WASM Target

Sage can compile agents to WebAssembly for browser execution.

Building for WASM

sage build hello.sg --target web

This compiles your Sage program through the full pipeline (parse, type-check, codegen) but targets wasm32-unknown-unknown instead of your native platform.

Output

The build produces a pkg/ directory containing:

pkg/
  hello.js          # JavaScript glue (wasm-bindgen)
  hello_bg.wasm     # WebAssembly binary

Prerequisites

The WASM target requires:

wasm32-unknown-unknown Rust target: rustup target add wasm32-unknown-unknown
wasm-bindgen-cli: cargo install wasm-bindgen-cli
(Optional) wasm-opt for size optimisation: install via binaryen

Target values

The --target flag accepts:

Value	Description
`native`	Default. Compile to a native binary.
`web` or `wasm`	Compile to WebAssembly for browser use.

How It Works

When targeting WASM, the codegen layer:

Generates a #[wasm_bindgen(start)] entry point instead of #[tokio::main]
Uses sage-runtime-web — a browser-compatible runtime that replaces tokio, reqwest, and native I/O with Web APIs
Produces a cdylib crate compiled with wasm-bindgen
Optionally runs wasm-opt -Oz for size optimisation

Using in a Web Page

<script type="module">
  import init from './pkg/hello.js';
  await init();
</script>

The WASM module initialises automatically via the #[wasm_bindgen(start)] entry point.

Limitations

divine (LLM calls) requires a browser-accessible OpenAI-compatible endpoint
Database and Shell tools are not available in WASM
Fs operations use browser storage APIs instead of the filesystem
Agent concurrency uses wasm_bindgen_futures::spawn_local (single-threaded)

Keyboard shortcuts

Sage