fix(library): per-library filter memory + reset-to-top, reset on app close

Genre/year/tag filters lived in global atoms with no per-library memory and
no reset on library switch, so a selection in one library (e.g. Anime) bled
into another (e.g. Shows). Sort/order/filterBy were already per-library but
persisted across app restarts.

Move all per-library filter state to in-memory preferences — genres/years/tags
get their own, and sort/order/filterBy stop using atomWithStorage: each library
remembers its own filters for the session and everything resets when the app is
fully closed. The library mount effect restores the active library's selection,
the shared useFilterReset clears it, and collections open with a clean slate.

Also fix the grid not returning to the top on a filter/sort change or reset:
it now pins to the top instantly and re-pins once the filtered fetch settles
(FlashList was restoring the previous offset as the new content grew);
pagination is left untouched.

app/(auth)/(tabs)/(home,libraries,search,favorites,watchlists)/collections/[collectionId].tsx

@@ -134,6 +134,12 @@ const page: React.FC = () => {
   useEffect(() => {
     navigation.setOptions({ title: collection?.Name || "" });
     setSortOrder([SortOrderOption.Ascending]);
+    // Collections open with a clean filter slate: the genre/year/tag atoms are
+    // global, so without this the previously viewed library's selection bleeds
+    // in (libraries now keep their own per-library memory).
+    setSelectedGenres([]);
+    setSelectedYears([]);
+    setSelectedTags([]);
 
     if (!collection) return;
 

app/(auth)/(tabs)/(libraries)/[libraryId].tsx

@@ -51,7 +51,9 @@ import {
   FilterByPreferenceAtom,
   filterByAtom,
   genreFilterAtom,
+  genrePreferenceAtom,
   getFilterByPreference,
+  getMultiFilterPreference,
   getSortByPreference,
   getSortOrderPreference,
   SortByOption,
@@ -62,9 +64,11 @@ import {
   sortOrderAtom,
   sortOrderOptions,
   sortOrderPreferenceAtom,
+  tagPreferenceAtom,
   tagsFilterAtom,
   useFilterOptions,
   yearFilterAtom,
+  yearPreferenceAtom,
 } from "@/utils/atoms/filters";
 import { useSettings } from "@/utils/atoms/settings";
 import type { TVOptionItem } from "@/utils/atoms/tvOptionModal";
@@ -103,6 +107,9 @@ const Page = () => {
   const [sortOrderPreference, setOrderByPreference] = useAtom(
     sortOrderPreferenceAtom,
   );
+  const [genrePreference, setGenrePreference] = useAtom(genrePreferenceAtom);
+  const [yearPreference, setYearPreference] = useAtom(yearPreferenceAtom);
+  const [tagPreference, setTagPreference] = useAtom(tagPreferenceAtom);
 
   const { orientation } = useOrientation();
 
@@ -184,6 +191,13 @@ const Page = () => {
       const fp = getFilterByPreference(libraryId, filterByPreference);
       _setFilterBy(fp ? [fp] : []);
     }
+
+    // Genres / years / tags: per-library saved preference (no URL params), so
+    // switching libraries restores each library's own selection instead of
+    // bleeding the previous one.
+    setSelectedGenres(getMultiFilterPreference(libraryId, genrePreference));
+    setSelectedYears(getMultiFilterPreference(libraryId, yearPreference));
+    setSelectedTags(getMultiFilterPreference(libraryId, tagPreference));
   }, [
     libraryId,
     sortOrderPreference,
@@ -192,6 +206,12 @@ const Page = () => {
     _setSortBy,
     filterByPreference,
     _setFilterBy,
+    genrePreference,
+    yearPreference,
+    tagPreference,
+    setSelectedGenres,
+    setSelectedYears,
+    setSelectedTags,
     searchParams.sortBy,
     searchParams.sortOrder,
     searchParams.filterBy,
@@ -236,6 +256,32 @@ const Page = () => {
     [libraryId, filterByPreference, setFilterByPreference, _setFilterBy],
   );
 
+  // Genres / years / tags: save the per-library memory then update the active
+  // atom (mirrors setSortBy; avoids a save-effect that would corrupt on switch).
+  const setGenres = useCallback(
+    (genres: string[]) => {
+      setGenrePreference({ ...genrePreference, [libraryId]: genres });
+      setSelectedGenres(genres);
+    },
+    [libraryId, genrePreference, setGenrePreference, setSelectedGenres],
+  );
+
+  const setYears = useCallback(
+    (years: string[]) => {
+      setYearPreference({ ...yearPreference, [libraryId]: years });
+      setSelectedYears(years);
+    },
+    [libraryId, yearPreference, setYearPreference, setSelectedYears],
+  );
+
+  const setTags = useCallback(
+    (tags: string[]) => {
+      setTagPreference({ ...tagPreference, [libraryId]: tags });
+      setSelectedTags(tags);
+    },
+    [libraryId, tagPreference, setTagPreference, setSelectedTags],
+  );
+
   const nrOfCols = useMemo(() => {
     if (Platform.isTV) {
       // TV uses flexWrap, so nrOfCols is just for mobile
@@ -379,18 +425,26 @@ const Page = () => {
 
   const flashListRef = useRef<FlashListRef<BaseItemDto>>(null);
 
-  // Reset the grid to the top whenever the active filters/sort change (e.g.
-  // pressing reset) — otherwise the list stays stuck at the previous offset.
+  // Jump the grid to the top when the filters/sort change (incl. reset).
+  const filterSignature = `${selectedGenres}|${selectedYears}|${selectedTags}|${sortBy[0]}|${sortOrder[0]}|${filterBy}`;
+  const pendingScrollTopRef = useRef(false);
+
+  // Instant feedback: pin to the top the moment the filters change, without
+  // waiting for the new fetch — and flag a re-pin for once it settles.
   useEffect(() => {
     flashListRef.current?.scrollToOffset({ offset: 0, animated: false });
-  }, [
-    selectedGenres,
-    selectedYears,
-    selectedTags,
-    sortBy,
-    sortOrder,
-    filterBy,
-  ]);
+    pendingScrollTopRef.current = true;
+  }, [filterSignature]);
+
+  // Safety net: FlashList can restore the previous offset as the filtered list
+  // grows, so re-pin once the fetch settles. Pagination keeps the same
+  // signature, so it never re-pins.
+  useEffect(() => {
+    if (pendingScrollTopRef.current && !isFetching) {
+      pendingScrollTopRef.current = false;
+      flashListRef.current?.scrollToOffset({ offset: 0, animated: false });
+    }
+  }, [isFetching, flatData]);
 
   const renderItem = useCallback(
     ({ item, index }: { item: BaseItemDto; index: number }) => (
@@ -541,7 +595,7 @@ const Page = () => {
                   });
                   return response.data.Genres || [];
                 }}
-                set={setSelectedGenres}
+                set={setGenres}
                 values={selectedGenres}
                 title={t("library.filters.genres")}
                 renderItemLabel={(item) => item.toString()}
@@ -568,7 +622,7 @@ const Page = () => {
                   });
                   return response.data.Years || [];
                 }}
-                set={setSelectedYears}
+                set={setYears}
                 values={selectedYears}
                 title={t("library.filters.years")}
                 renderItemLabel={(item) => item.toString()}
@@ -593,7 +647,7 @@ const Page = () => {
                   });
                   return response.data.Tags || [];
                 }}
-                set={setSelectedTags}
+                set={setTags}
                 values={selectedTags}
                 title={t("library.filters.tags")}
                 renderItemLabel={(item) => item.toString()}
@@ -673,11 +727,11 @@ const Page = () => {
       api,
       user?.Id,
       selectedGenres,
-      setSelectedGenres,
+      setGenres,
       selectedYears,
-      setSelectedYears,
+      setYears,
       selectedTags,
-      setSelectedTags,
+      setTags,
       sortBy,
       setSortBy,
       sortOrder,
@@ -785,15 +839,15 @@ const Page = () => {
       options: tvGenreFilterOptions,
       onSelect: (value: string) => {
         if (value === "__all__") {
-          setSelectedGenres([]);
+          setGenres([]);
         } else if (selectedGenres.includes(value)) {
-          setSelectedGenres(selectedGenres.filter((g) => g !== value));
+          setGenres(selectedGenres.filter((g) => g !== value));
         } else {
-          setSelectedGenres([...selectedGenres, value]);
+          setGenres([...selectedGenres, value]);
         }
       },
     });
-  }, [showOptions, t, tvGenreFilterOptions, selectedGenres, setSelectedGenres]);
+  }, [showOptions, t, tvGenreFilterOptions, selectedGenres, setGenres]);
 
   const handleShowYearFilter = useCallback(() => {
     showOptions({
@@ -801,15 +855,15 @@ const Page = () => {
       options: tvYearFilterOptions,
       onSelect: (value: string) => {
         if (value === "__all__") {
-          setSelectedYears([]);
+          setYears([]);
         } else if (selectedYears.includes(value)) {
-          setSelectedYears(selectedYears.filter((y) => y !== value));
+          setYears(selectedYears.filter((y) => y !== value));
         } else {
-          setSelectedYears([...selectedYears, value]);
+          setYears([...selectedYears, value]);
         }
       },
     });
-  }, [showOptions, t, tvYearFilterOptions, selectedYears, setSelectedYears]);
+  }, [showOptions, t, tvYearFilterOptions, selectedYears, setYears]);
 
   const handleShowTagFilter = useCallback(() => {
     showOptions({
@@ -817,15 +871,15 @@ const Page = () => {
       options: tvTagFilterOptions,
       onSelect: (value: string) => {
         if (value === "__all__") {
-          setSelectedTags([]);
+          setTags([]);
         } else if (selectedTags.includes(value)) {
-          setSelectedTags(selectedTags.filter((tag) => tag !== value));
+          setTags(selectedTags.filter((tag) => tag !== value));
         } else {
-          setSelectedTags([...selectedTags, value]);
+          setTags([...selectedTags, value]);
         }
       },
     });
-  }, [showOptions, t, tvTagFilterOptions, selectedTags, setSelectedTags]);
+  }, [showOptions, t, tvTagFilterOptions, selectedTags, setTags]);
 
   const handleShowSortByFilter = useCallback(() => {
     showOptions({