xenia-pos-local/docs

client-services — On-site Pack

Everything that runs inside the restaurant, on the local server box. This folder is its own git repo, nested inside the xenia-pos parent repo.

Read the global rules first: ../../docs/README.md. This file adds only the rules specific to this pack. The feature catalog, the cloud contract, known issues and site records all live in the parent's docs/.

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Services

Service	Stack	Dev port	Prod exposure	Image
local_backend	FastAPI + SQLAlchemy + SQLite (/app/data/pos.db)	8000	only through proxy / inner nginx	pos-backend
waiter_pwa	React + Vite + vite-plugin-pwa, axios, zustand, react-query, Dexie (IndexedDB)	5173	https://<host> (443)	pos-waiter
manager_dashboard	React + Vite	5174	https://<host>:4443	pos-manager
proxy	nginx:alpine, TLS termination	—	80 → 443 redirect, 443, 4443	stock

Request path in production

phone ──https──▶ proxy:443 ──http──▶ waiter_pwa nginx:80 ──┬─ /           → static SPA
                                                            ├─ /api/       → backend:8000
                                                            ├─ /api/ws/    → backend:8000 (WebSocket upgrade)
                                                            └─ /static/    → backend:8000/static/

Every hop must forward WebSocket upgrades: proxy_http_version 1.1, plus Upgrade and Connection headers, plus a long proxy_read_timeout. The manager calls the API same-origin, with relative paths. The waiter app resolves every backend URL through waiter_pwa/src/config/server.js: same-origin when served by the venue's server, absolute when running in the native app (see CS-8). Don't hardcode hosts.

Key files

File	Why it matters
local_backend/main.py	App setup, router registration, CORS, _run_migrations()
local_backend/services/cloud_sync.py	Every call to the cloud (see the parent's docs/reference/cloud-contract.md)
local_backend/roles.py, routers/deps.py	Roles, permission checks, auth dependencies
local_backend/routers/ws.py	Real-time event stream (seq + cursor replay)
waiter_pwa/src/config/server.js	Where the backend is: active venue, apiBase(), wsUrl(), assetUrl(), storageKey(), dbName(), deliveryMode()
waiter_pwa/src/api/client.js	axios instance: auth header, 401 → logout, network error → offline
waiter_pwa/src/context/SSEContext.jsx	Real-time lifecycle, event → store/cache updates, visibility refresh
waiter_pwa/src/db/posdb, src/services/offlineOrders	Offline cache and queued orders
nginx-proxy/nginx.conf	Proxy config used in dev / by hand
install.sh	Site installer. Writes its own copy of the proxy config.
docker-compose.yml / docker-compose.dev.yml	Prod (pull images) / dev override (build + expose ports)

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Pack-specific rules

CS-1. Schema changes go through _run_migrations(). A new table: create_all handles it. A new column on an existing table: append an ALTER TABLE <t> ADD COLUMN ... to the migrations list in local_backend/main.py, with a SQLite-safe default for NOT NULL. Add the column to the SQLAlchemy model and the Pydantic schema in the same commit. Never drop or rename columns.

CS-2. New real-time events need both ends. If the backend emits a new event type, handle it in waiter_pwa/src/context/SSEContext.jsx (and in the manager, if relevant), or state explicitly that it's ignored. Events carry IDs; clients re-fetch the full object (/api/orders/{id}) instead of trusting partial payloads.

CS-3. The waiter app must survive bad networks. Waiters walk in and out of WiFi range and phones sleep. Any new waiter flow must:

• work from the IndexedDB cache when offline, or clearly block with an offline state
• never lose an order that was entered (queue it)
• tolerate duplicate or replayed events

CS-4. Money and prices are snapshotted. Prices, costs and discounts are copied onto order items and logs when the action happens (snapshot pattern, PriceEventLog). Reports read the snapshots, never the live catalogue.

CS-5. The proxy config lives in two places. Edit nginx-proxy/nginx.conf and the heredoc in install.sh together (global Rule 9).

CS-6. Permissions are checked on the backend. Hiding a button in the UI is not access control. Every new endpoint declares its role or perm_* requirement through routers/deps.py.

CS-8. The waiter app never assumes it's served by the backend. The same waiter build runs same-origin (https domain, or plain http://<LAN IP>) and inside the native app talking to a remote venue server. So in waiter_pwa:

• REST goes through api/client.js (its baseURL is apiBase()). Any other fetch, EventSource or WebSocket must build its URL with apiBase() or wsUrl().
• Backend-served files (/static/... images, avatars) are rendered through assetUrl().
• Persistent venue-specific data (token, IDs of products/tables/zones) uses storageKey() for localStorage keys and zustand persist names. The IndexedDB name comes from dbName(). Device preferences (theme, payment safety…) stay global.
• Features that need a secure context (service worker, camera, notifications, clipboard) must degrade gracefully when deliveryMode() is 'plain-web'.

CS-7. Greek-market realities. Staff UIs are used by Greek staff and must render Greek correctly, including on thermal printers (codepage). Money uses €.

Common commands

# Dev: backend with reload
cd local_backend; uvicorn main:app --reload --port 8000

# Dev: frontends (Vite proxies /api and /api/ws to :8000)
cd waiter_pwa; npm run dev          # :5173
cd manager_dashboard; npm run dev   # :5174
cd waiter_pwa; npm run lint

# Build release images (VERSION comes from .env). See the parent's DEPLOYMENT_GUIDE.md.
docker compose -f docker-compose.yml -f docker-compose.dev.yml build
docker push registry.bonamin.gr/pos-backend:<ver>   # + pos-waiter, pos-manager

Testing

There is no automated test suite yet. Before committing:

• the backend starts cleanly against an existing pos.db (this catches missing migrations)
• npm run build passes for any frontend you touched
• the flow was exercised by hand (the parent's PLANS AND STRATEGIES/TESTING_CHECKLIST.md)
• printing was checked against real hardware or esc-pos-emulator

Say in the commit or hand-off what was and wasn't verified.