# Authentication System Fix Summary

## Issues Fixed

The original authentication system had several critical security and functionality issues:

### 1. **Client-side Only Authentication**
- **Problem**: No server-side user database or password verification
- **Solution**: Implemented complete server-side user authentication with persistent storage

### 2. **Device-based Storage**
- **Problem**: Apps were linked to localStorage user IDs rather than actual accounts
- **Solution**: Server-side user database with proper session management

### 3. **No Password Persistence**
- **Problem**: Passwords were never stored or validated server-side
- **Solution**: bcrypt password hashing with persistent storage

### 4. **Account ID Computation**
- **Problem**: Used email hash but didn't verify credentials
- **Solution**: Server assigns and returns authenticated user IDs

## Implementation Details

### 1. **Server-Side Dependencies Added**
```json
{
  "dependencies": {
    "bcrypt": "^5.1.1",
    "jsonwebtoken": "^9.0.2"
  }
}
```

### 2. **User Database Structure**
- **File**: `.data/.opencode-chat/users.json`
- **Format**: Array of user objects with hashed passwords
- **User Schema**:
  ```javascript
  {
    id: "uuid",
    email: "normalized-lowercase-email",
    password: "bcrypt-hashed-password",
    createdAt: "ISO-timestamp",
    lastLoginAt: "ISO-timestamp"
  }
  ```

### 3. **New API Endpoints**

#### User Registration
- **Endpoint**: `POST /api/register`
- **Payload**: `{ email, password }`
- **Response**: `{ ok: true, user: { id, email }, token, expiresAt }`
- **Validates**: Email format, password strength (6+ chars), unique email

#### User Login
- **Endpoint**: `POST /api/login`
- **Payload**: `{ email, password }`
- **Response**: `{ ok: true, user: { id, email }, token, expiresAt }`
- **Validates**: Password against stored bcrypt hash

#### User Session Management
- **Endpoint**: `GET /api/me` - Get current user info
- **Endpoint**: `POST /api/logout` - End user session

#### Secure Account Migration
- **Endpoint**: `POST /api/account/claim`
- **Requires**: Valid user authentication
- **Migrates**: Device apps to authenticated user account

### 4. **Session Token System**
- **Storage**: HTTP-only cookies + JWT tokens
- **Expiration**: 30 days (configurable)
- **Security**: bcrypt password hashing (12 rounds)
- **Validation**: Server-side token verification

### 5. **Client-Side Updates**

#### Enhanced Login Flow
- Tries server authentication first
- Stores session tokens in localStorage
- Falls back to old system for backwards compatibility
- Proper error handling and user feedback

#### Enhanced Registration Flow
- Server-side validation
- Immediate account creation and login
- Device app migration
- Password strength validation

#### API Request Enhancement
- Automatically includes session tokens
- Handles 401 responses by redirecting to login
- Maintains backwards compatibility with device-based auth

### 6. **Environment Configuration**

#### Required Environment Variables
```bash
# User authentication (recommended)
USER_SESSION_SECRET=your-secure-random-secret
USER_SESSION_TTL_MS=2592000000  # 30 days in milliseconds

# Optional overrides
PASSWORD_SALT_ROUNDS=12  # bcrypt rounds (default: 12)
```

#### Security Notes
- Default session secret is provided but should be overridden in production
- All passwords are hashed with bcrypt (12 rounds by default)
- Session tokens expire after 30 days
- Secure cookies in production (set COOKIE_SECURE=1)

### 7. **Backwards Compatibility**
- Old device-based authentication still works
- Gradual migration from client-side to server-side auth
- Account claiming works for both old and new accounts
- Existing apps continue to function

## Security Improvements

### 1. **Password Security**
- bcrypt hashing with 12 salt rounds
- Never store plaintext passwords
- Password strength validation

### 2. **Session Security**
- HTTP-only cookies prevent XSS attacks
- SameSite cookie protection
- Session token expiration
- Server-side token validation

### 3. **API Security**
- Authentication required for sensitive operations
- Proper error handling without information leakage
- Secure account migration process

## Testing

### 1. **Dependencies Test**
```bash
cd /home/engine/project/chat
node -e "const bcrypt = require('bcrypt'); console.log('bcrypt works:', bcrypt.hashSync('test', 12).length)"
```

### 2. **Server Startup**
```bash
cd /home/engine/project/chat
node server.js
# Should create users.json file in .data/.opencode-chat/
```

### 3. **API Testing**
```bash
# Register user
curl -X POST http://localhost:4000/api/register \
  -H "Content-Type: application/json" \
  -d '{"email":"test@example.com","password":"password123"}'

# Login user
curl -X POST http://localhost:4000/api/login \
  -H "Content-Type: application/json" \
  -d '{"email":"test@example.com","password":"password123"}'
```

## Migration Guide

### For Existing Users
1. **Automatic**: Old accounts continue to work with device-based auth
2. **Upgrade**: Users can register/login with the same email to upgrade
3. **Migration**: Apps automatically migrate to new authenticated account

### For Developers
1. **Update Environment**: Set `USER_SESSION_SECRET` for production
2. **Test Authentication**: Verify login/registration flows work
3. **Monitor Logs**: Watch for authentication events in logs

## Files Modified

### Server Changes
- `chat/server.js`: Complete authentication system implementation
- `chat/package.json`: Added bcrypt and jsonwebtoken dependencies

### Client Changes
- `chat/public/login.html`: Enhanced with server authentication
- `chat/public/signup.html`: Enhanced with server registration
- `chat/public/app.js`: Enhanced API calls with session tokens

## Summary

The authentication system has been completely overhauled from a client-side only system to a secure, server-side authentication system with:

- ✅ Persistent user database
- ✅ Secure password hashing
- ✅ Session token management
- ✅ Backwards compatibility
- ✅ Enhanced security
- ✅ Proper error handling

The system now properly supports user accounts that work across devices and browsers, with secure authentication and session management.