Insights & Innovations in Code

Writing

Engineering, backend APIs, full-stack apps, and applied AI.

Browse 1 series

All Posts Business Guides Tutorials

Multi-part build-alongs — complete systems, start to finish.

#cambodia #pos #offline-first #web design #architecture #typescript #content #postgresql #compliance #conversion Clear

Tutorials

Build a POS that survives the internet · part 2

Offline-first POS, part 2: never store a stock level

The schema decision that makes offline sync work: store append-only stock movements and derive the level, so two tills syncing in either order reach the same answer.

10 Aug 20264 min read2 views

Tutorials

Build a POS that survives the internet · part 4

Offline-first POS, part 4: idempotent sync and the last-item problem

Accepting a batch that contains sales you already have, per-sale transactions so one bad record cannot poison a batch, and what to do when two tills sold the same last item.

10 Aug 20263 min read3 views