fix(anime): isolate mark-watched requests and batch marks atomically

- Track mark writes with their own LatestRequest so a concurrent watch-state
  refresh can't supersede them, and re-read the store after a write to settle
  stale repaints
- Wrap batch markEpisodesWatched in a single transaction so partial rows and
  their lifetime summary rebuild can't land separately; defer clearing the
  active session's markedWatched flag until after commit

src/animeui/episode-list.ts

@@ -47,6 +47,11 @@ export function createEpisodeList({ api, setStatus, selectedAnime }: EpisodeList
    */
   let cueState: { url: string; state: 'loading' | 'playing' } | null = null;
   const watchStateRequests = new LatestRequest();
+  /**
+   * Mark writes carry their own token: a background refresh starting mid-write
+   * must not make the write look superseded and drop its repaint on the floor.
+   */
+  const markWrites = new LatestRequest();
   const playbacks = new LatestRequest();
 
   function formatEpisodeIndex(item: ListedEpisode): string {
@@ -199,7 +204,7 @@ export function createEpisodeList({ api, setStatus, selectedAnime }: EpisodeList
     const anime = selectedAnime();
     if (!anime || items.length === 0) return;
 
-    const request = watchStateRequests.begin();
+    const request = markWrites.begin();
     const attempt = await capture(() =>
       api.setWatched({
         sourceId: anime.sourceId,
@@ -213,7 +218,7 @@ export function createEpisodeList({ api, setStatus, selectedAnime }: EpisodeList
         })),
       }),
     );
-    if (!watchStateRequests.isCurrent(request)) return;
+    if (!markWrites.isCurrent(request)) return;
 
     if (!attempt.ok) {
       setStatus(describe(attempt.error), 'error');
@@ -233,6 +238,9 @@ export function createEpisodeList({ api, setStatus, selectedAnime }: EpisodeList
       if (isMarked === mark) changed += 1;
     }
     paint();
+    // A refresh that read the store before this write landed would repaint stale
+    // marks over the ones above, so re-read from the store to settle the list.
+    void refreshWatchState();
 
     // Nothing came back marked when marking is what was asked for: the write
     // had nowhere to land, which is what a disabled stats history looks like.
@@ -308,6 +316,7 @@ export function createEpisodeList({ api, setStatus, selectedAnime }: EpisodeList
     // A menu opened against the list that is going away has nothing left to act on.
     closeContextMenu();
     watchStateRequests.cancel();
+    markWrites.cancel();
     playbacks.cancel();
     listed = [];
     watched = new Set();

src/core/services/immersion-tracker-service.ts

@@ -30,6 +30,7 @@ import {
   applySessionLifetimeSummary,
   reconcileStaleActiveSessions,
   rebuildLifetimeSummaries as rebuildLifetimeSummaryTables,
+  rebuildLifetimeSummariesInTransaction,
   shouldBackfillLifetimeSummaries,
 } from './immersion-tracker/lifetime';
 import {
@@ -755,6 +756,12 @@ export class ImmersionTrackerService {
     // Every row this creates would otherwise rebuild the lifetime summaries on
     // its own, and a season's worth of episodes arrives in one call.
     let needsLifetimeRebuild = false;
+    // A half-applied batch would leave rows created without their marks, so the
+    // whole span of episodes and the summary rebuild land together or not at all.
+    let clearedActiveVideo = false;
+
+    this.db.exec('BEGIN IMMEDIATE');
+    try {
       for (const episode of episodes) {
         const statsPath = normalizeMediaPath(episode.statsPath);
         if (!statsPath) continue;
@@ -769,14 +776,20 @@ export class ImmersionTrackerService {
         markVideoWatched(this.db, videoId, watched);
         changed += 1;
 
-      // Clearing the mark on what is playing right now would otherwise be undone
+        if (!watched && this.sessionState?.videoId === videoId) clearedActiveVideo = true;
-      // the moment the session passes the completion threshold again.
-      if (!watched && this.sessionState?.videoId === videoId) {
-        this.sessionState.markedWatched = true;
-      }
       }
 
-    if (needsLifetimeRebuild) rebuildLifetimeSummaryTables(this.db);
+      if (needsLifetimeRebuild) rebuildLifetimeSummariesInTransaction(this.db);
+      this.db.exec('COMMIT');
+    } catch (error) {
+      this.db.exec('ROLLBACK');
+      throw error;
+    }
+
+    // Clearing the mark on what is playing right now would otherwise be undone
+    // the moment the session passes the completion threshold again. Set after the
+    // commit, so a rolled back clear does not suppress the automatic mark.
+    if (clearedActiveVideo && this.sessionState) this.sessionState.markedWatched = true;
     return changed;
   }