YPE-1180 Add Android example app build tests

[camrun91]

Description

We had broken example app builds. This adds the tests to build the Android app.

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation update
• refactor: Code refactoring (no functional changes)
• perf: Performance improvement
• test: Test additions or updates
• build: Build system or dependency changes
• ci: CI configuration changes
• chore: Other changes (maintenance, etc.)

Checklist

• My code follows the project's code style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• All commit messages follow conventional commits format
• I have updated the appropriate section in documentation (if needed)

Greptile Summary

This PR adds a GitHub Actions workflow that builds the Android example app on every PR targeting main, catching broken builds the way the existing example_ios_build.yml catches iOS regressions. The workflow is well-structured — it has an explicit permissions: contents: read, a 30-minute timeout, and leverages setup-java's built-in Gradle caching, and correctly uses ./gradlew assembleDebug directly from example/android.

Confidence Score: 5/5

Safe to merge — all previous review concerns have been addressed and the only remaining finding is a minor P2 style suggestion.

The workflow correctly uses ./gradlew assembleDebug from example/android, has explicit least-privilege permissions, a 30-minute timeout, and Gradle caching via setup-java. The sole remaining observation (missing --platform android on expo prebuild) is a non-blocking consistency suggestion that won't cause the workflow to fail on Ubuntu.

No files require special attention.

Important Files Changed

Filename	Overview
.github/workflows/android_example_test_build.yml	New workflow to build the Android example app on PRs to main; well-structured with timeout, least-privilege permissions, and Java/Gradle caching via setup-java, but expo prebuild is missing the --platform android flag.

Sequence Diagram

sequenceDiagram
    participant PR as Pull Request
    participant GH as GitHub Actions
    participant Ubuntu as ubuntu-latest runner
    participant Node as Node.js 20
    participant Java as Java 17 (Temurin)
    participant Expo as expo prebuild
    participant Gradle as Gradle (assembleDebug)

    PR->>GH: Triggered on PR to main
    GH->>Ubuntu: Spin up runner
    Ubuntu->>Ubuntu: Checkout repository
    Ubuntu->>Node: Setup Node.js 20 (npm cache)
    Ubuntu->>Java: Setup Java 17 (Gradle cache)
    Ubuntu->>Node: npm ci (root deps)
    Ubuntu->>Node: npm ci (example/ deps)
    Node->>Expo: npx expo prebuild
    Expo-->>Ubuntu: Generate example/android/ native project
    Ubuntu->>Gradle: ./gradlew assembleDebug
    Gradle-->>Ubuntu: Build APK (debug)
    Ubuntu-->>GH: Report success/failure
    GH-->>PR: Build status check

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This is a comment left during a code review.
Path: .github/workflows/android_example_test_build.yml
Line: 39-40

Comment:
**Missing `--platform android` flag on `expo prebuild`**

Without `--platform android`, Expo will generate native files for all configured platforms (both `ios` and `android`). On Ubuntu this means it'll write out an `ios/` directory alongside `android/`, doing unnecessary work and diverging from the pattern in `example_ios_build.yml` which uses `--platform ios`.

```suggestion
        run: npx expo prebuild --platform android
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (4): Last reviewed commit: "fix: cache and build" | Re-trigger Greptile}

[camrun91]

I believe that the current failure on the added test is legit and shows the failures I was seeing before my changes in the other PR.

[chatgpt-codex-connector]

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.
Credits must be used to enable repository wide code reviews.

[greptile-apps]

Greptile Summary

This PR adds a new GitHub Actions workflow (.github/workflows/android_example_test_build.yml) that builds the Android example app on every PR targeting main, addressing a gap where broken Android example app builds were going undetected in CI. The implementation is well-structured with timeout, least-privilege permissions, Gradle caching via setup-java, and correctly uses ./gradlew assembleDebug after expo prebuild. The only minor note is that expo prebuild is called without --platform android, causing the iOS native project directory to also be generated on a Linux runner unnecessarily.

Confidence Score: 5/5

Safe to merge — the workflow is well-structured with all previously raised concerns (timeout, permissions, Gradle caching, working directory) addressed.

All P1 findings from prior review rounds have been resolved. The only remaining finding is a P2 style suggestion (missing --platform android on expo prebuild), which does not affect correctness or merge safety.

No files require special attention.

Important Files Changed

Filename	Overview
.github/workflows/android_example_test_build.yml	New workflow that builds the Android example app on every PR to main; correctly uses ./gradlew assembleDebug after expo prebuild, with timeout, least-privilege permissions, and Gradle caching via setup-java. Minor: expo prebuild runs without --platform android, generating the iOS directory unnecessarily on a Linux runner.

Sequence Diagram

sequenceDiagram
    participant GH as GitHub (PR to main)
    participant Runner as ubuntu-latest Runner
    participant Node as Node.js 20
    participant Java as Java 17 (temurin)
    participant Expo as Expo CLI (prebuild)
    participant Gradle as Gradle (assembleDebug)

    GH->>Runner: Trigger on pull_request
    Runner->>Runner: Checkout repository
    Runner->>Node: Setup Node.js 20 + npm cache
    Runner->>Java: Setup Java 17 + Gradle cache
    Runner->>Node: npm ci (root deps)
    Runner->>Node: npm ci (example/ deps)
    Runner->>Expo: npx expo prebuild (generates android/ + ios/)
    Runner->>Gradle: ./gradlew assembleDebug (example/android)
    Gradle-->>Runner: Build success / failure

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_{Reviews (3): Last reviewed commit: "fix: cache and build" | Re-trigger Greptile}

[greptile-apps]

_{1 file reviewed, 3 comments}

_{Edit Code Review Agent Settings | Greptile}

[bmanquen]

I am learning about android and iOS so take my comments with a grain of salt.

[bmanquen]

Also I think we can probably test the android and ios builds in one github workflow file as long as they are in different jobs.