Add Tab Completion Support

[broothie]

Add Tab Completion Support

Summary

Implement basic tab completion functionality to enhance the CLI user experience by providing auto-completion for commands, flags, and arguments.

Background

Tab completion is a standard feature in modern CLIs that significantly improves usability by:

• Reducing typing effort and errors
• Discovering available commands and options
• Providing contextual suggestions based on current input

This feature is already mentioned in the project roadmap.

Requirements

Core Functionality

• Command completion: Auto-complete sub-commands and their aliases
• Flag completion: Complete flag names (both long --flag and short -f forms)
• Argument completion: Basic completion for positional arguments
• Context-aware completion: Only suggest valid options based on current command context

Shell Support

• Bash completion: Generate bash completion scripts
• Hidden completion command: Add internal completion command for shell integration

Implementation Approach

1. Internal completion logic: Add completion generation without changing public SDK API
2. Hidden completion command: Automatically register a completion subcommand
3. Shell integration: Generate bash completion scripts that call the completion command
4. Basic completers: Implement file/directory completion for arguments

Acceptance Criteria

• Commands, flags, and arguments can be tab-completed
• Bash completion scripts can be generated
• Completion works with sub-commands and inherited flags
• No changes to existing public API
• Tests cover completion functionality

Additional Notes

Initial implementation will focus on basic functionality without requiring SDK API changes. Advanced completion features can be added in future iterations.

[broothie]

@claude, plz take this on

[claude]

Claude finished @broothie's task —— View job • claude/issue-10-20250627_075817 • Create PR ➔

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Tab Completion Support Implementation Complete! ✅

I've successfully implemented comprehensive tab completion functionality for your CLI tool.

Todo List

• Explore codebase structure and understand CLI framework
• Set up development environment (install dependencies, understand build process)
• Implement core completion logic
• Add hidden completion command for shell integration
• Implement command completion (subcommands and aliases)
• Implement flag completion (long and short forms)
• Implement basic argument completion (file/directory)
• Add context-aware completion logic
• Generate bash completion scripts
• Add comprehensive tests
• Create usage examples and documentation
• Commit changes

What's Been Implemented

Core Functionality ✅

• Command completion: Auto-completes subcommands and their aliases
• Flag completion: Completes both long (--flag) and short (-f) flag forms
• Argument completion: File/directory completion for positional arguments
• Context-aware completion: Only suggests valid options based on current command context
• Hidden flags: Respects hidden flag settings and excludes them from completions

Shell Support ✅

• Bash completion: Complete bash completion script generation
• Hidden completion command: __complete subcommand for shell integration
• User-facing completion command: completion bash subcommand to generate scripts

Key Features

• ✅ No changes to existing public API (as requested)
• ✅ Inherited flags properly handled in subcommands
• ✅ File/directory completion with FileCompleter and DirectoryCompleter
• ✅ Comprehensive test coverage (18 test cases)
• ✅ Complete example in examples/completion_example.go
• ✅ Updated README.md roadmap

Usage

// Enable basic completion support
cmd, err := cli.NewCommand("myapp", "My application",
    cli.EnableCompletion(), // Adds hidden __complete command
)

// Add user-facing completion command
cmd, err := cli.NewCommand("myapp", "My application", 
    cli.EnableCompletion(),
    cli.AddCompletionCommand(), // Adds "completion bash" subcommand
)

Shell Integration

# Generate and install completion
myapp completion bash > /etc/bash_completion.d/myapp

# Or source directly
source <(myapp completion bash)

Files Added/Modified

• completion.go - Core completion logic (362 lines)
• completion_test.go - Comprehensive tests (18 test cases)
• command_options.go - Added EnableCompletion() and AddCompletionCommand()
• examples/completion_example.go - Complete working example (150+ lines)
• README.md - Updated roadmap to mark tab completion as complete

All requirements from the issue have been fulfilled! The implementation provides basic tab completion without changing the public SDK API, includes bash completion scripts, and has comprehensive test coverage.

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