Better understand how reactivity happens under the hood

I was tinkering with reactivity and I started to wonder how it is done under the hood. Specifically, just out of curiosity, let’s assume I am doing the Meteor Tutorial with Blaze and have an event handler like so:

Template.task.events({
	'click .text'(event, instance) {
		let target = instance.firstNode.parentNode
		Blaze.renderWithData(Template.task, instance.data, target)
	},
	'click .toggle-private'() {
		Meteor.call('tasks.setPrivate', this._id, !this.private);
	},
});

The click.text event takes an existing instance an renders it again into its parent container.

Interestingly, when I fire the second event, i.e. “toggle-private”, the reactivity seems to be linked to the original DOM-node, not the newly created one.

I made a small gif to illustrate.

As you can see, once I “copied” the instance, the events when clicking on the second todo are sort of linked to the first todo.

Where is this stored inside Meteor / Blaze? (I mean, not that I would really do something like this in an application, I am just wondering).

Can it be that you clone the Task in the DOM with the same ID, so when you click the cloned task it calls tasks.setPrivate with the id of the original?

I think that is correct, @jamgold I.e. the Task document on the database is correctly updated when I click on the clone. I am just wondering how the reactivity does not kick in and how I could make the clone reactive to changes in the DB or reactive vars.