sbroenne__mcp-server-excel/docs/CONTRIBUTING.md

Contributing to ExcelMcp

Thank you for your interest in contributing to Sbroenne.ExcelMcp! This project is designed to be extended by the community, especially to support coding agents like GitHub Copilot.

🎯 Project Vision

ExcelMcp aims to be the go-to command-line tool for coding agents to interact with Microsoft Excel files. We prioritize:

• Simplicity - Clear, predictable commands
• Reliability - Robust COM automation
• Extensibility - Easy to add new features
• Agent-Friendly - Designed for AI coding assistants

🚀 Getting Started

Development Environment

1. Prerequisites:

   • Windows OS (required for Excel COM)
   • Visual Studio 2022 or VS Code
   • .NET 10 SDK
   • Microsoft Excel installed

2. Setup:

   git clone https://github.com/sbroenne/mcp-server-excel.git
   cd ExcelMcp
   dotnet restore
   dotnet build
   

🚨 CRITICAL: Pull Request Workflow Required

All changes must be made through Pull Requests (PRs). Direct commits to main are prohibited.

Quick PR Process

1. Create feature branch: git checkout -b feature/your-feature
2. Make changes: Code, tests, documentation
3. Push branch: git push origin feature/your-feature
4. Create PR: Use GitHub's PR template
5. Address review: Make requested changes
6. Merge: After approval and CI checks pass

📋 Detailed workflow: See DEVELOPMENT.md for complete instructions.

3. Test Your Setup:

   dotnet run -- pq-list "path/to/test.xlsx"
   

📋 Development Guidelines

Code Style

• C# 12 features encouraged (file-scoped namespaces, records, pattern matching)
• Nullable reference types enabled - handle nulls properly
• No warnings - project must build with zero warnings
• XML documentation for public APIs
• Consistent naming - follow established patterns

Architecture Patterns

Command Pattern

All commands follow this structure:

// Interface
public interface IMyCommands
{
    int MyOperation(string[] args);
}

// Implementation  
public class MyCommands : IMyCommands
{
    public int MyOperation(string[] args)
    {
        // Validation
        if (!ValidateArgs(args, expectedCount, "usage string"))
            return 1;
            
        // Excel automation using batch API
        var task = Task.Run(async () =>
        {
            await using var batch = await ExcelSession.BeginBatchAsync(filePath);
            return batch.Execute((ctx, ct) =>
            {
                // Use ctx.Book for workbook access
                // Your implementation
                return 0; // Success
            });
        });
        return task.GetAwaiter().GetResult();
    }
}

Critical Rules

1. Always use batch API - Never manage Excel lifecycle manually
2. Excel uses 1-based indexing - collection.Item(1) is the first element
3. Use QueryTables.Add() not ListObjects.Add() - For loading Power Query data
4. Escape user input - Always use .EscapeMarkup() with Spectre.Console
5. Return 0 for success, 1+ for errors - Consistent exit codes

Excel COM Best Practices

• Late binding with dynamic types - Use Type.GetTypeFromProgID("Excel.Application")
• Proper error handling - Catch COMException and provide helpful messages
• Resource cleanup - Batch API handles COM object lifecycle automatically
• Input validation - Check file existence and argument counts early

Testing

Before submitting:

1. Manual testing with various Excel files
2. Verify Excel process cleanup - No excel.exe should remain after 5 seconds
3. Test error conditions - Missing files, invalid arguments, etc.
4. VBA script testing - For script-related commands, test with real VBA macros
5. Cross-version compatibility - Test with different Excel versions if possible

🔧 Adding New Commands

1. Create Interface

// Commands/INewCommands.cs
namespace ExcelMcp.Commands;

public interface INewCommands
{
    int NewOperation(string[] args);
}

2. Implement Command Class

// Commands/NewCommands.cs
using Spectre.Console;

namespace ExcelMcp.Commands;

public class NewCommands : INewCommands
{
    public int NewOperation(string[] args)
    {
        // Implementation following established patterns
    }
}

3. Register in Program.cs

Add to the switch expression in Main():

return args[0] switch
{
    "new-operation" => newCommands.NewOperation(args),
    // ... existing commands
    _ => ShowHelp()
};

4. Update Help Text

Add your command to the help output in ShowHelp().

📝 Pull Request Process

Before Submitting

• Code builds with zero warnings
• All existing commands still work
• Excel processes clean up properly
• Added appropriate error handling
• Updated help text if needed
• Tested with various Excel files

PR Description Template

## Summary
Brief description of changes

## Type of Change
- [ ] Bug fix
- [ ] New feature
- [ ] Breaking change
- [ ] Documentation update

## Testing
- [ ] Tested manually with Excel files
- [ ] Verified Excel process cleanup
- [ ] Tested error conditions
- [ ] VBA script execution tested (if applicable)
- [ ] No build warnings

## Checklist
- [ ] Code follows project conventions
- [ ] Self-review completed
- [ ] Updated documentation as needed

🎨 UI Guidelines

Spectre.Console Usage

// Success (green checkmark)
AnsiConsole.MarkupLine($"[green]✓[/] Operation succeeded");

// Error (red)  
AnsiConsole.MarkupLine($"[red]Error:[/] {message.EscapeMarkup()}");

// Warning (yellow)
AnsiConsole.MarkupLine($"[yellow]Note:[/] {message}");

// Info/debug (dim)
AnsiConsole.MarkupLine($"[dim]{message}[/]");

// Headers (cyan)
AnsiConsole.MarkupLine($"[cyan]{title}[/]");

Output Consistency

• Tables for structured data (query lists, sheet lists)
• Panels for code blocks (M code display)
• Progress indicators for long operations
• Clear error messages with actionable guidance

🐛 Bug Reports

When reporting bugs, please include:

• Excel version and Windows version
• Command used and arguments
• Expected behavior vs actual behavior
• Sample Excel file (if possible)
• Error messages (full text)

💡 Feature Requests

Great feature requests include:

• Use case description - Why is this needed?
• Proposed command syntax - How should it work?
• Excel operations involved - What APIs would be used?
• Target users - Coding agents? Direct users?

📚 Learning Resources

• Excel VBA Object Model Reference
• Power Query M Language Reference
• Spectre.Console Documentation
• .NET COM Interop Guide

📦 For Maintainers

• NuGet Publishing Guide - Complete guide for publishing all packages with OIDC trusted publishing

🏷️ Issue Labels

• bug - Something isn't working
• enhancement - New feature or improvement
• documentation - Documentation improvements
• good first issue - Good for newcomers
• help wanted - Extra attention needed
• excel-com - Excel COM automation issues
• power-query - Power Query specific
• coding-agent - Coding agent related

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Thank you for contributing to Sbroenne.ExcelMcp! Together we're making Excel automation more accessible to coding agents and developers worldwide. 🚀