feat(core,app,android,ios): filter the library on every client, including by download

The library filter moves from the desktop into pstr_core::browse and
gains a Downloaded filter: titles with at least one episode kept on the
device. The bridge's arrangement() takes the filter. Android and iOS get
a row of filter chips above the grid. The choice is remembered per
device, and shelves stay hidden under a filter, as on the desktop.

android/app/src/main/java/io/narl/protonstream/settings/SettingsStore.kt

@@ -46,6 +46,11 @@ class SettingsStore(context: Context) {
         get() = preferences.getBoolean(KEY_METADATA_OFFER_DISMISSED, false)
         set(value) { preferences.edit { putBoolean(KEY_METADATA_OFFER_DISMISSED, value) } }
 
+    /** Which titles the library last showed, as a `LibraryFilter` name; null for all. */
+    var libraryFilter: String?
+        get() = preferences.getString(KEY_LIBRARY_FILTER, null)
+        set(value) { preferences.edit { putString(KEY_LIBRARY_FILTER, value) } }
+
     /** Whether the library folds each franchise into one tile. */
     var libraryGrouped: Boolean
         get() = preferences.getBoolean(KEY_LIBRARY_GROUPED, true)
@@ -67,6 +72,7 @@ class SettingsStore(context: Context) {
         private const val KEY_CACHE_BUDGET_GIB = "cache_budget_gib"
         private const val KEY_LIBRARY_SORT = "library_sort"
         private const val KEY_LIBRARY_GROUPED = "library_grouped"
+        private const val KEY_LIBRARY_FILTER = "library_filter"
         private const val KEY_METADATA_OFFER_DISMISSED = "metadata_offer_dismissed"
     }
 }

android/app/src/main/java/io/narl/protonstream/ui/AppViewModel.kt

@@ -28,6 +28,7 @@ import io.narl.protonstream.native.NativeRuntime
 import io.narl.protonstream.settings.SettingsStore
 import io.narl.protonstream.ui.theme.AppearanceState
 import uniffi.pstr_android.ArrangementRecord
+import uniffi.pstr_android.LibraryFilter
 import uniffi.pstr_android.LibrarySort
 import uniffi.pstr_android.ShareRecord
 import uniffi.pstr_android.TitleRecord
@@ -57,6 +58,7 @@ data class AppUiState(
      * when the grid falls back to [titles] as they are.
      */
     val arrangement: ArrangementRecord? = null,
+    val filter: LibraryFilter = LibraryFilter.ALL,
     val sort: LibrarySort = LibrarySort.NAME,
     val grouped: Boolean = true,
     val shares: List<ShareRecord> = emptyList(),
@@ -135,12 +137,16 @@ class AppViewModel(context: Context, private val workManager: WorkManager) : Vie
         // The arrangement first, so the first grid is drawn the way the viewer
         // left it rather than A–Z and then re-sorted under them.
         viewModelScope.launch {
-            val (sort, grouped) = withContext(Dispatchers.IO) {
+            val (filter, sort, grouped) = withContext(Dispatchers.IO) {
                 SettingsStore(appContext).run {
-                    librarySort?.let { name -> LibrarySort.entries.firstOrNull { it.name == name } } to libraryGrouped
+                    Triple(
+                        libraryFilter?.let { name -> LibraryFilter.entries.firstOrNull { it.name == name } },
+                        librarySort?.let { name -> LibrarySort.entries.firstOrNull { it.name == name } },
+                        libraryGrouped,
+                    )
                 }
             }
-            mutableState.update { it.copy(sort = sort ?: it.sort, grouped = grouped) }
+            mutableState.update { it.copy(filter = filter ?: it.filter, sort = sort ?: it.sort, grouped = grouped) }
             reload()
         }
         catchUp()
@@ -171,7 +177,6 @@ class AppViewModel(context: Context, private val workManager: WorkManager) : Vie
         }
     }
 
-    /** Reorder the grid, or fold or unfold its franchises. */
     /** Sort and fold the library, and keep both for the next launch. */
     fun arrange(sort: LibrarySort, grouped: Boolean) {
         mutableState.update { it.copy(sort = sort, grouped = grouped) }
@@ -186,6 +191,15 @@ class AppViewModel(context: Context, private val workManager: WorkManager) : Vie
         }
     }
 
+    /** Narrow the grid to some titles, and keep the choice for the next launch. */
+    fun filter(filter: LibraryFilter) {
+        mutableState.update { it.copy(filter = filter) }
+        viewModelScope.launch {
+            withContext(Dispatchers.IO) { SettingsStore(appContext).libraryFilter = filter.name }
+            reloadLibrary(mutableState.value.query)
+        }
+    }
+
     fun search(query: String) {
         mutableState.update { it.copy(query = query) }
         searchQuery.value = query
@@ -858,7 +872,7 @@ class AppViewModel(context: Context, private val workManager: WorkManager) : Vie
                 Reloaded(
                     engine.shares(),
                     engine.library(query),
-                    engine.arrangement(query, current.sort, current.grouped),
+                    engine.arrangement(query, current.filter, current.sort, current.grouped),
                     engine.offlineFiles(),
                     engine.metadataSettings(),
                     engine.storageUsage(),
@@ -886,7 +900,7 @@ class AppViewModel(context: Context, private val workManager: WorkManager) : Vie
             withContext(Dispatchers.IO) {
                 val engine = NativeRuntime.engine()
                 val search = query.takeIf(String::isNotBlank)
-                engine.library(search) to engine.arrangement(search, current.sort, current.grouped)
+                engine.library(search) to engine.arrangement(search, current.filter, current.sort, current.grouped)
             }
         }.onSuccess { (titles, arrangement) ->
             mutableState.update { it.copy(titles = titles, arrangement = arrangement) }

android/app/src/main/java/io/narl/protonstream/ui/LibraryScreen.kt

@@ -63,6 +63,7 @@ import androidx.compose.material.icons.filled.Search
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
+import androidx.compose.material3.FilterChip
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextField
@@ -84,6 +85,7 @@ import androidx.compose.material3.DropdownMenu
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.HorizontalDivider
 import uniffi.pstr_android.EpisodeRecord
+import uniffi.pstr_android.LibraryFilter
 import uniffi.pstr_android.LibrarySort
 import uniffi.pstr_android.SeasonRecord
 import uniffi.pstr_android.TitleRecord
@@ -109,6 +111,16 @@ private data class Resumable(
 /** One tile of the grid: the title drawn, and how many more of its franchise it stands for. */
 private data class Tile(val title: TitleRecord, val folded: Int)
 
+/** The desktop's names for the filters, from `browse::Filter::label`. */
+internal fun LibraryFilter.label(): String = when (this) {
+    LibraryFilter.ALL -> "All"
+    LibraryFilter.SERIES -> "Series"
+    LibraryFilter.FILMS -> "Films"
+    LibraryFilter.WATCHING -> "Watching"
+    LibraryFilter.UNWATCHED -> "Not started"
+    LibraryFilter.DOWNLOADED -> "Downloaded"
+}
+
 /** The offer of posters and synopses, and its two answers. */
 internal class MetadataOffer(val onOpenSettings: () -> Unit, val onDismiss: () -> Unit)
 
@@ -151,6 +163,7 @@ internal fun LibraryScreen(
     onArrange: (LibrarySort, Boolean) -> Unit = { _, _ -> },
     onAddShare: () -> Unit = {},
     onOpenSettings: () -> Unit = {},
+    onFilter: (LibraryFilter) -> Unit = {},
 ) {
     val download = rememberDownload()
     val context = LocalContext.current
@@ -236,6 +249,7 @@ internal fun LibraryScreen(
                     onTitle,
                     onTitleMenu = { menuFor = it },
                     onResumeMenu = { menuResume = it },
+                    onFilter = onFilter,
                     metadataOffer = if (state.metadataSettings.enabled || offerDismissed) {
                         null
                     } else {
@@ -438,6 +452,7 @@ private fun LibraryGrid(
     onTitle: (TitleRecord) -> Unit,
     onTitleMenu: (TitleRecord) -> Unit,
     onResumeMenu: (Resumable) -> Unit,
+    onFilter: (LibraryFilter) -> Unit = {},
     metadataOffer: MetadataOffer? = null,
 ) {
     // The arrangement names titles by key; before it has arrived, the titles
@@ -499,7 +514,10 @@ private fun LibraryGrid(
             }
         }
         if (state.query.isBlank()) {
-            shelves.forEach { shelf ->
+            // Only over the whole library: under a filter, a shelf of titles
+            // the grid below is hiding reads as the filter not working. The
+            // bridge leaves them out too; this covers the frame before it.
+            shelves.takeIf { state.filter == LibraryFilter.ALL }.orEmpty().forEach { shelf ->
                 item(key = "shelf-${shelf.label}", span = { GridItemSpan(maxLineSpan) }) {
                     Column {
                         Text(shelf.label, style = MaterialTheme.typography.titleMedium)
@@ -520,9 +538,29 @@ private fun LibraryGrid(
                     }
                 }
             }
-            if (resumable.isNotEmpty() || shelves.isNotEmpty()) {
-                item(key = "library-heading", span = { GridItemSpan(maxLineSpan) }) {
-                    Text("All titles", style = MaterialTheme.typography.titleMedium, modifier = Modifier.padding(top = 8.dp))
+            item(key = "library-heading", span = { GridItemSpan(maxLineSpan) }) {
+                Column {
+                    if (resumable.isNotEmpty() || shelves.isNotEmpty()) {
+                        Text("All titles", style = MaterialTheme.typography.titleMedium, modifier = Modifier.padding(top = 8.dp))
+                    }
+                    LazyRow(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+                        items(LibraryFilter.entries, key = { it.name }) { filter ->
+                            FilterChip(
+                                selected = filter == state.filter,
+                                onClick = { onFilter(filter) },
+                                label = { Text(filter.label()) },
+                            )
+                        }
+                    }
+                }
+            }
+            if (tiles.isEmpty() && state.filter != LibraryFilter.ALL) {
+                item(key = "filtered-out", span = { GridItemSpan(maxLineSpan) }) {
+                    Text(
+                        "Nothing in the library fits that filter.",
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
                 }
             }
         }

android/app/src/main/java/io/narl/protonstream/ui/ProtonStreamApp.kt

@@ -233,6 +233,7 @@ fun ProtonStreamApp(
                                     addingShare = true
                                 },
                                 onOpenSettings = { destination = Destination.Settings },
+                                onFilter = model::filter,
                                 )
                         }
                         val titlePane = @Composable { selected: TitleRecord ->

crates/pstr-android/src/lib.rs

@@ -4,7 +4,7 @@
 //! than the catalog's internal Rust types. Kotlin owns lifecycle and drawing;
 //! Rust remains the sole owner of Proton sessions, SQLite and decrypted bytes.
 
-use std::collections::{BTreeMap, HashMap};
+use std::collections::{BTreeMap, HashMap, HashSet};
 use std::ffi::c_void;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::{Arc, OnceLock};
@@ -12,7 +12,7 @@ use std::sync::{Arc, OnceLock};
 use parking_lot::Mutex;
 use pstr_core::account::{DriveEntry, PendingSignIn, PlaceKind, SignIn};
 use pstr_core::appearance::{Accent, Appearance, Flavor, Palette};
-use pstr_core::browse::Sort;
+use pstr_core::browse::{Filter, Sort};
 use pstr_core::catalog::{Catalog, OfflineFile, TitleTrackPrefs, WatchState, build_rows};
 use pstr_core::chapters::{Chapter, ChapterRole};
 use pstr_core::config::AppDirs;
@@ -317,6 +317,17 @@ pub enum TitleNamesChoice {
     Romaji,
 }
 
+/// The shared `pstr_core::browse::Filter`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, uniffi::Enum)]
+pub enum LibraryFilter {
+    All,
+    Series,
+    Films,
+    Watching,
+    Unwatched,
+    Downloaded,
+}
+
 /// The shared `pstr_core::browse::Sort`.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, uniffi::Enum)]
 pub enum LibrarySort {
@@ -1460,19 +1471,31 @@ impl AndroidEngine {
         })
     }
 
-    /// The library grid for `search`, in `sort` order, each franchise folded
-    /// into one tile when `grouped` — and the shelves above it. Keys into
-    /// [`AndroidEngine::library`]'s titles, so the records cross the bridge
-    /// once.
+    /// The library grid for `search`, narrowed by `filter`, in `sort` order,
+    /// each franchise folded into one tile when `grouped` — and the shelves
+    /// above it. Keys into [`AndroidEngine::library`]'s titles, so the records
+    /// cross the bridge once.
     pub fn arrangement(
         &self,
         search: Option<String>,
+        filter: LibraryFilter,
         sort: LibrarySort,
         grouped: bool,
     ) -> Result<ArrangementRecord, BridgeError> {
         let query = search.unwrap_or_default();
+        let filter = filter_choice(filter);
         self.with_library(|cached| {
-            let titles = pstr_core::browse::search(&cached.library, &cached.metadata, &query);
+            let titles: Vec<&Title> =
+                pstr_core::browse::search(&cached.library, &cached.metadata, &query)
+                    .into_iter()
+                    .filter(|title| {
+                        filter.admits(title, |node| {
+                            cached
+                                .offline
+                                .contains(&(node.share_id.clone(), node.link_id.clone()))
+                        })
+                    })
+                    .collect();
             let tiles = pstr_core::browse::arrange(
                 &titles,
                 pstr_core::browse::Order {
@@ -1483,7 +1506,9 @@ impl AndroidEngine {
                     added: &cached.added,
                 },
             );
-            let shelves = if query.trim().is_empty() {
+            // Shelves are the whole library's, and only when it is shown
+            // whole.
+            let shelves = if query.trim().is_empty() && filter == Filter::All {
                 pstr_core::shelves::pick(&cached.library.titles, &cached.metadata, SHELVES)
                     .into_iter()
                     .map(|shelf| ShelfRecord {
@@ -2246,6 +2271,7 @@ impl AndroidEngine {
             metadata,
             added,
             titles,
+            offline: offline.into_keys().collect(),
         };
         let answer = read(&cached);
         *self.library_cache.lock() = Some(cached);
@@ -3092,6 +3118,8 @@ struct CachedLibrary {
     /// When each title last gained a file.
     added: HashMap<String, i64>,
     titles: Vec<TitleRecord>,
+    /// The files kept on this device, by share and link id.
+    offline: HashSet<(String, String)>,
 }
 
 /// How many provider lookups may be in flight at once.
@@ -3153,6 +3181,17 @@ fn appearance_record(appearance: Appearance) -> AppearanceRecord {
     }
 }
 
+fn filter_choice(filter: LibraryFilter) -> Filter {
+    match filter {
+        LibraryFilter::All => Filter::All,
+        LibraryFilter::Series => Filter::Series,
+        LibraryFilter::Films => Filter::Films,
+        LibraryFilter::Watching => Filter::Watching,
+        LibraryFilter::Unwatched => Filter::Unwatched,
+        LibraryFilter::Downloaded => Filter::Downloaded,
+    }
+}
+
 fn sort_choice(sort: LibrarySort) -> Sort {
     match sort {
         LibrarySort::Name => Sort::Name,
@@ -3904,7 +3943,12 @@ mod tests {
         }
 
         let arranged = engine
-            .arrangement(None, super::LibrarySort::Name, true)
+            .arrangement(
+                None,
+                super::LibraryFilter::All,
+                super::LibrarySort::Name,
+                true,
+            )
             .expect("arrange");
         assert_eq!(arranged.tiles.len(), 1);
         assert_eq!(arranged.tiles[0].key, "sousou no frieren");

crates/pstr-app/src/app.rs

@@ -427,37 +427,7 @@ impl Default for LibraryView {
     }
 }
 
-/// Which titles the grid shows.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, serde::Serialize, serde::Deserialize)]
-#[serde(rename_all = "snake_case")]
-pub enum Filter {
-    #[default]
-    All,
-    Series,
-    Films,
-    /// Started and not finished.
-    Watching,
-    /// Not started.
-    Unwatched,
-}
-
-impl Filter {
-    fn admits(self, title: &pstr_core::library::Title) -> bool {
-        use pstr_core::library::TitleKind;
-        let watched = title.watched_count();
-        match self {
-            Self::All => true,
-            Self::Series => title.kind == TitleKind::Series,
-            Self::Films => title.kind == TitleKind::Film,
-            Self::Watching => {
-                title.resume().is_some() || (watched > 0 && watched < title.episode_count())
-            }
-            Self::Unwatched => watched == 0 && title.resume().is_none(),
-        }
-    }
-}
-
-pub use pstr_core::browse::Sort;
+pub use pstr_core::browse::{Filter, Sort};
 
 /// What the library view is built from, besides the library itself.
 pub struct ViewInputs<'a> {
@@ -466,6 +436,8 @@ pub struct ViewInputs<'a> {
     pub names: TitleNames,
     /// When each title last gained a file, by key.
     pub added: &'a HashMap<String, i64>,
+    /// The files kept on this computer, for the Downloaded filter.
+    pub offline: &'a std::collections::HashSet<DownloadKey>,
 }
 
 /// How many shelves the library shows above the grid.
@@ -515,7 +487,14 @@ impl LibraryView {
 
         let titles: Vec<&Title> = pstr_core::browse::search(library, metadata, inputs.query)
             .into_iter()
-            .filter(|title| self.filter.admits(title))
+            .filter(|title| {
+                self.filter.admits(title, |node| {
+                    inputs.offline.contains(&DownloadKey {
+                        share_id: node.share_id.clone(),
+                        link_id: node.link_id.clone(),
+                    })
+                })
+            })
             .collect();
         let tiles = pstr_core::browse::arrange(
             &titles,
@@ -1114,7 +1093,11 @@ impl App {
                         *row = *item;
                     }
                 }
-                Event::OfflineFiles(files) => self.offline_files = files,
+                Event::OfflineFiles(files) => {
+                    // The Downloaded filter is drawn from these.
+                    self.view.stale |= self.view.filter == Filter::Downloaded;
+                    self.offline_files = files;
+                }
                 Event::Account(status) => {
                     if let AccountStatus::SignedIn(username) = &status
                         && self.account.busy
@@ -2284,6 +2267,7 @@ impl eframe::App for App {
                     metadata: &self.metadata,
                     names: self.engine.appearance().names,
                     added: &self.added,
+                    offline: &self.offline_files,
                 },
             );
 
@@ -2979,27 +2963,6 @@ mod tests {
         )
     }
 
-    #[test]
-    fn the_filters_split_the_library_by_kind() {
-        use pstr_core::library::{Title, TitleKind};
-        let title = |kind| Title {
-            key: "k".into(),
-            name: "n".into(),
-            year: None,
-            kind,
-            seasons: Vec::new(),
-            share_ids: Vec::new(),
-        };
-        let film = title(TitleKind::Film);
-        let series = title(TitleKind::Series);
-        assert!(Filter::All.admits(&film) && Filter::All.admits(&series));
-        assert!(Filter::Films.admits(&film) && !Filter::Films.admits(&series));
-        assert!(Filter::Series.admits(&series) && !Filter::Series.admits(&film));
-        // Nothing watched of either: not started, and not being watched.
-        assert!(Filter::Unwatched.admits(&film));
-        assert!(!Filter::Watching.admits(&film));
-    }
-
     #[test]
     fn a_screenshot_name_says_what_and_when_without_a_slash() {
         assert_eq!(

crates/pstr-app/src/ui/library.rs

@@ -327,17 +327,8 @@ fn shelf_controls(ui: &mut egui::Ui, view: &LibraryView, actions: &mut Vec<Actio
         actions.push(Action::SetGrouped(grouped));
     }
     ui.add_space(theme::space::L);
-    if let Some(filter) = ui::widgets::segmented(
-        ui,
-        view.filter,
-        &[
-            (Filter::All, "All"),
-            (Filter::Series, "Series"),
-            (Filter::Films, "Films"),
-            (Filter::Watching, "Watching"),
-            (Filter::Unwatched, "Not started"),
-        ],
-    ) {
+    let filters = Filter::ALL.map(|filter| (filter, filter.label()));
+    if let Some(filter) = ui::widgets::segmented(ui, view.filter, &filters) {
         actions.push(Action::SetShelf(filter, view.sort));
     }
 }

crates/pstr-core/src/browse.rs

@@ -7,7 +7,8 @@
 
 use std::collections::{HashMap, HashSet};
 
-use crate::library::{Library, Title, sort_name};
+use crate::catalog::CatalogNode;
+use crate::library::{Library, Title, TitleKind, sort_name};
 use crate::metadata::{MetadataRecord, TitleNames};
 
 /// What order a grid is in.
@@ -51,6 +52,60 @@ impl Sort {
     }
 }
 
+/// Which titles a grid shows.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, serde::Serialize, serde::Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum Filter {
+    #[default]
+    All,
+    Series,
+    Films,
+    /// Started and not finished.
+    Watching,
+    /// Not started.
+    Unwatched,
+    /// With at least one episode kept on this device.
+    Downloaded,
+}
+
+impl Filter {
+    pub const ALL: [Self; 6] = [
+        Self::All,
+        Self::Series,
+        Self::Films,
+        Self::Watching,
+        Self::Unwatched,
+        Self::Downloaded,
+    ];
+
+    pub fn label(self) -> &'static str {
+        match self {
+            Self::All => "All",
+            Self::Series => "Series",
+            Self::Films => "Films",
+            Self::Watching => "Watching",
+            Self::Unwatched => "Not started",
+            Self::Downloaded => "Downloaded",
+        }
+    }
+
+    /// Whether the grid shows `title`. `offline` says whether a file is kept
+    /// on this device, which only the front end knows.
+    pub fn admits(self, title: &Title, offline: impl Fn(&CatalogNode) -> bool) -> bool {
+        let watched = title.watched_count();
+        match self {
+            Self::All => true,
+            Self::Series => title.kind == TitleKind::Series,
+            Self::Films => title.kind == TitleKind::Film,
+            Self::Watching => {
+                title.resume().is_some() || (watched > 0 && watched < title.episode_count())
+            }
+            Self::Unwatched => watched == 0 && title.resume().is_none(),
+            Self::Downloaded => title.episodes().any(|episode| offline(&episode.node)),
+        }
+    }
+}
+
 /// The name to show for `title`: the provider's, in the form the viewer
 /// picked, else the share's.
 pub fn display_name<'a>(
@@ -393,4 +448,44 @@ mod tests {
         assert_eq!(found[0].key, "sousou no frieren");
         assert_eq!(search(&library, &metadata, "").len(), 3);
     }
+
+    #[test]
+    fn the_filters_split_the_library_by_kind_and_progress() {
+        let film = title("f", "Film", TitleKind::Film);
+        let series = title("s", "Series", TitleKind::Series);
+        let none = |_: &CatalogNode| false;
+        assert!(Filter::All.admits(&film, none) && Filter::All.admits(&series, none));
+        assert!(Filter::Films.admits(&film, none) && !Filter::Films.admits(&series, none));
+        assert!(Filter::Series.admits(&series, none) && !Filter::Series.admits(&film, none));
+        // Nothing watched of either: not started, and not being watched.
+        assert!(Filter::Unwatched.admits(&film, none));
+        assert!(!Filter::Watching.admits(&film, none));
+    }
+
+    #[test]
+    fn the_downloaded_filter_admits_a_title_with_any_episode_kept_offline() {
+        let node = |link: &str, episode| CatalogNode {
+            share_id: "s".into(),
+            link_id: link.into(),
+            volume_id: "v".into(),
+            parent_link_id: None,
+            name: format!("Show - S01E0{episode}.mkv"),
+            is_folder: false,
+            media_type: Some("video/x-matroska".into()),
+            size: Some(1),
+            active_revision_id: Some("r".into()),
+            parsed: crate::naming::ParsedName {
+                title: "Show".into(),
+                season: Some(1),
+                episode: Some(episode),
+                year: None,
+                episode_title: None,
+            },
+        };
+        let library = Library::build(vec![node("a", 1), node("b", 2)], &HashMap::new());
+        let show = &library.titles[0];
+
+        assert!(Filter::Downloaded.admits(show, |node| node.link_id == "b"));
+        assert!(!Filter::Downloaded.admits(show, |_| false));
+    }
 }

ios/ProtonStream/App/AppModel.swift

@@ -47,6 +47,7 @@ final class AppModel {
     /// when the grid falls back to `titles` as they are.
     var arrangement: ArrangementRecord?
     /// As the viewer last left them.
+    var filter: LibraryFilter = SettingsStore().libraryFilter
     var sort: LibrarySort = SettingsStore().librarySort
     var grouped = SettingsStore().libraryGrouped
     var shares: [ShareRecord] = []
@@ -118,6 +119,13 @@ final class AppModel {
         Task { await reloadLibrary(query) }
     }
 
+    /// Narrow the grid to some titles, and keep the choice for the next launch.
+    func setFilter(_ filter: LibraryFilter) {
+        self.filter = filter
+        SettingsStore().libraryFilter = filter
+        Task { await reloadLibrary(query) }
+    }
+
     func search(_ query: String) {
         self.query = query
         searchTask?.cancel()
@@ -787,6 +795,7 @@ final class AppModel {
     /// `reload`, for a caller that goes on to read what it loaded.
     func reloadNow() async {
         let query = query.trimmingCharacters(in: .whitespaces).isEmpty ? nil : self.query
+        let filter = filter
         let sort = sort
         let grouped = grouped
         do {
@@ -798,7 +807,7 @@ final class AppModel {
                 return Reloaded(
                     shares: try engine.shares(),
                     titles: try engine.library(search: query),
-                    arrangement: try engine.arrangement(search: query, sort: sort, grouped: grouped),
+                    arrangement: try engine.arrangement(search: query, filter: filter, sort: sort, grouped: grouped),
                     offline: try engine.offlineFiles(),
                     metadataSettings: try engine.metadataSettings(),
                     storage: try engine.storageUsage()
@@ -819,11 +828,12 @@ final class AppModel {
 
     private func reloadLibrary(_ query: String) async {
         let search = query.trimmingCharacters(in: .whitespaces).isEmpty ? nil : query
+        let filter = filter
         let sort = sort
         let grouped = grouped
         do {
             let (titles, arrangement) = try await run { engine in
-                (try engine.library(search: search), try engine.arrangement(search: search, sort: sort, grouped: grouped))
+                (try engine.library(search: search), try engine.arrangement(search: search, filter: filter, sort: sort, grouped: grouped))
             }
             self.titles = titles
             self.arrangement = arrangement

ios/ProtonStream/App/SettingsStore.swift

@@ -51,6 +51,15 @@ struct SettingsStore {
         nonmutating set { defaults.set(String(describing: newValue), forKey: Key.librarySort) }
     }
 
+    /// Which titles the library last showed.
+    var libraryFilter: LibraryFilter {
+        get {
+            let stored = defaults.string(forKey: Key.libraryFilter)
+            return Self.filters.first { String(describing: $0) == stored } ?? .all
+        }
+        nonmutating set { defaults.set(String(describing: newValue), forKey: Key.libraryFilter) }
+    }
+
     /// The library's offer of posters and synopses was turned down.
     var metadataOfferDismissed: Bool {
         get { bool(Key.metadataOfferDismissed, default: false) }
@@ -63,6 +72,7 @@ struct SettingsStore {
         nonmutating set { defaults.set(newValue, forKey: Key.libraryGrouped) }
     }
 
+    static let filters: [LibraryFilter] = [.all, .series, .films, .watching, .unwatched, .downloaded]
     private static let sorts: [LibrarySort] = [.name, .recent, .added, .release, .rating, .popularity]
 
     private func bool(_ key: String, default value: Bool) -> Bool {
@@ -75,6 +85,7 @@ struct SettingsStore {
         static let hardwareDecoding = "hardware_decoding"
         static let cacheBudgetGib = "cache_budget_gib"
         static let librarySort = "library_sort"
+        static let libraryFilter = "library_filter"
         static let libraryGrouped = "library_grouped"
         static let metadataOfferDismissed = "metadata_offer_dismissed"
     }

ios/ProtonStream/UI/LibraryView.swift

@@ -229,7 +229,10 @@ struct LibraryView: View {
                         }
                     }
                 }
-                if browsing {
+                // Only over the whole library: under a filter, a shelf of
+                // titles the grid below is hiding reads as the filter not
+                // working.
+                if browsing && model.filter == .all {
                     ForEach(shelves) { shelf in
                         VStack(alignment: .leading, spacing: 10) {
                             Text(shelf.label).textStyle(.titleMedium).foregroundStyle(scheme.onSurface)
@@ -248,6 +251,20 @@ struct LibraryView: View {
                         Text("All titles").textStyle(.titleMedium).foregroundStyle(scheme.onSurface).padding(.top, 8)
                     }
                 }
+                if browsing {
+                    ScrollView(.horizontal, showsIndicators: false) {
+                        HStack(spacing: 8) {
+                            ForEach(SettingsStore.filters, id: \.self) { filter in
+                                FilterChip(label: filter.label, selected: filter == model.filter) { model.setFilter(filter) }
+                            }
+                        }
+                    }
+                    if tiles.isEmpty && model.filter != .all {
+                        Text("Nothing in the library fits that filter.")
+                            .textStyle(.bodyMedium)
+                            .foregroundStyle(scheme.onSurfaceVariant)
+                    }
+                }
                 // Posters, three across on a phone.
                 LazyVGrid(columns: [GridItem(.adaptive(minimum: 108), spacing: 12, alignment: .top)], spacing: 16) {
                     ForEach(tiles) { tile in
@@ -421,6 +438,20 @@ private struct LibrarySkeleton: View {
     }
 }
 
+extension LibraryFilter {
+    /// The desktop's names for the filters, from `browse::Filter::label`.
+    var label: String {
+        switch self {
+        case .all: "All"
+        case .series: "Series"
+        case .films: "Films"
+        case .watching: "Watching"
+        case .unwatched: "Not started"
+        case .downloaded: "Downloaded"
+        }
+    }
+}
+
 /// The offer of posters and synopses, and its two answers.
 private struct MetadataOfferCard: View {
     let onOpenSettings: () -> Void