Link'u

The problem

The Link'u community (Sipe Sipe, Cochabamba) logged water meter readings by hand with no backups. As a growing community, they needed something that scales with them: the app works 100% offline, prints bills and keeps encrypted backups.

Highlights

1. 01SQLite as source of truth; permissions and calculations only in Electron's main process; money stored as integer cents.
2. 02AES-256-GCM encrypted cloud backups, versioned migrations with automatic pre-migration backup.
3. 03Auto-updates, late fees, PDF bills and photo login for operators (client request).
4. 0447 tests (Vitest) and GitHub Actions CI producing a Windows installer, portable build and AppImage.

What I learned

• → 01True offline-first: with no internet the app must work the same, and the cloud is only a backup.
• → 02Never store money as floats: integer cents avoid rounding errors on bills.
• → 03Listen to the client even when the idea isn’t the one you’d pick (like photo login): the software is for them.
• → 04Migrations with a prior backup: in an app running on someone else’s computer there’s no second chance.