rbxdev-ls

Roblox/Luau language server for VS Code with type checking, completions, and live game integration

Overview

rbxdev-ls is a VS Code extension that brings full Roblox API support and Luau type checking to your editor. It ships a custom language server that understands Roblox classes, services, data types, enums, and the Luau type system — providing completions, diagnostics, hover documentation, go-to-definition, rename, and formatting out of the box.

Beyond language features, the extension connects to a live Roblox game through a WebSocket executor bridge. This gives you a Game Tree explorer, a Properties panel, in-editor code execution, a Remote Spy, and instance manipulation — all without leaving VS Code. It also exposes 16 language model tools for GitHub Copilot and a built-in MCP server for Claude, Cursor, and other AI assistants, so your AI tools can interact with the running game directly.

Features

• Full Roblox API completions — Every class, method, property, enum, and data type in the Roblox API, always up to date
• Luau type checking — Strict, nonstrict, and nocheck modes with diagnostics for type mismatches, undefined variables, and deprecated APIs
• Live Game Tree — Browse the running game hierarchy, inspect properties, and manipulate instances from the VS Code sidebar
• In-editor code execution — Execute Luau files or selections in the game with a single keybinding
• Remote Spy — Monitor RemoteEvent and RemoteFunction calls in real time with copyable Luau reproduction code
• AI integration — 16 language model tools for GitHub Copilot plus a built-in MCP server for external AI assistants
• Bundle and execute — Bundle multi-file Luau projects with luau-bundle and execute the result in-game
• Save instances — Save the full DataModel or individual instances to .rbxl/.rbxm files with optional script decompilation
• Rojo sourcemap support — Reads sourcemap.json for go-to-definition and module resolution in Rojo-managed projects

Table of Contents

• Quick Start
• Language Features
• Live Game Integration
• AI Integration
• Diagnostics
• Settings
• Keybindings
• Game Tree Context Menu
• Bridge Setup
• License

Quick Start

1. Install rbxdev-ls from the VS Code Marketplace
2. Open a folder containing .lua or .luau files
3. Start coding — completions, type checking, and hover documentation activate immediately

For live game features, see Bridge Setup below.

Language Features

The language server provides the full set of editing features you expect from a typed language:

Live Game Integration

When an executor bridge is connected (see Bridge Setup), the extension adds a sidebar panel and several commands for interacting with the running game.

Game Tree Explorer

A tree view in the VS Code sidebar that mirrors the live game hierarchy. It shows every service and its children, updating when instances are added, removed, or renamed. Click any instance to view its properties in the Properties panel. Drag and drop instances to reparent them. Right-click for context actions (copy path, teleport, delete, view script source, create, clone, save).

Properties Panel

A webview panel that displays all properties of the selected instance with their current values. Edit property values directly — the changes apply to the live game immediately. Supports all Roblox property types including Vector3, Color3, CFrame, UDim2, and enum values.

Code Execution

Execute Luau code in the game without switching windows. The extension sends the code through the bridge and displays the result or error in the output panel.

Remote Spy

A dedicated panel that captures every RemoteEvent:FireServer and RemoteFunction:InvokeServer call between client and server. Each entry shows the remote name, method, arguments, and a copyable Luau snippet that reproduces the call. Filter by remote name, ignore specific remotes, and block remotes from firing.

Instance Manipulation

Create, clone, delete, and reparent instances directly from the Game Tree. Drag and drop to reparent. Right-click to access all actions. Save any instance (or the entire DataModel) to disk as .rbxl or .rbxm files.

AI Integration

GitHub Copilot Tools

The extension registers 16 language model tools that GitHub Copilot can call directly. These cover the same capabilities as the MCP tools: bridge status, code execution, game tree traversal, property read/write, instance manipulation, script decompilation, console output, and Remote Spy.

Built-in MCP Server

The extension includes an embedded MCP server that external AI assistants (Claude, Cursor, Windsurf) can connect to. When rbxdev-ls.mcp.enabled is true (the default), the server starts automatically and shares the extension's executor bridge. See the @0neshot101/rbxdev-mcp package for standalone MCP usage outside VS Code.

MCP Resources

Three read-only resources are exposed for AI tools that support MCP resource subscriptions:

Diagnostics

The language server reports diagnostics as you type, covering type errors, undefined variables, and deprecation warnings. You can suppress diagnostics on a per-line or per-block basis with ignore directives.

Settings

All settings are under the rbxdev-ls namespace in VS Code.

Keybindings

Game Tree Context Menu

Right-click any item in the Game Tree sidebar for these actions:

Bridge Setup

Live game features (Game Tree, Properties, code execution, Remote Spy) require a WebSocket bridge between VS Code and a Roblox executor. The bridge script ships with the repository and is hosted on GitHub for easy loading.

Connect the bridge

Add this to your executor's auto-execute folder so it runs when you join a game:

loadstring(game:HttpGetAsync'https://raw.githubusercontent.com/0neShot101/rbxdev-ls/main/scripts/executor-bridge.lua')()

When the bridge connects, the VS Code status bar shows Roblox: Connected (or Roblox: Studio for Studio plugin connections). The Game Tree populates automatically.

Custom bridge configuration

Pass a config table to override default bridge behavior:

loadstring(game:HttpGetAsync'https://raw.githubusercontent.com/0neShot101/rbxdev-ls/main/scripts/executor-bridge.lua')({
    host = 'ws://127.0.0.1:21324',
    reconnectDelay = 5,
    firstConnectDepth = 999,
    updateTreeDepth = 2,
    expandedTreeDepth = 2,
})

The default behavior sends a full tree dump on first connect so the extension has complete data for completions and path resolution, then switches to shallow updates to minimize overhead.

Custom port

If port 21324 is unavailable, change the port in VS Code settings (rbxdev-ls.executorBridge.port) and update the host parameter in the bridge config to match.

License

MIT © Andrew