POS System — Alexanders Schwartzmann

Ring up any sale in seconds — even with no internet

A point-of-sale that never freezes. The cashier keeps serving customers whether the wifi is up or down, and every sale syncs back automatically the moment the connection returns.

Make a saleStep 1 / 5

Add items

Tap products or scan — the total updates instantly.

Ayam BakarNasi BoxEs Teh

Never stops selling
A dropped connection can’t hold up the queue — the register just keeps working.
Fast at the counter
A few taps to ring up, take payment, and print — no waiting.
Nothing slips through
Every sale is saved and reconciled, so the books always match the till.

Problem

A retail counter can’t stop selling because the internet did. Cloud-only POS software fails exactly when it matters — at the register, mid-transaction, with a customer waiting.

Approach

Treat the register as an offline-first edge client of the commerce backend. It owns its own local state, prints locally, and syncs when it can.

Tauri desktop shell: a Rust core for native hardware access with a React UI.
Rust handles the unglamorous, critical parts — crash recovery, IPC to the web layer, and structured logging — so a lost frame or a killed process doesn’t lose a sale.
A tokenized design system as the single source of truth for POS typography and color — mirrored in TypeScript and lockstep-tested so the register never drifts.
ESC-POS receipt rendering over LAN, with device management and a sync API.

Offline-first is a posture, not a feature: every flow assumes the network is optional.

Architecture

Register (Tauri: Rust core + React UI, local store)
  ├─ sell offline ─────► local transactions
  ├─ Rust core ────────► crash recovery · IPC · logging · printer
  ├─ print ────────────► ESC-POS (LAN)
  └─ sync (online) ────► Commerce Backend (SSOT)
                          device mgmt · price rules · reconcile

Key decisions & trade-offs

Offline-first is a posture, not a feature. Every flow assumes the network is optional; sync is reconciliation, not the source of truth.
Design tokens as SSOT. POS type and color live as CSS variables mirrored in TS and lockstep-tested — no drifting inline values on the shop floor.
Hardening is honest. LAN/ESC-POS is pilot-ready; USB/Bluetooth/Serial transports and signed updates are tracked as explicit blockers, not hand-waved as done.

Result

A register that keeps trading through outages and reconciles cleanly — with a Rust core for the parts that must not fail and a design system rigorous enough to trust in production.

Masalah

Meja kasir tidak boleh berhenti jualan cuma karena internetnya mati. Software POS yang cloud-only justru gagal tepat saat paling dibutuhkan — di kasir, di tengah transaksi, dengan pelanggan menunggu.

Pendekatan

Perlakukan kasir sebagai klien edge yang offline-first dari backend commerce. Ia memiliki state lokalnya sendiri, mencetak secara lokal, dan menyinkron saat bisa.

Shell desktop Tauri: inti Rust untuk akses hardware native dengan UI React.
Rust menangani bagian yang tidak glamor tapi kritis — pemulihan dari crash, IPC ke lapisan web, dan logging terstruktur — jadi frame yang hilang atau proses yang terbunuh tidak menghilangkan transaksi.
Sistem desain ber-token sebagai satu-satunya sumber kebenaran untuk tipografi dan warna POS — dicerminkan di TypeScript dan diuji secara lockstep agar kasir tidak pernah melenceng.
Perenderan struk ESC-POS lewat LAN, dengan manajemen perangkat dan sebuah sync API.

Offline-first itu sikap, bukan fitur: tiap alur menganggap jaringan itu opsional.

Arsitektur

Register (Tauri: Rust core + React UI, local store)
  ├─ sell offline ─────► local transactions
  ├─ Rust core ────────► crash recovery · IPC · logging · printer
  ├─ print ────────────► ESC-POS (LAN)
  └─ sync (online) ────► Commerce Backend (SSOT)
                          device mgmt · price rules · reconcile

Keputusan kunci & trade-off

Offline-first itu sikap, bukan fitur. Tiap alur menganggap jaringan opsional; sync adalah rekonsiliasi, bukan sumber kebenaran.
Design token sebagai SSOT. Tipe dan warna POS hidup sebagai variabel CSS yang dicerminkan di TS dan diuji lockstep — tanpa nilai inline yang melenceng di lantai toko.
Pengerasan yang jujur. LAN/ESC-POS siap-pilot; transport USB/Bluetooth/Serial dan update bertanda-tangan dilacak sebagai penghambat eksplisit, bukan dianggap selesai begitu saja.

Hasil

Kasir yang tetap berdagang menembus gangguan dan rekonsiliasi dengan rapi — dengan inti Rust untuk bagian yang tidak boleh gagal dan sistem desain yang cukup ketat untuk dipercaya di produksi.

Offline-first — live

Flip the network off and keep selling. Every sale writes locally first; sync reconciles to the backend when the connection returns — nothing lost.

all reconciled

Sell a few — then go offline and keep selling.

Offline-first is a posture, not a feature. Every sale writes locally first, so the counter never stops for a dropped network. Sync is reconciliation — not the source of truth — so nothing is lost when the connection returns.

A Rust core for what must not fail

The Tauri shell is Rust: crash recovery, IPC to the web layer, and structured logging live in native code, so a killed process or a lost frame never loses a sale.

Offline-first is a posture

Every flow assumes the network is optional. Sales are local writes first; the register never waits on a round-trip to take money.

Sync is reconciliation, not truth

When the connection returns, local transactions reconcile against the backend SSOT — device management, price rules, and conflict handling included. Nothing queued is lost.

Hardening, honestly

LAN + ESC-POS receipts are pilot-ready; USB / Bluetooth / Serial transports and signed updates are tracked as explicit blockers, not hand-waved as done.

Struk LAN + ESC-POS siap-pilot; transport USB / Bluetooth / Serial dan update bertanda-tangan dilacak sebagai penghambat eksplisit, bukan dianggap selesai begitu saja.