New Twiddle

components.mirrored-input\.js

import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import { action } from '@ember/object';
export default class extends Component {
  @action
  handleChange(e) {
    this.args.changeset.set(this.args.name, e.target.value);
  }
}

controllers.application\.js

import Controller from '@ember/controller';
import Changeset from 'ember-changeset'
export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
	changeset = new Changeset({name: "initial value"})
}

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<br>


<MirroredInput @name="name" @changeset={{this.changeset}}/>

<div>
	Read-only changeset from getter: {{this.changeset.name}}
</div>

<br>
<br>

templates.components.mirrored-input\.hbs

These inputs should mirror each other

<div>
	<input value={{get @changeset @name}} {{on 'input' (fn this.handleChange)}}/>
</div>
<div>
	<input value={{get @changeset @name}} {{on 'input' (fn this.handleChange)}}/>
</div>
<div>
	<Input @value={{get @changeset @name}} {{on 'input' (fn this.handleChange)}}/>
</div>

twiddle\.json

{
  "version": "0.17.0",
  "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/3.3.1/jquery.js",
    "ember": "3.17.0",
    "ember-template-compiler": "3.17.0",
    "ember-testing": "3.17.0"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-changeset": "3.2.0",
    "ember-composable-helpers": "3.0.3"
  }
}