YAML LSP for Domain-Specific Language (VS Code LSP)

A modern, extensible Language Server Protocol (LSP) implementation for VS Code, supporting YAML, variable interpolation, file/module includes, and LLM-powered features.

Features

• YAML & Plain Text Support: Language features for YAML and plaintext files.
• Completions: Context-aware code completion for YAML keywords and custom schema.
• Diagnostics: Real-time diagnostics for uppercase words, undefined variables, and more.
• Variable Interpolation: Jinja2-style ${var} variable replacement using .vars.yaml files.
• File Includes: Import YAML files as modules using include directives.
• LLM Integration: Send prompts and data to LLMs (OpenRouter, DeepSeek, etc.) for code analysis, correction, and feedback.
• Schema Keyword Extraction: Extract and compare YAML schema keywords with your document.
• End-to-End Tests: Automated tests for both client and server.

Project Structure

.
├── client/                  # VS Code Language Client
│   ├── src/
│   │   ├── extension.ts     # Client entry point
│   │   └── test/            # End-to-end tests
│   └── ...
├── server/                  # Language Server
│   ├── src/
│   │   ├── server.ts        # Main LSP server
│   │   ├── include.ts       # Include/module logic for YAML
│   │   ├── logger.ts        # Logging utilities
│   │   ├── errorHandler.ts  # LLM and server error handling
│   │   └── expressions/     # Variable resolution and interpolation
│   └── ...
├── package.json             # Monorepo manifest
├── README.md                # This file
└── ...

Getting Started

1. Install dependencies

   npm install

2. Build the project

   npm run compile

   Or start in watch mode:

   npm run watch

3. Open in VS Code
   • Open this folder in VS Code.
   • Press F5 to launch the Extension Development Host.

Usage

• Open a YAML or plaintext file.
• Use completions for keywords like prompt, data, include, etc.
• Add variables in a .vars.yaml file at the workspace root. Use ${var} in your YAML to reference them.
• Use include: somefile.yaml to import YAML modules.
• Use the extension's commands or UI to send prompts/data to the LLM for feedback or correction.

Advanced

• Schema Keyword Extraction: Use the llm-schema.extractKeywords request to compare your YAML with a schema.
• LLM Feedback: Use the llm-feedback.insertComment request to get LLM-powered comments or corrections.
• Custom Includes: Extend server/src/include.ts to support new file types or module behaviors.

Testing

• Run all tests:

  cd client && npm test
  cd ../server && npm test

Contributing

Contributions are welcome! Please open issues or pull requests for improvements, bug fixes, or new features.