Kas Badminton
Real-time badminton club cash & match manager — 2-pair matchup calculations, dynamic QRIS generation, offline-first PWA, and single Go binary delivery via go:embed.
Tracking badminton shuttlecock usage per pair and splitting court fees manually across club members is chaotic, prone to missed debts, and creates ledger friction during sessions.
Solo Architect & Fullstack Engineer: end-to-end rewrite from v2 (Next.js/Prisma) to v4 (Go + SvelteKit static embedded), data migration, and live operations.
Single binary delivery with go:embed
Compiled SvelteKit static SPA directly into the Go binary using go:embed. Zero Node.js runtime on the VPS, instant sub-millisecond cold start, and idle RAM footprint below 16MB.
Realtime session sync via Server-Sent Events (SSE)
Chose unidirectional SSE over WebSockets for live match, debt, and balance updates across active courts — eliminating ping/pong connection overhead and saving mobile battery.
Dynamic QRIS & offline court-ready PWA
Generated exact-amount dynamic QRIS images on the client side with text-sharing fallbacks, paired with service worker caching for reliable operation in indoor courts with weak cellular signal.
Domain-driven idempotent debt reconciliation
Structured transactional balance state machines (player_balances) with goose migrations, ensuring debt recalculations remain 100% idempotent across repeated runs.
- Live and actively used in weekly production at kasbadminton.com
- Native arm64 automated CI/CD deployment with /healthz verification
- 99+ domain logic tests guaranteeing zero accounting discrepancies
- Zero runtime memory leaks and instant responsiveness on low-end devices