Perf(reader): stop manhwa scroll degrading after chapters and drawer use

app/detekt-baseline.xml

@@ -70,7 +70,7 @@
     <ID>FunctionNaming:FileConfirmationDialog.kt$@Composable fun FileConfirmationDialog( fileUri: String, onConfirm: () -&gt; Unit, onCancel: () -&gt; Unit )</ID>
     <ID>FunctionNaming:GridStateTiles.kt$@Composable fun ErrorTile( message: String, onRetry: (() -&gt; Unit)? = null, modifier: Modifier = Modifier )</ID>
     <ID>FunctionNaming:GridStateTiles.kt$@Composable fun LoadingTile( modifier: Modifier = Modifier, height: androidx.compose.ui.unit.Dp = 180.dp )</ID>
-    <ID>FunctionNaming:LibraryDrawerContent.kt$@Composable fun LibraryDrawerContent( libraryViewModel: LibraryViewModel, readerViewModel: ReaderViewModel, navController: NavController, onOpenFilePicker: () -&gt; Unit, onCloseDrawer: () -&gt; Unit ): Unit</ID>
+    <ID>FunctionNaming:LibraryDrawerContent.kt$@Composable fun LibraryDrawerContent( drawerSections: DrawerNovelSections, isLibraryEmpty: Boolean, onOpenFilePicker: () -&gt; Unit, onCloseDrawer: () -&gt; Unit, onLibraryClick: () -&gt; Unit, onDiscoverClick: () -&gt; Unit, onOpenLibraryItem: (LibraryItem) -&gt; Unit, onOpenLatestUpdate: (LibraryItem) -&gt; Unit ): Unit</ID>
     <ID>FunctionNaming:LibraryDrawerContent.kt$@Composable private fun ContinueReadingCard( item: LibraryItem, onClick: () -&gt; Unit ): Unit</ID>
     <ID>FunctionNaming:LibraryDrawerContent.kt$@Composable private fun DrawerSectionLabel(text: String): Unit</ID>
     <ID>FunctionNaming:LibraryDrawerContent.kt$@Composable private fun EmptyQuickAccessState(): Unit</ID>
@@ -149,7 +149,7 @@
     <ID>LongMethod:ExploreScreen.kt$@OptIn(ExperimentalMaterial3Api::class) @Composable fun ExploreScreen( exploreViewModel: ExploreViewModel, libraryViewModel: LibraryViewModel, onNavigateBack: () -&gt; Unit, onReadItem: (ExploreItem) -&gt; Unit ): Unit</ID>
     <ID>LongMethod:ExploreScreen.kt$@OptIn(ExperimentalMaterial3Api::class) @Composable private fun ActiveFilterBar( uiState: ExploreViewModel.ExploreUiState, hasActiveFilters: Boolean, onOpenFilters: () -&gt; Unit, onSourceSelect: (String?) -&gt; Unit, onTagToggle: (String) -&gt; Unit, onClearFilters: () -&gt; Unit ): Unit</ID>
     <ID>LongMethod:ExploreScreen.kt$@OptIn(ExperimentalMaterial3Api::class, ExperimentalLayoutApi::class) @Composable private fun FiltersBottomSheetContent( uiState: ExploreViewModel.ExploreUiState, onSourceSelect: (String?) -&gt; Unit, onTagToggle: (String) -&gt; Unit, onClearTags: () -&gt; Unit, onClose: () -&gt; Unit ): Unit</ID>
-    <ID>LongMethod:LibraryDrawerContent.kt$@Composable fun LibraryDrawerContent( libraryViewModel: LibraryViewModel, readerViewModel: ReaderViewModel, navController: NavController, onOpenFilePicker: () -&gt; Unit, onCloseDrawer: () -&gt; Unit ): Unit</ID>
+    <ID>LongMethod:LibraryDrawerContent.kt$@Composable fun LibraryDrawerContent( drawerSections: DrawerNovelSections, isLibraryEmpty: Boolean, onOpenFilePicker: () -&gt; Unit, onCloseDrawer: () -&gt; Unit, onLibraryClick: () -&gt; Unit, onDiscoverClick: () -&gt; Unit, onOpenLibraryItem: (LibraryItem) -&gt; Unit, onOpenLatestUpdate: (LibraryItem) -&gt; Unit ): Unit</ID>
     <ID>LongMethod:LibraryItemCard.kt$@OptIn(ExperimentalFoundationApi::class) @Composable fun LibraryItemCard( item: LibraryItem, isSelected: Boolean, isCurrent: Boolean, onClick: () -&gt; Unit, onLongClick: () -&gt; Unit, onNewTagClick: (() -&gt; Unit)? = null, onDelete: (() -&gt; Unit)? = null, onResetProgress: (() -&gt; Unit)? = null, onMarkFinished: (() -&gt; Unit)? = null )</ID>
     <ID>LongMethod:LibraryRepository.kt$LibraryRepository$suspend fun refreshLibraryUpdates( exploreRepository: ExploreRepository, ignoreActivityThreshold: Boolean = false ): Unit</ID>
     <ID>LongMethod:LibraryScreen.kt$@Composable private fun AddNovelSection( urlInput: String, onUrlChange: (String) -&gt; Unit, onAddClick: () -&gt; Unit, onOpenPdfClick: () -&gt; Unit ): Unit</ID>
@@ -184,6 +184,7 @@
     <ID>LongParameterList:ExploreGridSection.kt$( gridState: LazyGridState, modifier: Modifier = Modifier, uiState: ExploreViewModel.ExploreUiState, hasActiveFilters: Boolean, onItemSelect: (ExploreItem) -&gt; Unit, onLoadMore: () -&gt; Unit, onClearFilters: () -&gt; Unit, onRetryFailedSource: (String) -&gt; Unit )</ID>
     <ID>LongParameterList:ExploreScreen.kt$( uiState: ExploreViewModel.ExploreUiState, hasActiveFilters: Boolean, onOpenFilters: () -&gt; Unit, onSourceSelect: (String?) -&gt; Unit, onTagToggle: (String) -&gt; Unit, onClearFilters: () -&gt; Unit )</ID>
     <ID>LongParameterList:ExploreScreen.kt$( uiState: ExploreViewModel.ExploreUiState, modifier: Modifier = Modifier, hasActiveFilters: Boolean, onSearchQueryChange: (String) -&gt; Unit, onPerformSearch: () -&gt; Unit, onOpenFilters: () -&gt; Unit, onClearFilters: () -&gt; Unit, onSetBrowseMode: (BrowseMode) -&gt; Unit, onSourceSelect: (String?) -&gt; Unit, onTagToggle: (String) -&gt; Unit, onItemSelect: (ExploreItem) -&gt; Unit, onLoadMore: () -&gt; Unit, onRetryFailedSource: (String) -&gt; Unit )</ID>
+    <ID>LongParameterList:LibraryDrawerContent.kt$( drawerSections: DrawerNovelSections, isLibraryEmpty: Boolean, onOpenFilePicker: () -&gt; Unit, onCloseDrawer: () -&gt; Unit, onLibraryClick: () -&gt; Unit, onDiscoverClick: () -&gt; Unit, onOpenLibraryItem: (LibraryItem) -&gt; Unit, onOpenLatestUpdate: (LibraryItem) -&gt; Unit )</ID>
     <ID>LongParameterList:LibraryItemCard.kt$( item: LibraryItem, isSelected: Boolean, isCurrent: Boolean, onClick: () -&gt; Unit, onLongClick: () -&gt; Unit, onNewTagClick: (() -&gt; Unit)? = null, onDelete: (() -&gt; Unit)? = null, onResetProgress: (() -&gt; Unit)? = null, onMarkFinished: (() -&gt; Unit)? = null )</ID>
     <ID>LongParameterList:LibraryRepository.kt$LibraryRepository$( itemId: String, currentChapter: String = "", progress: FieldUpdate&lt;Int&gt; = FieldUpdate.Unchanged, currentChapterUrl: FieldUpdate&lt;String&gt; = FieldUpdate.Unchanged, lastScrollProgress: FieldUpdate&lt;Float&gt; = FieldUpdate.Unchanged, lastReadIndex: FieldUpdate&lt;Int&gt; = FieldUpdate.Unchanged, lastReadElementKey: FieldUpdate&lt;String&gt; = FieldUpdate.Unchanged, lastReadOffsetFraction: FieldUpdate&lt;Float&gt; = FieldUpdate.Unchanged )</ID>
     <ID>LongParameterList:LibraryRepository.kt$LibraryRepository$( itemId: String, currentChapter: String, progress: Int, currentChapterUrl: String? = null, lastScrollProgress: Float? = null, lastReadIndex: Int? = null, lastReadElementKey: String? = null, lastReadOffsetFraction: Float? = null )</ID>
@@ -301,12 +302,8 @@
     <ID>MagicNumber:BaseJsoupSource.kt$BaseJsoupSource$15000L</ID>
     <ID>MagicNumber:CacheKeyUtils.kt$CacheKeyUtils$0xff</ID>
     <ID>MagicNumber:CacheKeyUtils.kt$CacheKeyUtils$4</ID>
-    <ID>MagicNumber:ChapterDownloadQueue.kt$WorkManagerChapterDownloadQueue$3</ID>
     <ID>MagicNumber:ChapterDownloadQueue.kt$WorkManagerChapterDownloadQueue$30</ID>
-    <ID>MagicNumber:ChapterDownloadQueue.kt$WorkManagerChapterDownloadQueue$4</ID>
-    <ID>MagicNumber:ChapterDownloadQueue.kt$WorkManagerChapterDownloadQueue$5</ID>
     <ID>MagicNumber:ChapterListSheet.kt$100</ID>
-    <ID>MagicNumber:EasyReaderApplication.kt$EasyReaderApplication$0.25</ID>
     <ID>MagicNumber:EpubContentLoader.kt$EpubContentLoader$1024</ID>
     <ID>MagicNumber:EpubContentLoader.kt$EpubContentLoader$50</ID>
     <ID>MagicNumber:EpubContentLoader.kt$EpubContentLoader.&lt;no name provided&gt;$5</ID>
@@ -579,6 +576,8 @@
     <ID>MaxLineLength:ReaderProgressController.kt$ReaderProgressController$"saveProgress url=${io.aatricks.easyreader.util.UrlSanitizer.sanitize(resolvedChapterUrl)} index=$lastIndex elementKey=${if (lastElementKey.isNotEmpty()) "&lt;set&gt;" else "&lt;empty&gt;"} fraction=$lastFraction firstVisibleItemSize=${latest.firstVisibleItemSize}"</ID>
     <ID>MaxLineLength:ReaderProgressController.kt$ReaderProgressController$maxScrollOffset &gt; viewportHeight -&gt; ((scrollOffset / (maxScrollOffset - viewportHeight)) * 100f).coerceIn(0f, 100f)</ID>
     <ID>MaxLineLength:ReaderProgressController.kt$ReaderProgressController$val nextUiPendingRestoreOffsetFraction = if (uiPendingRestoreOffsetFraction != null) null else uiPendingRestoreOffsetFraction</ID>
+    <ID>MaxLineLength:ReaderScreen.kt$libraryViewModel</ID>
+    <ID>MaxLineLength:ReaderScreen.kt$val loadUrl = if (item.currentChapterUrl.isNotBlank()) item.currentChapterUrl else item.url</ID>
     <ID>MaxLineLength:ReaderViewModel.kt$ReaderViewModel$"persistLifecycleProgress skip snap-to-top url=${io.aatricks.easyreader.util.UrlSanitizer.sanitize(currentChapterUrl)} dbProgress=${existing.progress}"</ID>
     <ID>MaxLineLength:ReaderViewModel.kt$ReaderViewModel$"persistLifecycleProgress skip unstable url=${io.aatricks.easyreader.util.UrlSanitizer.sanitize(currentChapterUrl)} firstVisibleItemSize=${latest.firstVisibleItemSize} fraction=${latest.scrollOffsetFraction}"</ID>
     <ID>MaxLineLength:ReaderViewModel.kt$ReaderViewModel$"persistLifecycleProgress url=${io.aatricks.easyreader.util.UrlSanitizer.sanitize(currentChapterUrl)} index=${latest.scrollIndex} fraction=${latest.scrollOffsetFraction} firstVisibleItemSize=${latest.firstVisibleItemSize}"</ID>
@@ -630,8 +629,9 @@
     <ID>ReturnCount:ImageBoundsParser.kt$ImageBoundsParser$private fun parseJpeg(bytes: ByteArray): Pair&lt;Int, Int&gt;?</ID>
     <ID>ReturnCount:ImageBoundsParser.kt$ImageBoundsParser$private fun parsePng(bytes: ByteArray): Pair&lt;Int, Int&gt;?</ID>
     <ID>ReturnCount:ImageBoundsParser.kt$ImageBoundsParser$private fun parseWebP(bytes: ByteArray): Pair&lt;Int, Int&gt;?</ID>
-    <ID>ReturnCount:ImageCache.kt$ImageCache$fun promoteToDownloads(url: String): File?</ID>
     <ID>ReturnCount:ImageCache.kt$ImageCache$private fun File.isCachedImageValid(): Boolean</ID>
+    <ID>ReturnCount:ImageCache.kt$ImageCache$private fun promoteToDownloadsInternal(url: String): File?</ID>
+    <ID>ReturnCount:ImageDimensionCacheRepository.kt$ImageDimensionCacheRepository$suspend fun persistAll(entries: List&lt;Triple&lt;String, Int, Int&gt;&gt;): Boolean</ID>
     <ID>ReturnCount:ImageDownloader.kt$ImageDownloader$private fun parseImageResponse( response: Response, destinationFile: File? = null ): ImageFetchResult</ID>
     <ID>ReturnCount:ImageDownloader.kt$ImageDownloader$suspend fun executeImageRequest( imageUrl: String, pageUrl: String, priority: ImageRequestPriority, rangeHeader: String? = null, destinationFile: File? = null ): ImageFetchResult</ID>
     <ID>ReturnCount:ImageIntegrity.kt$ImageIntegrity$fun isValidImageFile(file: File): Boolean</ID>

app/src/main/java/io/aatricks/easyreader/EasyReaderApplication.kt

@@ -138,13 +138,25 @@ class EasyReaderApplication : Application(), SingletonImageLoader.Factory, Confi
     }
 
     private fun buildMemoryCache(context: PlatformContext): MemoryCache {
+        // Manhwa strips are region-decoded into HARDWARE-config slices (~screenWidth x 2048 x 4B
+        // ≈ 9MB each). At 0.25 the strong LRU (~32-64MB) holds only ~4-7 slices — well under one
+        // chapter, so a fast up/down drag or scrolling back re-decodes evicted slices every time.
+        // HARDWARE pixels live in graphics memory (AHardwareBuffer), not the Java heap, so a larger
+        // budget does not raise heap-OOM risk; 0.5 comfortably holds a full oscillation window.
         return MemoryCache.Builder()
-            .maxSizePercent(context, 0.25)
+            .maxSizePercent(context, MEMORY_CACHE_HEAP_FRACTION)
             .build()
     }
 
     companion object {
         private const val TAG = "EasyReaderApplication"
         private const val WEB_OFFLINE_PIPELINE_VERSION = 3
+
+        // Fraction of the app's available memory the Coil image cache may use. Manhwa strips are
+        // decoded into HARDWARE-config slices (~9MB each, in graphics memory not the Java heap), so
+        // a larger budget lets a full up/down oscillation window and >1 chapter's slices stay
+        // resident instead of being evicted and re-decoded on scroll-back. Dial back toward 0.25 if
+        // low-memory devices hit onTrimMemory / AHardwareBuffer-fd pressure.
+        private const val MEMORY_CACHE_HEAP_FRACTION = 0.5
     }
 }

app/src/main/java/io/aatricks/easyreader/data/model/ChapterContent.kt

@@ -70,12 +70,15 @@ data class ChapterContent(
     )
 
     /**
-     * Get all image URLs
+     * Get all image URLs, including images nested inside [ContentElement.PageContent]
      */
-    fun getAllImageUrls(): List<String> = paragraphs.flatMap { 
+    fun getAllImageUrls(): List<String> = collectImageUrls(paragraphs)
+
+    private fun collectImageUrls(elements: List<ContentElement>): List<String> = elements.flatMap {
         when (it) {
             is ContentElement.Image -> listOf(it.url)
             is ContentElement.ImageGroup -> it.images.map { img -> img.url }
+            is ContentElement.PageContent -> collectImageUrls(it.elements)
             else -> emptyList()
         }
     }

app/src/main/java/io/aatricks/easyreader/data/repository/ImageDimensionCacheRepository.kt

@@ -41,8 +41,9 @@ class ImageDimensionCacheRepository @Inject constructor(
         }
     }
 
-    suspend fun persistAll(entries: List<Triple<String, Int, Int>>) {
-        if (entries.isEmpty()) return
+    /** @return true when the rows reached the DB (or there was nothing valid to write). */
+    suspend fun persistAll(entries: List<Triple<String, Int, Int>>): Boolean {
+        if (entries.isEmpty()) return true
         val now = System.currentTimeMillis()
         val rows = entries
             .filter { it.first.isNotBlank() && it.second > 0 && it.third > 0 }
@@ -55,8 +56,8 @@ class ImageDimensionCacheRepository @Inject constructor(
                     parserVersion = CURRENT_PARSER_VERSION
                 )
             }
-        if (rows.isEmpty()) return
-        runCatching { dao.upsertAll(rows) }
+        if (rows.isEmpty()) return true
+        return runCatching { dao.upsertAll(rows) }.isSuccess
     }
 
     suspend fun prune(ttlMs: Long = DEFAULT_TTL_MS) {

app/src/main/java/io/aatricks/easyreader/data/repository/content/ImageCache.kt

@@ -23,18 +23,47 @@ class ImageCache @Inject constructor(
     fun getLikelyCachedMediaFile(url: String): File? =
         candidateFiles(url).firstOrNull { it.exists() && it.length() > 0L }
 
+    // Memoized: the reader probes this on the main thread for every image item entering
+    // composition (twice per item before the memo), and a fast up/down scroll re-enters items
+    // continuously — up to 3 candidate files × exists/length/mtime syscalls each time. Entries
+    // are dropped whenever a write path touches the url's candidate files (see mutators below
+    // and WebContentLoader.downloadAndCacheImageInternal); staleness is otherwise harmless
+    // because HttpMediaCacheFetcher re-checks disk authoritatively before serving.
     fun getLikelyMediaState(url: String): String {
+        // Hit path stays lookup-only (same shape as isCachedImageValid below): the size guard
+        // both costs a CHM sweep and, when it trips, would wipe the live chapter's hot entries
+        // on what was a plain read.
+        mediaStateMemo[url]?.let { return it }
+        if (mediaStateMemo.size > MAX_MEDIA_STATE_MEMO) mediaStateMemo.clear()
+        return mediaStateMemo.computeIfAbsent(url) { computeLikelyMediaState(it) }
+    }
+
+    private fun computeLikelyMediaState(url: String): String {
         val file = getLikelyCachedMediaFile(url) ?: return "missing"
         return "${file.absolutePath}:${file.length()}:${file.lastModified()}"
     }
 
+    fun invalidateMediaState(url: String) {
+        mediaStateMemo.remove(url)
+    }
+
     fun getRootDir(): File = mediaCacheDir
 
     fun getCacheSize(): Long = FileSizeUtils.calculateDirectorySize(mediaCacheDir)
 
     fun getDownloadsSize(): Long = FileSizeUtils.calculateDirectorySize(mediaDownloadsDir)
 
-    fun trimToSize(maxBytes: Long): Long = FileSizeUtils.trimDirectoryToSize(mediaCacheDir, maxBytes)
+    fun trimToSize(maxBytes: Long): Long {
+        // Trim runs routinely (after chapter loads, every ~30s during prefetch) and usually
+        // deletes nothing — the memo must survive those calls or the memoization is defeated.
+        // When files ARE deleted there is no per-url mapping back from file names, so drop the
+        // whole memo, and only AFTER the walk finishes: clearing first would let a concurrent
+        // probe re-memoize a file the walk is about to delete.
+        var deletedAny = false
+        val remaining = FileSizeUtils.trimDirectoryToSize(mediaCacheDir, maxBytes) { deletedAny = true }
+        if (deletedAny) mediaStateMemo.clear()
+        return remaining
+    }
 
     fun findExistingCachedMediaFile(url: String): File? =
         candidateFiles(url).firstOrNull { it.exists() && it.isCachedImageValid() }
@@ -59,6 +88,8 @@ class ImageCache @Inject constructor(
     private data class IntegrityKey(val path: String, val length: Long, val mtime: Long)
     private val integrityVerdicts = ConcurrentHashMap<IntegrityKey, Boolean>()
 
+    private val mediaStateMemo = ConcurrentHashMap<String, String>()
+
     private fun File.isCachedImageValid(): Boolean {
         if (!exists() || length() <= 0L) return false
         val key = IntegrityKey(absolutePath, length(), lastModified())
@@ -71,27 +102,40 @@ class ImageCache @Inject constructor(
 
     private companion object {
         private const val MAX_INTEGRITY_VERDICTS = 4096
+        private const val MAX_MEDIA_STATE_MEMO = 4096
     }
 
+    // Memo invalidation always FOLLOWS the disk mutation: invalidating first leaves a window
+    // where a concurrent probe re-memoizes the pre-mutation state, which then sticks.
     fun deleteCachedMediaFiles(url: String) {
         candidateFiles(url).forEach { it.delete() }
+        mediaStateMemo.remove(url)
     }
 
     fun deleteDownloadedMediaFile(url: String) {
         File(mediaDownloadsDir, CacheKeyUtils.keyFor(url)).delete()
+        mediaStateMemo.remove(url)
     }
 
     fun clearAll() {
         mediaCacheDir.deleteRecursively()
         mediaCacheDir.mkdirs()
+        mediaStateMemo.clear()
     }
 
     fun clearAllDownloads() {
         mediaDownloadsDir.deleteRecursively()
         mediaDownloadsDir.mkdirs()
+        mediaStateMemo.clear()
+    }
+
+    fun promoteToDownloads(url: String): File? = try {
+        promoteToDownloadsInternal(url)
+    } finally {
+        mediaStateMemo.remove(url)
     }
 
-    fun promoteToDownloads(url: String): File? {
+    private fun promoteToDownloadsInternal(url: String): File? {
         val key = CacheKeyUtils.keyFor(url)
         val target = File(mediaDownloadsDir, key)
         if (target.exists()) {

app/src/main/java/io/aatricks/easyreader/data/repository/content/WebContentLoader.kt

@@ -1018,6 +1018,12 @@ class WebContentLoader @Suppress("LongParameterList") @Inject constructor(
                     }
                 }.also { created ->
                     created.invokeOnCompletion {
+                        // Invalidate here — when the download attempt itself finishes — not in
+                        // the awaiter: the deferred is shared and outlives a cancelled awaiter
+                        // (Coil disposing a request mid-download), and an awaiter-side
+                        // invalidation would fire before the file lands, letting a probe
+                        // re-memoize "missing" that nothing ever corrects.
+                        imageCache.invalidateMediaState(imageUrl)
                         repositoryScope.launch {
                             imageDownloadMutex.withLock {
                                 if (inFlightImageDownloads[imageUrl]?.deferred === created) {