The sandbox was shipped in v0.17.2 but with a design issue: the MCP entry was auto-injected into editor configs by detecting services with type: sandbox. That meant it wasn’t visible in your mcps array, couldn’t be overridden, and didn’t follow the same pattern as everything else.

v0.18.0 fixes that.

What changed

mcp.sandbox()

Configure the sandbox like any other MCP:

import { defineConfig, mcp, service } from "@arvoretech/hub/config";

export default defineConfig({
  mcps: [
    mcp.sandbox(8080),
  ],
  services: [
    { name: "sandbox", type: "sandbox", port: 8080 },
  ],
});

mcp.sandbox(port) defaults to port 8080 if omitted.

No more auto-injection

hub generate no longer scans services for type: sandbox and force-injects the MCP. The entry flows through the normal MCP pipeline — same as any MCP with a url.

Agent context still works

The ## Sandbox Environment section injected into QA and coding agent prompts is now triggered by the presence of sandbox in your mcps array instead of services. Behavior is identical, the source of truth is just in the right place.

Migration

If you were on v0.17.2, add mcp.sandbox() to your mcps array and run hub generate again:

mcps: [
  mcp.sandbox(8080), // add this
],

Upgrade

npx @arvoretech/hub@0.18.0 generate