Offline-first architecture

Offline-first design

The shop must keep selling without internet.

Local database

The recommended stack uses SQLite with write-ahead logging; a spike to confirm has not been done..

Stack recommendation

The repo recommends a Rust core with a Flutter UI.

Sync between devices

Devices in one shop sync over the local network.

Multi-register shops

Several tills sharing one database or syncing peer to peer..

Time and ordering

Hybrid logical clocks are listed as a way to order events without perfect clocks..

Crash and power-cut safety

Atomic writes and journaling so a failure never loses a completed sale..

Core and logistics isolation

The ARCH module keeps logistics separate from the core POS so a fault in one cannot corrupt the other..

Packaging engine

Per ADR-0001 and ADR-0002, Simca Packaging is a server-side or developer-side engine that assembles and signs a package from a package spec.

Performance goals

The README says reliability over speed; the catalog lists performance targets as items..

Data model

The logistics subproject has a draft SQLite schema that executes; it is a file, not a product..

Update model

The README says buy once with an optional yearly fee for updates and the co-op.

Localization

English and Spanish, local number and date formats, accessible UI..

Local logs and diagnostics

Logs stay on the device and are shared only on request..

Launcher

The one download.

Offline mode

An explicit mode in which the launcher and app make no network request at all, like a game launcher's offline mode..

User-initiated signed updates

Updates are signed packages, applied only when the user asks, from a static server manifest or a file passed by USB or messenger.

Package spec

A small JSON file written by the launcher that lists the chosen elements.

Online sign-in

Only features that inherently need the online network need a sign-in: Tap to Pay, the co-op price counter, referral validation and the Logistics board relay.

Elements, not roles

ADR-0001 removed separate role builds.

Paired development

ADR-0002: every element is built first in Simca Packaging (thin manifest, prebuilt artifact, dependency links) and then immediately in Simca or Simca Logistics.

Build delivery

ADR-0002: packages are assembled from per-element prebuilt pieces and cached by spec hash; nothing is recompiled per customer and identical specs give identical builds.

Offline/Online toggle

ADR-0002: the launcher shows a plain-sight toggle.

Update notice for offline users

ADR-0002: an offline user is offered updates only when a connection exists, as a visible, dismissible notice.

Free-package profit threshold

ADR-0002: users start free, and a flat quarterly fee applies only after the business reaches a profit threshold measured locally from its own books, with nothing reported.

iOS launcher parity

ADR-0002: the iOS launcher must look and work like the other platforms; Apple rule limits are checked later and recorded as per-feature exceptions instead of being designed around now..

Offline guard test

A test in the packaging crate fails the build if network crates, sockets, URLs, process spawning or URL/token environment variables appear, or if a denied crate enters the lockfile.