XamlVisualEditor

XamlVisualEditor is an extensible Avalonia-based visual IDE for editing, previewing, inspecting, debugging, and automating XAML applications. It combines an AvaloniaEdit code surface, a live design surface, Dock-based tool windows, language services, debugger adapters, terminal integration, collaboration services, and a native .NET extension model.

The repository targets .NET 10 and is built around strict MVVM, ReactiveUI, compiled Avalonia bindings, Dock for Avalonia, Xaml.Behaviors, AvaloniaEdit, ProDataGrid, Microsoft.Extensions.DependencyInjection, and xUnit/Avalonia Headless tests.

Highlights

• Live XAML editing: parse, serialize, and round-trip XAML through XamlX-backed AST services with minimal text changes.
• Visual designer: instantiate Avalonia controls from AST nodes, map visuals back to source nodes, and support drag/drop, selection, resize handles, rulers, grids, margins, and padding adorners.
• Code editor: AvaloniaEdit integration with syntax highlighting, completion, semantic tokens, diagnostics, and execution-line rendering.
• Workspace tooling: open workspaces, build/clean/rebuild projects, restore state, select startup projects, and integrate file-system backed extension APIs.
• Language services: C# and XAML completion/diagnostics plus an LSP router for external language servers.
• Extension-first shell: built-in and packaged extensions contribute commands, menus, toolbar actions, views, language servers, property editors, and panels.
• Debugging: DAP and .NET SDK debugger integrations, launch validation, breakpoint/call-stack/locals/watch panels, and debug settings tooling.
• Developer panels: solution explorer, file explorer, toolbox, property editor, output/problems, references, tree inspectors, animation editor, collaboration, ACP, MCP, IDE bridge, LSP settings, terminal, and Git views.
• Collaboration and agents: ACP client services, OAuth/device-flow support, permissions, profile storage, and ProEdit-backed collaborative AST operations.
• Terminal and Git: managed terminal emulator/PTY support and Git status/diff parsing surfaced through extension panels.
• Test coverage: unit, integration, performance, and Avalonia Headless UI tests cover parsing, services, extension plumbing, UI flows, terminal behavior, LSP, ACP, previewer protocols, and workspace workflows.

Repository Layout

Path	Purpose
src/XamlVisualEditor.App	Avalonia application entry point, composition root, views, and resources.
src/XamlVisualEditor.Shell.ViewModels	Main window, documents, Dock factories, panels, and shell orchestration ViewModels.
src/XamlVisualEditor.Extensions	Native extension SDK contracts, host services, package loading, and contribution registries.
src/XamlVisualEditor.Xaml.*	XAML parsing, AST, serialization, intellisense, and language server components.
src/XamlVisualEditor.Designer.*	Designer abstractions, rendering, adorners, drag/drop, and previewer host.
src/XamlVisualEditor.CodeEditor	AvaloniaEdit integration and editor rendering helpers.
src/XamlVisualEditor.Workspace	MSBuild workspace loading, template discovery, assembly resolution, and CLI helpers.
src/XamlVisualEditor.Lsp	JSON-RPC/LSP client transport, routing, diagnostics, and test hooks.
src/XamlVisualEditor.Acp	Agent Client Protocol client, permissions, profiles, secrets, and process hosting.
src/XamlVisualEditor.Terminal*	Terminal emulator core, platform PTY providers, and Avalonia terminal view.
extensions/	Built-in extension projects for panels, commands, debugging, templates, Git, MCP, ACP, and compatibility hosts.
tests/	Unit, integration, performance, and Avalonia Headless UI test projects.
tools/	Extension samples, LSP harness, IDE bridge CLI, and extension host spike.
docs/	Internal architecture, extension migration, and API notes.
site/	Lunet documentation site published by GitHub Pages.

Build

Prerequisites:

• .NET SDK 10.0.x
• Git submodules initialized when working with the full workspace

git submodule update --init --recursive
dotnet restore XamlVisualEditor.slnx
dotnet build XamlVisualEditor.slnx -c Release --no-restore

Run the main test projects:

dotnet test tests/XamlVisualEditor.Tests.Unit/XamlVisualEditor.Tests.Unit.csproj -c Release
dotnet test tests/XamlVisualEditor.Tests.Integration/XamlVisualEditor.Tests.Integration.csproj -c Release
dotnet test tests/XamlVisualEditor.Tests.UI/XamlVisualEditor.Tests.UI.csproj -c Release

Run the application:

dotnet run --project src/XamlVisualEditor.App/XamlVisualEditor.App.csproj

Documentation

The documentation site is built with Lunet from site/.

./build-docs.sh
cd site
dotnet tool run lunet serve

The site covers product features, architecture, extension development, debugging, collaboration, language services, testing, CI, and release guidance. Existing internal notes remain in docs/ and are linked from the site reference section.

Extension Model

Extensions are packaged as NuGet packages with xve.extension.json at the package root and a .NET assembly implementing IXveExtension. The extension host exposes typed services for commands, views, workspace access, diagnostics, editor operations, navigation, terminal access, settings, storage, logging, dialogs, permissions, and panel hosts.

Sample extensions are available in tools/ExtensionSamples/HelloExtension and tools/ExtensionSamples/LspExtension.

dotnet pack tools/ExtensionSamples/HelloExtension/HelloExtension.csproj -c Release

NuGet Packages

Reusable libraries and built-in extensions carry repository, license, readme, icon, Source Link, and symbol package metadata. Release builds pack the solution into .nupkg and .snupkg artifacts, publish them to NuGet when NUGET_API_KEY is configured, and attach the packages to the GitHub release.

Contributing

Follow the repository engineering rules in AGENTS.md: strict SOLID and MVVM, passive views, ReactiveUI ViewModels, compiled Avalonia bindings, Xaml.Behaviors for UI input, Dock model state in ViewModels, ProDataGrid for tabular/tree data, Microsoft.Extensions.DependencyInjection from a single composition root, and tests for production behavior.

Before opening a pull request, build the solution, run the relevant test projects, and build the Lunet documentation site.