# Backend Structure Plan

## Directory Structure
```
backend/
├── app.py                 # Flask application entry point
├── config.py              # Configuration settings
├── requirements.txt       # Python dependencies
├── .env                   # Environment variables
├── models/                # Database models
│   ├── __init__.py
│   ├── user.py            # User model
│   ├── social_account.py  # Social media account model
│   ├── source.py          # RSS source model
│   ├── post.py            # Post content model
│   └── schedule.py        # Scheduling model
├── api/                   # API endpoints
│   ├── __init__.py
│   ├── auth.py            # Authentication endpoints
│   ├── sources.py         # Source management endpoints
│   ├── accounts.py        # Social account endpoints
│   ├── posts.py           # Post management endpoints
│   └── schedules.py       # Scheduling endpoints
├── services/              # Business logic
│   ├── __init__.py
│   ├── auth_service.py    # Authentication service
│   ├── linkedin_service.py# LinkedIn integration service
│   ├── content_service.py # Content generation service
│   └── schedule_service.py# Scheduling service
├── utils/                 # Utility functions
│   ├── __init__.py
│   ├── database.py        # Database connection
│   └── helpers.py         # Helper functions
└── scheduler/             # Task scheduling
    ├── __init__.py
    └── task_scheduler.py  # Scheduling implementation
```

## Key Components

### app.py
- Flask application initialization
- Configuration loading
- Blueprint registration
- CORS setup
- Error handlers

### config.py
- Environment-based configuration
- Database settings
- API keys and secrets
- Scheduler settings

### models/
- SQLAlchemy models for all database entities
- Relationship definitions
- Validation logic

### api/
- RESTful endpoints for all features
- Request validation
- Response formatting
- Authentication middleware

### services/
- Business logic implementation
- External API integrations
- Data processing and transformation

### utils/
- Database connection management
- Helper functions for common operations
- Error handling utilities

### scheduler/
- APScheduler implementation
- Task scheduling and execution
- Conflict resolution