android-arm64-devkit-skill

Create, build and deploy Android APKs on ARM64 Linux (DGX Spark, Raspberry Pi, ARM cloud): native aarch64 aapt2 for Gradle, plus adb install-and-verify over USB or VPN. Use for aarch64 APK work.

Thin wrapper over the scripts in this repo. One skill, two branches: pick your host and your transport. Every machine-specific value lives in config.sh (from config.example.sh) — never in this file.

Branch 1 — Host (pick yours)

Host	What changes
ARM64 Linux (DGX Spark, Raspberry Pi, ARM server/cloud)	Google's aapt2 / aidl / zipalign are x86-64 only, so Gradle dies with Exec format error → MUST override with the Debian aarch64 build (see "Build branch")
x86-64 Linux	Google's toolchain runs natively → skip the aapt2 override; the adb scripts still apply
Windows / macOS	These bash scripts do not run there → use the Android Studio workflow instead (see "Cross-references")

Branch 2 — Transport (pick yours)

Situation	Transport
Device attached to the machine running the scripts	USB — leave ADB_HOST empty, set DEVICE_SERIAL
Device on a VPN (e.g. Tailscale)	TCP — set ADB_HOST to the MagicDNS name; the port is discovered
Device attached to another host you can ssh into	remote adb — set ADB_REMOTE_HOST + ADB_REMOTE_BIN

Config — the only place personal values live

bash

cp {baseDir}/config.example.sh {baseDir}/config.sh
$EDITOR {baseDir}/config.sh

config.sh is gitignored and is never committed. Host names, IPs, serials, package ids and personal paths go here — not in this skill, not in any tracked file. Gradle-side values (sdk.dir, android.aapt2FromMavenOverride) belong to the project's local.properties / gradle.properties.

Create an app (scaffold)

bash

{baseDir}/scripts/new-project.sh ~/apps/MyApp com.example.myapp "My App"
cd ~/apps/MyApp && ./gradlew clean assembleDebug

Creates a minimal Gradle + Kotlin project (one Activity, adaptive icon, minSdk 26) that already carries the aarch64 aapt2 override. It refuses to overwrite an existing path and validates the package id.

Build branch (ARM64 host)

bash

sudo apt-get install -y android-sdk-build-tools android-sdk-platform-tools android-libaapt
{baseDir}/scripts/setup-aapt2-arm64.sh
{baseDir}/scripts/setup-aapt2-arm64.sh --write-gradle-property path/to/project
cd path/to/project && ./gradlew clean assembleDebug

Deploy + verify branch (any host)

Prepare the transport once — these values are personal, so they go in config.sh (never committed):

bash

cp {baseDir}/config.example.sh {baseDir}/config.sh
# USB:        ADB_HOST=""          DEVICE_SERIAL=<serial from `adb devices -l`>
# VPN (TCP):  ADB_HOST=<magicdns>  ADB_TCP_PORT=""   (the port is discovered)
# remote adb: ADB_REMOTE_HOST=<ssh alias>  ADB_REMOTE_BIN=<adb path on that host>

Then connect, install, verify, tear down:

bash

{baseDir}/scripts/adb-connect.sh        # discovers the port; writes .adb-device
{baseDir}/scripts/adb-install-verify.sh app/build/outputs/apk/debug/app-debug.apk
{baseDir}/scripts/adb-disconnect.sh     # add --restart-server to unwedge adb

adb-connect.sh never guesses the port: it reads it from an existing wireless transport or over USB, and fails loudly if wireless debugging is not exposed. adb-install-verify.sh prints the install result, the installed version/time, launches the activity, checks the focused window and the process pid, greps logcat for crashes, and captures a screenshot (warns below ~30 KB).

ARM64 host gotchas (any aarch64 distro)

Distro/toolchain facts, not host-specific values — values still live in config.sh or the project.

• Google's adb is x86-64 too. platform-tools/adb from the SDK will not run on aarch64 either; use the distro's adb (the setup step installs android-sdk-platform-tools, which provides one). Confirm with file "$(command -v adb)".
• Non-interactive shells skip the rc guard. Ubuntu's ~/.bashrc starts with case $- in *i*) ;; *) return;; esac; anything after it — including Android env exports — is skipped by ssh host 'cmd'. Put the ANDROID_HOME / JAVA_HOME / GRADLE_HOME exports before that guard, then verify with ssh host 'echo "$ANDROID_HOME"'.
• The distro aapt2 is older than AGP's. It parses android.jar for older platforms only; if a very new compileSdk fails with a resource-table error, lower compileSdk / targetSdk to a supported platform and re-test.

Operating Rules (for agents)

• MUST invoke the repo scripts by their {baseDir} path; never rewrite their logic inline.
• MUST run ./gradlew clean assembleDebug and require N actionable tasks: M executed with M > 0. A build with every task UP-TO-DATE means aapt2 never ran — it proves nothing.
• MUST create config.sh from config.example.sh before the adb scripts, and MUST NOT commit it or hardcode its values.
• MUST NOT hardcode the wireless adb port (e.g. 5555). OEMs randomize it on every wireless-debugging restart; let adb-connect.sh discover it.
• MUST treat adb-install-verify.sh output as the acceptance test: install + launch + focus + pid + logcat + screenshot. A screenshot < 30 KB is a cached black framebuffer (lockscreen), not success.
• MUST NOT claim success from BUILD SUCCESSFUL or install Success alone.
• When a binary capture crosses a Windows host, redirect inside cmd (cmd /c "adb ... > shot.png"); PowerShell's > writes UTF-16 and corrupts binaries.
• On a remote adb host, set ADB_REMOTE_HOST / ADB_REMOTE_BIN in config.sh; do not reimplement the ssh quoting — {baseDir}/scripts/lib/adb.sh handles it.
• The aapt2 override is marked experimental by AGP: re-test after any AGP major upgrade.

Key facts

• aapt2 override: android.aapt2FromMavenOverride=/usr/lib/android-sdk/build-tools/debian/aapt2
• d8 / apksigner are JVM wrappers → architecture-independent.
• Self-test suite: {baseDir}/tests/run-tests.sh

Troubleshooting

See {baseDir}/docs/troubleshooting.md — every trap was hit for real: Exec format error, UP-TO-DATE false success, dynamic wireless port, unauthorized key mismatch, device offline, VPN deep sleep, PowerShell UTF-16 corruption, stale/empty mounts, black screenshot with focus held.

Cross-references

• Windows / macOS host → the Android Studio workflow skill.
• DGX-Spark-specific operational notes (canonical layout, shell-rc env block, dynamic-port workflow) → the host manual under .agent/.

Scope

Debug APKs only — not for Play Store release signing.