Add comprehensive NVM feature gap analysis for phpvm

ANALYSIS_README.md

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+# phpvm Feature Analysis Summary
+
+This directory contains comprehensive analysis documents comparing phpvm with nvm (Node Version Manager) to identify feature gaps and create an implementation roadmap.
+
+## 📚 Documentation Files
+
+### 1. [NVM_FEATURE_GAPS.md](./NVM_FEATURE_GAPS.md)
+**Comprehensive Analysis Document** (599 lines)
+
+The main detailed analysis document including:
+- Executive summary of findings
+- Methodology and comparison approach
+- Side-by-side feature comparison tables
+- Detailed analysis of 18+ missing features
+- Implementation steps and code examples for each feature
+- 12-week implementation roadmap (5 phases)
+- Testing strategy and success criteria
+- Backward compatibility considerations
+- Effort estimates and timelines
+
+**Best for:** Development teams planning implementation
+
+### 2. [FEATURE_CHECKLIST.md](./FEATURE_CHECKLIST.md)
+**Quick Reference Checklist** (178 lines)
+
+A concise, checkbox-based tracking document including:
+- Status of all features (implemented vs missing)
+- Priority-based organization (HIGH/MEDIUM/LOW)
+- Command mapping table (NVM → PHPVM)
+- Implementation statistics
+- Progress tracking format
+- Quick reference legend
+
+**Best for:** Quick status checks and progress tracking
+
+## 🎯 Analysis Results at a Glance
+
+### Current Status
+- **Feature Parity:** ~60%
+- **Commands in phpvm:** 13
+- **Commands in nvm:** 22+
+- **Features to Add:** 18+
+
+### Missing Feature Categories
+
+#### 🔴 HIGH PRIORITY (9 features)
+Essential for feature parity with nvm:
+1. Alias Management (`alias`, `unalias`)
+2. Remote Version Listing (`ls-remote`)
+3. Command Execution (`exec`, `run`)
+4. Cache Management (`cache dir`, `cache clear`)
+
+#### 🟡 MEDIUM PRIORITY (6 features)
+Important for enhanced usability:
+5. Enhanced Install Flags (`--alias`, `--default`, `--save`)
+6. Enhanced Use Flags (`--silent`, `--save`)
+7. Version Resolution (`version`, `version-remote`)
+8. Unload Command (`unload`)
+9. Extension Migration (`reinstall-packages`)
+10. Debug Enhancement (`debug`)
+
+#### 🟢 LOW PRIORITY (3+ features)
+Nice to have for better UX:
+11. Smart Pattern Matching
+12. Color Customization (`set-colors`)
+13. Global Silent Mode
+14. Tab Completion
+
+## 📊 Implementation Timeline
+
+| Phase | Duration | Features |
+|-------|----------|----------|
+| Phase 1: Core Features | 3 weeks | Alias, Cache, Exec/Run |
+| Phase 2: Remote & Resolution | 3 weeks | ls-remote, Version resolution |
+| Phase 3: Enhanced Options | 2 weeks | Flags, Silent mode, Unload |
+| Phase 4: Advanced Features | 2 weeks | Migration, Debug, Patterns |
+| Phase 5: Testing & Docs | 2 weeks | Tests, Docs, Performance |
+| **Total** | **12 weeks** | **All features** |
+
+**Additional Time:**
+- Testing: 2-3 weeks
+- Documentation: 1 week
+- **Grand Total:** ~15 weeks
+
+## 🚀 Quick Start Guide
+
+### For Developers
+1. Read [NVM_FEATURE_GAPS.md](./NVM_FEATURE_GAPS.md) for detailed implementation guidance
+2. Start with HIGH priority features
+3. Follow the implementation steps for each feature
+4. Maintain backward compatibility
+5. Add tests for each new feature
+
+### For Project Managers
+1. Review [FEATURE_CHECKLIST.md](./FEATURE_CHECKLIST.md) for status overview
+2. Track progress using the checkbox format
+3. Monitor implementation against 12-week roadmap
+4. Use effort estimates for sprint planning
+
+### For Users
+1. Check [FEATURE_CHECKLIST.md](./FEATURE_CHECKLIST.md) to see what's coming
+2. See command mapping table for nvm → phpvm equivalents
+3. Understand which features are in progress
+4. Provide feedback on priorities
+
+## 💡 Key Insights
+
+### phpvm Strengths (vs nvm)
+- ✅ Built-in comprehensive self-tests
+- ✅ System information command
+- ✅ Multi-package-manager support
+- ✅ Repository setup guidance
+- ✅ WSL-specific handling
+- ✅ Timestamped logging
+- ✅ Atomic file operations
+
+### Areas for Improvement
+- ❌ No alias system (critical)
+- ❌ Cannot list remote versions
+- ❌ Cannot execute commands with specific versions
+- ❌ No cache management
+- ❌ Limited install/use options
+- ❌ No version pattern matching
+
+## 📈 Success Metrics
+
+phpvm achieves feature parity when:
+1. ✅ All HIGH priority features implemented
+2. ✅ At least 75% of MEDIUM priority features implemented
+3. ✅ Core functionality matches nvm behavior
+4. ✅ All tests pass on supported platforms
+5. ✅ Documentation complete
+6. ✅ Performance acceptable
+7. ✅ Positive user feedback
+
+## 🔄 Progress Tracking
+
+Track implementation progress in [FEATURE_CHECKLIST.md](./FEATURE_CHECKLIST.md):
+- Update checkboxes as features are completed
+- Mark status as ✅ Done, 🟡 Partial, or ❌ Missing
+- Track against the 12-week roadmap
+
+## 📝 Contributing
+
+When implementing features:
+1. Follow implementation steps in NVM_FEATURE_GAPS.md
+2. Update FEATURE_CHECKLIST.md with progress
+3. Write tests for new functionality
+4. Update documentation (README.md, help text)
+5. Maintain backward compatibility
+6. Add to CHANGELOG.md
+
+## ⚠️ Important Notes
+
+### PHP vs Node.js Differences
+- **No LTS:** PHP doesn't have LTS versions like Node.js
+- **Package Managers:** phpvm uses system package managers (apt, brew, etc.)
+- **Extensions:** PHP uses compiled C extensions, not npm packages
+- **Platform Specific:** Some features may vary by package manager
+
+### Backward Compatibility
+- All new features must be optional
+- Existing commands must work unchanged
+- Default behavior must remain consistent
+- Old .phpvmrc files must still work
+
+## 📞 Questions or Feedback?
+
+- **Detailed Analysis:** See [NVM_FEATURE_GAPS.md](./NVM_FEATURE_GAPS.md)
+- **Quick Reference:** See [FEATURE_CHECKLIST.md](./FEATURE_CHECKLIST.md)
+- **Issues:** Create a GitHub issue
+- **Discussions:** Use GitHub Discussions
+
+---
+
+**Analysis Date:** 2026-01-04  
+**Analysis Version:** 1.0  
+**phpvm Version Analyzed:** 1.7.0  
+**nvm Reference Version:** Latest (4662 lines)  
+**Prepared by:** GitHub Copilot Analysis

FEATURE_CHECKLIST.md

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+# phpvm Feature Parity Checklist
+
+A quick reference checklist of features needed to achieve full functional parity with nvm.
+
+## ✅ Already Implemented (Compatible with NVM)
+
+- [x] `phpvm install <version>` - Install PHP version
+- [x] `phpvm use <version>` - Switch to PHP version
+- [x] `phpvm uninstall <version>` - Remove PHP version
+- [x] `phpvm current` - Display active version
+- [x] `phpvm which [version]` - Show path to PHP binary
+- [x] `phpvm deactivate` - Disable phpvm temporarily
+- [x] `phpvm list` / `phpvm ls` - List installed versions
+- [x] `phpvm version` - Show phpvm version
+- [x] Auto-switching via `.phpvmrc` file
+
+## 🔴 HIGH PRIORITY - Missing Core Features
+
+### Alias System
+- [ ] `phpvm alias [pattern]` - List all aliases (or filter by pattern)
+- [ ] `phpvm alias <name> <version>` - Create/update version alias
+- [ ] `phpvm unalias <name>` - Remove alias
+- [ ] Support `default` alias concept
+- [ ] Support using aliases in `use`, `install`, etc.
+- [ ] Show aliases in `phpvm list` output
+
+### Remote Version Management
+- [ ] `phpvm ls-remote` - List all available PHP versions
+- [ ] `phpvm ls-remote <pattern>` - Filter remote versions by pattern
+- [ ] `phpvm ls-remote --no-colors` - Disable colored output
+- [ ] Package manager integration for version discovery
+
+### Command Execution
+- [ ] `phpvm exec <version> <command> [args]` - Execute command with specific PHP version
+- [ ] `phpvm run <version> [script] [args]` - Run PHP script with specific version
+- [ ] Support for `--silent` flag in exec/run
+- [ ] Preserve exit codes from executed commands
+
+### Cache Management
+- [ ] `phpvm cache dir` - Display cache directory location
+- [ ] `phpvm cache clear` - Clear all cached data
+- [ ] Create cache directory structure
+- [ ] Implement metadata caching for ls-remote
+
+## 🟡 MEDIUM PRIORITY - Enhanced Usability
+
+### Enhanced Install Command
+- [ ] `phpvm install <version> --alias=<name>` - Set alias after install
+- [ ] `phpvm install <version> --default` - Set as default after install
+- [ ] `phpvm install <version> --save` - Write to .phpvmrc after install
+- [ ] `phpvm install <version> --silent` - Silent installation
+- [ ] Support for `latest` keyword
+
+### Enhanced Use Command
+- [ ] `phpvm use <version> --silent` - Silent version switching
+- [ ] `phpvm use <version> --save` - Write to .phpvmrc after switch
+- [ ] Support for partial version matching
+
+### Version Resolution
+- [ ] `phpvm version <pattern>` - Resolve version pattern locally
+- [ ] `phpvm version-remote <pattern>` - Resolve version pattern remotely
+- [ ] Support patterns: "8", "8.2", "latest", "stable"
+- [ ] Smart version matching (e.g., "8" → "8.3.1")
+
+### Shell Integration
+- [ ] `phpvm unload` - Completely unload phpvm from shell
+- [ ] Enhanced unload to remove all functions
+- [ ] Clear all PHPVM_* environment variables
+
+### Package Migration
+- [ ] `phpvm reinstall-packages <source-version>` - Migrate extensions
+- [ ] List extensions from source version
+- [ ] Attempt installation in target version
+- [ ] Report success/failure for each extension
+
+### Debugging
+- [ ] `phpvm debug` - Comprehensive debug information
+- [ ] Show all PHPVM_* variables
+- [ ] Show PATH contents
+- [ ] Show alias list
+- [ ] Show cache information
+
+## 🟢 LOW PRIORITY - Nice to Have
+
+### Pattern Matching
+- [ ] Support partial versions in all commands
+- [ ] `phpvm install latest` - Install latest available
+- [ ] `phpvm install stable` - Install latest stable
+- [ ] `phpvm use 8` - Use latest 8.x installed
+
+### Customization
+- [ ] `phpvm set-colors <codes>` - Customize output colors
+- [ ] User configuration file support
+- [ ] Persistent color preferences
+
+### Silent Mode
+- [ ] Global `--silent` flag support
+- [ ] Silent mode for all commands
+- [ ] Configurable verbosity levels
+
+### Additional Enhancements
+- [ ] `phpvm list --no-colors` - Disable colors in list
+- [ ] `phpvm list --no-alias` - Hide aliases in list
+- [ ] Tab completion for bash/zsh
+- [ ] Man page documentation
+
+## 🎯 phpvm Unique Features (Not in NVM)
+
+These features are already in phpvm but not in nvm:
+
+- [x] `phpvm test` - Built-in comprehensive self-tests
+- [x] `phpvm info` / `phpvm sysinfo` - System information display
+- [x] `phpvm system` - Explicit system version command
+- [x] Multi-package-manager support (apt, dnf, yum, pacman, brew)
+- [x] Repository setup guidance for RHEL/Fedora
+- [x] WSL-specific detection and handling
+- [x] Comprehensive error handling with actionable solutions
+- [x] Timestamped logging
+- [x] Atomic file operations
+
+## Implementation Statistics
+
+### Current Status
+- **Features in phpvm:** 13 commands
+- **Features in nvm:** 22+ commands
+- **Features to add:** 18+ features
+- **Feature parity:** ~60%
+
+### Estimated Effort
+- **HIGH priority:** 4-5 weeks
+- **MEDIUM priority:** 4-5 weeks  
+- **LOW priority:** 2-3 weeks
+- **Total implementation:** 10-12 weeks
+- **Additional code:** ~1500-2000 lines
+- **Testing:** 2-3 weeks
+- **Documentation:** 1 week
+
+## Quick Reference: Command Mapping
+
+| NVM Command | PHPVM Equivalent | Status |
+|-------------|------------------|--------|
+| `nvm install <v>` | `phpvm install <v>` | ✅ Done |
+| `nvm uninstall <v>` | `phpvm uninstall <v>` | ✅ Done |
+| `nvm use <v>` | `phpvm use <v>` | ✅ Done |
+| `nvm current` | `phpvm current` | ✅ Done |
+| `nvm ls` | `phpvm list/ls` | ✅ Done |
+| `nvm ls-remote` | `phpvm ls-remote` | ❌ Missing |
+| `nvm which` | `phpvm which` | ✅ Done |
+| `nvm alias` | `phpvm alias` | ❌ Missing |
+| `nvm unalias` | `phpvm unalias` | ❌ Missing |
+| `nvm exec` | `phpvm exec` | ❌ Missing |
+| `nvm run` | `phpvm run` | ❌ Missing |
+| `nvm deactivate` | `phpvm deactivate` | ✅ Done |
+| `nvm unload` | `phpvm unload` | ❌ Missing |
+| `nvm version` | `phpvm version` | 🟡 Partial |
+| `nvm version-remote` | `phpvm version-remote` | ❌ Missing |
+| `nvm cache` | `phpvm cache` | ❌ Missing |
+| `nvm reinstall-packages` | `phpvm reinstall-packages` | ❌ Missing |
+| `nvm set-colors` | `phpvm set-colors` | ❌ Missing |
+| `nvm debug` | `phpvm debug` | 🟡 Partial (info) |
+| N/A | `phpvm test` | ✅ Unique |
+| N/A | `phpvm system` | ✅ Unique |
+| N/A | `phpvm auto` | ✅ Unique |
+
+## Legend
+
+- ✅ **Done** - Feature fully implemented
+- 🟡 **Partial** - Feature partially implemented
+- ❌ **Missing** - Feature not implemented
+- 🔴 **HIGH** - Essential for feature parity
+- 🟡 **MEDIUM** - Important for usability
+- 🟢 **LOW** - Nice to have
+
+---
+
+**Last Updated:** 2026-01-04  
+**Document Version:** 1.0  
+**For detailed analysis, see:** [NVM_FEATURE_GAPS.md](./NVM_FEATURE_GAPS.md)