Registrations, teams, merch, accommodation and payments for the whole festival, where one transaction routinely settles four different things at once.

01 Architecture

• Express in TypeScript on the Bun runtime over PostgreSQL, deployed to Kubernetes for the fest window and Compose the rest of the year.
• Payment reconciliation is idempotent by construction, so a replayed Easebuzz webhook can never double settle, and a polling path rescues the orders whose callback never lands.
• One payment resolves a registration, an accommodation slot, a food pass and a merch order together, which is why the settlement has to be atomic rather than four separate writes.
• Eight tiered LRU caches sit in front of the hottest read paths, tiered by how volatile the data actually is.
• Mail is never sent inline. The API writes to an outbox collection that a separate worker drains, so a mail provider outage delays a confirmation instead of failing a payment.
• Cloudflare R2 for uploads, with a React 19 + Vite operations console over the top.

02 What is in it

• Admin console: twenty routes covering events, registrations, transactions, coupons, merch, accommodation and bulk comms, with map based venue placement and CSV export behind a field picker.
• Mail worker: polls the outbox every few seconds, retries on capped exponential backoff, ships structured pino logs as its own Docker service.
• Access control: 600 wristband passes minted in Python across two tiers, rendered at high error correction so the festival logo can sit in the centre, each code tracking its tier, redemption count and per day scan state.
• Built and run across three editions, as Executive Member and then on the core committee.