This is a Hyperclay-compatible HTML editor application that provides secure email-based authentication for editing HTML documents with version control. The app serves both as a public viewer and an authenticated editor interface.

• Storage: Uses Val.town blob storage for persistence
• Versioning: Automatic version history with incremental numbering
• Default Content: Falls back to a Hyperclay starter template when no content exists
• Reset Capability: Admin can reset to default state (dangerous operation)

• Magic Link Auth: Email-based passwordless authentication
• Admin-Only Access: Only the configured admin email can authenticate
• Session Management: 30-day sessions with automatic extension
• Token Security: 15-minute expiring one-time-use tokens

• Edit Mode Cookies: Sets currentResource and isAdminOfCurrentResource cookies for authenticated admins
• Security: Server-side cookie setting with proper security attributes
• View Mode: Cookie clearing for public viewing

The application uses the Hono.js web framework for:

• Declarative routing (app.get(), app.post())
• Built-in cookie management (setCookie, getCookie, deleteCookie)
• Middleware support for authentication
• Consistent error handling

Blob Keys:
- `${APP_NAMESPACE}_app` - Current HTML document
- `${APP_NAMESPACE}_app_version_${n}` - Versioned HTML documents
- `${APP_NAMESPACE}_app_version_count` - Version counter
- `${APP_NAMESPACE}_auth_token_${token}` - Magic link tokens (15min TTL)
- `${APP_NAMESPACE}_session_${sessionId}` - User sessions (30day TTL)

• ADMIN_EMAIL - Email address allowed to authenticate (required)
• APP_NAMESPACE - Storage namespace prefix (default: 'default')
• DEBUG - Enable debug logging (default: false)

• Session Cookie: session=${sessionId} - HttpOnly, Secure, 30-day expiry
• Hyperclay Cookies (admin only):
  • currentResource=app - Identifies the resource being edited
  • isAdminOfCurrentResource=true - Enables Hyperclay edit mode

server.js (654 lines)
├── Configuration (lines 1-43)
│   ├── Imports (Hono, Val.town services)
│   ├── Environment variables
│   └── STORAGE_KEYS object
│
├── Core Services (lines 45-162)
│   ├── readBlob() - Unified blob reading
│   └── auth object - All authentication logic
│
├── Templates & Helpers (lines 164-358)
│   ├── TEMPLATES - HTML templates
│   ├── respond - Response helpers
│   └── handleAsync - Error wrapper
│
├── Application Logic (lines 380-443)
│   ├── sendMagicLink()
│   ├── getCurrentHTML()
│   ├── saveHTML()
│   └── getVersionHistory()
│
├── Middleware (lines 459-486)
│   └── requireAdmin - Protected routes
│
└── Routes (lines 490-651)
    ├── GET / - Main application
    ├── Auth endpoints (/auth/*)
    ├── POST /save/app - Save content
    ├── GET /versions - History
    └── GET /reset-dangerous - Reset

1. GET / - Serve HTML document

   • Check admin status from session cookie
   • Set Hyperclay cookies if admin
   • Return HTML content with no-cache headers

2. GET /auth/edit - Show email login form

3. POST /auth/edit - Process email submission

   • Validate admin email
   • Generate magic link token
   • Send email with magic link
   • Show confirmation page

4. GET /auth/verify?token=xxx - Verify magic link

   • Validate and consume token
   • Create session
   • Set session cookie
   • Redirect to main page

5. GET /auth/logout - Logout/view mode

   • Clear all cookies
   • Redirect to main page

6. POST /save/app - Save HTML document

   • Verify admin session
   • Validate HTML content
   • Save with versioning
   • Return success response

7. GET /versions - View version history

   • Verify admin session
   • Display all versions with HTML preview

8. GET /reset-dangerous - Reset to default

   • Verify admin session
   • Clear all versions and content
   • Reset to default HTML
   • Set message cookie and redirect

User enters email → Generate token → Send magic link → User clicks link
                                                         ↓
Session cookie set ← Create session ← Verify token ← Token consumed

• Public Access: View HTML document, access auth forms
• Admin Access: Save content, view versions, reset state
• Session Validation: Every admin operation checks session validity

• HttpOnly: Session cookies not accessible to JavaScript
• Secure: Only transmitted over HTTPS
• SameSite=Lax: CSRF protection
• Cache-Control: no-cache, no-store, must-revalidate

const STORAGE_KEYS = {
  app: `${APP_NAMESPACE}_app`,
  version: (n) => `${APP_NAMESPACE}_app_version_${n}`,
  versionCount: `${APP_NAMESPACE}_app_version_count`,
  token: (token) => `${APP_NAMESPACE}_auth_token_${token}`,
  session: (id) => `${APP_NAMESPACE}_session_${id}`,
};

const readBlob = async (key) => {
  const response = await blob.get(key);
  if (!response) return null;
  if (response instanceof Response) return await response.text();
  if (typeof response === "string") return response;
  return null;
};

const auth = {
  generateToken: () => crypto.randomUUID(),
  storeToken: async (token, email) => {/* ... */},
  verifyToken: async (token) => {/* ... */},
  createSession: async (email) => {/* ... */},
  verifySession: async (sessionId) => {/* ... */},
};

const TEMPLATES = {
  loginForm: (error?) => `/* HTML */`,
  checkEmail: (email) => `/* HTML */`,
  invalidToken: () => `/* HTML */`,
  versionHistory: (versions) => `/* HTML */`,
};

const respond = {
  error: (c, msg, status) => c.json({ msg, msgType: "error" }, status),
  success: (c, msg) => c.json({ msg, msgType: "success" }),
  unauthorized: (c) => c.json({ msg: "Unauthorized", msgType: "error" }, 401),
  setSessionCookie: (c, sessionId) => {/* ... */},
  setAdminCookies: (c) => {/* ... */},
};

const handleAsync = (handler) => async (c, next) => {
  try {
    return await handler(c, next);
  } catch (error) {
    // Centralized error handling
  }
};

• Blob Storage: Efficient key-value store for HTML content
• Session Extension: Automatic extension reduces re-authentication
• Version Limit: No built-in limit (consider implementing cleanup)
• Cache Headers: Prevents stale content with no-cache, no-store

• Runtime: Deno with TypeScript support
• Hosting: Serverless with automatic scaling
• Storage: Built-in blob storage (10MB free, 1GB pro)
• Email: Integrated email service for magic links
• URL Pattern: https://[username]-[valname].web.val.run

1. Multi-tenancy: Support multiple admin users
2. Version Cleanup: Automatic old version deletion
3. Backup/Export: Download HTML and version history
4. Rate Limiting: Prevent abuse of auth endpoints
5. Audit Logging: Track all admin actions