android-build

name	android-build
description	Build the Incrementum Android APK and install it to a connected phone. Use whenever the user wants to build the APK, make an android build, send/install the app to their phone, or test on mobile. Covers setting up the Android SDK/NDK env vars, running the Tauri android build, locating the output APK, and installing via adb.

Build & install the Incrementum Android APK

End-to-end mobile build workflow for this Tauri app. The build itself is npm run tauri:android:build (which runs tauri android build --ci --target aarch64 --apk), but the build fails instantly if ANDROID_HOME / NDK_HOME aren't set — that is the #1 (and so far only) way this build has failed. This skill makes sure the env is right before wasting a full Gradle+Rust compile.

Prerequisites — check these BEFORE running the build

1. Locate the Android SDK. On this machine it is installed via the Homebrew cask android-commandlinetools at:

   /opt/homebrew/share/android-commandlinetools
   

   Verify it exists with ls /opt/homebrew/share/android-commandlinetools/platforms. If the dir is missing entirely, the cask needs installing: brew install --cask android-commandlinetools (rare — it's already installed here).

2. Confirm the NDK is present. The NDK lives inside the SDK dir:

   ls /opt/homebrew/share/android-commandlinetools/ndk
   

   It should show a version dir like 27.2.12479018. That's the NDK version Tauri 2 expects. Export NDK_HOME pointing at the full version path (see step 3).

3. The env vars are NOT in the shell profile — they must be set in the same command that runs the build. Set all three together:

   export ANDROID_HOME=/opt/homebrew/share/android-commandlinetools
   export ANDROID_SDK_ROOT=$ANDROID_HOME
   export NDK_HOME=$ANDROID_HOME/ndk/27.2.12479018   # use the actual version from step 2
   

   (ANDROID_SDK_ROOT is set defensively; Tauri checks ANDROID_HOME and NDK_HOME directly.)

   If you'd rather not set these every time, offer to add them to ~/.zshrc — but don't do it unprompted.

Build the APK

Run the build in the background (it takes several minutes — full Gradle build plus Rust cross-compile for aarch64):

export ANDROID_HOME=/opt/homebrew/share/android-commandlinetools && \
export ANDROID_SDK_ROOT=$ANDROID_HOME && \
export NDK_HOME=$ANDROID_HOME/ndk/27.2.12479018 && \
npm run tauri:android:build

• Use run_in_background: true and a long timeout (600000 ms). You'll be notified on completion.
• If it fails with "Android SDK not found" / "ANDROID_HOME not set" → the env vars weren't set in that same command. Re-run with them set (don't trust a prior shell's exports — shell state does not persist between tool calls).
• Any other failure is a real code/config error — read the tail of the log and report it; don't blindly retry.

Locate the output APK

The build writes a single universal release APK to a fixed path:

src-tauri/gen/android/app/build/outputs/apk/universal/release/app-universal-release.apk

Confirm it exists and check its size (~30–40 MB is normal):

find src-tauri/gen/android -name "*.apk" -type f -exec ls -lh {} \;

Install to a connected phone

1. Find the device. The user's phone is a Pixel 9 Pro XL, serial 47241FDAS006KM, connected over USB:

   adb devices -l
   

   The serial can change across reconnects, so always read it from adb devices rather than hardcoding it. If no device shows up:

   • Ask the user to plug in / authorize USB debugging on the phone.
   • The adb on PATH is the Homebrew one at /opt/homebrew/bin/adb; the SDK also ships its own at $ANDROID_HOME/platform-tools/adb. Either works.

2. Install (reinstall over the existing copy):

   adb -s <SERIAL> install -r src-tauri/gen/android/app/build/outputs/apk/universal/release/app-universal-release.apk
   

   -r reinstalls and keeps data. Expect Success. If you get INSTALL_FAILED_UPDATE_INCOMPATIBLE (signature mismatch, e.g. switching between debug/release builds), uninstall first: adb -s <SERIAL> uninstall com.incrementum.app, then reinstall.

3. Verify it landed:

   adb -s <SERIAL> shell dumpsys package com.incrementum.app | grep -E "versionName|lastUpdateTime"
   

   The package name is com.incrementum.app and versionName tracks the project version from package.json / tauri.conf.json.

Notes

• The app's package name on this device is com.incrementum.app. Two other Incrementum packages may coexist (com.incrementum.incrementum_mobile, com.incrementum.android.debug) — don't install over those; target com.incrementum.app.
• The APK is universal, so it works on arm64 and x86_64 emulators alike — no per-ABI selection needed.
• This build does not require a clean git tree or a version bump; it builds whatever is in the working directory. That's the point — it's for getting the current code onto the phone for testing.
• Mobile UI differs from desktop; if the user is testing a specific feature on mobile, mention any mobile-specific caveats you know of after install.