Internationalization and RTL (React Native)

References: REGIONAL_PROFILE.md, SPEC.md NFR-PORT-002, MODULE_SHARED_STANDARDS.md.

The clinician Berry template does not apply to patient UI—layout and copy rules are here and in UI_UX_PATTERNS.md.

---

1. Phase 1 locales (mandatory)

Per REGIONAL_PROFILE.md §2:

Language	Direction	Locale tag
English	LTR	en
Pashto	RTL	ps-AF
Dari	RTL	fa-AF
Arabic (UAE)	RTL	ar-AE

---

2. Libraries

• i18next + react-i18next for string catalogs and namespaces (common, screens, errors).
• Use ICU-style interpolation for values; avoid string concatenation for RTL-sensitive copy.

---

3. RTL layout

• Call I18nManager.forceRTL(isRTL) (or Expo’s localization APIs) when locale changes; prefer restart or root remount if the runtime requires it for consistent layout on Android.
• Use start / end margin and padding (React Native supports start/end in styles) instead of left/right for mirrored layouts.
• Icons that imply direction (chevrons, back) SHOULD flip in RTL; symmetric icons need not.
• Mixed-direction content: names in Arabic with Latin MRN or lab units MUST use Unicode bidirectional isolation or WritingDirection / android:layoutDirection where needed (REGIONAL_PROFILE.md §2 Rules).

---

4. Dates, times, calendars

• Store UTC; display with locale-aware formatting (Intl.DateTimeFormat or dayjs/luxon with locale plugins).
• Support Gregorian display by default; Islamic Hijri / Solar Hijri calendars when tenant configures (REGIONAL_PROFILE.md §3)—surface a calendar picker mode if product requires.

---

5. Numbers and currency

• Locale-specific digit shaping where configured (REGIONAL_PROFILE.md §4).
• Currency: AFN, AED, and tenant-configured multi-currency with Intl.NumberFormat (REGIONAL_PROFILE.md §5).

---

6. Language fallback chain

1. Patient preferred language (from profile or app setting persisted server-side when available)
2. Facility default
3. Tenant default
4. English en

---

7. Testing

• Snapshot or Maestro flows for each RTL locale on at least one screen per major flow (login, home, booking, results).
• Manual test: mixed LTR tokens inside RTL paragraphs (phone numbers, codes).

---

8. Accessibility and locale

Screen readers MUST read content in the active app language; ensure accessibilityLabel keys are translated, not English-only.