From 553762fae8d47e40ef910e73d55c58bfbd8a057b Mon Sep 17 00:00:00 2001
From: AntsyLich <59261191+AntsyLich@users.noreply.github.com>
Date: Sun, 27 Sep 2026 22:55:41 +0600
Subject: [PATCH] Fix reading history being double counted

Restore groups a backup's history entries by chapter before comparing them with the stored row, so a backup carrying one entry per copy of a duplicated chapter no longer adds its reading time more than once or moves the last read backwards. A removed history entry keeps its 0 instead of becoming NULL, a tracker's start date skips removed history, and the reader clears a session's start time before saving it, so overlapping saves can't count it twice.
---
 .../domain/track/interactor/AddTracks.kt      |  5 +-
 .../tachiyomi/ui/reader/ReaderViewModel.kt    |  2 +-
 .../data/backup/RestoreRepositoryImpl.kt      | 46 ++++++++++---------
 3 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/app/src/main/java/eu/kanade/domain/track/interactor/AddTracks.kt b/app/src/main/java/eu/kanade/domain/track/interactor/AddTracks.kt
index 44dc760a0..e40e2ec6c 100644
--- a/app/src/main/java/eu/kanade/domain/track/interactor/AddTracks.kt
+++ b/app/src/main/java/eu/kanade/domain/track/interactor/AddTracks.kt
@@ -57,9 +57,8 @@ class AddTracks(
 
                 if (track.startDate <= 0) {
                     val firstReadChapterDate = getHistory.await(mangaId)
-                        .sortedBy { it.readAt }
-                        .firstOrNull()
-                        ?.readAt
+                        .mapNotNull { it.readAt?.takeIf { readAt -> readAt.time > 0 } }
+                        .minOrNull()
 
                     firstReadChapterDate?.let {
                         val startDate = firstReadChapterDate.time.convertEpochMillisZone(
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderViewModel.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderViewModel.kt
index 2edd7c0f8..de3ffc51b 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderViewModel.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderViewModel.kt
@@ -629,9 +629,9 @@ class ReaderViewModel(
             val chapterId = readerChapter.chapter.id!!
             val endTime = Date()
             val sessionReadDuration = chapterReadStartTime?.let { endTime.time - it } ?: 0
+            chapterReadStartTime = null
 
             upsertHistory.await(HistoryUpdate(chapterId, endTime, sessionReadDuration))
-            chapterReadStartTime = null
         }
     }
 
diff --git a/data/src/main/java/tachiyomi/data/backup/RestoreRepositoryImpl.kt b/data/src/main/java/tachiyomi/data/backup/RestoreRepositoryImpl.kt
index e1cbde202..ed13765fb 100644
--- a/data/src/main/java/tachiyomi/data/backup/RestoreRepositoryImpl.kt
+++ b/data/src/main/java/tachiyomi/data/backup/RestoreRepositoryImpl.kt
@@ -213,30 +213,32 @@ class RestoreRepositoryImpl(
         this.copy(id = 0L, mangaId = 0L, dateFetch = 0L, dateUpload = 0L)
 
     private suspend fun restoreHistory(manga: Manga, restoredHistory: List<RestoredHistory>) {
-        val toUpdate = restoredHistory.mapNotNull { history ->
-            val dbHistory = database.historyQueries
-                .getHistoryByChapterUrlAndMangaId(history.chapterUrl, manga.id)
-                .awaitAsOneOrNull()
-
-            if (dbHistory == null) {
-                val chapter = database.chaptersQueries
-                    .getChapterByUrlAndMangaId(history.chapterUrl, manga.id)
+        val toUpdate = restoredHistory
+            .groupBy { it.chapterUrl }
+            .mapNotNull { (chapterUrl, copies) ->
+                val readAt = copies.maxOf { it.readAt?.time ?: 0L }
+                val readDuration = copies.sumOf { it.readDuration }
+                val dbHistory = database.historyQueries
+                    .getHistoryByChapterUrlAndMangaId(chapterUrl, manga.id)
                     .awaitAsOneOrNull()
-                    // Chapter doesn't exist; skip
-                    ?: return@mapNotNull null
-                // New history entry
-                return@mapNotNull Triple(chapter._id, history.readAt, history.readDuration)
-            }
 
-            // Update history entry
-            Triple(
-                dbHistory.chapter_id,
-                max(history.readAt?.time ?: 0L, dbHistory.last_read?.time ?: 0L)
-                    .takeIf { it > 0L }
-                    ?.let { Date(it) },
-                max(history.readDuration, dbHistory.time_read) - dbHistory.time_read,
-            )
-        }
+                if (dbHistory == null) {
+                    val chapter = database.chaptersQueries
+                        .getChapterByUrlAndMangaId(chapterUrl, manga.id)
+                        .awaitAsOneOrNull()
+                        // Chapter doesn't exist; skip
+                        ?: return@mapNotNull null
+                    // New history entry
+                    return@mapNotNull Triple(chapter._id, Date(readAt), readDuration)
+                }
+
+                // Update history entry
+                Triple(
+                    dbHistory.chapter_id,
+                    Date(max(readAt, dbHistory.last_read?.time ?: 0L)),
+                    max(readDuration, dbHistory.time_read) - dbHistory.time_read,
+                )
+            }
 
         toUpdate.forEach { (chapterId, readAt, readDuration) ->
             database.historyQueries.upsert(chapterId, readAt, readDuration)