010122-multi-currency-architecturelisted

# Multi-Currency Architecture ## When to use When building e-commerce or subscription systems that need to display and charge in multiple currencies based on the user's geographic location. ## References | Topic | File | |---|---| | Currency + country + tax FK chain | `references/fk-chain.md` | | Price table design per currency | `references/price-table.md` | | Geo-based detection pipeline | `references/geo-detection.md` | | CurrencyProvider and admin CRUD | `references/currency-provider.md` | ## Quick checklist - [ ] `sys_currencies`: code, name, symbol, countryId FK, isDefault, isActive - [ ] `sys_taxes`: countryId FK, currencyId FK, name, rate, isActive - [ ] `prd_prices`: productId, variantId, currencyId FK, price, compareAtPrice, cost, isActive, validFrom, validUntil - [ ] Unique constraint: `(productId, variantId, currencyId)` with `NULLS NOT DISTINCT` - [ ] Geo detection: edge header (`cf-ipcountry`) → sys_countries → sys_currencies - [ ] Fallback chain: user preference cookie → geo detection → default currency (USD) - [ ] CurrencyProvider context: read-only (immutable without user preference) - [ ] Admin CRUD: generic factory with FK protection on DELETE