diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index b761fa505..e483b5c79 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -1,6 +1,6 @@
 # 📜 ObjectStack Copilot Instructions
 
-> **Last synced with repo structure:** 2026-04-02
+> **Last synced with repo structure:** 2026-04-13
 
 **Role:** You are the **Chief Protocol Architect** for the ObjectStack ecosystem.
 **Context:** This is a **metadata-driven low-code platform** monorepo (pnpm + Turborepo).
@@ -92,7 +92,8 @@ objectstack-ai/spec/
 │   ├── objectstack-api/
 │   ├── objectstack-ui/
 │   ├── objectstack-automation/
-│   └── objectstack-ai/
+│   ├── objectstack-ai/
+│   └── objectstack-i18n/
 │
 └── content/docs/          # 📝 Documentation content
     ├── getting-started/
@@ -232,6 +233,7 @@ The `skills/` directory contains domain-specific AI skill definitions. When work
 | UI Design | `skills/objectstack-ui/SKILL.md` | Designing Views, Dashboards, Apps |
 | Automation Design | `skills/objectstack-automation/SKILL.md` | Designing Flows, Workflows, Triggers |
 | AI Agent Design | `skills/objectstack-ai/SKILL.md` | Designing Agents, Tools, RAG pipelines |
+| **I18n Design** | `skills/objectstack-i18n/SKILL.md` | Translation bundles, locale config, coverage detection |
 
 ---
 
diff --git a/skills/objectstack-i18n/SKILL.md b/skills/objectstack-i18n/SKILL.md
new file mode 100644
index 000000000..ee332c0e7
--- /dev/null
+++ b/skills/objectstack-i18n/SKILL.md
@@ -0,0 +1,696 @@
+---
+name: objectstack-i18n
+description: >
+  Design internationalization (i18n) strategies for ObjectStack applications.
+  Use when creating multi-locale translation bundles, managing translation coverage,
+  configuring locale settings, or designing object-first translation structures.
+license: Apache-2.0
+compatibility: Requires @objectstack/spec Zod schemas (v4+)
+metadata:
+  author: objectstack-ai
+  version: "1.0"
+  domain: system
+  tags: i18n, translation, locale, internationalization, l10n
+---
+
+# Internationalization — ObjectStack I18n Protocol
+
+Expert instructions for designing internationalization (i18n) and localization (l10n)
+strategies using the ObjectStack specification. This skill covers translation bundle
+structures, locale configuration, object-first translation patterns, coverage detection,
+and integration with the I18nService.
+
+---
+
+## When to Use This Skill
+
+- You are **configuring i18n** for a new ObjectStack project.
+- You need to **create translation bundles** for multiple locales.
+- You are designing **object-first translation structures** (per-object translation files).
+- You need to **detect missing or stale translations** (coverage analysis).
+- You are integrating **AI-powered translation suggestions**.
+- You are implementing **locale-specific formatting** (dates, numbers, currency).
+- You need to understand **translation file organization strategies** (bundled, per_locale, per_namespace).
+
+---
+
+## Core Concepts
+
+### Translation Architecture Overview
+
+ObjectStack follows an **object-first translation model** inspired by Salesforce and Dynamics 365:
+
+1. **Object-First Aggregation**: All translatable content for an object (labels, fields, options, views, actions) is grouped under a single namespace: `o.{object_name}`.
+
+2. **Global Groups**: Non-object-bound translations (apps, navigation, messages) live at the top level.
+
+3. **Locale Files**: Each locale has its own complete translation bundle (e.g., `en.json`, `zh-CN.json`).
+
+4. **Coverage Detection**: The system can compare translation bundles against source metadata to identify missing, redundant, or stale entries.
+
+---
+
+## Translation Configuration
+
+### Stack-Level I18n Config
+
+Configure i18n settings in your `objectstack.config.ts`:
+
+```typescript
+import { defineStack } from '@objectstack/spec';
+
+export default defineStack({
+  i18n: {
+    defaultLocale: 'en',
+    supportedLocales: ['en', 'zh-CN', 'ja-JP', 'es-ES'],
+    fallbackLocale: 'en',
+    fileOrganization: 'per_locale',
+    messageFormat: 'simple',      // or 'icu' for complex plurals
+    lazyLoad: false,
+    cache: true,
+  },
+});
+```
+
+| Property | Type | Default | Description |
+|:---------|:-----|:--------|:------------|
+| `defaultLocale` | `string` | `'en'` | Default BCP-47 locale code |
+| `supportedLocales` | `string[]` | `['en']` | All supported locales |
+| `fallbackLocale` | `string` | same as `defaultLocale` | Fallback when translation missing |
+| `fileOrganization` | `'bundled'` \| `'per_locale'` \| `'per_namespace'` | `'per_locale'` | How translation files are organized |
+| `messageFormat` | `'simple'` \| `'icu'` | `'simple'` | Interpolation format (ICU for plurals/gender) |
+| `lazyLoad` | `boolean` | `false` | Load translations on demand |
+| `cache` | `boolean` | `true` | Cache loaded translations in memory |
+
+> **BCP-47 Locale Codes**: Use standard locale tags (e.g., `en-US`, `zh-CN`, `pt-BR`, `en-GB`).
+
+---
+
+## File Organization Strategies
+
+### 1. Bundled (Single File)
+
+All locales in one file. Best for small projects with few objects.
+
+```
+src/translations/
+  crm.translation.ts        # { en: {...}, "zh-CN": {...} }
+```
+
+**When to use:** Fewer than 5 objects, 2-3 locales, < 200 translation keys total.
+
+### 2. Per-Locale (Recommended)
+
+One file per locale containing all namespaces. Recommended when a single locale file stays under ~500 lines.
+
+```
+src/translations/
+  en.ts                     # TranslationData for English
+  zh-CN.ts                  # TranslationData for Chinese
+  ja-JP.ts                  # TranslationData for Japanese
+```
+
+**When to use:** Medium projects (5-20 objects), 3-5 locales, organized by language.
+
+### 3. Per-Namespace (Enterprise)
+
+One file per namespace (object) per locale. Recommended for large projects with many objects/languages. Aligns with Salesforce DX and ServiceNow conventions.
+
+```
+i18n/
+  en/
+    account.json            # ObjectTranslationData
+    contact.json
+    project_task.json
+    common.json             # messages + app labels
+  zh-CN/
+    account.json
+    contact.json
+    project_task.json
+    common.json
+```
+
+**When to use:** Large projects (20+ objects), 5+ locales, team collaboration, CI/CD pipelines.
+
+---
+
+## Object-First Translation Bundle
+
+### AppTranslationBundle Structure
+
+The `AppTranslationBundle` is the canonical format for a single locale:
+
+```typescript
+const zh: AppTranslationBundle = {
+  _meta: {
+    locale: 'zh-CN',
+    direction: 'ltr',
+  },
+
+  // Object-first translations
+  o: {
+    account: {
+      label: '客户',
+      pluralLabel: '客户',
+      description: '客户管理对象',
+      fields: {
+        name: { label: '客户名称', help: '公司或组织的法定名称' },
+        industry: {
+          label: '行业',
+          options: { tech: '科技', finance: '金融', retail: '零售' }
+        },
+        website: { label: '网站', placeholder: '输入网站地址' },
+      },
+      _options: {
+        status: { active: '活跃', inactive: '停用' },
+      },
+      _views: {
+        all_accounts: { label: '全部客户' },
+        my_accounts: { label: '我的客户' },
+      },
+      _sections: {
+        basic_info: { label: '基本信息' },
+        contact_info: { label: '联系方式' },
+      },
+      _actions: {
+        convert_lead: { label: '转换线索', confirmMessage: '确认转换为客户？' },
+        merge: { label: '合并客户', confirmMessage: '此操作无法撤销，确认合并？' },
+      },
+    },
+  },
+
+  // Global picklist options (not object-specific)
+  _globalOptions: {
+    currency: { usd: '美元', eur: '欧元', cny: '人民币' },
+  },
+
+  // App-level translations
+  app: {
+    crm: { label: '客户关系管理', description: '管理销售流程' },
+    helpdesk: { label: '服务台', description: '客户支持系统' },
+  },
+
+  // Navigation menu
+  nav: {
+    home: '首页',
+    settings: '设置',
+    reports: '报表',
+    admin: '管理',
+  },
+
+  // Dashboard translations
+  dashboard: {
+    sales_overview: { label: '销售概览', description: '销售漏斗与目标' },
+  },
+
+  // Report translations
+  reports: {
+    pipeline_report: { label: '管道报表' },
+  },
+
+  // Page translations
+  pages: {
+    landing: { title: '欢迎', description: '开始使用 ObjectStack' },
+  },
+
+  // UI messages (supports ICU MessageFormat if enabled)
+  messages: {
+    'common.save': '保存',
+    'common.cancel': '取消',
+    'common.delete': '删除',
+    'common.confirm': '确认',
+    'validation.required': '此字段为必填项',
+    'pagination.showing': '显示 {start} 到 {end}，共 {total} 条',
+  },
+
+  // Validation error messages
+  validationMessages: {
+    discount_limit: '折扣不能超过40%',
+    end_date_after_start: '结束日期必须晚于开始日期',
+  },
+
+  // Global notifications
+  notifications: {
+    record_created: { title: '创建成功', body: '记录已创建' },
+  },
+
+  // Global error messages
+  errors: {
+    'ERR_NETWORK': '网络连接失败',
+    'ERR_PERMISSION': '权限不足',
+  },
+};
+```
+
+---
+
+## Object-Level Translation Structure
+
+### ObjectTranslationNode
+
+All translatable content for a single object is aggregated under `o.{object_name}`:
+
+```typescript
+interface ObjectTranslationNode {
+  /** Singular label */
+  label: string;
+  /** Plural label */
+  pluralLabel?: string;
+  /** Description */
+  description?: string;
+  /** Help text */
+  helpText?: string;
+
+  /** Field translations */
+  fields?: Record<string, FieldTranslation>;
+
+  /** Object-scoped picklist options */
+  _options?: Record<string, Record<string, string>>;
+
+  /** View translations */
+  _views?: Record<string, { label?: string; description?: string }>;
+
+  /** Section translations (form tabs/sections) */
+  _sections?: Record<string, { label?: string }>;
+
+  /** Action translations */
+  _actions?: Record<string, { label?: string; confirmMessage?: string }>;
+
+  /** Notification translations */
+  _notifications?: Record<string, { title?: string; body?: string }>;
+
+  /** Error message translations */
+  _errors?: Record<string, string>;
+}
+```
+
+### FieldTranslation
+
+```typescript
+interface FieldTranslation {
+  /** Translated field label */
+  label?: string;
+  /** Help text */
+  help?: string;
+  /** Placeholder text for form inputs */
+  placeholder?: string;
+  /** Option value → translated label map */
+  options?: Record<string, string>;
+}
+```
+
+---
+
+## Naming Conventions
+
+| Context | Convention | Example |
+|:--------|:-----------|:--------|
+| Locale codes | BCP-47 | `en`, `en-US`, `zh-CN`, `pt-BR` |
+| Object keys in `o.*` | `snake_case` | `o.project_task`, `o.support_case` |
+| Field keys | `snake_case` | `fields.first_name`, `fields.due_date` |
+| Option values | lowercase | `options.status.in_progress` |
+| Message keys | dot-separated | `common.save`, `validation.required` |
+
+> **Critical:** Object names and field keys in translation bundles **must** match the `snake_case` names defined in your Object and Field schemas.
+
+---
+
+## Translation Coverage & Diff Detection
+
+### Coverage Analysis
+
+The `II18nService.getCoverage()` method compares a translation bundle against source metadata to detect:
+
+1. **Missing** — Keys that exist in metadata but not in the translation bundle
+2. **Redundant** — Keys in the bundle that have no matching metadata
+3. **Stale** — Keys where the source metadata has changed since translation
+
+```typescript
+const coverage = i18nService.getCoverage('zh-CN', 'account');
+
+console.log(coverage);
+// {
+//   locale: 'zh-CN',
+//   objectName: 'account',
+//   totalKeys: 120,
+//   translatedKeys: 105,
+//   missingKeys: 12,
+//   redundantKeys: 3,
+//   staleKeys: 0,
+//   coveragePercent: 87.5,
+//   items: [
+//     { key: 'o.account.fields.website.label', status: 'missing', locale: 'zh-CN' },
+//     ...
+//   ],
+//   breakdown: [
+//     { group: 'fields', totalKeys: 45, translatedKeys: 40, coveragePercent: 88.9 },
+//     { group: 'views', totalKeys: 8, translatedKeys: 8, coveragePercent: 100 },
+//   ],
+// }
+```
+
+### TranslationDiffItem
+
+```typescript
+interface TranslationDiffItem {
+  /** Dot-path translation key */
+  key: string;
+  /** Diff status: 'missing' | 'redundant' | 'stale' */
+  status: 'missing' | 'redundant' | 'stale';
+  /** Object name (if applicable) */
+  objectName?: string;
+  /** Locale code */
+  locale: string;
+  /** Hash of source metadata for stale detection */
+  sourceHash?: string;
+  /** AI-suggested translation */
+  aiSuggested?: string;
+  /** AI confidence score (0-1) */
+  aiConfidence?: number;
+}
+```
+
+---
+
+## AI-Powered Translation Suggestions
+
+### Using suggestTranslations()
+
+The `II18nService.suggestTranslations()` method enriches diff items with AI-generated translations:
+
+```typescript
+const missingItems = coverage.items.filter(item => item.status === 'missing');
+
+const suggestions = await i18nService.suggestTranslations('zh-CN', missingItems);
+
+suggestions.forEach(item => {
+  console.log(`${item.key}: ${item.aiSuggested} (confidence: ${item.aiConfidence})`);
+  // o.account.fields.website.label: 网站 (confidence: 0.95)
+});
+```
+
+> **Best Practice:** AI suggestions work best when:
+> - You provide source locale context (e.g., English labels)
+> - You include domain-specific glossaries
+> - You review and approve suggestions before committing
+
+---
+
+## Message Interpolation
+
+### Simple Format (Default)
+
+Use `{variable}` placeholders:
+
+```json
+{
+  "messages": {
+    "welcome": "Welcome, {userName}!",
+    "pagination": "Showing {start} to {end} of {total} items"
+  }
+}
+```
+
+Usage:
+```typescript
+i18n.t('messages.welcome', 'en', { userName: 'Alice' });
+// "Welcome, Alice!"
+```
+
+### ICU MessageFormat
+
+For complex pluralization, gender, and select:
+
+```typescript
+// Enable in stack config
+i18n: { messageFormat: 'icu' }
+```
+
+```json
+{
+  "messages": {
+    "inbox": "{count, plural, =0 {No messages} one {1 message} other {# messages}}",
+    "gender": "{gender, select, male {He} female {She} other {They}} replied"
+  }
+}
+```
+
+> **When to use ICU:**
+> - Languages with complex plural rules (Arabic, Slavic languages)
+> - Gender-aware translations
+> - Ordinal numbers (1st, 2nd, 3rd)
+> - Date/time/number formatting
+
+---
+
+## Integration with II18nService
+
+### Service Contract
+
+```typescript
+interface II18nService {
+  /** Translate a key */
+  t(key: string, locale: string, params?: Record<string, unknown>): string;
+
+  /** Get all translations for a locale */
+  getTranslations(locale: string): Record<string, unknown>;
+
+  /** Load translations */
+  loadTranslations(locale: string, translations: Record<string, unknown>): void;
+
+  /** List available locales */
+  getLocales(): string[];
+
+  /** Get default locale */
+  getDefaultLocale?(): string;
+
+  /** Set default locale */
+  setDefaultLocale?(locale: string): void;
+
+  /** Get object-first bundle */
+  getAppBundle?(locale: string): AppTranslationBundle | undefined;
+
+  /** Load object-first bundle */
+  loadAppBundle?(locale: string, bundle: AppTranslationBundle): void;
+
+  /** Get coverage analysis */
+  getCoverage?(locale: string, objectName?: string): TranslationCoverageResult;
+
+  /** AI-powered suggestions */
+  suggestTranslations?(
+    locale: string,
+    items: TranslationDiffItem[]
+  ): Promise<TranslationDiffItem[]>;
+}
+```
+
+### Plugin Setup
+
+```typescript
+import { ObjectKernel } from '@objectstack/core';
+import { I18nServicePlugin } from '@objectstack/service-i18n';
+
+const kernel = new ObjectKernel();
+kernel.use(new I18nServicePlugin({
+  defaultLocale: 'en',
+  localesDir: './i18n',
+  fallbackLocale: 'en',
+  registerRoutes: true,  // Auto-register REST endpoints
+  basePath: '/api/v1/i18n',
+}));
+
+await kernel.bootstrap();
+
+const i18n = kernel.getService<II18nService>('i18n');
+```
+
+---
+
+## Translation Workflow Best Practices
+
+### 1. Extract Keys from Metadata
+
+Use the CLI or API to extract all translatable keys from your metadata:
+
+```bash
+objectstack i18n extract --locale zh-CN --output i18n/zh-CN.json
+```
+
+This generates a skeleton bundle with all required keys.
+
+### 2. Translate
+
+Fill in the translations manually, or use AI suggestions:
+
+```bash
+objectstack i18n suggest --locale zh-CN --input i18n/zh-CN.json
+```
+
+### 3. Validate Coverage
+
+Run coverage analysis to detect missing or stale translations:
+
+```bash
+objectstack i18n coverage --locale zh-CN
+```
+
+### 4. Commit & Deploy
+
+Commit translation files to version control. ObjectStack automatically loads them at runtime.
+
+---
+
+## Advanced Patterns
+
+### Namespace Isolation (Multi-Plugin)
+
+When multiple plugins contribute translations, use namespaces to avoid collisions:
+
+```typescript
+const crmBundle: AppTranslationBundle = {
+  namespace: 'crm',
+  o: {
+    account: { label: '客户' },
+  },
+};
+
+const helpdeskBundle: AppTranslationBundle = {
+  namespace: 'helpdesk',
+  o: {
+    ticket: { label: '工单' },
+  },
+};
+```
+
+Keys are prefixed: `crm.o.account.label`, `helpdesk.o.ticket.label`.
+
+### Right-to-Left (RTL) Support
+
+```typescript
+const ar: AppTranslationBundle = {
+  _meta: {
+    locale: 'ar',
+    direction: 'rtl',
+  },
+  o: {
+    account: { label: 'حساب' },
+  },
+};
+```
+
+UI frameworks can use `_meta.direction` to apply RTL CSS.
+
+### Translation Memory Integration
+
+Implement custom `II18nService.suggestTranslations()` to integrate with:
+- Translation Management Systems (TMS) like Phrase, Crowdin, Lokalise
+- Machine translation APIs (Google Translate, DeepL)
+- Internal translation memory databases
+
+---
+
+## Common Pitfalls
+
+### ❌ Mismatched Object Names
+
+Translation keys must match metadata exactly:
+
+```typescript
+// Metadata
+{ name: 'project_task' }
+
+// Translation (WRONG)
+{ o: { projectTask: { label: '项目任务' } } }
+
+// Translation (CORRECT)
+{ o: { project_task: { label: '项目任务' } } }
+```
+
+### ❌ Hardcoded Option Values
+
+Always use lowercase machine values for options:
+
+```typescript
+// Metadata
+options: [
+  { value: 'in_progress', label: 'In Progress' },
+]
+
+// Translation (WRONG)
+options: { 'In Progress': '进行中' }
+
+// Translation (CORRECT)
+options: { in_progress: '进行中' }
+```
+
+### ❌ Ignoring Coverage Reports
+
+Stale translations can cause confusion. Always run coverage analysis before releases.
+
+---
+
+## Quick-Start Template
+
+```typescript
+// i18n/zh-CN.ts
+import type { AppTranslationBundle } from '@objectstack/spec';
+
+export default {
+  _meta: {
+    locale: 'zh-CN',
+    direction: 'ltr',
+  },
+
+  o: {
+    account: {
+      label: '客户',
+      pluralLabel: '客户',
+      fields: {
+        name: { label: '客户名称' },
+        email: { label: '邮箱', placeholder: '输入邮箱地址' },
+        status: {
+          label: '状态',
+          options: {
+            active: '活跃',
+            inactive: '停用',
+          },
+        },
+      },
+      _views: {
+        all_accounts: { label: '全部客户' },
+      },
+    },
+  },
+
+  app: {
+    crm: { label: '客户关系管理' },
+  },
+
+  nav: {
+    home: '首页',
+    settings: '设置',
+  },
+
+  messages: {
+    'common.save': '保存',
+    'common.cancel': '取消',
+  },
+} satisfies AppTranslationBundle;
+```
+
+---
+
+## References
+
+- [translation.zod.ts](./references/system/translation.zod.ts) — Translation schemas (AppTranslationBundle, ObjectTranslationNode, Coverage, Diff)
+- [i18n-service.ts](./references/contracts/i18n-service.ts) — II18nService interface contract
+- [i18n.zod.ts](./references/ui/i18n.zod.ts) — UI-level i18n object schema
+- [Schema index](./references/_index.md) — All bundled schemas
+
+---
+
+## See Also
+
+- **objectstack-data** — For understanding object and field metadata structure
+- **objectstack-ui** — For view, app, and action translations
+- **objectstack-automation** — For workflow and flow message translations
diff --git a/skills/objectstack-i18n/references/_index.md b/skills/objectstack-i18n/references/_index.md
new file mode 100644
index 000000000..f3487c7a7
--- /dev/null
+++ b/skills/objectstack-i18n/references/_index.md
@@ -0,0 +1,19 @@
+# objectstack-i18n — Zod Schema Reference
+
+> **Auto-generated** by `build-skill-references.ts`.
+> These files are copied from `packages/spec/src/` for AI agent consumption.
+> Do not edit — re-run `pnpm --filter @objectstack/spec run gen:skill-refs` to update.
+
+## Core Schemas
+
+- [`system/translation.zod.ts`](./system/translation.zod.ts) — Translation schemas: AppTranslationBundle, ObjectTranslationNode, TranslationConfig, TranslationCoverageResult, TranslationDiffItem
+- [`contracts/i18n-service.ts`](./contracts/i18n-service.ts) — II18nService interface contract
+- [`ui/i18n.zod.ts`](./ui/i18n.zod.ts) — UI-level i18n object schema
+
+## Dependencies (auto-resolved)
+
+These schemas are included in the references for completeness but are primarily managed by other skills:
+
+- **objectstack-data** — Object, Field schemas (source for translation extraction)
+- **objectstack-ui** — View, App, Dashboard schemas (UI translation sources)
+- **objectstack-automation** — Flow, Workflow schemas (automation message translations)
diff --git a/skills/objectstack-i18n/references/contracts/i18n-service.ts b/skills/objectstack-i18n/references/contracts/i18n-service.ts
new file mode 100644
index 000000000..4ed79b7c9
--- /dev/null
+++ b/skills/objectstack-i18n/references/contracts/i18n-service.ts
@@ -0,0 +1,105 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { AppTranslationBundle, TranslationCoverageResult, TranslationDiffItem } from '../system/translation.zod';
+
+/**
+ * II18nService - Internationalization Service Contract
+ *
+ * Defines the interface for translation and locale management in ObjectStack.
+ * Concrete implementations (i18next, custom, etc.)
+ * should implement this interface.
+ *
+ * Follows Dependency Inversion Principle - plugins depend on this interface,
+ * not on concrete i18n library implementations.
+ *
+ * Aligned with CoreServiceName 'i18n' in core-services.zod.ts.
+ */
+
+export interface II18nService {
+    /**
+     * Translate a message key for a given locale
+     * @param key - Translation key (e.g. 'o.account.label')
+     * @param locale - BCP-47 locale code (e.g. 'en-US', 'zh-CN')
+     * @param params - Optional interpolation parameters
+     * @returns Translated string, or the key itself if not found
+     */
+    t(key: string, locale: string, params?: Record<string, unknown>): string;
+
+    /**
+     * Get all translations for a locale
+     * @param locale - BCP-47 locale code
+     * @returns Translation data map
+     */
+    getTranslations(locale: string): Record<string, unknown>;
+
+    /**
+     * Load translations for a locale
+     * @param locale - BCP-47 locale code
+     * @param translations - Translation key-value data
+     */
+    loadTranslations(locale: string, translations: Record<string, unknown>): void;
+
+    /**
+     * List available locales
+     * @returns Array of BCP-47 locale codes
+     */
+    getLocales(): string[];
+
+    /**
+     * Get the current default locale
+     * @returns BCP-47 locale code
+     */
+    getDefaultLocale?(): string;
+
+    /**
+     * Set the default locale
+     * @param locale - BCP-47 locale code
+     */
+    setDefaultLocale?(locale: string): void;
+
+    // ── Object-first aggregation & diff detection ──────────────────────
+
+    /**
+     * Get object-first translation bundle for a locale.
+     *
+     * Returns all translations aggregated under `o.{objectName}` with
+     * global groups (app, nav, dashboard, etc.) at the top level.
+     *
+     * @param locale - BCP-47 locale code
+     * @returns Object-first AppTranslationBundle, or undefined if no data
+     */
+    getAppBundle?(locale: string): AppTranslationBundle | undefined;
+
+    /**
+     * Load an object-first translation bundle for a locale.
+     *
+     * @param locale - BCP-47 locale code
+     * @param bundle - Object-first AppTranslationBundle
+     */
+    loadAppBundle?(locale: string, bundle: AppTranslationBundle): void;
+
+    /**
+     * Get translation coverage for a locale, optionally scoped to a single object.
+     *
+     * Compares the supplied (or currently loaded) translation bundle against
+     * the source metadata to detect missing, redundant, and stale entries.
+     *
+     * @param locale - BCP-47 locale code
+     * @param objectName - Optional object name to scope the check
+     * @returns Coverage result with per-key diff items
+     */
+    getCoverage?(locale: string, objectName?: string): TranslationCoverageResult;
+
+    /**
+     * Request AI-powered translation suggestions for missing or stale keys.
+     *
+     * Implementations may call an internal AI agent, external TMS, or
+     * third-party translation API. Each returned diff item should have
+     * `aiSuggested` and `aiConfidence` populated.
+     *
+     * @param locale - Target BCP-47 locale code
+     * @param items - Diff items to generate suggestions for
+     * @returns Diff items enriched with `aiSuggested` and `aiConfidence`
+     */
+    suggestTranslations?(locale: string, items: TranslationDiffItem[]): Promise<TranslationDiffItem[]>;
+}
diff --git a/skills/objectstack-i18n/references/system/translation.zod.ts b/skills/objectstack-i18n/references/system/translation.zod.ts
new file mode 100644
index 000000000..7b23b16aa
--- /dev/null
+++ b/skills/objectstack-i18n/references/system/translation.zod.ts
@@ -0,0 +1,541 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+import { z } from 'zod';
+
+// ────────────────────────────────────────────────────────────────────────────
+// Locale
+// ────────────────────────────────────────────────────────────────────────────
+
+export const LocaleSchema = z.string().describe('BCP-47 Language Tag (e.g. en-US, zh-CN)');
+
+// ────────────────────────────────────────────────────────────────────────────
+// Object-level Translation (per-object file)
+// ────────────────────────────────────────────────────────────────────────────
+
+/**
+ * Field Translation Schema
+ * Translation data for a single field.
+ */
+export const FieldTranslationSchema = z.object({
+  label: z.string().optional().describe('Translated field label'),
+  help: z.string().optional().describe('Translated help text'),
+  placeholder: z.string().optional().describe('Translated placeholder text for form inputs'),
+  options: z.record(z.string(), z.string()).optional().describe('Option value to translated label map'),
+}).describe('Translation data for a single field');
+
+export type FieldTranslation = z.infer<typeof FieldTranslationSchema>;
+
+/**
+ * Object Translation Data Schema
+ *
+ * Translation data for a **single object** in a **single locale**.
+ * Use this schema to validate per-object translation files.
+ *
+ * File convention: `i18n/{locale}/{object_name}.json`
+ *
+ * @example
+ * ```json
+ * // i18n/en/account.json
+ * {
+ *   "label": "Account",
+ *   "pluralLabel": "Accounts",
+ *   "fields": {
+ *     "name": { "label": "Account Name", "help": "Legal name" },
+ *     "type": { "label": "Type", "options": { "customer": "Customer" } }
+ *   }
+ * }
+ * ```
+ */
+export const ObjectTranslationDataSchema = z.object({
+  /** Translated singular label for the object */
+  label: z.string().describe('Translated singular label'),
+  /** Translated plural label for the object */
+  pluralLabel: z.string().optional().describe('Translated plural label'),
+  /** Field-level translations keyed by field name (snake_case) */
+  fields: z.record(z.string(), FieldTranslationSchema).optional().describe('Field-level translations'),
+}).describe('Translation data for a single object');
+
+export type ObjectTranslationData = z.infer<typeof ObjectTranslationDataSchema>;
+
+// ────────────────────────────────────────────────────────────────────────────
+// Locale-level Translation Data (per-locale aggregate)
+// ────────────────────────────────────────────────────────────────────────────
+
+/**
+ * Translation Data Schema
+ * Supports i18n for labels, messages, and options within a single locale.
+ * Example structure:
+ * ```json
+ * {
+ *   "objects": { "account": { "label": "Account" } },
+ *   "apps": { "crm": { "label": "CRM" } },
+ *   "messages": { "common.save": "Save" }
+ * }
+ * ```
+ */
+export const TranslationDataSchema = z.object({
+  /** Object translations */
+  objects: z.record(z.string(), ObjectTranslationDataSchema).optional().describe('Object translations keyed by object name'),
+  
+  /** App/Menu translations */
+  apps: z.record(z.string(), z.object({
+    label: z.string().describe('Translated app label'),
+    description: z.string().optional().describe('Translated app description'),
+  })).optional().describe('App translations keyed by app name'),
+
+  /** UI Messages */
+  messages: z.record(z.string(), z.string()).optional().describe('UI message translations keyed by message ID'),
+  
+  /** Validation Error Messages */
+  validationMessages: z.record(z.string(), z.string()).optional().describe('Translatable validation error messages keyed by rule name (e.g., {"discount_limit": "折扣不能超过40%"})'),
+}).describe('Translation data for objects, apps, and UI messages');
+
+export type TranslationData = z.infer<typeof TranslationDataSchema>;
+
+// ────────────────────────────────────────────────────────────────────────────
+// Translation Bundle (all locales)
+// ────────────────────────────────────────────────────────────────────────────
+
+export const TranslationBundleSchema = z.record(LocaleSchema, TranslationDataSchema).describe('Map of locale codes to translation data');
+
+export type TranslationBundle = z.infer<typeof TranslationBundleSchema>;
+
+// ────────────────────────────────────────────────────────────────────────────
+// File Organization Convention
+// ────────────────────────────────────────────────────────────────────────────
+
+/**
+ * Translation File Organization Strategy
+ *
+ * Defines how translation files are organized on disk.
+ *
+ * - `bundled` — All locales in a single `TranslationBundle` file.
+ *   Best for small projects with few objects.
+ *   ```
+ *   src/translations/
+ *     crm.translation.ts        # { en: {...}, "zh-CN": {...} }
+ *   ```
+ *
+ * - `per_locale` — One file per locale containing all namespaces.
+ *   Recommended when a single locale file stays under ~500 lines.
+ *   ```
+ *   src/translations/
+ *     en.ts                     # TranslationData for English
+ *     zh-CN.ts                  # TranslationData for Chinese
+ *   ```
+ *
+ * - `per_namespace` — One file per namespace (object) per locale.
+ *   Recommended for large projects with many objects/languages.
+ *   Aligns with Salesforce DX and ServiceNow conventions.
+ *   ```
+ *   i18n/
+ *     en/
+ *       account.json            # ObjectTranslationData
+ *       contact.json
+ *       common.json             # messages + app labels
+ *     zh-CN/
+ *       account.json
+ *       contact.json
+ *       common.json
+ *   ```
+ */
+export const TranslationFileOrganizationSchema = z.enum([
+  'bundled',
+  'per_locale',
+  'per_namespace',
+]).describe('Translation file organization strategy');
+
+export type TranslationFileOrganization = z.infer<typeof TranslationFileOrganizationSchema>;
+
+// ────────────────────────────────────────────────────────────────────────────
+// Translation Configuration
+// ────────────────────────────────────────────────────────────────────────────
+
+/**
+ * Translation Configuration Schema
+ *
+ * Defines internationalization settings for the stack.
+ *
+ * @example
+ * ```typescript
+ * export default defineStack({
+ *   i18n: {
+ *     defaultLocale: 'en',
+ *     supportedLocales: ['en', 'zh-CN', 'ja-JP'],
+ *     fallbackLocale: 'en',
+ *     fileOrganization: 'per_locale',
+ *   },
+ *   translations: [...],
+ * });
+ * ```
+ */
+/**
+ * Message format standard used for interpolation, pluralization, and
+ * gender-aware translations.
+ *
+ * - `icu` — ICU MessageFormat (recommended for complex plurals, gender, select).
+ *   Strings may contain `{count, plural, one {# item} other {# items}}` patterns.
+ * - `simple` — Simple `{variable}` interpolation only (default).
+ */
+export const MessageFormatSchema = z.enum([
+  'icu',
+  'simple',
+]).describe('Message interpolation format: ICU MessageFormat or simple {variable} replacement');
+
+export type MessageFormat = z.infer<typeof MessageFormatSchema>;
+
+export const TranslationConfigSchema = z.object({
+  /** Default locale for the application */
+  defaultLocale: LocaleSchema.describe('Default locale (e.g., "en")'),
+  /** Supported BCP-47 locale codes */
+  supportedLocales: z.array(LocaleSchema).describe('Supported BCP-47 locale codes'),
+  /** Fallback locale when translation is not found */
+  fallbackLocale: LocaleSchema.optional().describe('Fallback locale code'),
+  /** How translation files are organized on disk */
+  fileOrganization: TranslationFileOrganizationSchema.default('per_locale')
+    .describe('File organization strategy'),
+  /**
+   * Message interpolation format.
+   * When set to `'icu'`, messages and validationMessages are expected to use
+   * ICU MessageFormat syntax (plurals, select, number/date skeletons).
+   * @default 'simple'
+   */
+  messageFormat: MessageFormatSchema.default('simple')
+    .describe('Message interpolation format (ICU MessageFormat or simple)'),
+  /** Load translations on demand instead of eagerly */
+  lazyLoad: z.boolean().default(false).describe('Load translations on demand'),
+  /** Cache loaded translations in memory */
+  cache: z.boolean().default(true).describe('Cache loaded translations'),
+}).describe('Internationalization configuration');
+
+export type TranslationConfig = z.infer<typeof TranslationConfigSchema>;
+
+// ────────────────────────────────────────────────────────────────────────────
+// Object-First Translation Node (object-first aggregated structure)
+// ────────────────────────────────────────────────────────────────────────────
+
+/** Translatable option map: option value → translated label */
+const OptionTranslationMapSchema = z.record(z.string(), z.string())
+  .describe('Option value to translated label map');
+
+/**
+ * ObjectTranslationNodeSchema
+ *
+ * Object-first aggregated translation node that groups **all** translatable
+ * content for a single object under one key. Aligns with Salesforce / Dynamics
+ * conventions where translations are organized per-object rather than per-category.
+ *
+ * Located at `o.{object_name}` inside an {@link AppTranslationBundle}.
+ *
+ * @example
+ * ```typescript
+ * const accountNode: ObjectTranslationNode = {
+ *   label: '客户',
+ *   pluralLabel: '客户',
+ *   description: '客户管理对象',
+ *   fields: {
+ *     name: { label: '客户名称', help: '公司或组织的法定名称' },
+ *     industry: { label: '行业', options: { tech: '科技', finance: '金融' } },
+ *   },
+ *   _options: { status: { active: '活跃', inactive: '停用' } },
+ *   _views: { all_accounts: { label: '全部客户' } },
+ *   _sections: { basic_info: { label: '基本信息' } },
+ *   _actions: {
+ *     convert_lead: { label: '转换线索', confirmMessage: '确认转换？' },
+ *   },
+ * };
+ * ```
+ */
+export const ObjectTranslationNodeSchema = z.object({
+  /** Translated singular label */
+  label: z.string().describe('Translated singular label'),
+  /** Translated plural label */
+  pluralLabel: z.string().optional().describe('Translated plural label'),
+  /** Translated object description */
+  description: z.string().optional().describe('Translated object description'),
+  /** Translated help text shown in tooltips or guidance panels */
+  helpText: z.string().optional().describe('Translated help text for the object'),
+
+  /** Field-level translations keyed by field name (snake_case) */
+  fields: z.record(z.string(), FieldTranslationSchema).optional()
+    .describe('Field translations keyed by field name'),
+
+  /**
+   * Global picklist / select option overrides scoped to this object.
+   * Keyed by field name → { optionValue: translatedLabel }.
+   */
+  _options: z.record(z.string(), OptionTranslationMapSchema).optional()
+    .describe('Object-scoped picklist option translations keyed by field name'),
+
+  /** View translations keyed by view name */
+  _views: z.record(z.string(), z.object({
+    label: z.string().optional().describe('Translated view label'),
+    description: z.string().optional().describe('Translated view description'),
+  })).optional().describe('View translations keyed by view name'),
+
+  /** Section (form section / tab) translations keyed by section name */
+  _sections: z.record(z.string(), z.object({
+    label: z.string().optional().describe('Translated section label'),
+  })).optional().describe('Section translations keyed by section name'),
+
+  /** Action translations keyed by action name */
+  _actions: z.record(z.string(), z.object({
+    label: z.string().optional().describe('Translated action label'),
+    confirmMessage: z.string().optional().describe('Translated confirmation message'),
+  })).optional().describe('Action translations keyed by action name'),
+
+  /** Notification message translations keyed by notification name */
+  _notifications: z.record(z.string(), z.object({
+    title: z.string().optional().describe('Translated notification title'),
+    body: z.string().optional().describe('Translated notification body (supports ICU MessageFormat when enabled)'),
+  })).optional().describe('Notification translations keyed by notification name'),
+
+  /** Error message translations keyed by error code */
+  _errors: z.record(z.string(), z.string()).optional()
+    .describe('Error message translations keyed by error code'),
+}).describe('Object-first aggregated translation node');
+
+export type ObjectTranslationNode = z.infer<typeof ObjectTranslationNodeSchema>;
+
+// ────────────────────────────────────────────────────────────────────────────
+// App Translation Bundle (object-first, full application)
+// ────────────────────────────────────────────────────────────────────────────
+
+/**
+ * AppTranslationBundleSchema
+ *
+ * Complete application translation bundle for a **single locale** using
+ * the **object-first** convention. All per-object translatable content
+ * is aggregated under `o.{object_name}`, while global (non-object-bound)
+ * translations are kept in dedicated top-level groups.
+ *
+ * This schema is designed for:
+ * - Translation workbench UIs (object-level editing & coverage)
+ * - CLI skeleton generation (`objectstack i18n extract`)
+ * - Automated diff/coverage detection
+ *
+ * @example
+ * ```typescript
+ * const zh: AppTranslationBundle = {
+ *   o: {
+ *     account: {
+ *       label: '客户',
+ *       fields: { name: { label: '客户名称' } },
+ *       _options: { industry: { tech: '科技' } },
+ *       _views: { all_accounts: { label: '全部客户' } },
+ *       _sections: { basic_info: { label: '基本信息' } },
+ *       _actions: { convert: { label: '转换' } },
+ *     },
+ *   },
+ *   _globalOptions: { currency: { usd: '美元', eur: '欧元' } },
+ *   app: { crm: { label: '客户关系管理', description: '管理销售流程' } },
+ *   nav: { home: '首页', settings: '设置' },
+ *   dashboard: { sales_overview: { label: '销售概览' } },
+ *   reports: { pipeline_report: { label: '管道报表' } },
+ *   pages: { landing: { title: '欢迎' } },
+ *   messages: { 'common.save': '保存' },
+ *   validationMessages: { 'discount_limit': '折扣不能超过40%' },
+ * };
+ * ```
+ */
+export const AppTranslationBundleSchema = z.object({
+  /**
+   * Bundle-level metadata.
+   * Provides locale-aware rendering hints such as text direction (bidi)
+   * and the canonical locale code this bundle represents.
+   */
+  _meta: z.object({
+    /** BCP-47 locale code this bundle represents */
+    locale: z.string().optional().describe('BCP-47 locale code for this bundle'),
+    /** Text direction for the locale */
+    direction: z.enum(['ltr', 'rtl']).optional().describe('Text direction: left-to-right or right-to-left'),
+  }).optional().describe('Bundle-level metadata (locale, bidi direction)'),
+
+  /**
+   * Namespace for plugin/extension isolation.
+   * When multiple plugins contribute translations, each should use a unique
+   * namespace to avoid key collisions (e.g. "crm", "helpdesk", "plugin-xyz").
+   */
+  namespace: z.string().optional()
+    .describe('Namespace for plugin isolation to avoid translation key collisions'),
+
+  /** Object-first translations keyed by object name (snake_case) */
+  o: z.record(z.string(), ObjectTranslationNodeSchema).optional()
+    .describe('Object-first translations keyed by object name'),
+
+  /** Global picklist options not bound to any specific object */
+  _globalOptions: z.record(z.string(), OptionTranslationMapSchema).optional()
+    .describe('Global picklist option translations keyed by option set name'),
+
+  /** App-level translations */
+  app: z.record(z.string(), z.object({
+    label: z.string().describe('Translated app label'),
+    description: z.string().optional().describe('Translated app description'),
+  })).optional().describe('App translations keyed by app name'),
+
+  /** Navigation menu translations */
+  nav: z.record(z.string(), z.string()).optional()
+    .describe('Navigation item translations keyed by nav item name'),
+
+  /** Dashboard translations keyed by dashboard name */
+  dashboard: z.record(z.string(), z.object({
+    label: z.string().optional().describe('Translated dashboard label'),
+    description: z.string().optional().describe('Translated dashboard description'),
+  })).optional().describe('Dashboard translations keyed by dashboard name'),
+
+  /** Report translations keyed by report name */
+  reports: z.record(z.string(), z.object({
+    label: z.string().optional().describe('Translated report label'),
+    description: z.string().optional().describe('Translated report description'),
+  })).optional().describe('Report translations keyed by report name'),
+
+  /** Page translations keyed by page name */
+  pages: z.record(z.string(), z.object({
+    title: z.string().optional().describe('Translated page title'),
+    description: z.string().optional().describe('Translated page description'),
+  })).optional().describe('Page translations keyed by page name'),
+
+  /** UI message translations (supports ICU MessageFormat when enabled) */
+  messages: z.record(z.string(), z.string()).optional()
+    .describe('UI message translations keyed by message ID (supports ICU MessageFormat)'),
+
+  /** Validation error message translations (supports ICU MessageFormat when enabled) */
+  validationMessages: z.record(z.string(), z.string()).optional()
+    .describe('Validation error message translations keyed by rule name (supports ICU MessageFormat)'),
+
+  /** Global notification translations not bound to a specific object */
+  notifications: z.record(z.string(), z.object({
+    title: z.string().optional().describe('Translated notification title'),
+    body: z.string().optional().describe('Translated notification body (supports ICU MessageFormat when enabled)'),
+  })).optional().describe('Global notification translations keyed by notification name'),
+
+  /** Global error message translations not bound to a specific object */
+  errors: z.record(z.string(), z.string()).optional()
+    .describe('Global error message translations keyed by error code'),
+}).describe('Object-first application translation bundle for a single locale');
+
+export type AppTranslationBundle = z.infer<typeof AppTranslationBundleSchema>;
+
+// ────────────────────────────────────────────────────────────────────────────
+// Translation Diff & Coverage
+// ────────────────────────────────────────────────────────────────────────────
+
+/**
+ * Translation Diff Status
+ *
+ * Status of a single translation entry compared to the source metadata.
+ */
+export const TranslationDiffStatusSchema = z.enum([
+  'missing',
+  'redundant',
+  'stale',
+]).describe('Translation diff status: missing from bundle, redundant (no matching metadata), or stale (metadata changed)');
+
+export type TranslationDiffStatus = z.infer<typeof TranslationDiffStatusSchema>;
+
+/**
+ * TranslationDiffItemSchema
+ *
+ * Describes a single translation key that is missing, redundant, or stale
+ * relative to the source metadata. Used by CLI/API diff detection.
+ *
+ * @example
+ * ```typescript
+ * const item: TranslationDiffItem = {
+ *   key: 'o.account.fields.website.label',
+ *   status: 'missing',
+ *   objectName: 'account',
+ *   locale: 'zh-CN',
+ * };
+ * ```
+ */
+export const TranslationDiffItemSchema = z.object({
+  /** Dot-path translation key (e.g. "o.account.fields.website.label") */
+  key: z.string().describe('Dot-path translation key'),
+  /** Diff status */
+  status: TranslationDiffStatusSchema.describe('Diff status of this translation key'),
+  /** Object name if the key belongs to an object translation node */
+  objectName: z.string().optional().describe('Associated object name (snake_case)'),
+  /** Locale code */
+  locale: z.string().describe('BCP-47 locale code'),
+  /**
+   * Hash of the source metadata value at the time the translation was made.
+   * Used by CLI/Workbench to detect stale translations without a full diff.
+   */
+  sourceHash: z.string().optional().describe('Hash of source metadata for precise stale detection'),
+  /**
+   * AI-suggested translation text for missing or stale entries.
+   * Populated by AI translation hooks or TMS integrations.
+   */
+  aiSuggested: z.string().optional().describe('AI-suggested translation for this key'),
+  /** Confidence score (0-1) for the AI suggestion */
+  aiConfidence: z.number().min(0).max(1).optional().describe('AI suggestion confidence score (0–1)'),
+}).describe('A single translation diff item');
+
+export type TranslationDiffItem = z.infer<typeof TranslationDiffItemSchema>;
+
+/**
+ * TranslationCoverageResultSchema
+ *
+ * Aggregated coverage result for a locale, optionally scoped to a single object.
+ * Returned by the i18n diff detection API.
+ *
+ * @example
+ * ```typescript
+ * const result: TranslationCoverageResult = {
+ *   locale: 'zh-CN',
+ *   totalKeys: 120,
+ *   translatedKeys: 105,
+ *   missingKeys: 12,
+ *   redundantKeys: 3,
+ *   staleKeys: 0,
+ *   coveragePercent: 87.5,
+ *   items: [ ... ],
+ * };
+ * ```
+ */
+/**
+ * Per-group coverage breakdown entry.
+ */
+export const CoverageBreakdownEntrySchema = z.object({
+  /** Group category (e.g. "fields", "views", "actions", "messages") */
+  group: z.string().describe('Translation group category'),
+  /** Total translatable keys in this group */
+  totalKeys: z.number().int().nonnegative().describe('Total keys in this group'),
+  /** Number of translated keys in this group */
+  translatedKeys: z.number().int().nonnegative().describe('Translated keys in this group'),
+  /** Coverage percentage for this group */
+  coveragePercent: z.number().min(0).max(100).describe('Coverage percentage for this group'),
+}).describe('Coverage breakdown for a single translation group');
+
+export type CoverageBreakdownEntry = z.infer<typeof CoverageBreakdownEntrySchema>;
+
+export const TranslationCoverageResultSchema = z.object({
+  /** BCP-47 locale code */
+  locale: z.string().describe('BCP-47 locale code'),
+  /** Optional object name scope */
+  objectName: z.string().optional().describe('Object name scope (omit for full bundle)'),
+  /** Total translatable keys derived from metadata */
+  totalKeys: z.number().int().nonnegative().describe('Total translatable keys from metadata'),
+  /** Number of keys that have a translation */
+  translatedKeys: z.number().int().nonnegative().describe('Number of translated keys'),
+  /** Number of missing translations */
+  missingKeys: z.number().int().nonnegative().describe('Number of missing translations'),
+  /** Number of redundant (orphaned) translations */
+  redundantKeys: z.number().int().nonnegative().describe('Number of redundant translations'),
+  /** Number of stale translations */
+  staleKeys: z.number().int().nonnegative().describe('Number of stale translations'),
+  /** Coverage percentage (0-100) */
+  coveragePercent: z.number().min(0).max(100).describe('Translation coverage percentage'),
+  /** Individual diff items */
+  items: z.array(TranslationDiffItemSchema).describe('Detailed diff items'),
+  /**
+   * Per-group coverage breakdown for translation project management.
+   * Each entry represents a logical group (e.g. "fields", "views", "actions",
+   * "messages") with its own coverage statistics.
+   */
+  breakdown: z.array(CoverageBreakdownEntrySchema).optional()
+    .describe('Per-group coverage breakdown'),
+}).describe('Aggregated translation coverage result');
+
+export type TranslationCoverageResult = z.infer<typeof TranslationCoverageResultSchema>;
diff --git a/skills/objectstack-i18n/references/ui/i18n.zod.ts b/skills/objectstack-i18n/references/ui/i18n.zod.ts
new file mode 100644
index 000000000..8e6f40d38
--- /dev/null
+++ b/skills/objectstack-i18n/references/ui/i18n.zod.ts
@@ -0,0 +1,205 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+import { z } from 'zod';
+
+/**
+ * I18n Object Schema
+ * Structured internationalization label with translation key and parameters.
+ * 
+ * @example
+ * ```typescript
+ * const label: I18nObject = {
+ *   key: 'views.task_list.label',
+ *   defaultValue: 'Task List',
+ *   params: { count: 5 },
+ * };
+ * ```
+ */
+export const I18nObjectSchema = z.object({
+  /** Translation key (e.g., "views.task_list.label", "apps.crm.description") */
+  key: z.string().describe('Translation key (e.g., "views.task_list.label")'),
+
+  /** Default value when translation is not available */
+  defaultValue: z.string().optional().describe('Fallback value when translation key is not found'),
+
+  /** Interpolation parameters for dynamic translations */
+  params: z.record(z.string(), z.union([z.string(), z.number(), z.boolean()])).optional().describe('Interpolation parameters (e.g., { count: 5 })'),
+});
+
+export type I18nObject = z.infer<typeof I18nObjectSchema>;
+
+/**
+ * I18n Label Schema
+ * 
+ * A plain string label for display purposes.
+ * i18n translation keys are auto-generated by the framework at registration time
+ * based on a standardized naming convention (e.g., `apps.<packageId>.<name>.label`).
+ * Developers only need to provide the default-language string; translations are
+ * managed through translation files, not inline i18n objects.
+ * 
+ * @example
+ * ```typescript
+ * const label: I18nLabel = "All Active";
+ * ```
+ */
+export const I18nLabelSchema = z.string().describe('Display label (plain string; i18n keys are auto-generated by the framework)');
+
+export type I18nLabel = z.infer<typeof I18nLabelSchema>;
+
+/**
+ * ARIA Accessibility Properties Schema
+ * 
+ * Common ARIA attributes for UI components to support screen readers
+ * and assistive technologies.
+ * 
+ * Aligned with WAI-ARIA 1.2 specification.
+ * 
+ * @see https://www.w3.org/TR/wai-aria-1.2/
+ * 
+ * @example
+ * ```typescript
+ * const aria: AriaProps = {
+ *   ariaLabel: 'Close dialog',
+ *   ariaDescribedBy: 'dialog-description',
+ *   role: 'dialog',
+ * };
+ * ```
+ */
+export const AriaPropsSchema = z.object({
+  /** Accessible label for screen readers */
+  ariaLabel: I18nLabelSchema.optional().describe('Accessible label for screen readers (WAI-ARIA aria-label)'),
+
+  /** ID of element that describes this component */
+  ariaDescribedBy: z.string().optional().describe('ID of element providing additional description (WAI-ARIA aria-describedby)'),
+
+  /** WAI-ARIA role override */
+  role: z.string().optional().describe('WAI-ARIA role attribute (e.g., "dialog", "navigation", "alert")'),
+}).describe('ARIA accessibility attributes');
+
+export type AriaProps = z.infer<typeof AriaPropsSchema>;
+
+/**
+ * Plural Rule Schema
+ *
+ * Defines plural forms for a translation key, following ICU MessageFormat / i18next conventions.
+ * Supports zero, one, two, few, many, other forms per CLDR plural rules.
+ *
+ * @see https://unicode.org/reports/tr35/tr35-numbers.html#Language_Plural_Rules
+ *
+ * @example
+ * ```typescript
+ * const plural: PluralRule = {
+ *   key: 'items.count',
+ *   zero: 'No items',
+ *   one: '{count} item',
+ *   other: '{count} items',
+ * };
+ * ```
+ */
+export const PluralRuleSchema = z.object({
+  /** Translation key for the plural form */
+  key: z.string().describe('Translation key'),
+  /** Form for zero quantity */
+  zero: z.string().optional().describe('Zero form (e.g., "No items")'),
+  /** Form for singular (1) */
+  one: z.string().optional().describe('Singular form (e.g., "{count} item")'),
+  /** Form for dual (2) — used in Arabic, Welsh, etc. */
+  two: z.string().optional().describe('Dual form (e.g., "{count} items" for exactly 2)'),
+  /** Form for few (2-4 in Slavic languages) */
+  few: z.string().optional().describe('Few form (e.g., for 2-4 in some languages)'),
+  /** Form for many (5+ in Slavic languages) */
+  many: z.string().optional().describe('Many form (e.g., for 5+ in some languages)'),
+  /** Default/fallback form */
+  other: z.string().describe('Default plural form (e.g., "{count} items")'),
+}).describe('ICU plural rules for a translation key');
+
+export type PluralRule = z.infer<typeof PluralRuleSchema>;
+
+/**
+ * Number Format Schema
+ *
+ * Defines number formatting rules for localization.
+ *
+ * @example
+ * ```typescript
+ * const format: NumberFormat = {
+ *   style: 'currency',
+ *   currency: 'USD',
+ *   minimumFractionDigits: 2,
+ * };
+ * ```
+ */
+export const NumberFormatSchema = z.object({
+  style: z.enum(['decimal', 'currency', 'percent', 'unit']).default('decimal')
+    .describe('Number formatting style'),
+  currency: z.string().optional().describe('ISO 4217 currency code (e.g., "USD", "EUR")'),
+  unit: z.string().optional().describe('Unit for unit formatting (e.g., "kilometer", "liter")'),
+  minimumFractionDigits: z.number().optional().describe('Minimum number of fraction digits'),
+  maximumFractionDigits: z.number().optional().describe('Maximum number of fraction digits'),
+  useGrouping: z.boolean().optional().describe('Whether to use grouping separators (e.g., 1,000)'),
+}).describe('Number formatting rules');
+
+export type NumberFormat = z.infer<typeof NumberFormatSchema>;
+
+/**
+ * Date Format Schema
+ *
+ * Defines date/time formatting rules for localization.
+ *
+ * @example
+ * ```typescript
+ * const format: DateFormat = {
+ *   dateStyle: 'medium',
+ *   timeStyle: 'short',
+ *   timeZone: 'America/New_York',
+ * };
+ * ```
+ */
+export const DateFormatSchema = z.object({
+  dateStyle: z.enum(['full', 'long', 'medium', 'short']).optional()
+    .describe('Date display style'),
+  timeStyle: z.enum(['full', 'long', 'medium', 'short']).optional()
+    .describe('Time display style'),
+  timeZone: z.string().optional().describe('IANA time zone (e.g., "America/New_York")'),
+  hour12: z.boolean().optional().describe('Use 12-hour format'),
+}).describe('Date/time formatting rules');
+
+export type DateFormat = z.infer<typeof DateFormatSchema>;
+
+/**
+ * Locale Configuration Schema
+ *
+ * Defines a complete locale configuration including language code,
+ * fallback chain, and formatting preferences.
+ *
+ * @example
+ * ```typescript
+ * const locale: LocaleConfig = {
+ *   code: 'zh-CN',
+ *   fallbackChain: ['zh-TW', 'en'],
+ *   direction: 'ltr',
+ *   numberFormat: { style: 'decimal', useGrouping: true },
+ *   dateFormat: { dateStyle: 'medium', timeStyle: 'short' },
+ * };
+ * ```
+ */
+export const LocaleConfigSchema = z.object({
+  /** BCP 47 language code (e.g., "en-US", "zh-CN", "ar-SA") */
+  code: z.string().describe('BCP 47 language code (e.g., "en-US", "zh-CN")'),
+
+  /** Ordered fallback chain for missing translations */
+  fallbackChain: z.array(z.string()).optional()
+    .describe('Fallback language codes in priority order (e.g., ["zh-TW", "en"])'),
+
+  /** Text direction */
+  direction: z.enum(['ltr', 'rtl']).default('ltr')
+    .describe('Text direction: left-to-right or right-to-left'),
+
+  /** Default number formatting */
+  numberFormat: NumberFormatSchema.optional().describe('Default number formatting rules'),
+
+  /** Default date formatting */
+  dateFormat: DateFormatSchema.optional().describe('Default date/time formatting rules'),
+}).describe('Locale configuration');
+
+export type LocaleConfig = z.infer<typeof LocaleConfigSchema>;