Feat: Automated Tracking + Proper Sync

src/features/reader/lib/chapterActions.ts

@@ -3,6 +3,7 @@ import { store, addHistory, addBookmark, removeBookmark,
          checkAndMarkCompleted, DEFAULT_MANGA_PREFS } from "@store/state.svelte";
 import { MARK_CHAPTER_READ, DELETE_DOWNLOADED_CHAPTERS } from "@api/mutations/chapters";
 import { ENQUEUE_CHAPTERS_DOWNLOAD }                     from "@api/mutations/downloads";
+import { trackingState }                                 from "@features/tracking/store/trackingState.svelte";
 
 const AVG_MIN_PER_PAGE = 0.33;
 
@@ -30,6 +31,8 @@ export function markChapterRead(id: number, markedRead: Set<number>) {
       if (!mangaId) return;
       const updated = store.activeChapterList.map(c => c.id === id ? { ...c, isRead: true } : c);
       checkAndMarkCompleted(mangaId, updated);
+      const ch = store.activeChapterList.find(c => c.id === id) ?? store.activeChapter;
+      if (ch) trackingState.updateFromRead(ch, store.activeChapterList, getMangaPrefs());
       const prefs = getMangaPrefs();
       if (prefs.deleteOnRead) {
         const ch = store.activeChapterList.find(c => c.id === id);
@@ -73,4 +76,4 @@ export function toggleBookmark(
     if (existing) removeBookmark(existing.chapterId);
     addBookmark({ mangaId: manga.id, mangaTitle: manga.title, thumbnailUrl: manga.thumbnailUrl, chapterId: ch.id, chapterName: ch.name, pageNumber });
   }
-}
+}

src/features/reader/lib/chapterLoader.ts

@@ -1,6 +1,7 @@
 import { store, openReader } from "@store/state.svelte";
 import { readerState }       from "../store/readerState.svelte";
 import { fetchPages }        from "./pageLoader";
+import { trackingState }     from "@features/tracking/store/trackingState.svelte";
 
 export function scheduleResumeDismiss() {
   setTimeout(() => { readerState.resumeFading = true; }, 1500);
@@ -23,6 +24,9 @@ export async function loadChapter(
   readerState.resetForChapter();
   store.pageUrls = [];
 
+  const mangaId = store.activeManga?.id;
+  if (mangaId) trackingState.loadForManga(mangaId);
+
   const bookmark = store.bookmarks.find(b => b.chapterId === id);
   const resumeTo = bookmark ? bookmark.pageNumber : 0;
   readerState.resumePage      = resumeTo > 1 ? resumeTo : 0;

src/features/series/components/SeriesDetail.svelte

@@ -18,6 +18,7 @@
     checkAndMarkCompleted as storeCheckAndMarkCompleted,
     clearMarkersForManga,
   } from "@store/state.svelte";
+  import { trackingState } from "@features/tracking/store/trackingState.svelte";
   import type { MangaPrefs } from "@store/state.svelte";
   import { DEFAULT_MANGA_PREFS } from "@store/state.svelte";
   import type { Manga, Chapter, Category } from "@types";
@@ -102,24 +103,21 @@
 
   const continueChapter = $derived((() => {
     if (!sortedChapters.length) return null;
-    const asc     = [...sortedChapters].sort((a, b) => a.sourceOrder - b.sourceOrder);
-    const anyRead = asc.some(c => c.isRead);
+    const asc      = [...sortedChapters].sort((a, b) => a.sourceOrder - b.sourceOrder);
+    const anyRead  = asc.some(c => c.isRead);
     const bookmark = store.activeManga
       ? store.bookmarks.find(b => b.mangaId === store.activeManga!.id)
       : null;
-    if (bookmark) {
-      const ch = asc.find(c => c.id === bookmark.chapterId);
-      if (ch) {
-        const isLastChapter = asc[asc.length - 1]?.id === ch.id;
-        const allRead = asc.every(c => c.isRead);
-        if (!(isLastChapter && allRead))
-          return { chapter: ch, type: "continue" as const, resumePage: bookmark.pageNumber };
-      }
+    const bookmarkedCh = bookmark ? asc.find(c => c.id === bookmark.chapterId) : null;
+    if (bookmarkedCh && !bookmarkedCh.isRead) {
+      return { chapter: bookmarkedCh, type: (anyRead ? "continue" : "start") as const, resumePage: bookmark!.pageNumber };
     }
     const inProgress  = asc.find(c => !c.isRead && (c.lastPageRead ?? 0) > 0);
-    if (inProgress) return { chapter: inProgress, type: "continue" as const, resumePage: inProgress.lastPageRead! };
     const firstUnread = asc.find(c => !c.isRead);
-    if (firstUnread) return { chapter: firstUnread, type: (anyRead ? "continue" : "start") as const, resumePage: null };
+    const target      = inProgress ?? firstUnread;
+    if (target) {
+      return { chapter: target, type: (anyRead ? "continue" : "start") as const, resumePage: null };
+    }
     return { chapter: asc[0], type: "reread" as const, resumePage: null };
   })());
 
@@ -258,7 +256,7 @@
 
   $effect(() => {
     const m = store.activeManga;
-    if (m) untrack(() => { acknowledgeUpdate(m.id); loadManga(m.id); loadChapters(m.id); loadCategories(m.id); });
+    if (m) untrack(() => { acknowledgeUpdate(m.id); loadManga(m.id); loadChapters(m.id); loadCategories(m.id); trackingState.loadForManga(m.id); });
   });
 
   let prevChapterId: number | null = null;
@@ -309,6 +307,8 @@
     chapters = chapters.map(c => c.id === chapterId ? { ...c, isRead } : c);
     if (store.activeManga) { chapterStore.set(store.activeManga.id, { data: chapters, fetchedAt: Date.now() }); checkAndMarkCompleted(store.activeManga.id, chapters); }
     if (isRead) {
+      const ch = chapters.find(c => c.id === chapterId);
+      if (ch) trackingState.updateFromRead(ch, chapters, { sortMode, sortDir, preferredScanlator: get("preferredScanlator") as string, scanlatorFilter: scanlatorFilter as string[], scanlatorBlacklist: scanlatorBlacklist as string[], scanlatorForce: scanlatorForce as boolean });
       if (get("deleteOnRead")) {
         const ch = chapters.find(c => c.id === chapterId);
         if (ch?.isDownloaded) {
@@ -334,17 +334,22 @@
     const idSet = new Set(ids);
     chapters = chapters.map(c => idSet.has(c.id) ? { ...c, isRead } : c);
     if (store.activeManga) { chapterStore.set(store.activeManga.id, { data: chapters, fetchedAt: Date.now() }); checkAndMarkCompleted(store.activeManga.id, chapters); }
-    if (isRead && get("deleteOnRead")) {
-      const toDelete = ids.filter(id => chapters.find(c => c.id === id)?.isDownloaded);
-      if (toDelete.length) {
-        const delayMs = (get("deleteDelayHours") as number) * 60 * 60 * 1000;
-        const doDelete = async () => {
-          await gql(DELETE_DOWNLOADED_CHAPTERS, { ids: toDelete }).catch(console.error);
-          chapters = chapters.map(c => toDelete.includes(c.id) ? { ...c, isDownloaded: false } : c);
-          if (store.activeManga) chapterStore.set(store.activeManga.id, { data: chapters, fetchedAt: Date.now() });
-        };
-        if (delayMs === 0) doDelete();
-        else setTimeout(doDelete, delayMs);
+    if (isRead) {
+      const ascending   = [...chapters].sort((a, b) => a.sourceOrder - b.sourceOrder);
+      const lastInBatch = ascending.filter(c => idSet.has(c.id)).at(-1);
+      if (lastInBatch) trackingState.updateFromRead(lastInBatch, chapters, { sortMode, sortDir, preferredScanlator: get("preferredScanlator") as string, scanlatorFilter: scanlatorFilter as string[], scanlatorBlacklist: scanlatorBlacklist as string[], scanlatorForce: scanlatorForce as boolean });
+      if (get("deleteOnRead")) {
+        const toDelete = ids.filter(id => chapters.find(c => c.id === id)?.isDownloaded);
+        if (toDelete.length) {
+          const delayMs = (get("deleteDelayHours") as number) * 60 * 60 * 1000;
+          const doDelete = async () => {
+            await gql(DELETE_DOWNLOADED_CHAPTERS, { ids: toDelete }).catch(console.error);
+            chapters = chapters.map(c => toDelete.includes(c.id) ? { ...c, isDownloaded: false } : c);
+            if (store.activeManga) chapterStore.set(store.activeManga.id, { data: chapters, fetchedAt: Date.now() });
+          };
+          if (delayMs === 0) doDelete();
+          else setTimeout(doDelete, delayMs);
+        }
       }
     }
   }

src/features/series/panels/TrackingPanel.svelte

@@ -1,11 +1,15 @@
 <script lang="ts">
-  import { CircleNotch, X, MagnifyingGlass, ArrowSquareOut, Lock, LockOpen, ArrowsClockwise } from "phosphor-svelte";
+  import { CircleNotch, X, MagnifyingGlass, ArrowSquareOut, Lock, LockOpen, ArrowsClockwise, ArrowLineDown } from "phosphor-svelte";
   import { gql }        from "@api/client";
   import Thumbnail      from "@shared/manga/Thumbnail.svelte";
-  import { GET_TRACKERS, GET_MANGA_TRACK_RECORDS, SEARCH_TRACKER } from "@api/queries/tracking";
-  import { BIND_TRACK, UPDATE_TRACK, UNBIND_TRACK, FETCH_TRACK } from "@api/mutations/tracking";
-  import { addToast }                     from "@store/state.svelte";
+  import { GET_TRACKERS, SEARCH_TRACKER } from "@api/queries/tracking";
+  import { BIND_TRACK, UPDATE_TRACK, UNBIND_TRACK } from "@api/mutations/tracking";
+  import { GET_CHAPTERS } from "@api/queries/chapters";
+  import { addToast, store }             from "@store/state.svelte";
+  import { trackingState }               from "@features/tracking/store/trackingState.svelte";
+  import { syncBackFromTracker }         from "@features/tracking/lib/trackingSync";
   import type { Tracker, TrackRecord, TrackSearch } from "@types";
+  import type { Chapter } from "@types/index";
 
   let { mangaId, mangaTitle, onClose }: {
     mangaId:    number;
@@ -16,8 +20,7 @@
   type TabId = "records" | number;
 
   let trackers:    Tracker[]     = $state([]);
-  let records:     TrackRecord[] = $state([]);
-  let loading:     boolean       = $state(true);
+  let loadingTrackers: boolean   = $state(true);
   let activeTab:   TabId         = $state("records");
 
   let searchQuery:   string        = $state("");
@@ -30,26 +33,22 @@
   let syncing:        number | null = $state(null);
   let editingChapter: number | null = $state(null);
   let chapterDraft:   number        = $state(0);
+  let applyingRecord: number | null = $state(null);
+
+  const records        = $derived(trackingState.records);
+  const loading        = $derived(trackingState.loading || loadingTrackers);
+  const loggedInTrackers = $derived(trackers.filter(t => t.isLoggedIn));
 
   function autoFocus(node: HTMLElement) { setTimeout(() => node.focus(), 50); }
 
-  async function load() {
-    loading = true;
-    try {
-      const [tRes, rRes] = await Promise.all([
-        gql<{ trackers: { nodes: Tracker[] } }>(GET_TRACKERS),
-        gql<{ manga: { trackRecords: { nodes: TrackRecord[] } } }>(GET_MANGA_TRACK_RECORDS, { mangaId }),
-      ]);
-      trackers = tRes.trackers.nodes;
-      records  = rRes.manga.trackRecords.nodes;
-    } catch (e: any) {
-      addToast({ kind: "error", title: "Failed to load tracking", body: e?.message });
-    } finally {
-      loading = false;
-    }
-  }
-
-  $effect(() => { load(); });
+  $effect(() => {
+    loadingTrackers = true;
+    gql<{ trackers: { nodes: Tracker[] } }>(GET_TRACKERS)
+      .then(r => { trackers = r.trackers.nodes; })
+      .catch(e => addToast({ kind: "error", title: "Failed to load trackers", body: e?.message }))
+      .finally(() => { loadingTrackers = false; });
+    trackingState.loadForManga(mangaId);
+  });
 
   $effect(() => {
     const tab = activeTab;
@@ -62,7 +61,6 @@
 
   function trackerFor(id: number)       { return trackers.find(t => t.id === id); }
   function recordFor(trackerId: number) { return records.find(r => r.trackerId === trackerId); }
-  const loggedInTrackers = $derived(trackers.filter(t => t.isLoggedIn));
 
   let searchTimer: ReturnType<typeof setTimeout>;
 
@@ -96,7 +94,7 @@
       const res = await gql<{ bindTrack: { trackRecord: TrackRecord } }>(
         BIND_TRACK, { mangaId, trackerId: activeTab, remoteId: result.remoteId }
       );
-      records   = [...records.filter(r => r.trackerId !== activeTab), res.bindTrack.trackRecord];
+      trackingState.patchRecord(res.bindTrack.trackRecord);
       activeTab = "records";
       addToast({ kind: "success", title: "Now tracking", body: result.title });
     } catch (e: any) {
@@ -110,7 +108,7 @@
     updatingRecord = record.id;
     try {
       await gql(UNBIND_TRACK, { recordId: record.id });
-      records = records.filter(r => r.id !== record.id);
+      trackingState.removeRecord(record.id);
       addToast({ kind: "info", title: "Unlinked from " + trackerFor(record.trackerId)?.name });
     } catch (e: any) {
       addToast({ kind: "error", title: "Failed to unlink", body: e?.message });
@@ -119,15 +117,11 @@
     }
   }
 
-  function patchRecord(updated: Partial<TrackRecord> & { id: number }) {
-    records = records.map(r => r.id === updated.id ? { ...r, ...updated } : r);
-  }
-
   async function updateStatus(record: TrackRecord, status: number) {
     updatingRecord = record.id;
     try {
       const res = await gql<{ updateTrack: { trackRecord: TrackRecord } }>(UPDATE_TRACK, { recordId: record.id, status });
-      patchRecord(res.updateTrack.trackRecord);
+      trackingState.patchRecord(res.updateTrack.trackRecord);
     } catch (e: any) {
       addToast({ kind: "error", title: "Update failed", body: e?.message });
     } finally {
@@ -139,7 +133,7 @@
     updatingRecord = record.id;
     try {
       const res = await gql<{ updateTrack: { trackRecord: TrackRecord } }>(UPDATE_TRACK, { recordId: record.id, scoreString });
-      patchRecord(res.updateTrack.trackRecord);
+      trackingState.patchRecord(res.updateTrack.trackRecord);
     } catch (e: any) {
       addToast({ kind: "error", title: "Update failed", body: e?.message });
     } finally {
@@ -151,7 +145,7 @@
     updatingRecord = record.id;
     try {
       const res = await gql<{ updateTrack: { trackRecord: TrackRecord } }>(UPDATE_TRACK, { recordId: record.id, private: !record.private });
-      patchRecord(res.updateTrack.trackRecord);
+      trackingState.patchRecord(res.updateTrack.trackRecord);
     } catch (e: any) {
       addToast({ kind: "error", title: "Update failed", body: e?.message });
     } finally {
@@ -162,9 +156,8 @@
   async function syncRecord(record: TrackRecord) {
     syncing = record.id;
     try {
-      const res = await gql<{ fetchTrack: { trackRecord: TrackRecord } }>(FETCH_TRACK, { recordId: record.id });
-      patchRecord(res.fetchTrack.trackRecord);
-      addToast({ kind: "success", title: "Synced from tracker" });
+      const fresh = await trackingState.syncRecordFromRemote(record.id);
+      if (fresh) addToast({ kind: "success", title: "Synced from tracker" });
     } catch (e: any) {
       addToast({ kind: "error", title: "Sync failed", body: e?.message });
     } finally {
@@ -179,6 +172,33 @@
 
   function cancelChapterEditor() { editingChapter = null; }
 
+  async function applyToLibrary(record: TrackRecord) {
+    applyingRecord = record.id;
+    try {
+      const chapRes = await gql<{ chapters: { nodes: Chapter[] } }>(GET_CHAPTERS, { mangaId });
+      const prefs   = store.settings.mangaPrefs?.[mangaId] ?? {};
+      const marked  = await syncBackFromTracker(
+        [record],
+        chapRes.chapters.nodes,
+        {
+          threshold:              store.settings.trackerSyncBackThreshold ?? null,
+          respectScanlatorFilter: store.settings.trackerRespectScanlatorFilter ?? true,
+          chapterPrefs:           prefs,
+        },
+        (query, vars) => gql(query, vars),
+      );
+      if (marked.length > 0) {
+        addToast({ kind: "success", title: `${marked.length} chapter${marked.length !== 1 ? "s" : ""} marked read` });
+      } else {
+        addToast({ kind: "info", title: "Already up to date" });
+      }
+    } catch (e: any) {
+      addToast({ kind: "error", title: "Apply failed", body: e?.message });
+    } finally {
+      applyingRecord = null;
+    }
+  }
+
   async function submitChapter(record: TrackRecord) {
     const val = Math.max(0, chapterDraft);
     editingChapter = null;
@@ -186,7 +206,7 @@
     updatingRecord = record.id;
     try {
       const res = await gql<{ updateTrack: { trackRecord: TrackRecord } }>(UPDATE_TRACK, { recordId: record.id, lastChapterRead: val });
-      patchRecord(res.updateTrack.trackRecord);
+      trackingState.patchRecord(res.updateTrack.trackRecord);
     } catch (e: any) {
       addToast({ kind: "error", title: "Update failed", body: e?.message });
     } finally {
@@ -269,6 +289,11 @@
                     <button class="record-icon-btn" title="Sync from tracker" disabled={syncing === record.id} onclick={() => syncRecord(record)}>
                       <ArrowsClockwise size={11} weight="light" class={syncing === record.id ? "anim-spin" : ""} />
                     </button>
+                    {#if store.settings.trackerSyncBack}
+                      <button class="record-icon-btn" title="Apply tracker progress to library" disabled={applyingRecord === record.id} onclick={() => applyToLibrary(record)}>
+                        <ArrowLineDown size={11} weight="light" class={applyingRecord === record.id ? "anim-spin" : ""} />
+                      </button>
+                    {/if}
                     <button class="record-icon-btn icon-danger" title="Unlink" disabled={isBusy} onclick={() => unbind(record)}>
                       <X size={11} weight="bold" />
                     </button>

src/features/settings/sections/TrackingSettings.svelte

@@ -3,7 +3,12 @@
   import { GET_TRACKERS } from "@api/queries/tracking";
   import { LOGIN_TRACKER_OAUTH, LOGIN_TRACKER_CREDENTIALS, LOGOUT_TRACKER } from "@api/mutations/tracking";
   import { open as openUrl } from "@tauri-apps/plugin-shell";
-  import type { Tracker } from "../../lib/types";
+  import { store, updateSettings, addToast } from "@store/state.svelte";
+  import { syncBackFromTracker } from "@features/tracking/lib/trackingSync";
+  import { GET_ALL_TRACKER_RECORDS } from "@api/queries/tracking";
+  import { GET_CHAPTERS } from "@api/queries/chapters";
+  import type { Tracker, TrackRecord } from "../../lib/types";
+  import type { Chapter } from "@types/index";
 
   let trackers        = $state<Tracker[]>([]);
   let trackersLoading = $state(false);
@@ -78,6 +83,42 @@
   }
 
   function focusEl(node: HTMLElement) { setTimeout(() => node.focus(), 0); }
+
+  let syncing = $state(false);
+
+  async function runSyncAll() {
+    syncing = true;
+    try {
+      const res = await gql<{ trackers: { nodes: any[] } }>(GET_ALL_TRACKER_RECORDS);
+      const allTrackers = res.trackers.nodes.filter((t: any) => t.isLoggedIn);
+      let totalMarked = 0;
+
+      for (const tracker of allTrackers) {
+        for (const record of tracker.trackRecords.nodes as TrackRecord[]) {
+          if (!record.manga?.id) continue;
+          const mangaId = record.manga.id;
+          const chapRes = await gql<{ chapters: { nodes: Chapter[] } }>(GET_CHAPTERS, { mangaId });
+          const prefs   = store.settings.mangaPrefs?.[mangaId] ?? {};
+
+          const marked = await syncBackFromTracker(
+            [record],
+            chapRes.chapters.nodes,
+            {
+              threshold:              store.settings.trackerSyncBackThreshold ?? null,
+              respectScanlatorFilter: store.settings.trackerRespectScanlatorFilter ?? true,
+              chapterPrefs:           prefs,
+            },
+            (query, vars) => gql(query, vars),
+          );
+          totalMarked += marked.length;
+        }
+      }
+
+      addToast({ kind: "success", title: "Sync complete", body: `${totalMarked} chapter${totalMarked !== 1 ? "s" : ""} marked read` });
+    } catch (e: any) {
+      addToast({ kind: "error", title: "Sync failed", body: e?.message });
+    } finally { syncing = false; }
+  }
 </script>
 
 <div class="s-panel">
@@ -148,4 +189,64 @@
     </div>
   </div>
 
+  <div class="s-section">
+    <p class="s-section-title">Sync back from tracker</p>
+    <div class="s-row">
+      <div class="s-row-info">
+        <span class="s-label">Enable sync back</span>
+        <span class="s-desc">Mark chapters read locally based on tracker progress</span>
+      </div>
+      <button class="s-toggle" class:on={store.settings.trackerSyncBack}
+        onclick={() => updateSettings({ trackerSyncBack: !store.settings.trackerSyncBack })}
+        role="switch" aria-checked={store.settings.trackerSyncBack}>
+        <span class="s-toggle-thumb"></span>
+      </button>
+    </div>
+
+    {#if store.settings.trackerSyncBack}
+      <label class="s-row">
+        <div class="s-row-info">
+          <span class="s-label">Chapter number tolerance</span>
+          <span class="s-desc">Allow source and tracker chapter numbers to differ by up to the set amount. When off, the tracker number is used as-is with no range check.</span>
+        </div>
+        <button role="switch" aria-checked={store.settings.trackerSyncBackThreshold !== null} class="s-toggle" class:on={store.settings.trackerSyncBackThreshold !== null}
+          onclick={() => updateSettings({ trackerSyncBackThreshold: store.settings.trackerSyncBackThreshold !== null ? null : 20 })}>
+          <span class="s-toggle-thumb"></span>
+        </button>
+      </label>
+      {#if store.settings.trackerSyncBackThreshold !== null}
+        <div class="s-row">
+          <div class="s-row-info"><span class="s-label">Tolerance</span><span class="s-desc">Max chapter number difference allowed (1–20)</span></div>
+          <div class="s-stepper">
+            <button class="s-step-btn" onclick={() => updateSettings({ trackerSyncBackThreshold: Math.max(1, (store.settings.trackerSyncBackThreshold ?? 20) - 1) })}>−</button>
+            <span class="s-step-val">{store.settings.trackerSyncBackThreshold}</span>
+            <button class="s-step-btn" onclick={() => updateSettings({ trackerSyncBackThreshold: Math.min(20, (store.settings.trackerSyncBackThreshold ?? 20) + 1) })}>+</button>
+          </div>
+        </div>
+      {/if}
+
+      <div class="s-row">
+        <div class="s-row-info">
+          <span class="s-label">Respect scanlator filter</span>
+          <span class="s-desc">Only mark chapters matching the series' active scanlator filter</span>
+        </div>
+        <button class="s-toggle" class:on={store.settings.trackerRespectScanlatorFilter}
+          onclick={() => updateSettings({ trackerRespectScanlatorFilter: !store.settings.trackerRespectScanlatorFilter })}
+          role="switch" aria-checked={store.settings.trackerRespectScanlatorFilter}>
+          <span class="s-toggle-thumb"></span>
+        </button>
+      </div>
+
+      <div class="s-row">
+        <div class="s-row-info">
+          <span class="s-label">Sync now</span>
+          <span class="s-desc">Apply tracker progress to all linked manga in your library</span>
+        </div>
+        <button class="s-btn" onclick={runSyncAll} disabled={syncing}>
+          {syncing ? "Syncing…" : "Sync all"}
+        </button>
+      </div>
+    {/if}
+  </div>
+
 </div>

src/features/tracking/lib/trackingSync.ts

@@ -1,4 +1,8 @@
 import type { Tracker, TrackRecord } from "@types/index";
+import type { Chapter } from "@types/index";
+import { FETCH_TRACK } from "@api/mutations/tracking";
+import { MARK_CHAPTERS_READ } from "@api/mutations/chapters";
+import { buildChapterList, type ChapterDisplayPrefs } from "@features/series/lib/chapterList";
 
 export interface TrackerWithRecords extends Tracker {
   trackRecords: { nodes: TrackRecord[] };
@@ -109,3 +113,57 @@ export function removeRecord(
     }
   );
 }
+
+export interface SyncBackOptions {
+  threshold:              number | null;
+  respectScanlatorFilter: boolean;
+  chapterPrefs:           ChapterDisplayPrefs;
+}
+
+export async function syncBackFromTracker(
+  records:  TrackRecord[],
+  chapters: Chapter[],
+  opts:     SyncBackOptions,
+  gqlFn:    (query: string, vars: Record<string, unknown>) => Promise<unknown>,
+): Promise<number[]> {
+  const eligible = opts.respectScanlatorFilter
+    ? buildChapterList(chapters, opts.chapterPrefs)
+    : chapters;
+
+  const toMark: number[] = [];
+
+  for (const record of records) {
+    let fresh: TrackRecord;
+    try {
+      const res = await gqlFn(FETCH_TRACK, { recordId: record.id }) as { fetchTrack: { trackRecord: TrackRecord } };
+      fresh = res.fetchTrack.trackRecord;
+    } catch {
+      continue;
+    }
+
+    const remote = fresh.lastChapterRead;
+    if (!remote || remote <= 0) continue;
+
+    let ceiling: number;
+
+    if (opts.threshold === null) {
+      ceiling = remote;
+    } else {
+      const match = eligible
+        .filter(c => Math.abs(c.chapterNumber - remote) <= opts.threshold!)
+        .sort((a, b) => Math.abs(a.chapterNumber - remote) - Math.abs(b.chapterNumber - remote))[0];
+      if (!match) continue;
+      ceiling = match.chapterNumber;
+    }
+
+    const unread = eligible.filter(c => !c.isRead && c.chapterNumber <= ceiling);
+    toMark.push(...unread.map(c => c.id));
+  }
+
+  const ids = [...new Set(toMark)];
+  if (ids.length > 0) {
+    await gqlFn(MARK_CHAPTERS_READ, { ids, isRead: true });
+  }
+
+  return ids;
+}

src/features/tracking/store/trackingState.svelte.ts

@@ -0,0 +1,92 @@
+import { gql }          from "@api/client";
+import { GET_MANGA_TRACK_RECORDS } from "@api/queries/tracking";
+import { UPDATE_TRACK, FETCH_TRACK } from "@api/mutations/tracking";
+import { buildChapterList } from "@features/series/lib/chapterList";
+import type { TrackRecord } from "@types/index";
+import type { Chapter }     from "@types/index";
+
+class TrackingState {
+  records:  TrackRecord[] = $state([]);
+  mangaId:  number | null = $state(null);
+  loading:  boolean       = $state(false);
+  error:    string | null = $state(null);
+
+  async loadForManga(id: number) {
+    if (this.mangaId === id && this.records.length > 0) return;
+    this.mangaId = id;
+    this.loading = true;
+    this.error   = null;
+    try {
+      const res = await gql<{ manga: { trackRecords: { nodes: TrackRecord[] } } }>(
+        GET_MANGA_TRACK_RECORDS, { mangaId: id }
+      );
+      if (this.mangaId !== id) return;
+      this.records = res.manga.trackRecords.nodes;
+    } catch (e: any) {
+      this.error = e?.message ?? "Failed to load tracking";
+    } finally {
+      this.loading = false;
+    }
+  }
+
+  async refresh() {
+    if (this.mangaId === null) return;
+    const id = this.mangaId;
+    this.loading = true;
+    try {
+      const res = await gql<{ manga: { trackRecords: { nodes: TrackRecord[] } } }>(
+        GET_MANGA_TRACK_RECORDS, { mangaId: id }
+      );
+      if (this.mangaId !== id) return;
+      this.records = res.manga.trackRecords.nodes;
+    } catch (e: any) {
+      this.error = e?.message ?? "Failed to refresh tracking";
+    } finally {
+      this.loading = false;
+    }
+  }
+
+  patchRecord(updated: Partial<TrackRecord> & { id: number }) {
+    this.records = this.records.map(r => r.id === updated.id ? { ...r, ...updated } : r);
+  }
+
+  removeRecord(id: number) {
+    this.records = this.records.filter(r => r.id !== id);
+  }
+
+  clear() {
+    this.records = [];
+    this.mangaId = null;
+    this.error   = null;
+  }
+
+  async syncRecordFromRemote(recordId: number) {
+    try {
+      const res = await gql<{ fetchTrack: { trackRecord: TrackRecord } }>(
+        FETCH_TRACK, { recordId }
+      );
+      this.patchRecord(res.fetchTrack.trackRecord);
+      return res.fetchTrack.trackRecord;
+    } catch {
+      return null;
+    }
+  }
+
+  async updateFromRead(chapter: Chapter, chapterList: Chapter[], prefs?: import("@features/series/lib/chapterList").ChapterDisplayPrefs) {
+    const filtered  = prefs ? buildChapterList(chapterList, { ...prefs, sortDir: "asc" }) : [...chapterList].sort((a, b) => a.sourceOrder - b.sourceOrder);
+    const idx       = filtered.findIndex(c => c.id === chapter.id);
+    if (idx < 0) return;
+    const position  = idx + 1;
+    const eligible  = this.records.filter(r => position > (r.lastChapterRead ?? 0));
+    for (const record of eligible) {
+      try {
+        const res = await gql<{ updateTrack: { trackRecord: TrackRecord } }>(
+          UPDATE_TRACK, { recordId: record.id, lastChapterRead: position }
+        );
+        this.patchRecord(res.updateTrack.trackRecord);
+      } catch {}
+    }
+  }
+}
+
+export const trackingState = new TrackingState();