docs: add Phase 7 — Multilanguage (English, Spanish, Portuguese)

.planning/REQUIREMENTS.md

@@ -72,6 +72,15 @@ Requirements for beta-ready release. Each maps to roadmap phases.
 - [x] **CHAT-04**: Chat respects RBAC — users can only chat with agents belonging to tenants they have access to
 - [x] **CHAT-05**: Chat interface feels responsive — typing indicators, message streaming or fast response display
 
+### Multilanguage
+
+- [ ] **I18N-01**: Portal UI fully localized in English, Spanish, and Portuguese (all pages, labels, buttons, error messages)
+- [ ] **I18N-02**: Language switcher accessible from anywhere in the portal — selection persists across sessions
+- [ ] **I18N-03**: AI Employees detect user language and respond accordingly, or use a language configured per agent
+- [ ] **I18N-04**: Agent templates, wizard steps, and onboarding flow are fully translated in all three languages
+- [ ] **I18N-05**: Error messages, validation text, and system notifications are localized
+- [ ] **I18N-06**: Adding a new language requires only translation files, not code changes (extensible i18n architecture)
+
 ## v2 Requirements
 
 Deferred to future release. Tracked but not in current roadmap.
@@ -161,12 +170,19 @@ Which phases cover which requirements. Updated during roadmap creation.
 | CHAT-03 | Phase 6 | Complete |
 | CHAT-04 | Phase 6 | Complete |
 | CHAT-05 | Phase 6 | Complete |
+| I18N-01 | Phase 7 | Pending |
+| I18N-02 | Phase 7 | Pending |
+| I18N-03 | Phase 7 | Pending |
+| I18N-04 | Phase 7 | Pending |
+| I18N-05 | Phase 7 | Pending |
+| I18N-06 | Phase 7 | Pending |
 
 **Coverage:**
 - v1 requirements: 25 total (all complete)
 - RBAC requirements: 6 total (Phase 4, all complete)
 - Employee Design requirements: 5 total (Phase 5, all complete)
-- Web Chat requirements: 5 total (Phase 6)
+- Web Chat requirements: 5 total (Phase 6, all complete)
+- Multilanguage requirements: 6 total (Phase 7)
 
 ---
 *Requirements defined: 2026-03-23*