examples/ui/hello_input/meta/hello_input.cmx

{
  "program": {
    "binary": "bin/app"
  },
  "sandbox": {
    "dev": [ "class/input" ],
    "services": [
        "fuchsia.sys.Environment",
        "fuchsia.sys.Launcher",
        "fuchsia.ui.scenic.Scenic"
    ]
  }
}