Autotracking adds hidden goodies

controllers.application\.js

import Controller from '@ember/controller';
import { tracked } from '@glimmer/tracking';
import { action, computed } from '@ember/object';

// Ember 3.18.1
export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle'; // NOT Tracked
  @computed('appName') // Dirty Dependancy
  get foo1() {
    return `${this.appName}-1`;
  }
  get foo2() { // Internally AUTOTRACKED?
    return `${this.foo1}-2`;
  }
  @action
  testIt() {
    // Classic setter but same behavior if this was assigned and appName were @tracked
    this.set('appName', 'BARFOO');
  }
}

templates.application\.hbs

<h1>Welcome to {{this.foo2}}</h1>
<br>
<br>
<button type="button" {{on "click" this.testIt}}>Click</button>

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}