Optimize APK size: arm64-only, remove extractNativeLibs=false, add Android build docs to README

Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/4f02e4a3-e88b-422b-9009-a7eb331ff567

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot

.github/workflows/release.yml

@@ -48,9 +48,8 @@ jobs:
           NDK_HOME="$ANDROID_HOME/ndk/29.0.14206865"
           CMAKE_BIN="$ANDROID_HOME/cmake/3.22.1/bin/cmake"
 
-          # Only build arm64 and arm32.  x86 removed to reduce APK size —
-          # modern emulators use x86_64 or ARM translation.
-          for ABI in arm64-v8a armeabi-v7a; do
+          # arm64 only — matches RuntimeIdentifiers in osu.Android.props.
+          for ABI in arm64-v8a; do
             echo "::group::Building osu_native for $ABI"
             "$CMAKE_BIN" -B "build-native/$ABI" -S osu.Android/Native \
               -DCMAKE_TOOLCHAIN_FILE="$NDK_HOME/build/cmake/android.toolchain.cmake" \

README.md

@@ -51,7 +51,7 @@ You can see some examples of custom rulesets by visiting the [custom ruleset dir
 
 Please make sure you have the following prerequisites:
 
-- A desktop platform with the [.NET 8.0 SDK](https://dotnet.microsoft.com/download) installed.
+- A desktop platform with the [.NET 10.0 SDK](https://dotnet.microsoft.com/download/dotnet/10.0) installed (this fork targets .NET 10; upstream ppy/osu uses .NET 8).
 
 When working with the codebase, we recommend using an IDE with intelligent code completion and syntax highlighting, such as the latest version of [Visual Studio](https://visualstudio.microsoft.com/vs/), [JetBrains Rider](https://www.jetbrains.com/rider/), or [Visual Studio Code](https://code.visualstudio.com/) with the [EditorConfig](https://marketplace.visualstudio.com/items?itemName=EditorConfig.EditorConfig) and [C# Dev Kit](https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.csdevkit) plugin installed.
 
@@ -96,6 +96,68 @@ When running locally to do any kind of performance testing, make sure to add `-c
 
 If the build fails, try to restore NuGet packages with `dotnet restore`.
 
+#### Building for Android
+
+**Prerequisites:**
+- [.NET 10.0 SDK](https://dotnet.microsoft.com/download/dotnet/10.0) (this fork targets .NET 10)
+- JDK 17 (`sudo apt install openjdk-17-jdk` or use [Microsoft's JDK](https://learn.microsoft.com/en-us/java/openjdk/download))
+- Android workload: `dotnet workload install android`
+
+**Debug build** (auto-signed with debug keystore, suitable for local testing):
+
+```shell
+dotnet build -c Debug osu.Android/osu.Android.csproj
+```
+
+The APK will be at `osu.Android/bin/Debug/net10.0-android/sh.ppy.osulazer.apk`. Debug builds are always signed with the Android debug keystore and can be installed directly via `adb install`.
+
+**Release build** (optimised with AOT, trimming, and compression):
+
+```shell
+dotnet publish -c Release osu.Android/osu.Android.csproj -f net10.0-android
+```
+
+The APK will be at `osu.Android/bin/Release/net10.0-android/publish/sh.ppy.osulazer.apk`.
+
+**Signing the Release APK:**
+
+Release APKs may not be automatically signed by the .NET SDK. If you get `INSTALL_PARSE_FAILED_NO_CERTIFICATES` when installing, sign the APK manually:
+
+```shell
+# Find your build-tools (adjust version as needed)
+BUILD_TOOLS="$ANDROID_HOME/build-tools/$(ls $ANDROID_HOME/build-tools | sort -V | tail -1)"
+
+# Zipalign (required before signing)
+"$BUILD_TOOLS/zipalign" -f -p 4 sh.ppy.osulazer.apk sh.ppy.osulazer-aligned.apk
+mv sh.ppy.osulazer-aligned.apk sh.ppy.osulazer.apk
+
+# Sign with debug keystore (or your own release keystore)
+"$BUILD_TOOLS/apksigner" sign \
+  --ks ~/.android/debug.keystore \
+  --ks-pass pass:android \
+  --key-pass pass:android \
+  --ks-key-alias androiddebugkey \
+  sh.ppy.osulazer.apk
+
+# Verify
+"$BUILD_TOOLS/apksigner" verify sh.ppy.osulazer.apk
+```
+
+If `~/.android/debug.keystore` does not exist, generate it:
+
+```shell
+keytool -genkeypair -v -keystore ~/.android/debug.keystore \
+  -storepass android -keypass android -alias androiddebugkey \
+  -keyalg RSA -keysize 2048 -validity 10000 \
+  -dname "CN=Android Debug,O=Android,C=US"
+```
+
+**Install via ADB:**
+
+```shell
+adb install sh.ppy.osulazer.apk
+```
+
 ### Testing with resource/framework modifications
 
 Sometimes it may be necessary to cross-test changes in [osu-resources](https://github.com/ppy/osu-resources) or [osu-framework](https://github.com/ppy/osu-framework). This can be quickly achieved using included commands:

osu.Android.props

@@ -1,11 +1,10 @@
 <Project>
   <PropertyGroup>
     <SupportedOSPlatformVersion>33.0</SupportedOSPlatformVersion>
-    <!-- arm64-v8a covers 99%+ of modern Android devices.
-         armeabi-v7a is kept for older 32-bit devices.
-         x86 removed — only used by legacy emulators; modern x86_64 emulators
-         run arm64 binaries via native translation (no dedicated x86 build needed). -->
-    <RuntimeIdentifiers>android-arm;android-arm64</RuntimeIdentifiers>
+    <!-- arm64-v8a only.  Modern Android devices are 99%+ arm64; 32-bit arm32 (armeabi-v7a)
+         adds ~200 MB of duplicate native libraries for negligible device coverage.
+         x86 was already removed — modern x86_64 emulators run arm64 via translation. -->
+    <RuntimeIdentifiers>android-arm64</RuntimeIdentifiers>
     <AndroidPackageFormat>apk</AndroidPackageFormat>
     <!-- CJK and Mideast encodings are needed for song metadata display.
          Rare covers supplementary Unicode blocks. West is the default Latin set. -->

osu.Android/AndroidManifest.xml

@@ -1,7 +1,7 @@
 <?xml version='1.0' encoding='utf-8'?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="sh.ppy.osulazer" android:installLocation="auto">
 	<uses-sdk android:minSdkVersion="33" android:targetSdkVersion="36" />
-	<application android:extractNativeLibs="false" android:allowBackup="true" android:supportsRtl="true" android:label="osu!" android:icon="@mipmap/ic_launcher" android:roundIcon="@mipmap/ic_launcher" android:largeHeap="true">
+	<application android:allowBackup="true" android:supportsRtl="true" android:label="osu!" android:icon="@mipmap/ic_launcher" android:roundIcon="@mipmap/ic_launcher" android:largeHeap="true">
         <provider android:name="androidx.core.content.FileProvider" android:authorities="sh.ppy.osulazer.fileprovider" android:grantUriPermissions="true" android:exported="false">
             <meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="@xml/filepaths" />
         </provider>

osu.Android/osu.Android.csproj

@@ -27,10 +27,8 @@
     <None Remove="Native\CMakeLists.txt" />
   </ItemGroup>
   <!-- Include pre-built native libraries when present (built by the release workflow or local NDK build).
-       When absent, native features (Oboe audio, Vulkan probe) are gracefully disabled at runtime.
-       x86 removed — only arm64 and arm32 are shipped (see RuntimeIdentifiers in osu.Android.props). -->
+       When absent, native features (Oboe audio, Vulkan probe) are gracefully disabled at runtime. -->
   <ItemGroup>
     <AndroidNativeLibrary Include="libs\arm64-v8a\libosu_native.so" Condition="Exists('libs\arm64-v8a\libosu_native.so')" Abi="arm64-v8a" />
-    <AndroidNativeLibrary Include="libs\armeabi-v7a\libosu_native.so" Condition="Exists('libs\armeabi-v7a\libosu_native.so')" Abi="armeabi-v7a" />
   </ItemGroup>
 </Project>