utzcoz's perosnal blog

Focus on AOSP, XR, and testing tools.

Working on open-source projects:Robolectric,boringdroid,MaruOS,DigitalisX64,aospbooks

aospandroidtooling

Diffing AOSP Releases

Every time a new Android version lands I want the same narrow thing: which repositories changed, and which of those changes are worth opening the source for. AOSP is a few hundred git projects stitched together by a repo manifest, so “what’s new in Android 17” is never one diff. It’s the union of a few hundred per-project diffs, almost all of them routine, a handful of them the actual story. I got tired of eyeballing the manifest by hand, so for the AOSP Internals book I wrote a small...

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Recent posts

43 total

Using Claude Code on AOSP-scale projects

I’ve been using Claude Code on four AOSP-scale projects: an ARM64-to-x86_64 binary translator, a multi-window patchset for Android, a Chromium WebXR port, and a 64-chapter book on AOSP internals. None of them are the kind of work a coding agent does well out of the box. They’re long. They’re forks of huge upstream codebases. They need a running emulator (or...

claude-codeaospandroid

Fixing the blurry LUKS password screen after upgrading to Ubuntu 25.10

After upgrading from Ubuntu 25.04 to 25.10, I noticed something annoying: the disk-encryption password screen that appears right after the firmware logo had become noticeably low-resolution. The motherboard logo was fuzzy, the password field looked like it had been stretched from 800×600, and the whole thing felt like a regression from the crisp screen I had on 25.04. If you’ve...

ubuntulinuxplymouth

Android emulator won't boot on AMD GPU? It's your Vulkan driver.

I lost days to this. The Android emulator would launch, show the boot animation, and just sit there. No error dialog in Android Studio, no crash popup, nothing. An infinite boot loop with zero indication of what went wrong. If you have an AMD GPU on Linux with AMDVLK installed, this post should save you some time. The problem I’m...

androidemulatorvulkan

How Android Studio's @Preview Actually Works: Extension Points, ViewAdapters, and LayoutLib

Android Studio’s design panel is not a monolithic system. It is a pluggable framework where each UI technology (Compose, Wear Tiles, Glance AppWidgets, Custom Views) registers its own “designer module” via IntelliJ extension points. This post uses Wear Tiles and Glance AppWidgets as case studies to show how new Compose-based platforms expand the designer and tooling infrastructure, on both the...

android-studioaospcompose

AOSP Split APK Architecture - Comprehensive Analysis Report

1. Executive Summary Split APKs allow an Android application to be delivered as multiple APK files instead of a single monolithic APK. Introduced in Android L (API 21), split APKs provide: Reduced download sizes via config splits (density, ABI, language-specific resources) Modular features via feature splits (on-demand delivery of app modules) Incremental updates by updating individual splits without replacing the...

aospsplit-apkandroid

The Intelligent OS: How AppFunctions and ComputerControl Power Android's AI Agent Ecosystem

I. The Big Picture 1. The shift to task delegation The Android Developers Blog describes the change: “User expectations for AI on their devices are fundamentally shifting how they interact with their apps.” The traditional model – users manually opening apps, navigating UIs, completing tasks step by step – is giving way to task delegation. Users tell an AI agent...

aospappfunctionscomputercontrol

Building a Custom Jekyll Theme with Claude Code

I’m not a frontend engineer, and I wanted to replace the minima theme on my Jekyll blog with a custom one – no frontend experience required. I used Claude Code to build the entire theme in a single session. What Was Done Built a Complete Local Theme Claude Code read the existing repository structure, fetched the reference design, and produced...

claude-codejekyllfrontend

Robolectric Native Runtime: Architecture & Implementation Report

1. Introduction Robolectric is the de-facto standard for running Android unit tests on the JVM without a device or emulator. Historically, Robolectric used hand-written Java “shadow” classes to approximate the behavior of Android framework native code. In Android O (API 26), Robolectric introduced Native Runtime — a mechanism to load real AOSP native libraries (compiled for host platforms) and delegate...

robolectricnative-runtimejni

APKM File Format Spec from APKMirror

1) Overview .apkm is a file format created by APKMirror to distribute Android applications that are built using Android App Bundle (AAB). Since Google Play generates device-specific split APK sets from AAB files at install time, third-party distributors like APKMirror cannot distribute a single monolithic APK for bundle-based apps. The .apkm format solves this by packaging the base APK together...

apkapkmirrorfile-format