Offline till (in progress)

An Electron desktop till that sells through network outages. It's on unmerged branches, with a matching API PR. Nothing on this page is on master yet.

Shape

• Electron 44 app Totlob POS (com.totlob.pos), packaged with electron-builder as .dmg, .exe and .AppImage. It serves itself from totlob://till.
• SQLite (better-sqlite3) file till.db holds a catalogue snapshot.
• Local-first reads, even online: the grid, search, categories, sections and scanner all read locally. Only live stock and today's automatic discounts are fetched (syncCatalog, getLiveFigures).

One policy table

src/offline/policy.ts decides every endpoint's behaviour without the network:

The branch's ADR is docs/adr/0002-the-till-sells-offline-and-refuses-the-rest.md.

Offline sales

1. The till gives the server 2.5 s.
2. With no answer, it completes the sale locally and prints a local number (e.g. K7Q-000184).
3. The sale is queued in the outbox with an offline block.

Outbox rules

• Entries are drained in order, with retry backoff.
• Each entry belongs to the user who made it.
• Sign-out waits for the outbox to empty, and cashing up waits for an empty queue.

UI

• LinkBadge.tsx: the connection status on the nav rail
• SyncDialog.tsx: the Sync queue screen, with Sync now and progress

Offline controls

• Discount approval offline: approver PIN hashes are stored in the OS keystore and checked locally, with the server's lockout mirrored.
• Discount caps per sale and per drawer limit exposure while offline.
• A local customer directory allows lookups offline.

Related unmerged work

• feat/browse-pos-without-drawer: abandoned in favour of always requiring a drawer.
• feat/pos-category-tree-lines: connector lines in the category pane.