Unity Code Native

Description

Unity Code Native is a high-performance Rust backend that powers advanced Unity development tools. Originally designed for Unity process detection, it has evolved into a comprehensive language server suite that provides intelligent IDE features for Unity's UI Toolkit and C# documentation systems.

Main Features

🎨 USS Language Server

A feature-complete language server for Unity Style Sheets (USS) that brings modern IDE capabilities to Unity's UI Toolkit development:

• High performance: Written in rust, built from ground up for performance. Get instant feedback (diagnostics) on syntax and values as you type! 100% high performance as a game dev's code should be!
• Syntax Highlighting: Of course!
• Comprehensive Auto-completion: Property names, values, selectors, pseudo-classes, and asset URLs. For element names, it know all Unity Engine UXML element's lile Button and Label and will provide auto completion when you type them. For url, auto completion will complete from Assets all the way down to the individual sprite in the image(if it is a multiple sprite image asset).
• Advanced Diagnostics: Syntax validation, asset path (eg. url() functions) validation, property value validation, everything you ever need and more. 100% USS native, validates every property that USS has and can check the value you provide it with accuracy, almost produce the same errors (and more) as Unity itself does. It goes above and beyond and try to validate property values even if it has var() in it, which no one, not Unity, or any CSS language server does(though it is not 100% accurate because we never know what variables value will be at runtime).
• Intelligent Hover Documentation: Rich tooltips with syntax examples and keyword explanations. No need to check official docs when you have quick hover docs that is completely Unity specific, no browser or CSS shenanigans(almost). Also, a link to official (mostly Unity's) docs is provided.
• Code Formatting: Document and selection formatting for USS and TSS files
• Refactoring: Rename operations for ID and class selectors

📚 C# Documentation System

Automated XML documentation extraction and compilation for Unity projects:

• Package Documentation: Extracts XML docs from Unity packages in Library/PackageCache
• User Code Documentation: Processes user assemblies with full member documentation
• Assembly Watching: Real-time updates when Unity recompiles assemblies
• Inheritance Resolution: Resolves <inheritdoc> references across assemblies
• Efficient Storage: Compiles documentation into optimized JSON format

🔍 Unity Process Detection

Original core functionality for Unity Editor integration:

• Detects running Unity Editor instances for specific projects
• Monitors Hot Reload for Unity status
• UDP-based messaging protocol for real-time communication
• Cross-platform process monitoring

Why Rust?

Rust provides the perfect balance of performance and safety for this project:

• Process Detection: JavaScript's process detection is too slow (requires PowerShell on Windows), and C# lacks parent process ID access
• Performance: Rust allows precise control over system resource usage without unnecessary overhead
• Memory Safety: Critical for long-running language server processes
• Cross-platform: Single codebase supports Windows, macOS, and Linux
• Async Efficiency: Tokio provides excellent single-threaded async performance

Usage

As a Language Server

The primary use case is as a language server for USS files in Unity projects. The binary integrates with VS Code extensions and other LSP-compatible editors to provide:

• Real-time syntax highlighting and error detection
• Context-aware auto-completion as you type
• Hover documentation for properties and values
• Code formatting and refactoring capabilities

Command Line Usage

For Unity process detection and monitoring:

unity_code_native.exe "C:\path\to\your\Unity\Project"

The tool will detect running Unity Editor instances and provide status information via UDP messaging.

Test

Some tests rely on the embedded Unity Project in UnityProject directory. Unity Engine generated files is needed for some tests to pass. So if you want to run full tests, you need to use Unity Engine to open the embedded Unity Project in UnityProject directory before running the tests.

Build

Ensure you have the latest Rust toolchain installed:

cargo build --release

The resulting binary in target/release/ is self-contained and can be deployed anywhere.

Cross-platform: Build on your target platform for optimal compatibility.

Development

For rapid development iterations:

# Fast build without optimizations
cargo build --profile release-fast

# Copy to target directory (adjust path as needed)
Copy-Item -Path target\release-fast\unity_code_native.exe -Destination F:\projects\js\UnityCode\bin\win_x64

Architecture

• Single-threaded async: Uses Tokio for efficient async operations without threading complexity
• tree-sitter: Leverages tree-sitter-css for robust USS parsing
• tower-lsp: Implements Language Server Protocol for editor integration
• Cross-platform: Supports Windows, macOS, and Linux

Version 1.0 Release

This 1.0 release represents a mature, production-ready language server with comprehensive USS support and robust C# documentation features. The USS language server is particularly feature-complete, offering an experience comparable to modern CSS tooling but tailored specifically for Unity's UI Toolkit development workflow.