Sage Agent Language - VS Code Extension

Language support for the Sage Agent Programming Language (.sag files).

Features

Everything works out of the box - no additional installation required!

Syntax Highlighting - Full TextMate grammar for .sag files
Diagnostics - Real-time error checking as you type
Hover Info - Type information and documentation on hover
Auto-completion - Keyword and context-aware suggestions
Go to Definition - Navigate to tool and type definitions

The extension includes bundled Language Server binaries for:

Linux (x64, ARM64)
macOS (Intel, Apple Silicon)
Windows (x64)

Installation

From VS Code Marketplace

Open VS Code
Go to Extensions (Ctrl+Shift+X / Cmd+Shift+X)
Search for "Sage Agent Language"
Click Install
Open a .sag file - everything works automatically!

From VSIX File

code --install-extension sage-agent-language-0.3.0.vsix

Configuration

Setting	Description	Default
`sag.server.path`	Custom path to sag-lsp binary (optional)	(uses bundled)
`sag.trace.server`	Trace LSP communication	`off`

Example

agent WeatherAgent {
  description: "An agent that provides weather information"
  version: "1.0.0"

  model {
    provider: "anthropic"
    name: "claude-sonnet-4-20250514"
  }

  state {
    lastCity?: string
  }

  tool get_weather(city: string) -> WeatherData {
    description: "Get current weather for a city"
    let data = await http.get(`https://api.weather.com/${city}`)
    return data
  }

  on user_message {
    let weather = get_weather("San Francisco")
    emit response(weather)
  }
}

type WeatherData {
  temperature: number
  humidity: number
  description: string
}

Supported Language Features

Agents - agent, tool, state, model, protocols, on
Control Flow - if, else, for, while, match, return
Error Handling - try, catch, finally, throw
Functions - fn, async, await
Types - type, string, number, boolean, array, record, optional, tuple
Operators - Arithmetic, comparison, logical, optional chaining (?.), null coalescing (??)
Patterns - Destructuring, match expressions with guards
Strings - Double-quoted and template literals with ${interpolation}
Comments - Line (//) and block (/* */)

Status Bar Indicator

The status bar shows the Language Server state:

✓ Sage LSP - Full LSP support is active
⚠ Sage (syntax only) - LSP not available (syntax highlighting still works)

Development

Testing the Extension Locally

Prerequisites

Node.js (v18 or later)
VS Code
Rust toolchain (for building the LSP server)

Step 1: Build the LSP Server

From the repository root:

cargo build --release --bin sag-lsp

Step 2: Install Extension Dependencies

cd editors/vscode
npm install

Step 3: Compile the Extension

npm run compile

Step 4: Launch Extension in Debug Mode

Open the editors/vscode folder in VS Code
Press F5 to launch the Extension Development Host
Open a .sag file to test

Packaging

npm run package

This creates sage-agent-language-x.x.x.vsix.

License

MIT

Sage Agent Language

sagesyn