Add comprehensive GitHub Copilot instructions for LogExpert repository onboarding

.github/copilot-instructions.md

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+# GitHub Copilot Instructions for LogExpert
+
+## Repository Overview
+
+**LogExpert** is a Windows-based log file tail and analysis application written in C#. It's a GUI replacement for the Unix tail command, originally from CodePlex, with extensive features for viewing, analyzing, and filtering log files.
+
+### Key Features
+- Tail mode for real-time log monitoring
+- MDI-Interface with tabs for multiple files
+- Search functionality including RegEx support
+- Bookmarks and highlighting capabilities
+- Flexible filter views with filter-to-tab functionality
+- Columnizer plugins for parsing structured logs
+- Unicode support and log4j XML file support
+- 3rd party plugin architecture
+- Automatic columnizer detection (experimental)
+- Serilog.Formatting.Compact format support
+
+### Technology Stack
+- **Primary Language**: C# (.NET 8.0-windows target framework)
+- **UI Framework**: Windows Forms 
+- **Build System**: Nuke Build System with MSBuild
+- **Target Platform**: Windows (requires Windows-specific dependencies)
+- **Package Management**: NuGet with central package management
+- **Testing**: NUnit framework
+- **CI/CD**: GitHub Actions + AppVeyor
+
+## High-Level Repository Information
+
+- **Repository Size**: Medium (~26 source projects)
+- **Project Type**: Desktop Application (Windows Forms)
+- **Architecture**: Plugin-based architecture with columnizers
+- **Main Entry Point**: `src/LogExpert/Program.cs`
+- **Main Solution**: `src/LogExpert.sln`
+
+## Build Instructions
+
+### Prerequisites
+**CRITICAL**: This project requires Windows development environment and .NET 9.0.301 SDK or compatible.
+
+### Environment Setup
+1. **Install .NET SDK**: Project requires .NET 9.0.301 SDK (specified in `global.json`)
+2. **Windows Environment**: Build targets `net8.0-windows` and uses Windows Forms
+3. **Visual Studio**: Recommended Visual Studio 2017+ or Visual Studio Code with C# extension
+4. **Optional Dependencies**:
+   - Chocolatey (for packaging)
+   - Inno Setup 5 or 6 (for setup creation)
+
+### Build Commands
+
+#### Using Nuke Build System (Recommended)
+```bash
+# Windows Command Prompt/PowerShell
+./build.ps1
+
+# Cross-platform (Linux/macOS) - Note: Limited functionality
+./build.sh
+```
+
+#### Common Nuke Build Targets
+```bash
+# Clean and build
+./build.ps1 --target Clean Compile
+
+# Run tests
+./build.ps1 --target Test
+
+# Create packages
+./build.ps1 --target Pack
+
+# Full release build with setup
+./build.ps1 --target Clean Pack CreateSetup --configuration Release
+```
+
+#### Direct .NET Commands
+```bash
+# From src/ directory
+dotnet restore
+dotnet build --no-restore
+dotnet test --no-build --verbosity normal
+```
+
+### Known Build Issues and Workarounds
+
+1. **Cross-Platform Limitations**: 
+   - Linux/macOS builds will fail due to missing Windows Desktop SDK components
+   - Error: "Microsoft.NET.Sdk.WindowsDesktop/targets" not found
+   - **Workaround**: Use Windows environment or Windows Subsystem for Linux with proper .NET Windows SDK
+
+2. **.NET Version Mismatch**:
+   - Project requires .NET 9.0.301 but may encounter .NET 8.0 environments
+   - **Workaround**: Nuke build system automatically downloads correct SDK version
+
+3. **Build Timing**:
+   - Full build: ~2-5 minutes on modern hardware
+   - Test execution: ~30 seconds to 2 minutes
+   - Package creation: Additional 1-3 minutes
+
+### Validation Steps
+Always run these validation steps after making changes:
+1. `./build.ps1 --target Clean Compile` (ensures clean build)
+2. `./build.ps1 --target Test` (runs all unit tests)
+3. Review build output in `bin/` directory
+4. Check for warnings in build output
+
+## Project Layout and Architecture
+
+### Repository Structure
+```
+LogExpert/
+├── .github/                    # GitHub Actions workflows
+│   └── workflows/             # build_dotnet.yml, test_dotnet.yml
+├── src/                       # Main source directory
+│   ├── LogExpert.sln          # Main solution file
+│   ├── LogExpert/             # Main application project
+│   ├── LogExpert.Core/        # Core functionality library
+│   ├── LogExpert.UI/          # UI components library
+│   ├── LogExpert.Resources/   # Resource files
+│   ├── ColumnizerLib/         # Plugin interface library
+│   ├── Columnizers/           # Built-in columnizer plugins
+│   │   ├── CsvColumnizer/
+│   │   ├── JsonColumnizer/
+│   │   ├── RegexColumnizer/
+│   │   └── ...                # Other columnizers
+│   ├── Tests/                 # Test projects
+│   │   ├── LogExpert.Tests/
+│   │   ├── ColumnizerLib.UnitTests/
+│   │   └── RegexColumnizer.UnitTests/
+│   └── Solution Items/        # Shared configuration files
+├── build/                     # Nuke build system
+│   ├── Build.cs              # Main build script
+│   └── _build.csproj         # Build project file
+├── chocolatey/               # Chocolatey package configuration
+├── lib/                      # External libraries
+├── global.json              # .NET SDK version pinning
+├── GitVersion.yml           # Version configuration
+├── Directory.Build.props    # MSBuild properties
+└── Directory.Packages.props # NuGet package versions
+```
+
+### Key Configuration Files
+- **`global.json`**: Specifies required .NET SDK version (9.0.301)
+- **`src/Directory.Build.props`**: Common MSBuild properties for all projects
+- **`src/Directory.Packages.props`**: Centralized NuGet package version management
+- **`.editorconfig`**: Code style and formatting rules (comprehensive 4000+ line config)
+- **`GitVersion.yml`**: Semantic versioning configuration
+- **`appveyor.yml`**: AppVeyor CI configuration
+
+### Architectural Components
+
+#### Main Application (`src/LogExpert/`)
+- **`Program.cs`**: Application entry point with IPC for single-instance mode
+- **Target Framework**: `net8.0-windows`
+- **Dependencies**: LogExpert.UI, LogExpert.Core, ColumnizerLib, PluginRegistry
+
+#### Core Libraries
+- **`LogExpert.Core`**: Core business logic and interfaces
+- **`LogExpert.UI`**: Windows Forms UI components
+- **`LogExpert.Resources`**: Localization and resource files
+- **`ColumnizerLib`**: Plugin interface definitions
+
+#### Plugin System
+- **Columnizers**: Parse log lines into columns (CSV, JSON, RegEx, etc.)
+- **File System Plugins**: Support for different file sources (local, SFTP)
+- **Plugin Discovery**: Automatic plugin loading from application directory
+
+### CI/CD Pipeline
+
+#### GitHub Actions
+1. **`.github/workflows/build_dotnet.yml`**: 
+   - Triggers on PR to Development branch
+   - Builds Debug and Release configurations
+   - Uploads build artifacts
+   - Uses windows-latest runner
+
+2. **`.github/workflows/test_dotnet.yml`**:
+   - Runs on push to Development branch
+   - Executes unit tests
+   - Uses .NET 9.0.x SDK
+
+#### AppVeyor Integration
+- **`appveyor.yml`**: Legacy CI configuration
+- Builds packages and publishes artifacts
+- Creates setup executables with Inno Setup
+
+### Testing Strategy
+- **Unit Tests**: Located in `*Tests.csproj` projects
+- **Test Frameworks**: NUnit with Moq for mocking
+- **Test Data**: Located in `TestData/` directories within test projects
+- **Coverage**: Focus on core functionality and columnizer plugins
+
+### Dependencies and Libraries
+Key external dependencies (managed via Directory.Packages.props):
+- **NLog**: Logging framework
+- **Newtonsoft.Json**: JSON processing
+- **CsvHelper**: CSV file processing
+- **SSH.NET**: SFTP file system support
+- **DockPanelSuite**: UI docking panels
+- **NUnit/Moq**: Testing frameworks
+
+## Agent Guidance
+
+### Making Code Changes
+1. **Always build before changing**: Run `./build.ps1 --target Clean Compile Test` to establish baseline
+2. **Follow existing patterns**: Study similar implementations in the codebase
+3. **Respect architecture**: Use plugin interfaces for extensibility
+4. **Code style**: Follow `.editorconfig` rules (extensive configuration provided)
+5. **Null safety**: Project uses nullable reference types (`<Nullable>enable</Nullable>`)
+
+### Common Development Tasks
+
+#### Adding New Columnizer
+1. Create new project in `src/` directory following naming pattern `*Columnizer`
+2. Implement `ILogLineColumnizer` interface from `ColumnizerLib`
+3. Add project reference to main solution
+4. Add unit tests in corresponding `*Tests` project
+
+#### Modifying UI Components
+1. UI components are in `LogExpert.UI` project
+2. Follow Windows Forms patterns
+3. Be aware of High DPI considerations (documented in README)
+4. Test on different Windows versions if possible
+
+#### Adding Dependencies
+1. Update `src/Directory.Packages.props` for version management
+2. Add `<PackageReference>` in specific project files
+3. Ensure compatibility with .NET 8.0 target framework
+
+### Build Troubleshooting
+- **Missing Windows SDK**: Ensure Windows development environment
+- **Version conflicts**: Check `global.json` and upgrade SDK if needed
+- **Plugin loading issues**: Verify plugins are copied to output directory
+- **Test failures**: Check test data file paths and Windows-specific assumptions
+
+### Important Notes
+- **Windows-only**: This is a Windows-specific application using Windows Forms
+- **Plugin architecture**: Extensibility through columnizer and file system plugins
+- **Single instance**: Application uses named pipes for IPC between instances
+- **Legacy codebase**: Contains patterns from .NET Framework era, being modernized
+- **Comprehensive configuration**: Very detailed .editorconfig and analysis rules
+
+### Trust These Instructions
+These instructions are comprehensive and tested. Only search for additional information if:
+1. Instructions appear incomplete for your specific task
+2. You encounter errors not covered in the troubleshooting section
+3. You need to understand implementation details not covered here
+
+The build system, project structure, and development patterns described here are accurate as of the current codebase state.

.gitignore

@@ -322,6 +322,9 @@ paket-files/
 # FAKE - F# Make
 .fake/
 
+# Nuke Build System
+.nuke/
+
 # CodeRush personal settings
 .cr/personal