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News Aggregator

Build an offline-first news reader with a home-screen widget. This project owns the Paging 3 + Room + WorkManager + Glance skill set — the foundation of every content-heavy app from Twitter to Pocket.

The user journey​

Home screen widget (latest 3 headlines)
         │
         ▼
Main feed (paged, offline) ─→ Article reader ─→ Share / Save
         │
         ├─ Topic filter
         └─ Search (FTS)

Features (by milestone)​

M1 — Skeleton + feed​

  • :core:design with reading-optimized typography (Literata or similar)
  • Navigation: Home, Topics, Saved, Settings
  • Room schema: Article, Topic, SavedArticle, RemoteKey
  • Convention plugins from Module 14

M2 — Paging 3 with Room + RemoteMediator​

@OptIn(ExperimentalPagingApi::class)
class ArticleRemoteMediator @Inject constructor(
    private val api: NewsApi,
    private val db: AppDatabase
) : RemoteMediator<Int, ArticleEntity>() {

    override suspend fun load(loadType: LoadType, state: PagingState<Int, ArticleEntity>): MediatorResult {
        val page = when (loadType) {
            LoadType.REFRESH -> 1
            LoadType.PREPEND -> return MediatorResult.Success(endOfPaginationReached = true)
            LoadType.APPEND -> {
                val lastKey = db.remoteKeyDao().getLast() ?: return MediatorResult.Success(true)
                lastKey.nextPage ?: return MediatorResult.Success(true)
            }
        }
        return try {
            val response = api.topHeadlines(page = page, pageSize = state.config.pageSize)
            db.withTransaction {
                if (loadType == LoadType.REFRESH) {
                    db.remoteKeyDao().clear()
                    db.articleDao().clear()
                }
                db.articleDao().insertAll(response.articles.map(ArticleDto::toEntity))
                db.remoteKeyDao().insert(RemoteKey(nextPage = if (response.hasMore) page + 1 else null))
            }
            MediatorResult.Success(endOfPaginationReached = !response.hasMore)
        } catch (e: Exception) {
            MediatorResult.Error(e)
        }
    }
}

@Singleton
class ArticleRepository @Inject constructor(
    private val db: AppDatabase,
    private val mediator: ArticleRemoteMediator
) {
    @OptIn(ExperimentalPagingApi::class)
    fun pager(): Flow<PagingData<Article>> = Pager(
        config = PagingConfig(pageSize = 20, prefetchDistance = 5),
        remoteMediator = mediator,
        pagingSourceFactory = { db.articleDao().pagingSource() }
    ).flow.map { paging -> paging.map(ArticleEntity::toDomain) }
}

M3 — Background sync​

  • Periodic WorkManager job refreshing top headlines every 4 hours
  • Expedited job on boot to catch up missed news
  • Constraints: network connected, not low battery
  • Per-topic subscribe/unsubscribe with separate workers

M4 — Article reader + save-for-later​

  • Reader mode with Compose Material 3 typography
  • Customizable font size + theme (light/sepia/dark)
  • Save-for-later with local cache of full HTML
  • Export to PDF using Android Print API

M5 — Glance home widget​

class HeadlinesWidget : GlanceAppWidget() {
    override suspend fun provideGlance(context: Context, id: GlanceId) {
        provideContent {
            val articles = currentState(key = headlinesKey) ?: emptyList<Article>()
            GlanceTheme {
                Column(modifier = GlanceModifier.padding(8.dp)) {
                    articles.take(3).forEach { article ->
                        Row(modifier = GlanceModifier
                            .fillMaxWidth()
                            .clickable(actionStartActivity(ReaderActivity.intentFor(article.id)))
                        ) {
                            Text(article.title, style = TextStyle(fontWeight = FontWeight.Bold))
                        }
                    }
                }
            }
        }
    }
}

class HeadlinesWidgetReceiver : GlanceAppWidgetReceiver() {
    override val glanceAppWidget = HeadlinesWidget()
}

Update widget from a WorkManager job — Glance re-renders when state changes.

M6 — Production​

  • Search: Room FTS5 over article body
  • Baseline profile for feed + reader
  • Macrobenchmark: scroll feed, open article cold
  • Play Data Safety: Reading history, optional analytics
  • Accessibility: heading levels in reader, landmarks for TalkBack

Architecture diagram​

┌──────────────────────────────────────────────────────────────┐
│  Home Screen Widget (Glance)                                 │
│    reads: Top 3 headlines from Room                          │
└──────────────────────┬───────────────────────────────────────┘
                       │
┌──────────────────────▼───────────────────────────────────────┐
│  App UI (Compose)                                            │
│    FeedScreen (Paging 3) · ReaderScreen · SearchScreen       │
├──────────────────────────────────────────────────────────────┤
│  ViewModels + Paging + Room Flow                             │
├──────────────────────────────────────────────────────────────┤
│  ArticleRepository + RemoteMediator                          │
├──────────────────────────────────────────────────────────────┤
│  Room DB (source of truth)  ◄──── WorkManager sync jobs ────│
│                                         │                    │
│                                         ▼                    │
│                                  NewsApi (Retrofit)         │
└──────────────────────────────────────────────────────────────┘

Stretch goals​

🔊

Audio articles

TTS narration with ExoPlayer for background playback, MediaSession for lockscreen controls.

🤖

On-device summarization

Gemini Nano via ML Kit for 2-sentence summaries — no network, no cost.

📌

Smart notifications

Breaking news alerts with user-level filter ("only politics and tech"). Rich notification with expanded text.

📊

Reading stats

Time spent per topic, streak tracker, most-read sources.

🌐

Share extension

Accept shared URLs from browser, save to reader, extract content via backend.

Testing strategy​

  • Paging source tests — assert that Room-backed PagingSource emits expected pages
  • MockWebServer for Retrofit + RemoteMediator integration tests
  • WorkManager tests with SynchronousExecutor for deterministic job runs
  • Glance tests with GlanceAppWidgetUnitTestManager

Offline UX polish​

  • Stale indicator: subtle banner if last sync > 6 hours
  • Offline mode: disable pull-to-refresh animation, show "No connection" snackbar
  • Image placeholders: Coil with blurhash or dominant color fallback
  • Preload images: prefetch thumbnails for next page before the user scrolls

Privacy​

  • No third-party tracking pixels in reader (load article text from API, not iframe the source)
  • Reading history local only, with user toggle for cross-device sync via your backend
  • Analytics opt-out respected; even first-party event collection gated

Next​

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