Description

Google Play flagged two prebuilt .so files in our production AAB as non-compliant with Android's 16 KB page-size requirement, both in the x86_64 ABI:

• base/lib/x86_64/libconceal.so — from react-native-keychain via com.facebook.conceal:1.1.3 (last released in 2016, archived upstream).
• base/lib/x86_64/libsecp256k1.so — from react-native-fast-crypto, shipped as an IMPORTED prebuilt in its CMake config (not rebuilt from source).

Neither library can be realistically rebuilt with 16 KB alignment:

• Facebook Conceal has been unmaintained since 2018; there is no source-of-truth fork with 16 KB alignment.
• react-native-fast-crypto consumes libsecp256k1.so as a prebuilt binary; the existing yarn patch already adds -DANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES=ON for the bridge code we compile, but it does not regenerate the imported libsecp256k1.so files.

x86_64 is only ever used by Chromebook ARC++/ARCVM and emulators — no real phone ships with an x86_64 CPU. Dropping the x86_64 ABI from production AABs silences the Play warning without affecting users.

What this PR does

Two changes that need to land together:

1. android/gradle.properties.release — remove x86_64 from reactNativeArchitectures so React Native's own native libs (Hermes, RN core) aren't built for that ABI in the production AAB.

2. android/app/build.gradle — add ndk.abiFilters(*reactNativeArchitectures()) inside defaultConfig. Without this, AGP packages every ABI shipped in dependency AARs regardless of reactNativeArchitectures, which is what put the x86_64 libconceal.so and libsecp256k1.so into the AAB in the first place.

A small refactor of the reactNativeArchitectures() helper to return a List (via .toList()) makes the Groovy spread *reactNativeArchitectures() into abiFilters(String...) robust across AGP/Groovy versions.

What this PR does NOT change

• android/gradle.properties (default) — local dev still gets x86_64 emulator support.
• android/gradle.properties.github (CI E2E, x86_64 only) — the new abiFilters resolves to ["x86_64"] in that context, so emulator tests continue to work.
• android/gradle.properties.github.dual-versions (armeabi-v7a,arm64-v8a) — already excludes x86_64.
• scripts/build.sh -PreactNativeArchitectures=... CLI overrides — still respected by the helper.

Follow-up work (out of scope)

The same .so files still ship for arm64-v8a with 4 KB alignment. If/when Play extends the warning to arm64, or enforces the runtime 16 KB device requirement more aggressively on Android 15+ devices in 16 KB mode, these will need structural fixes:

• Replace react-native-fast-crypto with react-native-quick-crypto@1.x (we only consume scrypt).
• Drop the Conceal dependency from react-native-keychain (yarn patch or upgrade to v10) — safe because minSdk = 24 means the Conceal cipher path is never selected at runtime.

Changelog

CHANGELOG entry: null

Related issues

Fixes: Google Play 16 KB page-size warning for base/lib/x86_64/libconceal.so and base/lib/x86_64/libsecp256k1.so.

Manual testing steps

Feature: Production AAB no longer contains x86_64 ABI

  Scenario: A production release build is generated
    Given a clean checkout of this branch
    When the production AAB is built via the standard release workflow
      (the same one that does `cp android/gradle.properties.release android/gradle.properties`
       before `./gradlew bundleProdRelease`)
    Then `unzip -l app-prod-release.aab | grep '/lib/'` shows only
      `lib/arm64-v8a/`, `lib/armeabi-v7a/`, and `lib/x86/` entries
    And no `lib/x86_64/` entries appear in the output
    And no `libconceal.so` or `libsecp256k1.so` files appear under any
      `lib/x86_64/` path

  Scenario: Local dev on x86_64 emulator still works
    Given a developer running `yarn android` on an Intel Mac with an x86_64 emulator
    When the debug variant is built using the default `android/gradle.properties`
    Then x86_64 native libs are still produced and the app installs and runs

  Scenario: CI E2E on x86_64 emulator still works
    Given CI overlays `android/gradle.properties.github` (reactNativeArchitectures=x86_64)
    When `./gradlew assembleProdDebug` runs
    Then the resulting APK contains a `lib/x86_64/` directory and Detox tests pass

Screenshots/Recordings

Before

Play Console flagged:

• base/lib/x86_64/libconceal.so
• base/lib/x86_64/libsecp256k1.so

After

Production AAB contains no lib/x86_64/ directory — both warnings cleared.

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I've included tests if applicable — N/A (build-config change; verification is via the unzip -l check on the produced AAB)
• I've documented my code using JSDoc format if applicable — N/A
• I've applied the right labels on the PR — team-mobile-platform

Performance checks (if applicable)

• I've tested on Android — verified locally that the abiFilters change does not break the gradle.properties.github (x86_64-only) path used by CI E2E.
• I've tested with a power user scenario — N/A (no JS behavior change)
• I've instrumented key operations with Sentry traces — N/A

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

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