# Design: Rich Integration for CLI Help

## Architectural Decision

### Why Rich?

1. **Terminal capability detection**: Rich automatically detects terminal capabilities and degrades gracefully on systems without color support
2. **Minimal impact**: Rich is a pure Python library with no external dependencies beyond standard library
3. **Mature and stable**: Widely used in CLI tools (e.g., poetry, black, pytest)
4. **Rich components**: Provides panels, tables, syntax highlighting, and progress bars
5. **Cross-platform**: Works consistently on Linux, macOS, and Windows

### Integration Approach

#### Option A: Custom Help Formatter (Chosen)
- Create a `print_rich_help()` function that completely replaces argparse help
- Gives full control over layout and styling
- Cleaner separation of concerns
- Easier to maintain and enhance

#### Option B: Rich ArgumentParser Subclass
- Extend `argparse.ArgumentParser` with Rich formatter
- More complex integration with argparse internals
- Less control over overall layout
- Rejected for simplicity

#### Option C: Keep argparse, Post-Process Output
- Pipe argparse output through Rich
- Limited formatting capabilities
- Doesn't leverage Rich's full potential
- Rejected for suboptimal results

## Trade-offs

### Benefits
- Improved user experience with better organized help
- Easier discovery of CLI options
- Professional appearance
- Better accessibility with color coding and visual hierarchy

### Costs
- Adds one external dependency (Rich ~2MB installed)
- Slight increase in startup time for help display
- Additional maintenance for help content

### Mitigations
- Pin Rich version to stable release
- Use lazy import (only import Rich when help is requested)
- Minimal impact on normal CLI usage (help is infrequent)
- Rich is well-maintained and unlikely to introduce breaking changes

## Dependency Policy Alignment

This change adds Rich as a dependency. Justification:
1. Rich is a standard library for CLI tools in Python ecosystem
2. Minimal dependency policy allows "essential" dependencies
3. Help display is a critical user-facing feature
4. Single-purpose library (terminal formatting) with clear boundaries
5. No transitive dependencies that could conflict

## Implementation Structure

```python
# In cli.py
from rich.console import Console
from rich.panel import Panel
from rich.table import Table
from rich.syntax import Syntax

def print_rich_help():
    console = Console()

    # Title panel
    console.print(Panel(...))

    # Usage section
    console.print(Rule("Usage"))
    ...

    # Options table
    options_table = Table(...)
    console.print(options_table)

    # Examples section
    console.print(Rule("Examples"))
    code = Syntax(..., lexer="bash")
    console.print(code)

    # Footer
    console.print(...)

    sys.exit(0)
```

## Testing Strategy

1. **Terminal variations**: Test with TERM=dumb, TERM=xterm-256color, no terminal
2. **PyInstaller builds**: Verify Rich bundles correctly in executables
3. **Python versions**: Test across supported Python versions (3.7-3.12)
4. **Performance**: Measure startup time overhead
5. **Visual regression**: Capture help output on different terminals

## Future Enhancements

1. Interactive help mode with menu-driven option exploration
2. Searchable help (Rich has built-in search capabilities)
3. Contextual help (Rich can show specific sections on demand)
4. Progress bars for long operations (using Rich's Progress component)
