Session 12: i18n (10 languages, cookie-based), Africa tier .99, locale switcher, RTL Arabic (1305 tests)

docs/SYSTEM-MANIFEST.md

@@ -218,6 +218,41 @@ Container runtime (Session 9 finding):
   in production and the container OOM-loops (44 restarts observed on
   the live host before the fix was identified).
 
+### Pricing tiers (Session 12 — Africa tier added)
+| Var                          | Required | Default | Used By                            | Doc? |
+| ---------------------------- | -------- | ------- | ---------------------------------- | ---- |
+| `STRIPE_PRICE_AFRICA`        | no       | (none)  | `web/components/Pricing`, `stripeService` (post-DB-CHECK migration) | ✓ S12 |
+
+**Blocker**: the existing migrations (001 + 011) declare `tier IN
+('free','analyst','desk')` as a CHECK constraint on `users.tier` and
+`user_profiles.tier`. The `africa` tier value will VIOLATE that
+constraint until the constraint is updated. The frontend Pricing page
+shows the tier now (UX), but the click handler short-circuits to an
+honest "coming soon" message rather than triggering checkout. Required
+follow-up: manual SQL to drop + re-add the CHECK across both tables
+including 'africa' (cannot be done in this session per the no-migration
+rule).
+
+### Internationalization (Session 12)
+| Var / file                   | Required | Default | Used By                            | Doc? |
+| ---------------------------- | -------- | ------- | ---------------------------------- | ---- |
+| `NEXT_LOCALE` cookie         | no       | en      | `web/middleware.ts`, switcher      | ✓ S12 |
+| `web/src/lib/locales.ts`     | n/a      | n/a     | locale registry (10 languages)     | ✓ S12 |
+| `web/src/locales/{code}.json`| n/a      | n/a     | per-locale translation dictionaries | ✓ S12 |
+
+Locale-detection priority (left wins): URL prefix (reserved for future
+`[locale]/` segment) → `NEXT_LOCALE` cookie → `Accept-Language`
+header → `'en'`. Resolved locale rides on the request via the
+`x-vyndr-locale` header; server components read it through
+`next/headers`, client components consume it via `LocaleContext`.
+
+**Side effect**: every Next.js page is now `ƒ (Dynamic)` instead of
+`○ (Static)` because the root layout reads request headers. If FCP
+regresses meaningfully, the fix is to move locale resolution
+client-side (cookie-only, no `headers()` in layout) — that re-enables
+static prerendering at the cost of a brief English flash on first
+paint for non-English users.
+
 ### Engine 2
 | Var                          | Doc? |
 | ---------------------------- | ---- |