New Twiddle

components.my-component\.js

import Component from '@glimmer/component';
import { inject as service } from '@ember/service';
import { action } from '@ember/object';
import { tracked } from '@glimmer/tracking';

export default class extends Component {
  @service session;
  @service myService;
  @tracked value;
  @tracked count = 0;
  
  @action
  setWithMyService() {
     this.myService.setData();
     this.value = this.session.store._data;
     this.count++;
  }
  
  @action
  setWithSessionThis() {
    this.session.setDataWithThis();
    this.value = this.session.store._data;
    this.count++;
  }
  
  @action
  setWithSessionSet() {
    this.session.setDataWithSet();
    this.value = this.session.store._data;
    this.count++;
  }
}

controllers.application\.js

import Controller from '@ember/controller';

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
}

services.my-service\.js

import Service, { inject as service } from '@ember/service';
import { set } from '@ember/object';

export default class MyService extends Service {
  @service session; 
  
  setData() {
     set(this.session.data, 'setBy', 'myService');
   }
}

services.session\.js

import Session from 'ember-simple-auth/services/session';
import { set } from '@ember/object';

export default class SessionService extends Session {
    setDataWithThis() {
      this.set('data.setBy', 'sessionWithThis');
    }
  
    setDataWithSet() {
      set(this.data, 'setBy', 'sessionWithSet');
    }
}

session-stores.application\.js

import EphemeralStore from 'ember-simple-auth/session-stores/ephemeral';

export default class ApplicationStorage extends EphemeralStore {
    key = 'session';
}

templates.application\.hbs

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

templates.components.my-component\.hbs

<p>Call count {{this.count}}</p>
<p>Session key set by: {{this.value}}</p>
<button {{on "click" this.setWithMyService}}>Set using my service</button>
<button {{on "click" this.setWithSessionThis}}>Set using session this</button>
<button {{on "click" this.setWithSessionSet}}>Set using session set</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",
    "ember-simple-auth": "3.0.0"
  }
}