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+# MOC Auto-Generation Feature
+
+## Overview
+
+The LEGO Instructions Manager now includes automatic MOC (My Own Creation) set number generation, making it easier to track and organize your custom LEGO builds without manually managing set numbers.
+
+## Features
+
+### 🤖 Automatic Number Generation
+- **Sequential Numbering**: Automatically generates MOC numbers in sequence (MOC-10000, MOC-10001, MOC-10002, etc.)
+- **Conflict-Free**: Ensures no duplicate MOC numbers
+- **Customizable Prefix**: Default is "MOC" but can be changed
+- **User-Scoped Option**: Can scope MOC numbers per user or globally
+
+### 🔌 API Endpoints
+
+#### 1. Generate Next MOC Number
+```
+GET /api/moc/generate
+```
+
+**Query Parameters:**
+- `prefix` (optional): MOC prefix, default is 'MOC'
+- `user_scoped` (optional): Scope to current user, default is 'true'
+
+**Response:**
+```json
+{
+  "success": true,
+  "moc_number": "MOC-10001",
+  "prefix": "MOC",
+  "user_scoped": true
+}
+```
+
+**Example Usage:**
+```javascript
+fetch('/api/moc/generate')
+  .then(response => response.json())
+  .then(data => {
+    console.log('Next MOC number:', data.moc_number);
+  });
+```
+
+#### 2. Validate MOC Number
+```
+POST /api/moc/validate
+```
+
+**Request Body:**
+```json
+{
+  "set_number": "MOC-12345",
+  "user_scoped": true
+}
+```
+
+**Response:**
+```json
+{
+  "success": true,
+  "available": true,
+  "set_number": "MOC-12345"
+}
+```
+
+#### 3. Check MOC Format
+```
+GET /api/moc/check-format?set_number=MOC-10001&prefix=MOC
+```
+
+**Response:**
+```json
+{
+  "is_moc": true,
+  "set_number": "MOC-10001",
+  "prefix": "MOC"
+}
+```
+
+## Database Schema
+
+The `Set` model includes MOC support fields:
+
+```python
+is_moc = db.Column(db.Boolean, default=False, nullable=False, index=True)
+moc_designer = db.Column(db.String(100), nullable=True)  # Designer/creator name
+moc_description = db.Column(db.Text, nullable=True)      # Detailed description
+```
+
+## Frontend Integration
+
+### HTML Form Example
+
+When creating a new set, users can toggle MOC mode:
+
+```html
+<div class="form-check form-switch mb-3">
+    <input class="form-check-input" type="checkbox" id="is_moc" name="is_moc">
+    <label class="form-check-label" for="is_moc">
+        <strong>This is a MOC (My Own Creation)</strong>
+    </label>
+</div>
+
+<div id="mocSection" style="display: none;">
+    <div class="alert alert-success">
+        <i class="bi bi-lightbulb"></i> 
+        MOC set number will be auto-generated: 
+        <strong id="mocNumberPreview">Loading...</strong>
+    </div>
+</div>
+
+<div id="officialSection">
+    <label for="set_number">Set Number</label>
+    <input type="text" id="set_number" name="set_number" required>
+</div>
+```
+
+### JavaScript Integration
+
+```javascript
+// Handle MOC toggle
+document.getElementById('is_moc').addEventListener('change', function() {
+    const mocSection = document.getElementById('mocSection');
+    const officialSection = document.getElementById('officialSection');
+    const setNumberInput = document.getElementById('set_number');
+    
+    if (this.checked) {
+        // Show MOC section, hide official section
+        mocSection.style.display = 'block';
+        officialSection.style.display = 'none';
+        setNumberInput.removeAttribute('required');
+        
+        // Fetch next MOC number
+        fetchNextMocNumber();
+    } else {
+        // Show official section, hide MOC section
+        mocSection.style.display = 'none';
+        officialSection.style.display = 'block';
+        setNumberInput.setAttribute('required', 'required');
+    }
+});
+
+// Fetch next MOC number from API
+function fetchNextMocNumber() {
+    fetch('/api/moc/generate')
+        .then(response => response.json())
+        .then(data => {
+            if (data.success) {
+                document.getElementById('mocNumberPreview').textContent = data.moc_number;
+                // Optionally store in hidden field
+                document.getElementById('moc_number_hidden').value = data.moc_number;
+            }
+        })
+        .catch(error => {
+            console.error('Error fetching MOC number:', error);
+            document.getElementById('mocNumberPreview').textContent = 'Error generating number';
+        });
+}
+```
+
+## Backend Implementation
+
+### Service Layer
+
+The `MOCNumberGenerator` service handles all MOC number logic:
+
+```python
+from app.services.moc_generator import MOCNumberGenerator
+
+# Generate next MOC number
+moc_number = MOCNumberGenerator.generate_next_number(
+    prefix='MOC',
+    user_id=current_user.id  # Optional: scope to user
+)
+
+# Validate MOC number availability
+is_available = MOCNumberGenerator.validate_moc_number(
+    'MOC-12345',
+    user_id=current_user.id
+)
+
+# Check if number follows MOC format
+is_moc = MOCNumberGenerator.is_moc_number('MOC-10001')
+```
+
+### Route Layer
+
+MOC routes are organized in `app/routes/moc.py`:
+
+```python
+from flask import Blueprint, jsonify
+from flask_login import login_required, current_user
+from app.services.moc_generator import MOCNumberGenerator
+
+bp = Blueprint('moc', __name__, url_prefix='/api/moc')
+
+@bp.route('/generate', methods=['GET'])
+@login_required
+def generate_moc_number():
+    moc_number = MOCNumberGenerator.generate_next_number(
+        user_id=current_user.id
+    )
+    return jsonify({
+        'success': True,
+        'moc_number': moc_number
+    })
+```
+
+## Configuration
+
+### Customizing MOC Prefix
+
+Edit `app/services/moc_generator.py`:
+
+```python
+class MOCNumberGenerator:
+    DEFAULT_PREFIX = 'MOC'      # Change to 'CUSTOM' or any prefix
+    DEFAULT_START = 10000        # Starting number for MOCs
+```
+
+### Per-User vs Global Numbering
+
+**Per-User Numbering** (default):
+- Each user has their own MOC number sequence
+- MOC-10000 can exist for multiple users
+- API: `user_scoped=true`
+
+**Global Numbering**:
+- All users share the same MOC number sequence
+- Ensures unique MOC numbers across the entire system
+- API: `user_scoped=false`
+
+## Use Cases
+
+### Creating a New MOC
+
+1. User clicks "Add New Set"
+2. User toggles "This is a MOC" checkbox
+3. System automatically generates MOC-10000 (or next available)
+4. User fills in MOC designer, description, and other details
+5. System saves set with is_moc=True
+
+### Importing Multiple MOCs
+
+```python
+from app.services.moc_generator import MOCNumberGenerator
+
+for moc_data in moc_import_list:
+    moc_number = MOCNumberGenerator.generate_next_number()
+    new_set = Set(
+        set_number=moc_number,
+        set_name=moc_data['name'],
+        is_moc=True,
+        moc_designer=moc_data['designer'],
+        theme='MOC',
+        year_released=moc_data['year']
+    )
+    db.session.add(new_set)
+
+db.session.commit()
+```
+
+### Filtering MOCs
+
+```python
+# Get all MOCs
+mocs = Set.query.filter_by(is_moc=True).all()
+
+# Get MOCs by designer
+designer_mocs = Set.query.filter_by(
+    is_moc=True,
+    moc_designer='John Doe'
+).all()
+
+# Get MOCs by number range
+mocs_range = Set.query.filter(
+    Set.is_moc == True,
+    Set.set_number.like('MOC-10%')
+).all()
+```
+
+## Troubleshooting
+
+### MOC Number Not Generating
+
+**Issue**: API returns error or "Error generating number"
+
+**Solutions**:
+1. Check that user is logged in (endpoint requires authentication)
+2. Verify database connection
+3. Check browser console for JavaScript errors
+4. Ensure `moc_bp` is registered in `app/__init__.py`
+
+### Duplicate MOC Numbers
+
+**Issue**: Same MOC number assigned to multiple sets
+
+**Solutions**:
+1. Check database constraints on `set_number` field
+2. Verify `user_scoped` parameter matches your use case
+3. Run database migration to add unique constraint if missing
+
+### MOC Toggle Not Working
+
+**Issue**: Toggle switch doesn't show/hide sections
+
+**Solutions**:
+1. Check JavaScript console for errors
+2. Verify element IDs match between HTML and JavaScript
+3. Ensure Bootstrap JavaScript is loaded (for styling)
+
+## Future Enhancements
+
+Potential improvements for the MOC feature:
+
+- [ ] Bulk MOC number generation API
+- [ ] MOC number recycling (reuse deleted MOC numbers)
+- [ ] Custom number formats (e.g., MOC-YYYY-NNNN for year-based)
+- [ ] MOC templates for common builds
+- [ ] MOC sharing/export functionality
+- [ ] Integration with MOC platforms like Rebrickable
+
+## Related Documentation
+
+- [Main README](../README.md) - General application documentation
+- [Setup Guide](../SETUP_GUIDE.md) - Installation and configuration
+- [API Documentation](../docs/api.md) - Complete API reference (if exists)
+- [Database Schema](../docs/database.md) - Database structure (if exists)
+
+## Support
+
+For issues or questions about MOC auto-generation:
+
+1. Check existing issues on Gitea
+2. Review this documentation
+3. Check application logs for errors
+4. Create a new issue with:
+   - Steps to reproduce
+   - Expected vs actual behavior
+   - Browser console logs
+   - Server logs (if applicable)
+
+---
+
+**Last Updated**: December 2024  
+**Feature Version**: 1.0  
+**Compatibility**: LEGO Instructions Manager v1.3.0+