agent-sandbox

A secure, embeddable, WASM-based sandbox for AI agents. 40+ built-in CLI tools, a JavaScript runtime, <13ms startup, no Docker/VMs required.

Installation

Rust

cargo add agent-sandbox

Node.js

npm install @parassharmaa/agent-sandbox

Prebuilt binaries are available for macOS (arm64, x64), Linux (x64, arm64), and Windows (x64).

Quick Start

Rust

use agent_sandbox::{Sandbox, config::SandboxConfig};

let config = SandboxConfig {
    work_dir: "/path/to/workdir".into(),
    ..Default::default()
};
let sandbox = Sandbox::new(config)?;

let result = sandbox.exec("grep", &["TODO".into(), "/work/main.rs".into()]).await?;
println!("{}", String::from_utf8_lossy(&result.stdout));

// Execute JavaScript inside the sandbox
let js_result = sandbox.exec_js("console.log('Hello from JS!')").await?;

Node.js

import { Sandbox } from "@parassharmaa/agent-sandbox";

const sandbox = new Sandbox({ workDir: "/path/to/workdir" });
const result = await sandbox.exec("grep", ["TODO", "/work/main.rs"]);
console.log(result.stdout.toString());

// Execute JavaScript inside the sandbox
const jsResult = await sandbox.execJs("console.log('Hello from JS!')");

const changes = await sandbox.diff();
await sandbox.destroy();

Features

• 40+ tools: cat, grep, find, sed, awk, jq, git, tar, zip, and more
• Built-in JavaScript runtime (Boa engine) via node command or execJs() API
• Filesystem sandboxing with path traversal prevention
• Resource limits: fuel, timeout, memory
• Change tracking via filesystem snapshots
• AOT precompiled WASM — <13ms cold start, ~55us cached
• Node.js bindings (NAPI)

JavaScript Runtime

The sandbox includes a built-in JavaScript engine (Boa) that runs entirely inside the WASM sandbox. Use it via the node command or the execJs() convenience method.

// Inline evaluation
await sandbox.exec("node", ["-e", "console.log('hello')"]);

// Evaluate and print result
await sandbox.exec("node", ["-p", "2 + 3 * 4"]); // stdout: "14"

// Run a script file (from /work)
await sandbox.writeFile("script.js", Buffer.from(`
  const data = [1, 2, 3, 4, 5];
  console.log(JSON.stringify({ sum: data.reduce((a, b) => a + b) }));
`));
await sandbox.exec("node", ["/work/script.js"]);

// Convenience method
await sandbox.execJs("console.log('quick and easy')");

Supported JS features: ES2023+ (variables, arrow functions, destructuring, template literals, Promises, Map/Set, JSON, Math, RegExp, Array methods, and more). No network access or Node.js built-in modules — runs in pure WASM isolation.

Limitations

• No network access (WASI p1)
• No process spawning or shell pipes
• JS runtime has no Node.js built-in modules (fs, http, etc.)
• Single-threaded execution
• Same-architecture precompiled binary

Best for: file-manipulation agents (code analysis, refactoring, git ops), sandboxed JS evaluation. Not for: arbitrary network requests, API calls, databases, GPU.

License

MIT