reservation can suffer from a double-booking race condition and provides the groundwork for iterating toward a safe solution using Next.js, PostgreSQL, and Redis.

Use this sandbox to observe lost updates under concurrent load and to experiment with mitigation techniques such as optimistic locking, transactional guards, and distributed locks.

• Race-condition reproduction – The POST handler in src/app/api/buy-bad/route.ts intentionally reads, waits, and updates inventory to showcase lost updates.
• Load generation – src/app/api/api-test/route.ts floods the bad purchase endpoint with concurrent requests to surface the issue.
• Inventory model – The inventoryTable schema is backed by Postgres and wired through src/lib/db.ts.
• Redis initializer – src/app/api/create-inventory-key/route.ts seeds the cache via src/lib/redis.ts.
• Health probe – src/app/api/health/route.ts offers a lightweight readiness check.
• Baseline UI – src/app/page.tsx and src/app/layout.tsx host a minimal front end scaffold.

• Node.js 18+
• PostgreSQL database reachable via DATABASE_URL
• Redis instance reachable via REDIS_URL
• PNPM (recommended) or any package manager referenced in package.json