fix: avoid ANR during live text style updates

app/src/main/java/eu/kanade/presentation/reader/settings/ReaderSettingsDialog.kt

@@ -9,7 +9,6 @@ import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalView
 import androidx.compose.ui.window.DialogWindowProvider
@@ -33,15 +32,11 @@ fun ReaderSettingsDialog(
         stringResource(MR.strings.pref_category_text_reader),
     )
     val pagerState = rememberPagerState { tabTitles.size }
-    val initialTextStyle = remember { viewModel.preferences.textReaderStyle() }
-
     BoxWithConstraints {
         TabbedDialog(
             modifier = Modifier.heightIn(max = maxHeight * 0.75f),
             onDismissRequest = {
-                if (viewModel.preferences.textReaderStyle() != initialTextStyle) {
-                    viewModel.onTextSettingsChanged()
-                }
+                viewModel.flushTextSettingsReload()
                 onDismissRequest()
                 onShowMenus()
             },
@@ -51,7 +46,7 @@ fun ReaderSettingsDialog(
             val window = (LocalView.current.parent as? DialogWindowProvider)?.window
 
             LaunchedEffect(pagerState.currentPage) {
-                if (pagerState.currentPage == 2) {
+                if (pagerState.currentPage == 2 || pagerState.currentPage == 3) {
                     window?.setDimAmount(0f)
                     onHideMenus()
                 } else {

app/src/main/java/eu/kanade/presentation/reader/settings/TextSettingsPage.kt

@@ -34,7 +34,10 @@ internal fun ColumnScope.TextSettingsPage(viewModel: ReaderSettingsViewModel) {
         valueRange = 32..72,
         steps = 19,
         valueString = fontSize.toString(),
-        onChange = fontSizePref::set,
+        onChange = { value ->
+            fontSizePref.set(value)
+            viewModel.requestTextSettingsReload()
+        },
         pillColor = MaterialTheme.colorScheme.surfaceContainerHighest,
     )
 
@@ -46,7 +49,10 @@ internal fun ColumnScope.TextSettingsPage(viewModel: ReaderSettingsViewModel) {
         valueRange = 90..180,
         steps = 17,
         valueString = "$lineSpacing%",
-        onChange = lineSpacingPref::set,
+        onChange = { value ->
+            lineSpacingPref.set(value)
+            viewModel.requestTextSettingsReload()
+        },
         pillColor = MaterialTheme.colorScheme.surfaceContainerHighest,
     )
 
@@ -58,7 +64,10 @@ internal fun ColumnScope.TextSettingsPage(viewModel: ReaderSettingsViewModel) {
         valueRange = 0..48,
         steps = 11,
         valueString = paragraphSpacing.toString(),
-        onChange = paragraphSpacingPref::set,
+        onChange = { value ->
+            paragraphSpacingPref.set(value)
+            viewModel.requestTextSettingsReload()
+        },
         pillColor = MaterialTheme.colorScheme.surfaceContainerHighest,
     )
 
@@ -68,7 +77,10 @@ internal fun ColumnScope.TextSettingsPage(viewModel: ReaderSettingsViewModel) {
         fontFamilies.forEach { (label, value) ->
             FilterChip(
                 selected = fontFamily == value,
-                onClick = { fontFamilyPref.set(value) },
+                onClick = {
+                    fontFamilyPref.set(value)
+                    viewModel.requestTextSettingsReload()
+                },
                 label = { Text(stringResource(label)) },
             )
         }

app/src/main/java/eu/kanade/tachiyomi/source/kavita/KavitaCompat.kt

@@ -0,0 +1,37 @@
+package eu.kanade.tachiyomi.source.kavita
+
+import eu.kanade.tachiyomi.source.Source
+
+private const val KAVITA_PACKAGE_PREFIX = "eu.kanade.tachiyomi.extension.all.kavita."
+
+internal fun Source.isKavitaSource(): Boolean =
+    this::class.java.name.startsWith(KAVITA_PACKAGE_PREFIX)
+
+/**
+ * Kavita extension chapter URLs are normally /Chapter/{id}. Keep compatibility
+ * with older/alternate forms used by reading lists and previous releases.
+ */
+internal fun String.toKavitaChapterId(): Int? {
+    Regex("""(?:^|/)Chapter/(\d+)""", RegexOption.IGNORE_CASE)
+        .find(this)
+        ?.groupValues
+        ?.getOrNull(1)
+        ?.toIntOrNull()
+        ?.let { return it }
+
+    Regex("""(?:^|/)chapter_(\d+)""", RegexOption.IGNORE_CASE)
+        .find(this)
+        ?.groupValues
+        ?.getOrNull(1)
+        ?.toIntOrNull()
+        ?.let { return it }
+
+    Regex("""[?&]chapterId=(\d+)""", RegexOption.IGNORE_CASE)
+        .find(this)
+        ?.groupValues
+        ?.getOrNull(1)
+        ?.toIntOrNull()
+        ?.let { return it }
+
+    return null
+}

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

@@ -223,6 +223,16 @@ class ReaderActivity : BaseActivity() {
                     ReaderViewModel.Event.ReloadViewerChapters -> {
                         viewModel.state.value.viewerChapters?.let(::setChapters)
                     }
+                    ReaderViewModel.Event.RefreshCurrentTextPage -> {
+                        viewModel.state.value.viewer?.refreshCurrentPage()
+                    }
+                    ReaderViewModel.Event.ReloadTextViewerChapters -> {
+                        val state = viewModel.state.value
+                        val chapters = state.viewerChapters
+                        if (chapters != null) {
+                            state.viewer?.refreshTextChapters(chapters)
+                        }
+                    }
                     ReaderViewModel.Event.PageChanged -> {
                         displayRefreshHost.flash()
                     }
@@ -254,7 +264,8 @@ class ReaderActivity : BaseActivity() {
                 readerState = viewModel.state,
                 onChangeReadingMode = viewModel::setMangaReadingMode,
                 onChangeOrientation = viewModel::setMangaOrientationType,
-                onTextSettingsChanged = viewModel::reloadTextReaderStyle,
+                onTextSettingsPreview = viewModel::previewTextReaderStyle,
+                onTextSettingsCommit = viewModel::commitTextReaderStyle,
                 preferences = readerPreferences,
             )
         }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderViewModel.kt

@@ -40,6 +40,7 @@ import eu.kanade.tachiyomi.source.model.Page
 import eu.kanade.tachiyomi.source.online.HttpSource
 import eu.kanade.tachiyomi.ui.reader.loader.ChapterLoader
 import eu.kanade.tachiyomi.ui.reader.loader.DownloadPageLoader
+import eu.kanade.tachiyomi.ui.reader.loader.TextReaderPage
 import eu.kanade.tachiyomi.ui.reader.model.InsertPage
 import eu.kanade.tachiyomi.ui.reader.model.ReaderChapter
 import eu.kanade.tachiyomi.ui.reader.model.ReaderPage
@@ -56,6 +57,7 @@ import eu.kanade.tachiyomi.util.storage.DiskUtil
 import eu.kanade.tachiyomi.util.storage.cacheImageDir
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asStateFlow
@@ -823,9 +825,21 @@ class ReaderViewModel(
         mutableState.update { it.copy(dialog = null) }
     }
 
-    fun reloadTextReaderStyle() {
+    fun previewTextReaderStyle() {
         val chapter = state.value.currentChapter ?: return
         if (chapter.pageLoader?.usesTextReaderStyle != true) return
+        val style = readerPreferences.textReaderStyle()
+        val textPages = chapter.pages?.filterIsInstance<TextReaderPage>().orEmpty()
+        if (textPages.isEmpty()) return
+
+        textPages.forEach { it.updateStyle(style) }
+        eventChannel.trySend(Event.RefreshCurrentTextPage)
+    }
+
+    fun commitTextReaderStyle() {
+        val chapter = state.value.currentChapter ?: return
+        if (chapter.pageLoader?.usesTextReaderStyle != true) return
+        if (chapter.pages?.any { it is TextReaderPage } != true) return
         val chapterLoader = loader ?: return
         val requestedPage = (state.value.currentPage - 1).coerceAtLeast(0)
         val oldLastIndex = (chapter.pages?.lastIndex ?: 0).coerceAtLeast(0)
@@ -833,17 +847,14 @@ class ReaderViewModel(
 
         viewModelScope.launchIO {
             try {
-                chapter.pageLoader?.recycle()
-                chapter.pageLoader = null
-                chapter.state = ReaderChapter.State.Wait
-                chapter.requestedPage = requestedPage
-                chapterLoader.loadChapter(chapter)
-                val newLastIndex = (chapter.pages?.lastIndex ?: 0).coerceAtLeast(0)
-                chapter.requestedPage = (readingProgress * newLastIndex).roundToInt().coerceIn(0, newLastIndex)
-                eventChannel.send(Event.ReloadViewerChapters)
+                val oldLoader = chapterLoader.reloadTextChapter(chapter, readingProgress) ?: return@launchIO
+                eventChannel.send(Event.ReloadTextViewerChapters)
+                // Give old visible holders time to detach before closing resources such as EpubReader.
+                delay(2000)
+                oldLoader.recycle()
             } catch (e: Throwable) {
                 if (e is CancellationException) throw e
-                logcat(LogPriority.ERROR, e) { "Failed to reload text reader style" }
+                logcat(LogPriority.ERROR, e) { "Failed to repaginate text reader style" }
             }
         }
     }
@@ -1037,6 +1048,8 @@ class ReaderViewModel(
 
     sealed interface Event {
         data object ReloadViewerChapters : Event
+        data object RefreshCurrentTextPage : Event
+        data object ReloadTextViewerChapters : Event
         data object PageChanged : Event
         data class SetOrientation(val orientation: Int) : Event
         data class SetCoverResult(val result: SetAsCoverResult) : Event

app/src/main/java/eu/kanade/tachiyomi/ui/reader/loader/ChapterLoader.kt

@@ -7,6 +7,8 @@ import eu.kanade.tachiyomi.data.download.DownloadProvider
 import eu.kanade.tachiyomi.source.Source
 import eu.kanade.tachiyomi.source.bookoasis.isBookOasisSource
 import eu.kanade.tachiyomi.source.bookoasis.toBookOasisChapterRef
+import eu.kanade.tachiyomi.source.kavita.isKavitaSource
+import eu.kanade.tachiyomi.source.kavita.toKavitaChapterId
 import eu.kanade.tachiyomi.source.online.HttpSource
 import eu.kanade.tachiyomi.ui.reader.model.ReaderChapter
 import eu.kanade.tachiyomi.ui.reader.setting.ReaderPreferences
@@ -20,6 +22,7 @@ import tachiyomi.domain.source.model.StubSource
 import tachiyomi.i18n.MR
 import tachiyomi.source.local.LocalSource
 import tachiyomi.source.local.io.Format
+import kotlin.math.roundToInt
 
 /**
  * Loader used to retrieve the [PageLoader] for a given chapter.
@@ -71,6 +74,36 @@ class ChapterLoader(
         }
     }
 
+
+    suspend fun reloadTextChapter(chapter: ReaderChapter, readingProgress: Float): PageLoader? {
+        return withIOContext {
+            val newLoader = getPageLoader(chapter)
+            if (!newLoader.usesTextReaderStyle) {
+                newLoader.recycle()
+                return@withIOContext null
+            }
+
+            try {
+                val pages = newLoader.getPages()
+                    .onEach { it.chapter = chapter }
+                if (pages.isEmpty()) {
+                    throw Exception(context.stringResource(MR.strings.page_list_empty_error))
+                }
+
+                val oldLoader = chapter.pageLoader
+                chapter.pageLoader = newLoader
+                chapter.requestedPage = (readingProgress * pages.lastIndex)
+                    .roundToInt()
+                    .coerceIn(0, pages.lastIndex)
+                chapter.state = ReaderChapter.State.Loaded(pages)
+                oldLoader
+            } catch (e: Throwable) {
+                newLoader.recycle()
+                throw e
+            }
+        }
+    }
+
     /**
      * Checks [chapter] to be loaded based on present pages and loader in addition to state.
      */
@@ -91,6 +124,7 @@ class ChapterLoader(
             source,
         )
         val bookOasisRef = dbChapter.url.toBookOasisChapterRef()
+        val kavitaChapterId = dbChapter.url.toKavitaChapterId()
 
         return when {
             isDownloaded -> DownloadPageLoader(
@@ -112,6 +146,16 @@ class ChapterLoader(
             source is HttpSource && source.isBookOasisSource() && bookOasisRef != null -> {
                 BookOasisFilePageLoader(context, source, bookOasisRef, readerPreferences.textReaderStyle())
             }
+            source is HttpSource && source.isKavitaSource() && kavitaChapterId != null -> {
+                KavitaCompatPageLoader(
+                    context = context,
+                    chapter = chapter,
+                    source = source,
+                    chapterCache = chapterCache,
+                    chapterId = kavitaChapterId,
+                    textStyle = readerPreferences.textReaderStyle(),
+                )
+            }
             source is HttpSource -> HttpPageLoader(chapter, source, chapterCache)
             source is StubSource -> error(context.stringResource(MR.strings.source_not_installed, source.toString()))
             else -> error(context.stringResource(MR.strings.loader_not_implemented_error))

app/src/main/java/eu/kanade/tachiyomi/ui/reader/loader/EpubPageLoader.kt

@@ -26,10 +26,7 @@ internal class EpubPageLoader(
 
         if (textPages.isNotEmpty()) {
             return textPages.mapIndexed { index, text ->
-                ReaderPage(index).apply {
-                    stream = { TextPageRenderer.render(text, style) }
-                    status = Page.State.Ready
-                }
+                TextReaderPage(index, text, style)
             }
         }
 

app/src/main/java/eu/kanade/tachiyomi/ui/reader/loader/KavitaCompatPageLoader.kt

@@ -0,0 +1,169 @@
+package eu.kanade.tachiyomi.ui.reader.loader
+
+import android.content.Context
+import com.hippo.unifile.UniFile
+import eu.kanade.tachiyomi.data.cache.ChapterCache
+import eu.kanade.tachiyomi.network.await
+import eu.kanade.tachiyomi.source.online.HttpSource
+import eu.kanade.tachiyomi.ui.reader.model.ReaderChapter
+import eu.kanade.tachiyomi.ui.reader.model.ReaderPage
+import eu.kanade.tachiyomi.ui.reader.setting.TextReaderStyle
+import mihon.core.archive.epubReader
+import okhttp3.Request
+import org.json.JSONObject
+import java.io.File
+import java.io.IOException
+import java.util.Locale
+
+/**
+ * Compatibility loader for Kavita document chapters.
+ *
+ * The Kavita extension renders every chapter through /Reader/image. That works
+ * for image/archive content, but EPUB/TXT can fail while Kavita is preparing an
+ * image cache. For document files, download the original chapter and use
+ * Mihon's native document reader instead. Other formats keep the extension's
+ * normal HttpPageLoader behavior.
+ */
+internal class KavitaCompatPageLoader(
+    private val context: Context,
+    private val chapter: ReaderChapter,
+    private val source: HttpSource,
+    private val chapterCache: ChapterCache,
+    private val chapterId: Int,
+    private val textStyle: TextReaderStyle,
+) : PageLoader() {
+
+    override var isLocal: Boolean = false
+    override val usesTextReaderStyle: Boolean
+        get() = delegate?.usesTextReaderStyle == true
+
+    private var delegate: PageLoader? = null
+
+    override suspend fun getPages(): List<ReaderPage> {
+        check(!isRecycled)
+
+        val format = detectDocumentFormat()
+        val loader = when (format) {
+            "epub", "txt" -> createDocumentLoader(format)
+            else -> HttpPageLoader(chapter, source, chapterCache)
+        }
+
+        delegate = loader
+        isLocal = loader.isLocal
+        return loader.getPages()
+    }
+
+    override suspend fun loadPage(page: ReaderPage) {
+        delegate?.loadPage(page)
+    }
+
+    override fun retryPage(page: ReaderPage) {
+        delegate?.retryPage(page)
+    }
+
+    override fun recycle() {
+        delegate?.recycle()
+        delegate = null
+        super.recycle()
+    }
+
+    private suspend fun detectDocumentFormat(): String? {
+        val apiBase = source.baseUrl.trimEnd('/') + "/api"
+        val request = Request.Builder()
+            .url("$apiBase/Chapter?chapterId=$chapterId")
+            .headers(source.headers)
+            .get()
+            .build()
+
+        source.client.newCall(request).await().use { response ->
+            if (!response.isSuccessful) {
+                // Preserve the extension's normal behavior when chapter metadata
+                // cannot be queried. It may still be readable as image content.
+                return null
+            }
+
+            val body = response.body.string()
+            if (body.isBlank()) return null
+
+            val chapterJson = JSONObject(body)
+            val files = chapterJson.optJSONArray("files") ?: return null
+            for (i in 0 until files.length()) {
+                val file = files.optJSONObject(i) ?: continue
+                val extension = normalizeExtension(
+                    file.optString("extension").ifBlank { file.optString("filePath") },
+                )
+                if (extension == "epub" || extension == "txt") {
+                    return extension
+                }
+
+                // Current Kavita format enum: EPUB == 3. TXT has no dedicated
+                // enum value in upstream Kavita, so it is detected by extension.
+                if (file.optInt("format", -1) == 3) {
+                    return "epub"
+                }
+            }
+        }
+        return null
+    }
+
+    private fun normalizeExtension(value: String): String =
+        value.substringAfterLast('.', value)
+            .trim()
+            .trimStart('.')
+            .lowercase(Locale.ROOT)
+
+    private suspend fun createDocumentLoader(format: String): PageLoader {
+        val file = getOrDownloadDocument(format)
+        val uniFile = UniFile.fromFile(file)
+            ?: throw IOException("Unable to open cached Kavita ${format.uppercase()} file")
+
+        return when (format) {
+            "epub" -> EpubPageLoader(uniFile.epubReader(context), textStyle)
+            "txt" -> TextPageLoader(uniFile, textStyle)
+            else -> error("Unsupported Kavita document format: $format")
+        }
+    }
+
+    private suspend fun getOrDownloadDocument(format: String): File {
+        val cacheDir = File(context.cacheDir, "kavita_reader").apply { mkdirs() }
+        val target = File(cacheDir, "${source.id}-$chapterId.$format")
+        if (target.isFile && target.length() > 0L) return target
+
+        val temp = File(cacheDir, "${target.name}.part")
+        if (temp.exists()) temp.delete()
+
+        val apiBase = source.baseUrl.trimEnd('/') + "/api"
+        val request = Request.Builder()
+            .url("$apiBase/Download/chapter?chapterId=$chapterId")
+            .headers(source.headers)
+            .get()
+            .build()
+
+        source.client.newCall(request).await().use { response ->
+            if (!response.isSuccessful) {
+                val message = when (response.code) {
+                    403 -> "Kavita account does not have Download permission"
+                    404 -> "Kavita original file is missing or no longer available"
+                    500 -> "Kavita could not access the original $format file"
+                    else -> "Kavita document download failed: HTTP ${response.code}"
+                }
+                throw IOException(message)
+            }
+
+            temp.outputStream().use { output ->
+                response.body.byteStream().use { input -> input.copyTo(output) }
+            }
+        }
+
+        if (temp.length() <= 0L) {
+            temp.delete()
+            throw IOException("Kavita returned an empty ${format.uppercase()} file")
+        }
+
+        if (!temp.renameTo(target)) {
+            temp.copyTo(target, overwrite = true)
+            temp.delete()
+        }
+        return target
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/reader/loader/TextPageLoader.kt

@@ -1,7 +1,6 @@
 package eu.kanade.tachiyomi.ui.reader.loader
 
 import com.hippo.unifile.UniFile
-import eu.kanade.tachiyomi.source.model.Page
 import eu.kanade.tachiyomi.ui.reader.model.ReaderPage
 import eu.kanade.tachiyomi.ui.reader.setting.TextReaderStyle
 import java.nio.ByteBuffer
@@ -22,10 +21,7 @@ internal class TextPageLoader(
         val bytes = file.openInputStream().use { it.readBytes() }
         val text = decodeText(bytes)
         return TextPageRenderer.paginate(text, style).mapIndexed { index, pageText ->
-            ReaderPage(index).apply {
-                stream = { TextPageRenderer.render(pageText, style) }
-                status = Page.State.Ready
-            }
+            TextReaderPage(index, pageText, style)
         }
     }
 

app/src/main/java/eu/kanade/tachiyomi/ui/reader/loader/TextReaderPage.kt

@@ -0,0 +1,29 @@
+package eu.kanade.tachiyomi.ui.reader.loader
+
+import eu.kanade.tachiyomi.source.model.Page
+import eu.kanade.tachiyomi.ui.reader.model.ReaderPage
+import eu.kanade.tachiyomi.ui.reader.setting.TextReaderStyle
+
+/**
+ * A rendered text page whose style can be changed without rebuilding the chapter.
+ * Page boundaries remain stable during the live preview; a full repagination is done
+ * once when the settings dialog is dismissed.
+ */
+internal class TextReaderPage(
+    index: Int,
+    private val pageText: String,
+    initialStyle: TextReaderStyle,
+) : ReaderPage(index) {
+
+    @Volatile
+    private var style: TextReaderStyle = initialStyle
+
+    init {
+        stream = { TextPageRenderer.render(pageText, style) }
+        status = Page.State.Ready
+    }
+
+    fun updateStyle(newStyle: TextReaderStyle) {
+        style = newStyle
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/reader/setting/ReaderSettingsViewModel.kt

@@ -6,14 +6,18 @@ import eu.kanade.tachiyomi.ui.reader.ReaderViewModel
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
 
 class ReaderSettingsViewModel(
     readerState: StateFlow<ReaderViewModel.State>,
     val onChangeReadingMode: (ReadingMode) -> Unit,
     val onChangeOrientation: (ReaderOrientation) -> Unit,
-    val onTextSettingsChanged: () -> Unit,
+    private val onTextSettingsPreview: () -> Unit,
+    private val onTextSettingsCommit: () -> Unit,
     val preferences: ReaderPreferences,
 ) : ViewModel() {
 
@@ -26,4 +30,26 @@ class ReaderSettingsViewModel(
         .map { it.manga }
         .distinctUntilChanged()
         .stateIn(viewModelScope, SharingStarted.Lazily, null)
+
+    private var textSettingsReloadJob: Job? = null
+    private var textSettingsDirty = false
+
+    fun requestTextSettingsReload() {
+        textSettingsDirty = true
+        textSettingsReloadJob?.cancel()
+        textSettingsReloadJob = viewModelScope.launch {
+            delay(100)
+            onTextSettingsPreview()
+            textSettingsReloadJob = null
+        }
+    }
+
+    fun flushTextSettingsReload() {
+        if (!textSettingsDirty) return
+        textSettingsReloadJob?.cancel()
+        textSettingsReloadJob = null
+        onTextSettingsPreview()
+        textSettingsDirty = false
+        onTextSettingsCommit()
+    }
 }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/Viewer.kt

@@ -26,6 +26,14 @@ interface Viewer {
      */
     fun setChapters(chapters: ViewerChapters)
 
+    /** Rebinds only the currently visible page(s), used for lightweight text-style preview. */
+    fun refreshCurrentPage() {}
+
+    /** Replaces repaginated text pages without expensive per-item diffing where possible. */
+    fun refreshTextChapters(chapters: ViewerChapters) {
+        setChapters(chapters)
+    }
+
     /**
      * Tells this viewer to move to the given [page].
      */

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewer.kt

@@ -380,6 +380,17 @@ abstract class PagerViewer(val activity: ReaderActivity) : Viewer {
         pager.setCurrentItem(currentItem, false)
     }
 
+    override fun refreshCurrentPage() {
+        refreshAdapter()
+    }
+
+    override fun refreshTextChapters(chapters: ViewerChapters) {
+        setChaptersInternal(chapters)
+        val pages = chapters.currChapter.pages ?: return
+        val page = pages[min(chapters.currChapter.requestedPage, pages.lastIndex)]
+        moveToPage(page)
+    }
+
     /**
      * Called from the containing activity when a key [event] is received. It should return true
      * if the event was handled, false otherwise.

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonAdapter.kt

@@ -35,7 +35,7 @@ class WebtoonAdapter(val viewer: WebtoonViewer) : RecyclerView.Adapter<RecyclerV
      * Updates this adapter with the given [chapters]. It handles setting a few pages of the
      * next/previous chapter to allow seamless transitions.
      */
-    fun setChapters(chapters: ViewerChapters, forceTransition: Boolean) {
+    fun setChapters(chapters: ViewerChapters, forceTransition: Boolean, useDiff: Boolean = true) {
         val newItems = mutableListOf<Any>()
 
         // Forces chapter transition if there is missing chapters
@@ -65,13 +65,18 @@ class WebtoonAdapter(val viewer: WebtoonViewer) : RecyclerView.Adapter<RecyclerV
 
         chapters.nextChapter?.pages?.let(newItems::addAll)
 
-        updateItems(newItems)
+        updateItems(newItems, useDiff)
     }
 
-    private fun updateItems(newItems: List<Any>) {
-        val result = DiffUtil.calculateDiff(Callback(items, newItems))
-        items = newItems
-        result.dispatchUpdatesTo(this)
+    private fun updateItems(newItems: List<Any>, useDiff: Boolean) {
+        if (useDiff) {
+            val result = DiffUtil.calculateDiff(Callback(items, newItems))
+            items = newItems
+            result.dispatchUpdatesTo(this)
+        } else {
+            items = newItems
+            notifyDataSetChanged()
+        }
     }
 
     fun refresh() {

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt

@@ -353,6 +353,19 @@ class WebtoonViewer(val activity: ReaderActivity, val isContinuous: Boolean = tr
             min(position + 3, adapter.itemCount - 1),
         )
     }
+
+    override fun refreshCurrentPage() {
+        refreshAdapter()
+    }
+
+    override fun refreshTextChapters(chapters: ViewerChapters) {
+        val forceTransition = config.alwaysShowChapterTransition || currentPage is ChapterTransition
+        adapter.setChapters(chapters, forceTransition, useDiff = false)
+        val pages = chapters.currChapter.pages ?: return
+        val page = pages[min(chapters.currChapter.requestedPage, pages.lastIndex)]
+        moveToPage(page)
+        currentPage = page
+    }
 }
 
 // Double the cache size to reduce rebinds/recycles incurred by the extra layout space on scroll direction changes