Install the Wear OS Watch Face

GlycemicGPT ships an optional Wear OS watch face that shows your glucose, trend arrow, insulin on board, and time at a glance. It's optional -- the platform and mobile app work without it.

The watch face is harder to install than the phone app. Wear OS doesn't allow APK downloads from the watch's browser, so installing requires connecting the watch to a computer over ADB. If that sounds like more than you want to deal with, skip this -- the phone app gives you everything important.

What you'll need

A Wear OS watch running Wear OS 5 or newer. Newer watches running Wear OS 6 get a smoother experience -- the phone app can push the watch face to them automatically.
The GlycemicGPT phone app already installed and signed in (see Install the Android App)
Your phone and watch already paired through the Wear OS app
A computer with Android Platform Tools installed -- this gives you the adb command. Install with:
- macOS: brew install android-platform-tools (requires Homebrew)
- Linux: sudo apt install android-tools-adb (Ubuntu/Debian) or sudo dnf install android-tools (Fedora)
- Windows: download the Platform Tools zip, unzip, and add the folder to your PATH
Comfort with running commands in a terminal -- if you've never done that, see the terminal note in Get Started
USB cable or willingness to use wireless ADB

Heads up: The watch install steps below are the most technical part of setting up GlycemicGPT. If they feel beyond what you want to deal with, skip the watch face -- the phone app gives you everything important. The roadmap includes a smoother installation path (Watch Face Push API expansion, possibly Play Store distribution) but that's not available yet.

How it works (so the steps below make sense)

The watch face is two pieces:

wear-device -- a small Wear OS app that runs on the watch. It listens for data the phone forwards (glucose, insulin on board, etc.) and provides complications -- the small data tiles you can put on a watch face.
watchface -- the actual watch face APK (built using Watch Face Format, WFF).

Depending on your watch's Wear OS version, the procedure is slightly different:

Wear OS 6+ watches: install wear-device once via ADB. From then on, the phone app pushes the watch face directly using the Watch Face Push API. This is the easier path.
Wear OS 5 watches: install both wear-device and watchface via ADB. The phone app cannot push faces to Wear OS 5; the face is a regular installed APK.

Not sure which you have? Open Settings on your watch, scroll to System → About → Versions. If Wear OS version is 6.x or newer, you're on the easier path.

Step 1: Enable developer mode on your watch

On the watch, go to Settings → System → About → Versions
Tap Build number seven times. The watch will say "You are now a developer."
Go back to Settings → Developer Options, enable ADB debugging and Debug over Wi-Fi (or Debug over Bluetooth depending on your watch).

The watch will show an IP address and port at the top of the Developer Options screen -- something like 192.168.1.42:5555. Note it.

Step 2: Connect ADB to the watch

The exact command depends on your watch and connection:

Option A: Wireless ADB (most common -- no cable needed)

On your computer:

adb connect 192.168.1.42:5555

Replace the IP and port with what your watch shows at the top of the Developer Options screen on the watch (the value you noted in step 1, in the form <ip>:<port>). The watch will pop a dialog asking to allow ADB access -- accept it. (You may need to also tap "Always allow from this computer" so you don't get prompted again.)

Verify the connection:

adb devices

You should see your watch listed.

Option B: USB ADB (if your watch has a USB charging cradle)

Plug the watch into the cradle, plug the cradle into your computer's USB port. Run adb devices -- the watch should appear.

Step 3: Download the watch APKs

Open github.com/GlycemicGPT/GlycemicGPT/releases
From the latest release, download:
- wear-device-release.apk -- always needed
- watchface-release.apk -- only needed for Wear OS 5 watches (Wear OS 6+ users skip this)

Step 4: Install on the watch

If your watch is the only Android device connected over ADB, this works:

# Install wear-device (always)
adb install wear-device-release.apk

# Wear OS 5 only -- also install the watch face
adb install watchface-release.apk

If you have both your phone and watch connected, list devices first to find your watch's serial:

adb devices
# Output (example):
# 192.168.1.42:5555    device    <- watch
# RF8M21XXXXX          device    <- phone

Then target the watch explicitly:

adb -s 192.168.1.42:5555 install wear-device-release.apk
adb -s 192.168.1.42:5555 install watchface-release.apk  # Wear OS 5 only

Success means the install worked.

Step 5 (Wear OS 6+ only): Push the watch face from the phone

Open the GlycemicGPT phone app, go to Settings → Watch.

The app should detect your connected watch. Tap Push watch face. The phone uploads the WFF APK to the watch via the Watch Face Push API; the watch face appears in your watch's available faces almost immediately.

To switch to it: long-press the current watch face on your watch, scroll through the faces, find GlycemicGPT and tap to activate. (Or use the face customization screen on your phone.)

Step 6 (Wear OS 5 only): Switch to the GlycemicGPT face

You already installed it in step 4. Long-press the current watch face on your watch, scroll through the available faces, find GlycemicGPT, tap to activate.

Step 7: Confirm data is flowing

Within a minute, the watch face should show:

Your latest glucose reading
A trend arrow (up / down / flat)
Your insulin on board (IoB)
Current time

If the watch face shows -- for glucose for more than 5 minutes after a fresh setup:

Make sure the phone app is signed in and your pump/CGM is connected
Make sure your watch is connected to your phone (Wear OS app shows "Connected")
Open the GlycemicGPT phone app once -- it sometimes needs a manual nudge to start forwarding to the watch

Updating the watch face

When a new GlycemicGPT release ships:

Wear OS 6+: open the phone app, go to Settings → Watch, tap Push watch face again. The new face replaces the old one.

Wear OS 5: download the new wear-device-release.apk and watchface-release.apk, run adb install -r to upgrade in place:

adb -s <watch-serial> install -r wear-device-release.apk
adb -s <watch-serial> install -r watchface-release.apk

A few honest notes

The Wear OS install is genuinely the most complicated step in setting up GlycemicGPT. ADB to a watch is a developer-grade workflow. The roadmap includes a smoother distribution path (Watch Face Push API expansion, possibly Play Store distribution) but it's not there yet.
The watch face is read-only. No interactions with it can deliver insulin, change pump settings, or modify your data.
Battery impact on the watch: the face is a normal Wear OS face that updates once per glucose reading interval (~5 minutes). Battery cost is similar to other glucose-monitoring watch faces.

Install the Wear OS Watch Face

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