# 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:
```bash
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`:

```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`:
```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:

```groovy
// 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:

```groovy
// 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