opencode-mobile/distribution/fdroid-submission/SIZE-OPTIMIZATION.md

APK Size Optimization for F-Droid / IzzyOnDroid

Current state

Artifact	Size
Universal AAB (app-release.aab)	58.5 MB
Per-ABI APK (estimated)	~20–25 MB
IzzyOnDroid per-APK limit	30 MB

bundletool is not installed in this environment, so per-ABI APK sizes were not measured directly. The estimate above is based on typical Expo/Hermes React Native apps:

• Hermes JS engine binary: ~8–10 MB per ABI
• React Native native libraries: ~5–8 MB per ABI
• JavaScript bundle (ABI-independent): ~6–8 MB
• Assets (icons, splash, etc.): ~2–3 MB

Conclusion: arm64-v8a APK is likely ~20–25 MB — within IzzyOnDroid's 30 MB limit. No ABI splits required for the initial submission.

To verify when bundletool is available:

bundletool build-apks \
  --bundle=android/app/build/outputs/bundle/release/app-release.aab \
  --output=apks.apks \
  --mode=universal

# For per-ABI sizes:
bundletool build-apks \
  --bundle=android/app/build/outputs/bundle/release/app-release.aab \
  --output=apks-splits.apks \
  --mode=default

unzip apks-splits.apks -d apk-splits/
ls -lh apk-splits/splits/

---

If arm64-v8a APK exceeds 30 MB — fix approach

Option A: ABI splits in Expo config plugin (recommended)

android/app/build.gradle is regenerated by npx expo prebuild on every CI run, so direct edits are overwritten. The correct approach is an Expo config plugin.

Create plugins/withAbiSplits.js:

const { withAppBuildGradle } = require('@expo/config-plugins');

module.exports = function withAbiSplits(config) {
  return withAppBuildGradle(config, (config) => {
    const contents = config.modResults.contents;
    // Insert splits block inside android { ... } after defaultConfig
    if (!contents.includes('splits {')) {
      config.modResults.contents = contents.replace(
        /defaultConfig \{/,
        `splits {
        abi {
            reset()
            enable true
            universalApk true
            include "armeabi-v7a", "arm64-v8a", "x86", "x86_64"
        }
    }
    defaultConfig {`
      );
    }
    return config;
  });
};

Register in app.json:

{
  "expo": {
    "plugins": [
      "./plugins/withAbiSplits.js"
    ]
  }
}

After npx expo prebuild, android/app/build.gradle will contain the splits block. Run ./gradlew assembleRelease — produces separate APKs per ABI.

For IzzyOnDroid / F-Droid: attach app-arm64-v8a-release.apk to the GitHub release.

Option B: fdroid Gradle product flavor

Add a fdroid flavor that includes only arm64-v8a:

// In the config plugin or directly in build.gradle (pre-prebuild override)
android {
    flavorDimensions "distribution"
    productFlavors {
        fdroid {
            dimension "distribution"
            ndk {
                abiFilters "arm64-v8a"
            }
        }
        play {
            dimension "distribution"
        }
    }
}

Build with: ./gradlew assembleFdroidRelease

This also provides a clean hook for excluding FCM artifacts (see below).

---

FCM / expo-notifications

expo-notifications compiles FCM receiver classes even when only local notifications are used (the app only calls scheduleNotificationAsync — no push token retrieval). F-Droid scanner may flag com.google.firebase:firebase-messaging as NonFreeNet or NonFreeDep.

Mitigation for F-Droid mainline: add a fdroid product flavor that excludes the FCM artifact:

// In config plugin
android {
    flavorDimensions "distribution"
    productFlavors {
        fdroid {
            dimension "distribution"
        }
    }
}

configurations.fdroidImplementation {
    exclude group: 'com.google.firebase', module: 'firebase-messaging'
}

Or patch expo-notifications build.gradle via a Gradle init script to replace the FCM dependency with a no-op stub in the fdroid flavor.

This is not required for IzzyOnDroid (more tolerant of GMS dependencies if they are not actively invoked). Track the F-Droid reviewer's feedback before investing in this fix — they may accept without it given the local-only usage.

---

Action items (when ready to optimize)

1. Install bundletool: sudo apt-get install bundletool or download JAR from https://github.com/google/bundletool/releases
2. Run build-apks --mode=default to measure per-ABI sizes
3. If arm64-v8a > 30 MB: implement config plugin (Option A above)
4. For F-Droid mainline FCM concern: implement fdroid product flavor (Option B)
5. Document measured sizes in this file once known