sugar

```python
# Automated solution for batch processing user uploads to S3
# Generated by Sugar autonomous coding agent
# Constraints: Max 50MB file size, Python 3.11+, boto3 1.34.0+

import os
import boto3
from datetime import datetime
from typing import List, Dict

class S3BatchUploader:
    """Automated S3 batch uploader with validation and error handling"""
    
    def __init__(self, bucket_name: str, region: str = 'us-east-1'):
        self.s3 = boto3.client('s3', region_name=region)
        self.bucket_name = bucket_name
        self.max_size = 50 * 1024 * 1024  # 50MB
        
    def validate_file(self, file_path: str) -> bool:
        """Validate file size and existence"""
        if not os.path.exists(file_path):
            raise FileNotFoundError(f"File {file_path} not found")
        if os.path.getsize(file_path) > self.max_size:
            raise ValueError(f"File {file_path} exceeds 50MB limit")
        return True
    
    def upload_batch(self, file_paths: List[str], prefix: str = 'uploads/') -> Dict:
        """Upload multiple files to S3 with timestamped prefix"""
        timestamp = datetime.utcnow().strftime('%Y%m%d_%H%M%S')
        results = {'success': [], 'failed': []}
        
        for file_path in file_paths:
            try:
                self.validate_file(file_path)
                key = f"{prefix}{timestamp}/{os.path.basename(file_path)}"
                self.s3.upload_file(file_path, self.bucket_name, key)
                results['success'].append({
                    'file': file_path,
                    's3_key': key,
                    'size': os.path.getsize(file_path)
                })
            except Exception as e:
                results['failed'].append({
                    'file': file_path,
                    'error': str(e)
                })
        
        return results

# Example usage
if __name__ == "__main__":
    uploader = S3BatchUploader(bucket_name='user-uploads-prod')
    test_files = ['/data/user1/photo.jpg', '/data/user2/document.pdf']
    
    result = uploader.upload_batch(test_files)
    print(f"Uploaded {len(result['success'])} files successfully")
    if result['failed']:
        print(f"Failed to upload {len(result['failed'])} files")
```

**Test Cases:**
```python
import pytest

def test_upload_batch():
    uploader = S3BatchUploader('test-bucket')
    # Mock boto3 client would be injected here in real tests
    result = uploader.upload_batch(['/tmp/test.txt'])
    assert len(result['success']) == 1
    assert result['success'][0]['s3_key'].startswith('uploads/')
```

**Documentation:**
- **Purpose**: Automates user upload processing to S3
- **Constraints**: 50MB file size limit, Python 3.11+
- **Output**: JSON with success/failure tracking
- **Dependencies**: boto3 1.34.0+