# Security & Quality Improvement Specification

## Overview
This document outlines the comprehensive security hardening and quality improvements for the Saorsa Browser (sb) project based on the code review findings.

## Critical Security Issues to Address

### 1. Path Traversal Vulnerability (HIGH)
**Current Risk**: Users can access any file system location
**Solution**: Implement strict path validation

```rust
pub fn validate_path(path: &Path, base_dir: &Path) -> Result<PathBuf, SecurityError> {
    let canonical_path = path.canonicalize()?;
    let canonical_base = base_dir.canonicalize()?;
    
    if !canonical_path.starts_with(canonical_base) {
        return Err(SecurityError::PathTraversal);
    }
    
    Ok(canonical_path)
}
```

### 2. Resource Exhaustion (MEDIUM)
**Current Risk**: Large files can consume all memory
**Solution**: File size limits and streaming

```rust
const MAX_FILE_SIZE: u64 = 10 * 1024 * 1024; // 10MB
const MAX_PREVIEW_SIZE: u64 = 1024 * 1024; // 1MB for preview

pub fn check_file_size(path: &Path) -> Result<u64, FileError> {
    let metadata = fs::metadata(path)?;
    if metadata.len() > MAX_FILE_SIZE {
        return Err(FileError::FileTooLarge(metadata.len()));
    }
    Ok(metadata.len())
}
```

## Testing Requirements

### Coverage Requirements
- **Minimum**: 80% line coverage
- **Critical**: 100% coverage for security functions
- **Edge Cases**: All error paths tested

### Test Categories
1. **Unit Tests**: Individual function testing
2. **Integration Tests**: Component interaction
3. **Security Tests**: Vulnerability prevention
4. **Performance Tests**: Large file handling

## Performance Improvements

### File Operation Optimization
- Add file size checks before operations
- Implement directory content caching
- Use streaming for large file previews

### Memory Management
- Limit preview content size
- Implement proper cleanup
- Add memory usage monitoring

## Implementation Phases

### Phase 1: Security Foundation (CRITICAL)
- [ ] Create security validation module
- [ ] Implement path traversal protection
- [ ] Add file size limits
- [ ] Secure error messaging

### Phase 2: Testing Infrastructure (CRITICAL)
- [ ] Set up comprehensive test framework
- [ ] Write failing tests for all functionality
- [ ] Add security-focused test suite
- [ ] Implement performance benchmarks

### Phase 3: Core Implementation (HIGH)
- [ ] Update all file operations for security
- [ ] Remove dead code and unused fields
- [ ] Fix deprecation warnings
- [ ] Improve error handling

### Phase 4: Performance & Documentation (MEDIUM)
- [ ] Add caching layer
- [ ] Implement streaming for large files
- [ ] Add comprehensive documentation
- [ ] Create user guides

## Success Criteria

### Security
- ✅ No path traversal vulnerabilities
- ✅ File size limits enforced
- ✅ Error messages don't leak sensitive info
- ✅ All inputs validated

### Testing
- ✅ ≥80% test coverage achieved
- ✅ All critical paths tested
- ✅ Security vulnerabilities prevented
- ✅ Performance regressions caught

### Performance
- ✅ Large directories load quickly
- ✅ Memory usage bounded
- ✅ UI remains responsive
- ✅ File operations efficient

### Code Quality
- ✅ No dead code or unused variables
- ✅ All deprecation warnings fixed
- ✅ Comprehensive documentation
- ✅ Clean, maintainable architecture