Dynamically added items do not trigger observers - polymer

Question

I'm adding some items to an Array, using the Array mutation methods. The items are displayed within a <dom-repeat> and can can be edited on the fly. While the edits do change the data in the object, any attached observers do not fire to indicate that a change occurred.
tl;dr
I'm properly using the Array mutation methods to push items
this.push("data.contents", {
id: 1,
name: "Modifying this text doesn't trigger an observer"
});
I'm displaying the items in a dom-repeat
These items are displayed using a <dom-repeat>, and the sub-property name is displayed in a <paper-input> where they can be amended on the fly.
<template>
<template is="dom-repeat" items="[[data.contents]]">
<paper-input value="{{item.name::input}}"></paper-input>
</template>
</template>
It seems that while the data is modified in the object itself, any attached observers do not fire for these sub-properties.
I'm attaching wildcard observers
I'm observing using the usual wildcard observers like so:
observers: [
"logChange(data.*)"
],
Notes
Note that:
Changing the item via a direct this.set() like so:
this.set("data.contents.0.name", "Foo")
will trigger the observers just fine
An MCVE for the above.
How to use:
Press the button to push some items to the Array
Edit any one of the added items
Console should log that a change occurred in any of the items (it doesn't)
<base href="https://polygit.org/components/">
<script src="webcomponentsjs/webcomponents-lite.min.js"></script>
<link href="polymer/polymer.html" rel="import">
<link href="paper-input/paper-input.html" rel="import">
<link href="paper-button/paper-button.html" rel="import">
<dom-module id="x-example">
<template>
<paper-button on-tap="pushItem">Push to Array</paper-button>
<template is="dom-repeat" items="[[data.contents]]">
<paper-input value="{{item.name::input}}"></paper-input>
</template>
</template>
<script>
HTMLImports.whenReady(function() {
"use strict";
Polymer({
is: "x-example",
properties: {
data: {
type: Object,
value: {
contents: []
}
}
},
observers: [
"logChange(data.*)"
],
pushItem: function() {
this.push("data.contents", {
id: 1,
name: "Modifying this text doesn't trigger an observer"
})
},
logChange: function() {
console.log("change occured!");
}
});
});
</script>
</dom-module>
<x-example></x-example>

Answer 1

Solved here: https://github.com/Polymer/polymer/issues/4140#issuecomment-259465035
The observer isn't firing because you have one-way binding annotations on the items property, which prevents change notifications from flowing up to the element. Change it to: items="{{data.contents}}" and you'll see the changes.
In essence, turn this:
<template is="dom-repeat" items="[[data.contents]]">
<paper-input value="{{item.name::input}}"></paper-input>
</template>
to this
<template is="dom-repeat" items="{{data.contents}}">
<paper-input value="{{item.name::input}}"></paper-input>
</template>