“Back” function reverts to 1.0 behavior, 1.0 apps are compatible, and more.

Android Wear 2.0 is in a bit of a troubled development period. The big update was delayed from "Fall 2016" to 2017, ostensibly because testers reacted poorly to the new OS. Now Google is back with another Android Wear 2.0 Developer Preview, and this one is #4.

The first thing on deck for developer preview 4 is the removal of a big Wear 2.0 change: how "back" works. Earlier developer previews changed "back" on Android Wear from a swipe gesture to the watch's hardware button. Using the screen for every navigation control except back was strange. The new developer preview reverts this change. The hardware button now maps to "power" like it did in Wear 1.0. All apps now automatically support swipe-to-dismiss, too.
There are also lots of watch-to-phone communication additions. A new OAuth API lets watch apps open an authentication screen on the phone, allowing standalone apps to easily sign in. Preview 3 added an on-watch Play Store, and new "cross-device promotion" APIs allow watch apps to point a user to download a connected phone app.

Speaking of the Play Store—in Developer Preview 3 Google changed the way watch apps work. In Wear 1.0, back when there was no Watch Play Store, watch apps came packaged inside phone apps. Standalone apps didn't exist. In Wear 2.0 Preview 3, the Watch Play Store was added, and standalone watch apps were born. But the watch-app-packaged-with-phone-app system was shut off. This meant that every app in the fledgling Android Wear ecosystem needed to be updated.

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Compatibility with Wear 1.0 apps is being restored in this developer preview. When users download an app with an embedded Wear APK in it, they will now be asked if they want to install the phone app. This is a pleasant change from the auto-install method in Wear 1.0. Just because you have an app on your phone doesn't mean you want it on your watch. Now users have the option.

Despite support for the old app install system, Google's blog post says it "strongly recommends" that developers move to the standalone watch app model. These recent developments sound like stop-gap measures.

Google is also bringing monetization options for watch apps on par with phone apps that have on-watch in-app billing. Authorization on the watch happens quickly and easily via a 4-digit PIN users can set up.

The fourth Wear 2.0 Developer Preview is out now. Google says that a fifth developer preview is planned later next year.