Add comprehensive PR description for preinstall enhancements

PR_DESCRIPTION.md

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+# Enhanced run_comfyui.bat with Automated Dependency Checking and CUDA PyTorch Installation
+
+## Author's Note
+
+**Important**: I am not a professional coder and have relied heavily on Cursor AI for the development of this script. While I have done my best to ensure its functionality and safety, I kindly request a thorough review by experienced developers before merging. Please pay special attention to:
+- Batch file logic and error handling
+- Python command-line invocations
+- Virtual environment detection logic
+- Dependency checking implementation
+- User interaction flow
+
+## Overview
+
+This PR enhances the `run_comfyui.bat` startup script for Windows users, significantly improving the user experience by automatically checking dependencies, detecting virtual environments, and offering intelligent installation options. The script now provides a polished, user-friendly interface with clear error messages and troubleshooting guidance.
+
+## Key Features
+
+### 1. **Automated Dependency Checking**
+- Checks all critical Python dependencies before launching ComfyUI
+- Separates critical vs. optional dependencies
+- Provides clear prompts for missing packages
+- Offers installation options: Install All, Critical Only, or Cancel
+
+### 2. **CUDA PyTorch Auto-Installation**
+- Automatically detects CPU-only PyTorch installations
+- Offers to automatically uninstall CPU version and install CUDA-enabled version
+- Shows progress bars during installation (`--progress-bar on`)
+- Verifies installation before proceeding
+- Provides clear warnings about NVIDIA GPU requirements
+
+### 3. **Virtual Environment Awareness**
+- Detects if running in a virtual environment
+- Provides appropriate warnings about installation impacts
+- Offers guidance on creating virtual environments for safer package management
+
+### 4. **Enhanced User Experience**
+- UTF-8 encoding support for proper Unicode character display
+- ASCII art banner with "Comfy" text
+- Progress bars for all pip installations
+- User-friendly error messages with actionable troubleshooting steps
+- Clear, informative prompts throughout the installation process
+
+### 5. **Comprehensive Error Handling**
+- Detailed error messages for common issues:
+  - Python not found
+  - Installation failures
+  - CUDA out of memory errors
+  - Module not found errors
+- Provides specific troubleshooting steps for each error type
+
+## Files Changed
+
+- **`run_comfyui.bat`** (408 lines, +347 insertions, -61 deletions)
+  - Enhanced startup script with all new features
+  - UTF-8 encoding support
+  - Comprehensive dependency checking
+  - CUDA PyTorch detection and auto-installation
+  - Virtual environment detection
+  - Progress bars for installations
+  - User-friendly error messages
+
+- **`create_shortcut.ps1`** (1 line addition)
+  - PowerShell script for creating desktop shortcuts
+  - Helper utility for easier access
+
+## Screenshots
+
+### ASCII Art Banner
+The script displays a polished ASCII art banner with "Comfy" text:
+```
+╔═══════════════════════════════════════════════════════════╗
+║                                                           ║
+║       ██████╗ ██████╗ ███╗   ███╗███████╗██╗   ██╗       ║
+║      ██╔════╝██╔═══██╗████╗ ████║██╔════╝╚██╗ ██╔╝       ║
+║      ██║     ██║   ██║██╔████╔██║█████╗   ╚████╔╝        ║
+║      ██║     ██║   ██║██║╚██╔╝██║██╔══╝    ╚██╔╝         ║
+║      ╚██████╗╚██████╔╝██║ ╚═╝ ██║██║        ██║          ║
+║       ╚═════╝ ╚═════╝ ╚═╝     ╚═╝╚═╝        ╚═╝          ║
+║                                                           ║
+║         The most powerful open source node-based          ║
+║         application for generative AI                    ║
+║                                                           ║
+╚═══════════════════════════════════════════════════════════╝
+```
+
+### Key User Interactions
+
+**Dependency Checking Prompt:**
+```
+╔═══════════════════════════════════════════════════════════╗
+║            Missing Required Packages                      ║
+╚═══════════════════════════════════════════════════════════╝
+
+▓ ComfyUI needs some additional software to run.
+  The following critical packages are missing:
+  yaml, torch, numpy
+
+▓ [Heads Up] You're using your main Python installation.
+  Installing packages here might affect other programs that use Python.
+
+▓ Installation Options:
+    [I] Install all missing packages (recommended)
+    [C] Install only critical packages
+    [N] Cancel and exit
+```
+
+**CUDA PyTorch Detection:**
+```
+╔═══════════════════════════════════════════════════════════╗
+║     CPU-Only PyTorch Detected - CUDA Version Required     ║
+╚═══════════════════════════════════════════════════════════╝
+
+▓ Your PyTorch installation doesn't support GPU acceleration.
+  ComfyUI requires CUDA-enabled PyTorch to run properly.
+
+▓ We can automatically install the CUDA-enabled version for you.
+  This will:
+     1. Remove the current CPU-only version
+     2. Install the CUDA-enabled version (this will take several minutes)
+     3. Continue to launch ComfyUI automatically
+
+Would you like to install CUDA-enabled PyTorch now? (Y/N):
+```
+
+## Testing Recommendations
+
+To thoroughly test this PR, please verify the following scenarios:
+
+1. **Clean Environment**: Run the script in an environment with no Python or ComfyUI dependencies installed
+2. **Missing Critical Dependencies**: Manually uninstall one or more critical dependencies (e.g., `pyyaml`) and verify the script correctly identifies them
+3. **Missing Optional Dependencies**: Uninstall an optional dependency and verify the script offers to install it or skip
+4. **CPU-Only PyTorch**: Install a CPU-only version of PyTorch and verify the script detects it and offers to install the CUDA version
+5. **CUDA-Enabled PyTorch**: Ensure a CUDA-enabled PyTorch is installed and verify the script proceeds directly to launching ComfyUI
+6. **Virtual Environment**: Test running the script within an activated virtual environment
+7. **System Python**: Test running the script with system Python (not in a virtual environment)
+8. **Error Handling**: Verify that all error messages are clear, informative, and provide helpful troubleshooting steps
+9. **Progress Bars**: Verify that progress bars display correctly during pip installations
+10. **ASCII Art**: Confirm the ASCII art banner renders correctly in a standard Windows command prompt
+
+## Technical Details
+
+### UTF-8 Encoding
+- Uses `chcp 65001` to enable UTF-8 encoding for proper Unicode character display
+- Ensures ASCII art and box-drawing characters render correctly
+
+### Dependency Checking
+- Uses `importlib.util.find_spec()` to check for module availability
+- Separates critical dependencies (required for ComfyUI to run) from optional dependencies
+- Provides user with clear installation options
+
+### CUDA PyTorch Detection
+- Checks PyTorch version string for "+cpu" indicator
+- Verifies CUDA availability using `torch.cuda.is_available()`
+- Automatically updates CUDA availability variables after installation
+- Continues to launch ComfyUI after successful installation
+
+### Progress Bars
+- Uses `--progress-bar on` flag for all pip installations
+- Provides visual feedback during long installations (especially PyTorch)
+
+## Backward Compatibility
+
+- ✅ All changes are backward compatible
+- ✅ No breaking changes to existing functionality
+- ✅ Works with both system Python and virtual environments
+- ✅ Existing users can continue using the script as before
+
+## Benefits
+
+1. **Improved User Experience**: Users get clear guidance on what's missing and how to fix it
+2. **Reduced Support Burden**: Common issues are caught and resolved automatically
+3. **Better Error Messages**: Users understand what went wrong and how to fix it
+4. **Professional Appearance**: Polished interface with ASCII art and clear formatting
+5. **GPU Support**: Automatically ensures users have CUDA-enabled PyTorch for optimal performance
+
+## Additional Notes
+
+- The script maintains all original functionality while adding new features
+- All user prompts are optional - users can cancel at any time
+- Installation commands use `python -m pip` for consistency
+- Error handling provides actionable troubleshooting steps
+- The script is designed to be safe and non-destructive
+
+## Request for Review
+
+Given my limited coding experience, I would greatly appreciate:
+- Code review focusing on batch file best practices
+- Verification of Python command invocations
+- Testing in various Windows environments
+- Feedback on error handling and user prompts
+- Suggestions for improvements
+
+Thank you for your time and consideration!
+