Add modal sandbox support (#192)

* add modal sandbox example

* add test instructions

---------

Co-authored-by: Nathan Flurry <NathanFlurry@users.noreply.github.com>

examples/modal/src/modal.ts

@@ -0,0 +1,123 @@
+import { ModalClient } from "modal";
+import { SandboxAgent } from "sandbox-agent";
+import { detectAgent, buildInspectorUrl, waitForHealth } from "@sandbox-agent/example-shared";
+import { fileURLToPath } from "node:url";
+import { resolve } from "node:path";
+import { run } from "node:test";
+
+const PORT = 3000;
+const APP_NAME = "sandbox-agent";
+
+async function buildSecrets(modal: ModalClient) {
+  const envVars: Record<string, string> = {};
+  if (process.env.ANTHROPIC_API_KEY) 
+    envVars.ANTHROPIC_API_KEY = process.env.ANTHROPIC_API_KEY;
+  if (process.env.OPENAI_API_KEY) 
+    envVars.OPENAI_API_KEY = process.env.OPENAI_API_KEY;
+
+  if (Object.keys(envVars).length === 0) return [];
+  return [await modal.secrets.fromObject(envVars)];
+}
+
+export async function setupModalSandboxAgent(): Promise<{
+  baseUrl: string;
+  cleanup: () => Promise<void>;
+}> {
+  const modal = new ModalClient();
+  const app = await modal.apps.fromName(APP_NAME, { createIfMissing: true });
+
+  const image = modal.images
+    .fromRegistry("ubuntu:22.04")
+    .dockerfileCommands([
+      "RUN apt-get update && apt-get install -y curl ca-certificates",
+      "RUN curl -fsSL https://releases.rivet.dev/sandbox-agent/0.2.x/install.sh | sh",
+    ]);
+
+  const secrets = await buildSecrets(modal);
+
+  console.log("Creating Modal sandbox!");
+  const sb = await modal.sandboxes.create(app, image, {
+    secrets: secrets, 
+    encryptedPorts: [PORT],
+  });
+  console.log(`Sandbox created: ${sb.sandboxId}`);
+
+  const exec = async (cmd: string) => {
+    const p = await sb.exec(["bash", "-c", cmd], {
+      stdout: "pipe",
+      stderr: "pipe",
+    });
+    const exitCode = await p.wait();
+    if (exitCode !== 0) {
+      const stderr = await p.stderr.readText();
+      throw new Error(`Command failed (exit ${exitCode}): ${cmd}\n${stderr}`);
+    }
+  };
+
+  if (process.env.ANTHROPIC_API_KEY) {
+    console.log("Installing Claude agent...");
+    await exec("sandbox-agent install-agent claude");
+  }
+  if (process.env.OPENAI_API_KEY) {
+    console.log("Installing Codex agent...");
+    await exec("sandbox-agent install-agent codex");
+  }
+
+  console.log("Starting server...");
+
+  await sb.exec(
+    ["bash", "-c", `sandbox-agent server --no-token --host 0.0.0.0 --port ${PORT} &`],
+  );
+
+  const tunnels = await sb.tunnels();
+  const tunnel = tunnels[PORT];
+  if (!tunnel) {
+    throw new Error(`No tunnel found for port ${PORT}`);
+  }
+  const baseUrl = tunnel.url;
+
+  console.log("Waiting for server...");
+  await waitForHealth({ baseUrl });
+
+  const cleanup = async () => {
+    try {
+      await sb.terminate();
+    } catch (error) {
+      console.warn("Cleanup failed:", error instanceof Error ? error.message : error);
+    }
+  };
+
+  return { baseUrl, cleanup };
+}
+
+export async function runModalExample(): Promise<void> {
+  const { baseUrl, cleanup } = await setupModalSandboxAgent();
+
+  const handleExit = async () => {
+    await cleanup();
+    process.exit(0);
+  };
+
+  process.once("SIGINT", handleExit);
+  process.once("SIGTERM", handleExit);
+
+  const client = await SandboxAgent.connect({ baseUrl });
+  const session = await client.createSession({ agent: detectAgent(), sessionInit: { cwd: "/root", mcpServers: [] } });
+  const sessionId = session.id;
+
+  console.log(`  UI: ${buildInspectorUrl({ baseUrl, sessionId })}`);
+  console.log("  Press Ctrl+C to stop.");
+
+  await new Promise(() => {});
+}
+
+const isDirectRun = Boolean(
+  process.argv[1] && resolve(process.argv[1]) === fileURLToPath(import.meta.url),
+);
+
+if (isDirectRun) {
+  runModalExample().catch((error) => {
+    console.error(error instanceof Error ? error.message : error);
+    process.exit(1);
+  });
+}