R8: emit compiler r8.json into the AAB, and bump 10.0.x pack R8 off 8.11.18 (Play scores 9.0.32, not 8.11.18)

[yuseok-kim-edushare]

Android framework version

net10.0-android

Affected platform version

Microsoft.Android.Sdk 36.1.69

Description

This is scoped to the shrinking and optimization percentages on Play Console. The obfuscation / -dontobfuscate work (#12535, #12575 and the [r8-obfuscation] stack) is separate and untouched here.

With $(AndroidLinkTool)=r8, R8 already runs with shrinking enabled, yet Play's App Bundle Explorer shows optimization and shrinking as - and only obfuscation gets a value (from mapping.txt). Per the DEX code optimization docs, for AGP 8.10+ the percentages come from BUNDLE-METADATA/com.android.tools/r8.json. The docs also say Play falls back to mapping.txt when r8.json is absent; in our measurements that fallback produced obfuscation only, never the other two.

The SDK never produces or embeds that file:

• R8.cs has no build-metadata output. $(AndroidR8ExtraArguments) cannot be used for it from outside the SDK: D8.WriteArg writes the whole property as one response-file line, and R8's FlagFile treats one line as one token, so --build-metadata-output <path> arrives as a single unknown option. (The flag itself is supported by 8.11.18 — this is an SDK limitation, not an R8 one.)
• _PrepareBuildApk adds exactly one AndroidAppBundleMetaDataFile entry, com.android.tools.build.obfuscation/proguard.map. Nothing for com.android.tools/r8.json.

Measurements (production .NET MAUI app, same project, same R8 flags, AndroidPackageFormat=aab, no AGP metadata injected anywhere)

	DEX compiled by	r8.json in AAB	version in that json	Play shrinking / optimization
stock	pack 8.11.18	none	—	-
A	pack 8.11.18	generated via setBuildMetadataConsumer	8.11.18	- (obfuscation 37% from mapping)
B	R8 9.0.32 via AndroidR8JarPath	generated by 9.0.32	9.0.32	percentages shown
111	pack 8.11.18	A's json, only version changed	9.0.32	percentages shown
112	R8 9.0.32	B's json, only version changed	8.11.18	-

111/112 keep DEX bytes and dexFiles[].checksum unchanged; only the version string differs. Diffing honest 8.11.18 vs 9.0.32 json (same input): identical stats, options, dexFiles[].checksum; 8.11 additionally has compilation.*; 9.0 has no key 8.11 lacks.

Together that isolates the gate to the version string in r8.json. Two points only: 8.11.18 is rejected, 9.0.32 is accepted. The cutoff between them was not probed (it could be 8.12, 9.0.0, or something else). There is no honest way for pack 8.11.18 to produce a version Play will score.

Ask — two separable changes

1. Generate and embed r8.json (backportable without changing the jar): an R8 task parameter that writes --build-metadata-output and the path as two response-file lines, plus one AndroidAppBundleMetaDataFile entry for com.android.tools/r8.json next to the existing proguard.map one. main already pins 9.4.17 and the net11 line (release/11.0.1xx-preview6) already pins 9.1.31; (1) is likely sufficient there. We uploaded and scored 9.0.32, and later the same production app compiled with main's R8 9.4.17 (src/r8 fat jar) — Play still filled optimization, obfuscation, and shrinking.
2. Bump src/r8/build.gradle on release/10.0.1xx (the live net10.0-android pack line; tools jar is 8.11.18 today) to a compiler that emits a version Play accepts. 9.0.32 is the version we first uploaded and Play scored; 9.4.17 is the main pin and also scored. Change (1) alone still emits "version": "8.11.18", which Play does not score. Rewriting version in json is not an SDK solution.

Follow-up, not required to get Play to read the file: the [r8-obfuscation] PRs (#12575, #12628–#12634) address -dontobfuscate / JNI renaming, not this. _CalculateProguardConfigurationFiles still passes tools/proguard-android.txt (line 16: -dontoptimize). The SDK does not currently ship proguard-android-optimize.txt. Switching that default would let compiler r8.json report optimizations enabled; it is independent of emit+embed and of the obfuscation stack.

Out of scope: -dontobfuscate / JNI remapping, shrinkResources, fabricating androidGradlePluginVersion, running Gradle in the SDK.

Steps to Reproduce

1. Release net10.0-android, AndroidLinkTool=r8, AndroidCreateProguardMappingFile=true, AndroidPackageFormat=aab, dotnet publish.
2. unzip -l app.aab | grep BUNDLE-METADATA → only proguard.map.
3. Upload → App Bundle Explorer → shrinking/optimization -.
4. Set AndroidR8JarPath to an R8 9.0.32 jar, produce r8.json via setBuildMetadataConsumer (or CLI --build-metadata-output on its own line), add it via AndroidAppBundleMetaDataFile Include="com.android.tools/r8.json:<path>", publish, upload.
5. Percentages appear. The same DEX with json version 8.11.18 (honest pack output, or 112 in the table) shows - again.

Did you find any workaround?

the csproj targets in step 4 — an external 9.0.32 jar plus an out-of-band json producer. Apps should not have to carry that.

Relevant log output

[yuseok-kim-edushare]

I did some custom tasks and config that passed minimum percentage score from play store console,
Also I do test and check something really needded process that performing in aab build time

exactly said in this comments
#12535 (comment)

[yuseok-kim-edushare]

I test main branch's R8 (ver. 9.4.17) in my company's production app, and play console still recognize Optimized, Obfuscated, Shrinked

[yuseok-kim-edushare]

Following is my proguard-android-optimize.txt I missed to attach it

# Same keep rules as the .NET Android SDK's proguard-android.txt, but
# WITHOUT -dontoptimize. Play's DEX "optimization ratio" stays 0 / "-"
# if any --pg-conf file contains -dontoptimize (it is a global kill switch).
# R8 ignores most ProGuard -optimizations filters; omitting -dontoptimize
# is enough to let full-mode R8 optimize.

-allowaccessmodification

# Preserve some attributes that may be required for reflection.
-keepattributes AnnotationDefault,
                EnclosingMethod,
                InnerClasses,
                RuntimeVisibleAnnotations,
                RuntimeVisibleParameterAnnotations,
                RuntimeVisibleTypeAnnotations,
                Signature

-keep public class com.google.vending.licensing.ILicensingService
-keep public class com.android.vending.licensing.ILicensingService
-keep public class com.google.android.vending.licensing.ILicensingService
-dontnote com.android.vending.licensing.ILicensingService
-dontnote com.google.vending.licensing.ILicensingService
-dontnote com.google.android.vending.licensing.ILicensingService

# For native methods, see https://www.guardsquare.com/manual/configuration/examples#native
-keepclasseswithmembernames,includedescriptorclasses class * {
    native <methods>;
}

# Keep setters in Views so that animations can still work.
-keepclassmembers public class * extends android.view.View {
    void set*(***);
    *** get*();
}

# We want to keep methods in Activity that could be used in the XML attribute onClick.
-keepclassmembers class * extends android.app.Activity {
    public void *(android.view.View);
}

# For enumeration classes, see https://www.guardsquare.com/manual/configuration/examples#enumerations
-keepclassmembers enum * {
    public static **[] values();
    public static ** valueOf(java.lang.String);
}

-keepclassmembers class * implements android.os.Parcelable {
    public static final ** CREATOR;
}

# Preserve annotated Javascript interface methods.
-keepclassmembers class * {
    @android.webkit.JavascriptInterface <methods>;
}

# The support libraries contains references to newer platform versions.
# Don't warn about those in case this app is linking against an older
# platform version. We know about them, and they are safe.
-dontnote android.support.**
-dontnote androidx.**
-dontwarn android.support.**
-dontwarn androidx.**

# Understand the @Keep support annotation.
-keep class android.support.annotation.Keep

-keep @android.support.annotation.Keep class * {*;}

-keepclasseswithmembers class * {
    @android.support.annotation.Keep <methods>;
}

-keepclasseswithmembers class * {
    @android.support.annotation.Keep <fields>;
}

-keepclasseswithmembers class * {
    @android.support.annotation.Keep <init>(...);
}

# These classes are duplicated between android.jar and org.apache.http.legacy.jar.
-dontnote org.apache.http.**
-dontnote android.net.http.**

# These classes are duplicated between android.jar and core-lambda-stubs.jar.
-dontnote java.lang.invoke.**

[jonathanpeppers]

Can you try the example listed on:

• [r8] Include build metadata in app bundles #12646

It will download a newer version of r8, and include r8.json in your .aab file. Wondering if that improves the Google Play screenshot you shared? Thanks!