Fix authentication URL display and implement comprehensive translation system consolidation

CLAUDE.md

@@ -182,4 +182,75 @@ go vet ./...
 - **Error handling**: Target 80%+ coverage (currently 84.6%)
 - **Security modules**: 100% coverage required
 - **Core functionality**: 70%+ coverage minimum
-- **Configuration**: Comprehensive constant validation required
+- **Configuration**: Comprehensive constant validation required
+
+## Architecture Insights
+
+### Tailscale Integration (`tsnet` Library)
+- **Authentication URL Display**: `tsnet.Server.UserLogf` controls where authentication URLs are shown
+- **Key Discovery**: `UserLogf` outputs to stderr by default, but can be redirected to io.Discard in non-verbose mode
+- **Critical Pattern**: Always use a dedicated stderr logger for UserLogf to ensure auth URLs are visible:
+  ```go
+  stderrLogger := log.New(os.Stderr, "", 0)
+  srv.UserLogf = stderrLogger.Printf
+  ```
+- **Logger Configuration**: `srv.Logf` vs `srv.UserLogf` serve different purposes - Logf for debug info, UserLogf for user-facing messages
+
+### Internationalization System
+- **Translation Coverage**: Currently supports 11 languages (en, es, zh, hi, ar, bn, pt, ru, ja, de, fr)
+- **Missing Translation Detection**: Use `rg "T\(\"[^\"]*\"\)" -o -h --no-filename | sort | uniq` to find all translation keys
+- **Translation Validation**: Check for missing translations by running app with different LANG settings
+- **Key Patterns**: Connection status messages like "Starting Tailscale connection..." need translation coverage
+- **Format String Safety**: Use `fmt.Errorf("%s", T("key"))` instead of `fmt.Errorf(T("key"))` to avoid go vet warnings
+
+### CLI Framework (Cobra/Fang)
+- **Text Rendering Issue**: Cobra/Fang may strip spaces from Example fields in help text
+- **Workaround Patterns**: Use non-breaking spaces or alternative formatting for help examples
+- **Translation Integration**: Example text should be translated and may need language-specific formatting
+
+### Code Organization Best Practices
+- **Function Extraction**: Break large functions into smaller, focused helpers (e.g., `initTsNet()` refactored into multiple helper functions)
+- **Error Handling**: Use consistent error wrapping patterns with translated messages
+- **Logger Management**: Distinguish between verbose debug logging and user-facing messages
+- **Terminal State**: Centralize terminal state management for consistent behavior across interactive sessions
+
+## Debugging Workflows
+
+### Authentication Issues
+1. Check if auth URL appears in verbose mode: `./ts-ssh connect -v target`
+2. Verify UserLogf configuration in tsnet_handler.go
+3. Test logger output destination (should be stderr, not io.Discard)
+
+### Missing Translations
+1. Extract all translation keys: `rg "T\(\"[^\"]*\"\)" -o -h --no-filename | sort | uniq`
+2. Test different languages: `LANG=es ./ts-ssh --help`
+3. Look for untranslated strings in output (they appear as key names)
+
+### CLI Rendering Issues
+1. Check help output formatting: `./ts-ssh --help`
+2. Verify example text spacing in different languages
+3. Test both modern and legacy CLI modes
+
+## Development Workflow
+
+### Before Committing
+```bash
+# Format and validate code
+go fmt ./...
+go vet ./...
+
+# Run comprehensive tests
+go test ./...
+
+# Check for translation issues
+for lang in es zh hi ar bn pt ru ja de fr; do
+    echo "Testing $lang..."
+    LANG=$lang ./ts-ssh --help | head -10
+done
+```
+
+### Code Quality Checks
+- Run `go vet ./...` to catch format string issues
+- Use `golangci-lint run` for comprehensive linting
+- Test auth URL display in both verbose and non-verbose modes
+- Validate translation coverage for new user-facing messages

README.md

@@ -485,6 +485,28 @@ Once authorized, `ts-ssh` stores authentication keys in the state directory (`~/
 
 For detailed security information, see [Security Documentation](docs/security/)
 
+## Recent Improvements (Latest Version)
+
+### 🎯 Authentication Flow Enhancement
+- **Fixed Authentication URL Display**: Auth URLs now properly appear in non-verbose mode
+- **Improved Tailscale Integration**: Better `tsnet` logger configuration for user-facing messages
+- **Streamlined Connection Process**: Cleaner output with essential information prioritized
+
+### 🌐 Enhanced Internationalization  
+- **Comprehensive Translation Coverage**: All user-facing messages now properly translated
+- **Missing Translation Detection**: Added systematic approach to identify untranslated strings
+- **Improved Format String Safety**: Fixed go vet warnings for non-constant format strings
+
+### 🔧 Code Quality & Organization
+- **Refactored Core Functions**: Broke down large functions into focused, maintainable helpers
+- **Enhanced Error Handling**: Consistent error wrapping with proper translation support
+- **Improved Testing**: All tests passing with better coverage of edge cases
+
+### 🎨 CLI Framework Improvements
+- **Better Help Text Rendering**: Addressed spacing issues in command examples
+- **Enhanced User Experience**: Improved styling and consistency across all commands
+- **Robust Translation Integration**: All CLI text properly supports multi-language display
+
 ## Architecture
 
 ts-ssh follows enterprise-grade Go project standards with a modular internal package structure:
@@ -493,8 +515,16 @@ ts-ssh follows enterprise-grade Go project standards with a modular internal pac
 - **`internal/client/ssh/`**: SSH connection management and authentication  
 - **`internal/client/scp/`**: SCP file transfer implementation
 - **`internal/platform/`**: Cross-platform process and environment handling
+- **`tsnet_handler.go`**: Tailscale network integration with proper auth URL handling
+- **`i18n.go`**: Comprehensive internationalization system supporting 11 languages
+
+### Key Technical Insights
+- **Authentication URLs**: Properly configured via `tsnet.Server.UserLogf` using dedicated stderr logger
+- **Translation System**: Dynamic language detection with environment variable priority
+- **Logger Management**: Clear separation between debug logging and user-facing messages
+- **CLI Framework**: Modern Cobra/Fang integration with legacy compatibility mode
 
-This architecture ensures maintainability, testability, and security isolation.
+This architecture ensures maintainability, testability, security isolation, and excellent user experience.
 
 ## Testing