diff --git a/CLAUDE.md b/CLAUDE.md
index 182d249..244c55b 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -4,13 +4,15 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## Project Overview
 
-Taiwan NPO (Non-Profit Organization) management platform built with Laravel 10 (PHP 8.1+). Features member lifecycle management, multi-tier financial approval workflows, issue tracking, and document management. UI is in Traditional Chinese. Currency is TWD (NT$).
+Taiwan NPO (Non-Profit Organization) management platform built with Laravel 10 (PHP 8.1+). Features member lifecycle management, multi-tier financial approval workflows, issue tracking, CMS with headless API, and document management. UI is in Traditional Chinese. Currency is TWD (NT$).
+
+A companion Next.js frontend (`usher-site`) consumes the headless CMS API for the public website.
 
 ## Commands
 
 ```bash
 # Development
-php artisan serve && npm run dev    # Start both servers
+php artisan serve --port=8001 && npm run dev    # Start both servers (port 8000 often occupied)
 
 # Testing
 php artisan test                              # Run all tests
@@ -38,17 +40,56 @@ php artisan db:seed --class=FinancialWorkflowTestDataSeeder  # Finance test data
 
 ## Architecture
 
+### Dual Role: Admin App + Headless CMS API
+
+This app serves two purposes:
+1. **Admin app** — Blade-based UI at `/admin/*` for internal management (members, finance, issues, CMS)
+2. **Headless CMS API** — JSON API at `/api/v1/*` consumed by the Next.js public site
+
 ### Route Structure
 
-Routes split across `routes/web.php` and `routes/auth.php`. Admin routes use group pattern:
+Routes split across `routes/web.php`, `routes/auth.php`, and `routes/api.php`.
+
+**Admin routes** use group pattern:
 ```php
 Route::middleware(['auth', 'admin'])->prefix('admin')->name('admin.')->group(...)
 ```
-- **Public**: `/register/member`, `/documents`
+- **Public**: `/register/member` (controlled by `REGISTRATION_ENABLED` env), `/documents`
 - **Member** (auth only): dashboard, payment submission
 - **Admin** (auth + admin): `/admin/*` with `admin.{module}.{action}` named routes
 
-The `admin` middleware (`EnsureUserIsAdmin`) allows access if user has `admin` role OR any permissions at all.
+The `admin` middleware (`EnsureUserIsAdmin`) allows access if user has `admin` role OR any permissions at all. A separate `CheckPaidMembership` middleware gates member-only features.
+
+**API routes** (`/api/v1/*`):
+- `GET /articles` — paginated, filter by type/category/tag/search
+- `GET /articles/{slug}` — detail with related articles
+- `GET /categories` — all categories with article counts
+- `GET /pages/{slug}` — page with hierarchical children
+- `GET /homepage` — aggregated homepage data (featured, latest by type, about, categories)
+- `GET /public-documents` — document library with search/filter
+- `GET /public-documents/{uuid}` — document detail by UUID
+
+**API response wrapping**: Single resources are wrapped in `{ "data": {...} }`. The homepage endpoint is NOT wrapped. Collections use Laravel pagination.
+
+### CMS Content Models
+
+**Article** — 4 content types (`news`, `notice`, `column`, `activity`), 4 access levels (`public`, `members`, `board`, `admin`), 3 statuses (`draft`, `published`, `archived`). Supports scheduled publishing (`published_at`), expiration (`expires_at`), pinning (`display_order`), EasyMDE markdown editor, and file attachments.
+
+**Page** — Hierarchical parent/child pages with custom fields (JSON), optional template field. Used for static content like "About Us".
+
+**Document** — Versioned document library with auto-generated `public_uuid` for shareable URLs. Semantic versioning (1.0, 1.1...), SHA256 file integrity, access levels, auto-archive on expiry. QR code generation at `/documents/{uuid}/qrcode`.
+
+Common query scopes across content models: `active()`, `published()`, `forAccessLevel(?User)`, `pinned()`, `byContentType($type)`.
+
+### Next.js Static Site Integration
+
+The public site is fully static after `next build`. Laravel triggers cache revalidation on content changes:
+
+- `SiteRevalidationService::revalidateArticle($slug)` — called in admin CMS controllers after publish/update
+- `SiteRevalidationService::revalidateDocument($slug)` — called via `DocumentObserver` on CRUD
+- Config in `config/services.php` → `nextjs.revalidate_url`, `nextjs.revalidate_token`
+- `SiteAssetSyncService` copies uploads to the Next.js `public/` directory for static serving
+- CORS allows `usher.org.tw`, `localhost:3000`, `*.vercel.app` (see `config/cors.php`)
 
 ### Multi-Tier Approval Workflows
 
@@ -81,27 +122,33 @@ Complex business logic in `app/Services/`:
 - `SettingsService`: System-wide settings with caching
 - `FinanceDocumentApprovalService`: Multi-tier approval orchestration
 - `PaymentVerificationService`: Payment workflow coordination
+- `SiteRevalidationService`: Next.js cache invalidation webhook
+- `SiteAssetSyncService`: Copy uploads to Next.js `public/` for static serving
 
 Global helper: `settings('key')` returns cached setting values (defined in `app/helpers.php`, autoloaded).
 
 ### RBAC Structure
 
-Uses Spatie Laravel Permission. Core financial roles:
-- `finance_requester`, `finance_cashier`, `finance_accountant`, `finance_chair`, `finance_board_member`
+Uses Spatie Laravel Permission. Core roles:
+- **Financial**: `finance_requester`, `finance_cashier`, `finance_accountant`, `finance_chair`, `finance_board_member`
+- **CMS**: `secretary_general` (full CMS), `membership_manager` (article management)
+- `admin` role has full access
+
+CMS permissions: `view/create/edit/delete/publish_articles`, `manage_all_articles`, plus equivalents for pages and announcements.
 
 Permission checks: `$user->can('permission-name')` or `@can('permission-name')` in Blade.
 
 ### Data Security Patterns
 
 - **National ID**: AES-256 encrypted (`national_id_encrypted`), SHA256 hashed for search (`national_id_hash`), virtual accessor `national_id` decrypts on read
-- **File uploads**: Private disk storage, served via authenticated controller
-- **Audit logging**: `AuditLogger::log($action, $auditable, $metadata)` — static class, call in controllers
+- **File uploads**: Private disk storage, served via authenticated controller. `DownloadFile` helper handles RFC 5987 UTF-8 filenames (Chinese filename support)
+- **Audit logging**: `AuditLogger::log($action, $auditable, $metadata)` — static class, call in controllers (not automatic via observers)
 
 ### Member Lifecycle
 
 States: `pending` → `active` → `expired` / `suspended`
 
-Identity types: `patient`, `parent`, `social`, `other` (病友/家長分類). Members can have `guardian_member_id` for parent-child relationships.
+Identity types: `patient`, `parent`, `social`, `other` (病友/家長分類). Members can have `guardian_member_id` for parent-child relationships. Members have optional `line_id` for LINE messaging.
 
 ```php
 $member->hasPaidMembership()   // Active with future expiry
@@ -109,6 +156,12 @@ $member->canSubmitPayment()    // Pending with no pending payment
 $member->getNextFeeType()      // entrance_fee or annual_fee
 ```
 
+Public registration controlled by `REGISTRATION_ENABLED` env var — when disabled, existing members can still login but `/register/member` routes are not registered.
+
+### Issue Tracking
+
+Built-in issue tracker with auto-generated numbers (`ISS-{year}-{seq}`). Statuses: `new` → `assigned` → `in_progress` → `review` → `closed`. Types: `work_item`, `project_task`, `maintenance`, `member_request`. Supports parent/child relationships, time logging (estimated vs actual hours), and member association.
+
 ### Conventions
 
 - **Status values**: Defined as class constants (e.g., `FinanceDocument::STATUS_PENDING`), not enums or magic strings
@@ -116,13 +169,15 @@ $member->getNextFeeType()      // entrance_fee or annual_fee
 - **DB transactions**: Used in controllers for multi-step operations
 - **UI text**: Hardcoded Traditional Chinese strings (no `__()` translation layer)
 - **Dark mode**: Supported throughout — use `dark:` Tailwind prefix for styles
+- **Blade stacks**: `@stack('styles')` in `<head>` and `@stack('scripts')` before `</body>` for page-specific assets (EasyMDE, charts, etc.)
 
 ### Custom Artisan Commands
 
 - `assign:role` — Manual role assignment
-- `import:members` / `import:accounting-data` / `import:documents` — Bulk imports
+- `import:members` / `import:accounting-data` / `import:documents` / `import:article-documents` — Bulk imports
 - `send:membership-expiry-reminders` — Automated email notifications
-- `archive:expired-documents` — Document lifecycle cleanup
+- `documents:archive-expired` — Auto-archive documents past expiry (respects `auto_archive_on_expiry` flag)
+- `nextjs:push-assets` — Manual trigger for git push of synced assets to Next.js repo
 
 ### Testing Patterns
 
@@ -145,11 +200,17 @@ Test accounts (password: `password`):
 ## Key Files
 
 - `routes/web.php` — All web routes (admin routes under `/admin` prefix)
+- `routes/api.php` — Headless CMS API v1 routes
 - `config/accounting.php` — Account codes, amount tier thresholds, currency settings
+- `config/services.php` → `nextjs` — Next.js integration config (revalidation, asset sync)
+- `config/cors.php` — CORS allowed origins for API
 - `app/Models/FinanceDocument.php` — Core financial workflow logic with 27+ status constants
 - `app/Models/Member.php` — Member lifecycle with encrypted field handling
+- `app/Models/Article.php` — CMS article with content types, access levels, scopes
+- `app/Models/Document.php` — Versioned document library with UUID access
 - `app/Traits/HasApprovalWorkflow.php` — Shared multi-tier approval behavior
 - `app/Traits/HasAccountingEntries.php` — Double-entry bookkeeping behavior
+- `app/Services/SiteRevalidationService.php` — Next.js revalidation webhook
 - `app/helpers.php` — Global `settings()` helper (autoloaded via composer)
 - `database/seeders/` — RoleSeeder, ChartOfAccountSeeder, TestDataSeeder
 - `docs/SYSTEM_SPECIFICATION.md` — Complete system specification