feat: interface-size (UI scale) presets

Webview-zoom-style presets: Extra small 0.8 / Small 0.9 / Default 1.0 /
Large 1.2 / Extra large 1.5, applied through SLINT_SCALE_FACTOR set at
the top of main() before any thread or the backend exists. The env var
overrides the compositor DPR, so the value is last observed DPR x
preset; the Default preset leaves the var unset (stock DPR handling,
including live monitor changes, stays intact). last_dpr is persisted
from the winit window (real compositor DPR) on the 5s renderer-sentinel
timer.

- const-bake guard: strip SLINT_SCALE_FACTOR in qbz-ui build.rs so the
  slint compiler never bakes the factor into the generated code
- new UiScale global + scale-divided window minimums keep the physical
  minimum constant across presets (XL fits a 1366x768 screen); the
  three window-geometry gates in main.rs use the process-active factor
- artwork decode targets scale with the preset: sharp covers at >=1.2,
  smaller decoded-cache footprint below 1.0
- Settings > Appearance "Interface size" row below Language (replaces
  the commented-out percentage placeholder and its orphan properties),
  restart-to-apply toast
- Typography.boost = 1.1 on Extra small only, so body text stays
  readable at the 0.8 factor; Small (0.9) needs no compensation
- i18n: new strings added to all 7 locale catalogs

Known accepted limitation: slight text softness at fractional scale
factors (owner-accepted; diagnostic notes live in
qbz-nix-docs/ui-scale-presets/).

cc

crates/qbz-ui/build.rs

@@ -2,6 +2,11 @@
 //! single entry point. Translations are bundled (pure-Rust, no C dep) from
 //! `translations/<lang>/LC_MESSAGES/qbz-slint.po`; msgid = English source, no context.
 fn main() {
+    // SLINT_SCALE_FACTOR is a RUNTIME preference in this app (main.rs sets it
+    // from the persisted interface-size preset). If it leaks into the BUILD
+    // environment, the slint compiler const-propagates the factor and the
+    // runtime override becomes a permanent no-op — strip it unconditionally.
+    std::env::remove_var("SLINT_SCALE_FACTOR");
     let config = slint_build::CompilerConfiguration::new()
         .with_bundled_translations("translations")
         .with_default_translation_context(slint_build::DefaultTranslationContext::None);

crates/qbz-ui/translations/de/LC_MESSAGES/qbz-ui.po

@@ -4174,3 +4174,21 @@ msgstr "JACK ist nicht bit-perfekt"
 
 msgid "The JACK backend routes audio through the JACK graph, which resamples to the graph's sample rate. For bit-perfect playback use ALSA (direct) or PipeWire with passthrough."
 msgstr "Das JACK-Backend leitet die Audioausgabe durch den JACK-Graphen, der auf die Graph-Abtastrate resampled. Für bit-perfekte Wiedergabe verwende ALSA (direkt) oder PipeWire mit Passthrough."
+
+msgid "Extra large"
+msgstr "Extra groß"
+
+msgid "INTERFACE"
+msgstr "OBERFLÄCHE"
+
+msgid "Interface size"
+msgstr "Oberflächengröße"
+
+msgid "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+msgstr "Skaliert die gesamte Oberfläche, wie der Browser-Zoom. Klein zeigt mehr Inhalt auf dem Bildschirm, Groß und Extra groß verbessern die Lesbarkeit (Neustart erforderlich)"
+
+msgid "Interface size changed — restart QBZ to apply"
+msgstr "Oberflächengröße geändert — QBZ neu starten, um sie zu übernehmen"
+
+msgid "Extra small"
+msgstr "Extra klein"

crates/qbz-ui/translations/en/LC_MESSAGES/qbz-ui.po

@@ -60,3 +60,21 @@ msgstr[1] "Added {} tracks to queue"
 
 msgid "Unfollow on Qobuz"
 msgstr "Unfollow on Qobuz"
+
+msgid "Extra large"
+msgstr "Extra large"
+
+msgid "INTERFACE"
+msgstr "INTERFACE"
+
+msgid "Interface size"
+msgstr "Interface size"
+
+msgid "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+msgstr "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+
+msgid "Interface size changed — restart QBZ to apply"
+msgstr "Interface size changed — restart QBZ to apply"
+
+msgid "Extra small"
+msgstr "Extra small"

crates/qbz-ui/translations/es/LC_MESSAGES/qbz-ui.po

@@ -4231,3 +4231,21 @@ msgstr "JACK no es bit-perfect"
 
 msgid "The JACK backend routes audio through the JACK graph, which resamples to the graph's sample rate. For bit-perfect playback use ALSA (direct) or PipeWire with passthrough."
 msgstr "El backend de JACK enruta el audio por el grafo de JACK, que remuestrea a la frecuencia del grafo. Para reproducción bit-perfect usa ALSA (directo) o PipeWire con passthrough."
+
+msgid "Extra large"
+msgstr "Extra grande"
+
+msgid "INTERFACE"
+msgstr "INTERFAZ"
+
+msgid "Interface size"
+msgstr "Tamaño de la interfaz"
+
+msgid "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+msgstr "Escala toda la interfaz, como el zoom del navegador. Pequeño muestra más contenido en pantalla, Grande y Extra grande mejoran la legibilidad (requiere reiniciar)"
+
+msgid "Interface size changed — restart QBZ to apply"
+msgstr "Tamaño de la interfaz cambiado — reinicia QBZ para aplicar"
+
+msgid "Extra small"
+msgstr "Extra pequeño"

crates/qbz-ui/translations/fr/LC_MESSAGES/qbz-ui.po

@@ -4174,3 +4174,21 @@ msgstr "JACK n'est pas bit-perfect"
 
 msgid "The JACK backend routes audio through the JACK graph, which resamples to the graph's sample rate. For bit-perfect playback use ALSA (direct) or PipeWire with passthrough."
 msgstr "Le backend JACK achemine l'audio via le graphe JACK, qui rééchantillonne à la fréquence du graphe. Pour une lecture bit-perfect, utilisez ALSA (direct) ou PipeWire avec passthrough."
+
+msgid "Extra large"
+msgstr "Très grand"
+
+msgid "INTERFACE"
+msgstr "INTERFACE"
+
+msgid "Interface size"
+msgstr "Taille de l'interface"
+
+msgid "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+msgstr "Met à l'échelle toute l'interface, comme le zoom du navigateur. Petit affiche plus de contenu à l'écran, Grand et Très grand améliorent la lisibilité (redémarrage requis)"
+
+msgid "Interface size changed — restart QBZ to apply"
+msgstr "Taille de l'interface modifiée — redémarrez QBZ pour appliquer"
+
+msgid "Extra small"
+msgstr "Très petit"

crates/qbz-ui/translations/ja/LC_MESSAGES/qbz-ui.po

@@ -4121,3 +4121,21 @@ msgstr "ビットパーフェクトなHi-Fi再生を求めるオーディオフ
 
 msgid "Built with Slint, and powered by Rodio and Symphonia. With thanks to Qobuz, MusicBrainz, Song.link/Odesli, LRCLIB, lyrics.ovh, Lucide, and Kawarp."
 msgstr "Slintで構築し、RodioとSymphoniaを採用しています。Qobuz、MusicBrainz、Song.link/Odesli、LRCLIB、lyrics.ovh、Lucide、Kawarpに感謝します。"
+
+msgid "Extra large"
+msgstr "特大"
+
+msgid "INTERFACE"
+msgstr "インターフェース"
+
+msgid "Interface size"
+msgstr "インターフェースのサイズ"
+
+msgid "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+msgstr "ブラウザのズームのようにインターフェース全体を拡大縮小します。「小」は画面により多くのコンテンツを表示し、「大」と「特大」は読みやすさを向上させます（再起動が必要）"
+
+msgid "Interface size changed — restart QBZ to apply"
+msgstr "インターフェースのサイズを変更しました — 適用するには QBZ を再起動してください"
+
+msgid "Extra small"
+msgstr "極小"

crates/qbz-ui/translations/pt/LC_MESSAGES/qbz-ui.po

@@ -4174,3 +4174,21 @@ msgstr "JACK não é bit-perfect"
 
 msgid "The JACK backend routes audio through the JACK graph, which resamples to the graph's sample rate. For bit-perfect playback use ALSA (direct) or PipeWire with passthrough."
 msgstr "O backend JACK roteia o áudio pelo grafo do JACK, que faz resample para a taxa do grafo. Para reprodução bit-perfect, use ALSA (direto) ou PipeWire com passthrough."
+
+msgid "Extra large"
+msgstr "Extra grande"
+
+msgid "INTERFACE"
+msgstr "INTERFACE"
+
+msgid "Interface size"
+msgstr "Tamanho da interface"
+
+msgid "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+msgstr "Dimensiona toda a interface, como o zoom do navegador. Pequeno mostra mais conteúdo na tela, Grande e Extra grande melhoram a legibilidade (requer reinicialização)"
+
+msgid "Interface size changed — restart QBZ to apply"
+msgstr "Tamanho da interface alterado — reinicie o QBZ para aplicar"
+
+msgid "Extra small"
+msgstr "Extra pequeno"

crates/qbz-ui/translations/ru/LC_MESSAGES/qbz-ui.po

@@ -4145,3 +4145,21 @@ msgstr "Нативный клиент музыкального стриминг
 
 msgid "Built with Slint, and powered by Rodio and Symphonia. With thanks to Qobuz, MusicBrainz, Song.link/Odesli, LRCLIB, lyrics.ovh, Lucide, and Kawarp."
 msgstr "Создано на Slint, работает на Rodio и Symphonia. Благодарим Qobuz, MusicBrainz, Song.link/Odesli, LRCLIB, lyrics.ovh, Lucide и Kawarp."
+
+msgid "Extra large"
+msgstr "Очень большой"
+
+msgid "INTERFACE"
+msgstr "ИНТЕРФЕЙС"
+
+msgid "Interface size"
+msgstr "Размер интерфейса"
+
+msgid "Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)"
+msgstr "Масштабирует весь интерфейс, как масштаб страницы в браузере. Маленький вмещает больше контента на экране, Большой и Очень большой улучшают читаемость (требуется перезапуск)"
+
+msgid "Interface size changed — restart QBZ to apply"
+msgstr "Размер интерфейса изменён — перезапустите QBZ, чтобы применить"
+
+msgid "Extra small"
+msgstr "Очень маленький"

crates/qbz-ui/ui/app.slint

@@ -17,16 +17,19 @@ import { SplashScreen } from "splash/SplashScreen.slint";
 import { LoginScreen } from "login/LoginScreen.slint";
 import { AppShell } from "shell/AppShell.slint";
 import { Toast } from "primitives/Toast.slint";
-import { ShellState, MiniPlayerState, NowPlayingState, AppearanceState } from "state.slint";
+import { ShellState, MiniPlayerState, NowPlayingState, AppearanceState, UiScale } from "state.slint";
 import { MiniShell } from "miniplayer/MiniShell.slint";
 
 // Re-export the theming globals so the Rust layer can push palettes (Theme.c /
 // Theme.is-system) and keep the dropdown index (ThemeState.mode) in sync.
 export { Theme, ThemeColors } from "foundation/semantic-colors.slint";
 export { ThemeState } from "foundation/theme-state.slint";
+// Typography is exported for the Small-preset font compensation only: Rust
+// seeds `Typography.boost = 1.1` when the interface-size preset is Small.
+export { Typography } from "foundation/typography.slint";
 
 // Re-export the state globals so the Rust layer can populate them.
-export { HomeState, HomeActions, DiscoverState, DiscoverActions, SectionDescriptor, ConfigRow, DiscoverBrowseState, DiscoverBrowseActions, ForYouState, ExternalRecoState, ExternalRecoActions, MixState, GenreFilterState, GenreFilterActions, AlbumState, ArtistState, NavState, ShellState, SessionState, SettingsState, AlbumActions, ArtistActions, ArtworkActions, NowPlayingState, QueueState, LyricsState, LyricsLineItem, SearchState, SearchActions, NetworkSidebarState, NetworkSidebarActions, MusicianState, MusicianActions, LabelState, LabelActions, AwardState, AwardActions, AwardEntry, ArtistReleasesState, ArtistReleasesActions, LocationViewState, LocationViewActions, FavoritesState, FavoritesActions, PlaylistPickerState, PlaylistPickerActions, DuplicateConfirmState, DuplicateConfirmActions, PlaylistState, PlaylistActions, SidebarState, SidebarActions, SidebarFolderPopupState, CreatePlaylistState, CreatePlaylistActions, EditPlaylistState, EditPlaylistActions, CreateFolderState, CreateFolderActions, MyQbzCreateState, MyQbzCreateActions, DragState, DragActions, PlaylistManagerState, PlaylistManagerActions, OfflineManagerState, OfflineManagerActions, BlacklistState, BlacklistActions, BlacklistedArtistItem, MyQbzState, MyQbzActions, MixtapeCardItem, MyQbzAddState, MyQbzAddActions, MyQbzAddRow, MyQbzDetailState, MyQbzDetailActions, MixtapeDetailItem, MyQbzEditState, MyQbzEditActions, MyQbzMixState, MyQbzMixActions, DiscoBuilderState, DiscoBuilderActions, DiscoGroup, DiscoCandidate, LocalLibraryState, LocalLibraryActions, LibraryFoldersState, LibFolderEditState, LibraryManageActions, LibraryScanState, LibAlbumFilterState, LocalAlbumState, LocalAlbumActions, TagEditorState, TagEditorActions, FolderEditState, FolderEditActions, ToastState, TextUtil, QconnectDevState, QconnectDevice, CastState, CastDevice, CastActions, AppearanceState, MyQbzBrandingState, EphemeralPlayChoiceState, EphemeralPlayChoiceActions, PlexSettingsState, PlexAuthActions, PlexSectionItem, ScrobbleState, ScrobbleActions, DiscordState, OfflineState, OfflineModeActions, OfflineFavoritesState, OfflineFavoritesActions, ImportLogEntry, PlaylistImportState, PlaylistImportActions, DacWizardState, DacWizardActions, DacCandidateRow, RemediationRow, DacConfigRow, InfoCreditRow, InfoCreditPair, AlbumCreditPerformer, AlbumCreditTrack, TrackInfoState, TrackInfoActions, AlbumInfoState, AlbumInfoActions, BookletState, BookletActions, SuggestionsState, SuggestionsActions, SuggestionCard, PlaylistSuggestionsState, PlaylistSuggestionsActions, PlaylistSuggestionRow, VisualizerState, ImmersiveState, ImmersiveSearchActions, ImmersiveActions, MiniPlayerState, WindowControlActions, PurchasesState, PurchasesActions, PurchaseAlbumItem, PurchaseTrackItem, PurchaseAlbumGroup, PurchaseTrackGroup, PurchaseFormatItem, PurchaseDetailState, PurchaseDetailActions, PurchaseDetailTrack, KeybindingRow, KeybindingCategoryGroup, KeybindingsState, KeybindingsActions, KeyboardShortcutsState, LinkResolverState, LinkResolverActions, UiFocusState, SleepTimerState, SleepTimerActions, LogRow, LogViewerState, DiagRow, DiagnosticsState, ReportIssueState, ReportIssueActions, AboutState, AboutActions, AboutContributorRow, AboutContributorGroup, WhatsNewState, WhatsNewActions, WhatsNewBlock, WhatsNewTocEntry } from "state.slint";
+export { HomeState, HomeActions, DiscoverState, DiscoverActions, SectionDescriptor, ConfigRow, DiscoverBrowseState, DiscoverBrowseActions, ForYouState, ExternalRecoState, ExternalRecoActions, MixState, GenreFilterState, GenreFilterActions, AlbumState, ArtistState, NavState, ShellState, SessionState, SettingsState, AlbumActions, ArtistActions, ArtworkActions, NowPlayingState, QueueState, LyricsState, LyricsLineItem, SearchState, SearchActions, NetworkSidebarState, NetworkSidebarActions, MusicianState, MusicianActions, LabelState, LabelActions, AwardState, AwardActions, AwardEntry, ArtistReleasesState, ArtistReleasesActions, LocationViewState, LocationViewActions, FavoritesState, FavoritesActions, PlaylistPickerState, PlaylistPickerActions, DuplicateConfirmState, DuplicateConfirmActions, PlaylistState, PlaylistActions, SidebarState, SidebarActions, SidebarFolderPopupState, CreatePlaylistState, CreatePlaylistActions, EditPlaylistState, EditPlaylistActions, CreateFolderState, CreateFolderActions, MyQbzCreateState, MyQbzCreateActions, DragState, DragActions, PlaylistManagerState, PlaylistManagerActions, OfflineManagerState, OfflineManagerActions, BlacklistState, BlacklistActions, BlacklistedArtistItem, MyQbzState, MyQbzActions, MixtapeCardItem, MyQbzAddState, MyQbzAddActions, MyQbzAddRow, MyQbzDetailState, MyQbzDetailActions, MixtapeDetailItem, MyQbzEditState, MyQbzEditActions, MyQbzMixState, MyQbzMixActions, DiscoBuilderState, DiscoBuilderActions, DiscoGroup, DiscoCandidate, LocalLibraryState, LocalLibraryActions, LibraryFoldersState, LibFolderEditState, LibraryManageActions, LibraryScanState, LibAlbumFilterState, LocalAlbumState, LocalAlbumActions, TagEditorState, TagEditorActions, FolderEditState, FolderEditActions, ToastState, TextUtil, QconnectDevState, QconnectDevice, CastState, CastDevice, CastActions, AppearanceState, MyQbzBrandingState, EphemeralPlayChoiceState, EphemeralPlayChoiceActions, PlexSettingsState, PlexAuthActions, PlexSectionItem, ScrobbleState, ScrobbleActions, DiscordState, OfflineState, OfflineModeActions, OfflineFavoritesState, OfflineFavoritesActions, ImportLogEntry, PlaylistImportState, PlaylistImportActions, DacWizardState, DacWizardActions, DacCandidateRow, RemediationRow, DacConfigRow, InfoCreditRow, InfoCreditPair, AlbumCreditPerformer, AlbumCreditTrack, TrackInfoState, TrackInfoActions, AlbumInfoState, AlbumInfoActions, BookletState, BookletActions, SuggestionsState, SuggestionsActions, SuggestionCard, PlaylistSuggestionsState, PlaylistSuggestionsActions, PlaylistSuggestionRow, VisualizerState, ImmersiveState, ImmersiveSearchActions, ImmersiveActions, MiniPlayerState, WindowControlActions, PurchasesState, PurchasesActions, PurchaseAlbumItem, PurchaseTrackItem, PurchaseAlbumGroup, PurchaseTrackGroup, PurchaseFormatItem, PurchaseDetailState, PurchaseDetailActions, PurchaseDetailTrack, KeybindingRow, KeybindingCategoryGroup, KeybindingsState, KeybindingsActions, KeyboardShortcutsState, LinkResolverState, LinkResolverActions, UiFocusState, UiScale, SleepTimerState, SleepTimerActions, LogRow, LogViewerState, DiagRow, DiagnosticsState, ReportIssueState, ReportIssueActions, AboutState, AboutActions, AboutContributorRow, AboutContributorGroup, WhatsNewState, WhatsNewActions, WhatsNewBlock, WhatsNewTocEntry } from "state.slint";
 
 // Which top-level screen is shown. The app starts on `splash` while it
 // restores a saved session, then resolves to `shell` or `login`.
@@ -41,8 +44,11 @@ export component AppWindow inherits Window {
         : "QBZ";
     preferred-width: 1180px;
     preferred-height: 760px;
-    min-width: 940px;
+    // Divide the interface-size preset back out so the PHYSICAL minimum stays
-    min-height: 600px;
+    // constant across presets (a plain 940px logical minimum at the XL preset
+    // would be 1410 physical px — taller than a 1366x768 screen).
+    min-width: 940px / UiScale.factor;
+    min-height: 600px / UiScale.factor;
     background: Theme.surface-main;
 
     // Resolved by the Rust layer from the desktop environment (e.g. the

crates/qbz-ui/ui/foundation/typography.slint

@@ -1,18 +1,25 @@
 // Typography scale — font sizes and weights.
 
 export global Typography {
-    out property <length> legal: 13px;
+    // Small-preset font compensation. The interface-size preset scales the
-    out property <length> link: 14px;
+    // whole window (SLINT_SCALE_FACTOR), so at Small (0.8) body text would
-    out property <length> body: 15px;
+    // drop to 12px — too small. Rust seeds `boost = 1.1` for that preset
-    out property <length> subtitle: 15px;
+    // only (net body 15 × 0.8 × 1.1 ≈ 13.2px, readable); every other preset
-    out property <length> button: 17px;
+    // keeps 1.0. Layout metrics take the full 0.8 on purpose — the extra
+    // density is the point of Small.
+    in-out property <float> boost: 1.0;
+    out property <length> legal: 13px * boost;
+    out property <length> link: 14px * boost;
+    out property <length> body: 15px * boost;
+    out property <length> subtitle: 15px * boost;
+    out property <length> button: 17px * boost;
     // Canonical page / section title — Home section headings ("New
     // Releases", ...) and the hero titles on Album / Artist / Playlist
     // / Mixtape detail pages. One size for all, for consistency.
-    out property <length> section: 18px;
+    out property <length> section: 18px * boost;
-    out property <length> heading: 19px;
+    out property <length> heading: 19px * boost;
-    out property <length> title: 25px;
+    out property <length> title: 25px * boost;
-    out property <length> wordmark: 29px;
+    out property <length> wordmark: 29px * boost;
 
     out property <int> regular: 400;
     out property <int> medium: 500;

crates/qbz-ui/ui/settings/AppearanceSettings.slint

@@ -267,15 +267,15 @@ export component AppearanceSettings inherits VerticalLayout {
             }
         }
     }
-    // UI Scale — hidden per owner request (only the global scale factor works
+    // Interface size — the working replacement for the old percentage "UI
-    // for now). Code kept commented for re-enable; do NOT delete.
+    // Scale" placeholder that was parked here (commented, unwired). Window
-    /*
+    // scale-factor preset via SLINT_SCALE_FACTOR (main.rs); restart to apply.
     SettingRow {
-        unsupported: true;
+        label: @tr("Interface size");
-        label: @tr("UI Scale");
+        description: @tr("Scales the whole interface, like browser zoom. Small fits more content on screen, Large and Extra large improve readability (requires restart)");
         QbzSelect {
-            menu-width: 140px;
+            menu-width: 200px;
-            options: AppearanceState.ui-scales;
+            options: AppearanceState.ui-scale-options;
             current-index: AppearanceState.ui-scale-index;
             selected(i) => {
                 AppearanceState.ui-scale-index = i;
@@ -283,7 +283,6 @@ export component AppearanceSettings inherits VerticalLayout {
             }
         }
     }
-    */
 
     SettingRow {
         label: @tr("Immersive search");

crates/qbz-ui/ui/state.slint

@@ -2904,12 +2904,14 @@ export global AppearanceState {
     in-out property <string> auto-theme-detected-de: "";
 
     // --- TYPOGRAPHY / SCALE / LANGUAGE -------------------------------------
+    // NOTE: the old Tauri-style percentage `ui-scales` placeholder properties
+    // that lived here were superseded by the working interface-size presets
+    // (`ui-scale-options` / `ui-scale-index` in the INTERFACE SIZE block
+    // further down, wired to SLINT_SCALE_FACTOR in main.rs).
     in-out property <[string]> languages: [@tr("Auto"), "English", "Español", "Français", "Deutsch", "Português", "Русский", "日本語"];
     in-out property <int> language-index: 0;
     in-out property <[string]> fonts: ["LINE Seed JP", "Montserrat", "Noto Sans", "Source Sans 3", "System"];
     in-out property <int> font-index: 0;
-    in-out property <[string]> ui-scales: ["80%", "85%", "90%", "95%", "100%", "110%", "125%", "150%", "175%"];
-    in-out property <int> ui-scale-index: 4;
 
     // Immersive search action — what selecting a result in the Immersive search
     // cortinilla does (index: 0=Disabled, 1=Replace queue, 2=Play next,
@@ -3005,6 +3007,13 @@ export global AppearanceState {
     in-out property <[string]> renderer-options: [@tr("Auto (recommended)"), @tr("GPU"), @tr("GPU (compatibility)"), @tr("Software")];
     in-out property <int> renderer-index: 0;
 
+    // --- INTERFACE SIZE ----------------------------------------------------
+    // Window scale-factor preset (XS 0.8 / Small 0.9 / Default 1.0 /
+    // Large 1.2 / XL 1.5) — startup-time choice, restart to apply.
+    // Index 2 = Default.
+    in-out property <[string]> ui-scale-options: [@tr("Extra small"), @tr("Small"), @tr("Default"), @tr("Large"), @tr("Extra large")];
+    in-out property <int> ui-scale-index: 2;
+
     // --- IMMERSIVE ---------------------------------------------------------
     in-out property <[string]> immersive-views: [
         @tr("Remember last used"), @tr("Coverflow"), @tr("Static"), @tr("Vinyl"), @tr("Visualizer"),
@@ -3619,6 +3628,15 @@ export global LocationViewActions {
     callback load-more();
 }
 
+// Interface-size preset (UI scale). Seeded once from Rust before the shell
+// renders. The actual scaling happens through the window scale factor
+// (SLINT_SCALE_FACTOR set in main.rs) — this global only lets bindings that
+// must stay PHYSICALLY constant divide the preset back out (e.g. the window
+// minimums, so an XL window still fits a 1366x768 screen).
+export global UiScale {
+    in-out property <float> factor: 1.0;
+}
+
 // Shell chrome state — collapsible left sidebar and right-side panels.
 // Globals are imported directly by the shell components, so toggles
 // need no callback plumbing.

crates/qbz/src/artwork.rs

@@ -23,6 +23,22 @@ const MAX_CONCURRENT: usize = 16;
 /// modest DPI without holding full ~600px source textures in memory.
 const DECODE_SIZE: u32 = 264;
 
+/// Interface-size preset multiplier for decode targets, set ONCE at startup
+/// (main.rs, before any artwork job runs). Under a scaled UI every card gets
+/// `preset ×` more physical pixels, so decode sizes must grow with it or
+/// covers go soft at Large/XL; Small shrinks them, saving decoded-cache RAM.
+static UI_SCALE_FACTOR: std::sync::OnceLock<f32> = std::sync::OnceLock::new();
+
+pub fn set_ui_scale_factor(factor: f32) {
+    let _ = UI_SCALE_FACTOR.set(factor);
+}
+
+/// Scale a base decode size by the interface-size preset, rounded up.
+pub fn scaled_decode(base: u32) -> u32 {
+    let factor = UI_SCALE_FACTOR.get().copied().unwrap_or(1.0);
+    (base as f32 * factor).ceil() as u32
+}
+
 /// Default image-cache size budget (matches the Tauri default).
 pub const MAX_CACHE_BYTES: u64 = 200 * 1024 * 1024;
 
@@ -241,7 +257,7 @@ impl ArtworkTarget {
     /// huge buffers in the model — a 2000-row playlist would hold
     /// hundreds of MB. Decode row thumbnails small.
     fn decode_size(&self) -> u32 {
-        match self {
+        scaled_decode(match self {
             ArtworkTarget::SearchTrack { .. }
             | ArtworkTarget::FavoriteTrack { .. }
             | ArtworkTarget::MixTrack { .. }
@@ -261,7 +277,7 @@ impl ArtworkTarget {
             // Detail list-row thumbnails render at 36px.
             ArtworkTarget::MyQbzDetailRow { .. } => 96,
             _ => DECODE_SIZE,
-        }
+        })
     }
 }
 

crates/qbz/src/main.rs

@@ -293,6 +293,11 @@ fn seed_tray_appearance(w: &AppWindow, tray: &tray_settings::TraySettings) {
     appearance.set_renderer_index(crate::ui_prefs::renderer_index(
         &crate::ui_prefs::load().renderer,
     ));
+    // Interface-size row (all platforms). Same choke point as the renderer
+    // row so the dropdown always reflects the persisted value.
+    appearance.set_ui_scale_index(crate::ui_prefs::ui_scale_index(
+        &crate::ui_prefs::load().ui_scale,
+    ));
 }
 
 /// Refresh the blacklist count + enabled flag on `BlacklistState` (T10).
@@ -1097,13 +1102,16 @@ fn install_browser_mouse_nav(window: &AppWindow) {
             // (mirrors miniplayer.rs). The startup restore clamps to the
             // monitor; here we just record what the WM settled on. A change
             // guard avoids redundant writes on the many no-op events the WM
-            // emits. The app minimum is 940x600 (app.slint) — ignore smaller
+            // emits. The app minimum is 940x600 PHYSICAL-equivalent — the
-            // frames (minimize reports 0x0, mid-transition frames undershoot).
+            // .slint mins divide the interface-size preset out, so the
+            // LOGICAL minimum scales with it (XL windows sit well below 940
+            // logical). Ignore smaller frames (minimize reports 0x0,
+            // mid-transition frames undershoot).
             WindowEvent::Resized(size) => {
                 let scale = slint_window.scale_factor().max(0.01) as f64;
                 let lw = (size.width as f64 / scale) as f32;
                 let lh = (size.height as f64 / scale) as f32;
-                if lw >= 940.0 && lh >= 600.0 {
+                if lw >= 940.0 / active_ui_scale() && lh >= 600.0 / active_ui_scale() {
                     let mut prefs = crate::ui_prefs::load();
                     if (prefs.window_width - lw).abs() > 0.5
                         || (prefs.window_height - lh).abs() > 0.5
@@ -5744,11 +5752,48 @@ fn poll_ready<F: std::future::Future>(fut: F) -> Option<F::Output> {
     }
 }
 
+/// Interface-size preset factor active for THIS process run. The persisted
+/// pref can change mid-session (Settings dropdown), but the window scale only
+/// applies on restart — geometry math must use the factor the window was
+/// actually created with, so read this, not the pref.
+static ACTIVE_UI_SCALE: std::sync::OnceLock<f32> = std::sync::OnceLock::new();
+
+fn active_ui_scale() -> f32 {
+    ACTIVE_UI_SCALE.get().copied().unwrap_or(1.0)
+}
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // UI SCALE PRESET — must run FIRST: SLINT_SCALE_FACTOR has to be in the
+    // environment before the backend/window exist (winit reads it at window
+    // creation), and `set_var` must run before any thread spawns (the tokio
+    // runtime below). The env var OVERRIDES the compositor DPR rather than
+    // multiplying it, so the last observed real DPR is baked into the value
+    // (see `last_dpr` in ui_prefs). Default preset => the var is NOT set at
+    // all: stock DPR handling (incl. live monitor changes) stays intact.
+    let ui_scale_factor = {
+        let prefs = crate::ui_prefs::load();
+        let factor = crate::ui_prefs::ui_scale_factor(&prefs.ui_scale);
+        if factor != 1.0 {
+            let effective = prefs.last_dpr.max(0.5) * factor;
+            std::env::set_var("SLINT_SCALE_FACTOR", effective.to_string());
+        }
+        let _ = ACTIVE_UI_SCALE.set(factor);
+        factor
+    };
+
     // Composite logger: stderr (unchanged) + a bounded in-memory ring + an on-disk
     // file, all redacted at the write choke point. Feeds the in-app log viewer and
     // the diagnostics bundle. Honours RUST_LOG (default "info").
     qbz_log::install("info");
+    if ui_scale_factor != 1.0 {
+        log::info!(
+            "[ui-scale] preset factor {ui_scale_factor} -> SLINT_SCALE_FACTOR={}",
+            std::env::var("SLINT_SCALE_FACTOR").unwrap_or_default()
+        );
+    }
+    // Artwork decode targets grow with the preset so covers stay sharp at
+    // Large/XL (and shrink RAM at Small). Set before any artwork job runs.
+    crate::artwork::set_ui_scale_factor(ui_scale_factor);
 
     // Install the rustls process-level CryptoProvider ONCE, before ANY TLS use.
     // The full binary compiles BOTH rustls providers (aws-lc-rs via qbz-cast's
@@ -5816,11 +5861,30 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     // for a few seconds (renderer/driver init crashes happen at or shortly
     // after realization; surviving this long counts as a working renderer).
     // Single-shot timer — the binding must outlive this scope's run loop.
+    // Piggybacked: persist the REAL compositor DPR as `last_dpr` (the surface
+    // is mapped by now, so winit reports the true value — unlike right after
+    // creation on Wayland). Read from the WINIT window, not the Slint one:
+    // SLINT_SCALE_FACTOR overrides Slint's factor but winit still sees the
+    // compositor's. The next scaled launch bakes this into the env value.
     let _renderer_sentinel_timer = slint::Timer::default();
+    let sentinel_weak = window.as_weak();
     _renderer_sentinel_timer.start(
         slint::TimerMode::SingleShot,
         std::time::Duration::from_secs(5),
-        clear_renderer_sentinel,
+        move || {
+            clear_renderer_sentinel();
+            if let Some(w) = sentinel_weak.upgrade() {
+                w.window().with_winit_window(|win| {
+                    let real_dpr = win.scale_factor() as f32;
+                    let mut prefs = crate::ui_prefs::load();
+                    if real_dpr > 0.1 && (prefs.last_dpr - real_dpr).abs() > 0.01 {
+                        log::info!("[ui-scale] observed compositor DPR {real_dpr} -> persisted");
+                        prefs.last_dpr = real_dpr;
+                        crate::ui_prefs::save(&prefs);
+                    }
+                });
+            }
+        },
     );
     // Now that the AppWindow (and its translation global context) exists, switch
     // the Slint bundled translations to `lang` and reseed the non-reactive
@@ -5840,6 +5904,16 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     window
         .global::<ShellState>()
         .set_reduce_motion(!use_gpu_renderer);
+    // Interface-size preset: publish the factor so `.slint` bindings that must
+    // stay physically constant (the window minimums) can divide it back out.
+    // Extra small also gets the font compensation: a plain 0.8 drops body text
+    // to 12px; boosting Typography tokens ~10% lands at ~13px (readable) while
+    // layout metrics keep the full 0.8 — that density is the point of XS.
+    // Small (0.9) needs none: body lands at 13.5px on its own.
+    window.global::<UiScale>().set_factor(ui_scale_factor);
+    if ui_scale_factor < 0.85 {
+        window.global::<Typography>().set_boost(1.1);
+    }
     // Diagnostic for the circle-AA investigation (and the future UI-scale
     // presets): femtovg's fringe AA halves at fractional scale factors
     // (internal dpi = ceil(scale)), so knowing the real factor matters.
@@ -5894,21 +5968,36 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     // Main window geometry: restore the persisted LOGICAL size + (best-effort)
     // position, each clamped to the current monitor so a smaller / disconnected
     // display never opens an oversized or stranded window. 0 size = never saved
-    // → keep the `.slint` preferred size. The monitor query is best-effort
+    // → keep the `.slint` preferred size, EXCEPT under a >1 interface-size
-    // (`with_winit_window` returns None before the surface exists → the WM's own
+    // preset, where even the preferred size may exceed a small monitor once the
-    // clamping is the fallback, and the Resized handler re-saves the result).
+    // preset multiplies it — clamp it exactly like a restored one. Monitor
-    if restored_prefs.window_width >= 940.0 && restored_prefs.window_height >= 600.0 {
+    // sizes are divided by the SLINT scale factor (the effective, preset-baked
-        let mut w = restored_prefs.window_width;
+    // one); winit's own factor is the raw compositor DPR and under-clamps when
-        let mut h = restored_prefs.window_height;
+    // a preset is active. The minimum is physically constant across presets
+    // (mirrors the `/ UiScale.factor` bindings in app.slint). The monitor query
+    // is best-effort (`with_winit_window` returns None before the surface
+    // exists → the WM's own clamping is the fallback, and the Resized handler
+    // re-saves the result).
+    let min_logical_w = 940.0 / ui_scale_factor;
+    let min_logical_h = 600.0 / ui_scale_factor;
+    // Plausibility gate for the persisted size: at least the scaled minimum,
+    // but never stricter than the historical 940x600 (so sizes saved under a
+    // previous, less-scaled preset still restore — the .slint mins clamp them
+    // up if the current preset needs more).
+    let has_saved_size = restored_prefs.window_width >= min_logical_w.min(940.0)
+        && restored_prefs.window_height >= min_logical_h.min(600.0);
+    if has_saved_size || ui_scale_factor > 1.0 {
+        let mut w = if has_saved_size { restored_prefs.window_width } else { 1180.0 };
+        let mut h = if has_saved_size { restored_prefs.window_height } else { 760.0 };
+        let slint_scale = (window.window().scale_factor() as f64).max(0.01);
         window.window().with_winit_window(|win| {
             if let Some(mon) = win.current_monitor() {
-                let scale = win.scale_factor().max(0.01);
+                let avail_w = (mon.size().width as f64 / slint_scale) as f32;
-                let avail_w = (mon.size().width as f64 / scale) as f32;
+                let avail_h = (mon.size().height as f64 / slint_scale) as f32;
-                let avail_h = (mon.size().height as f64 / scale) as f32;
+                if avail_w >= min_logical_w {
-                if avail_w >= 940.0 {
                     w = w.min(avail_w);
                 }
-                if avail_h >= 600.0 {
+                if avail_h >= min_logical_h {
                     h = h.min(avail_h);
                 }
             }
@@ -8255,6 +8344,19 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                     qbz_i18n::t("Renderer changed — restart QBZ to apply"),
                 );
             }
+            "ui-scale" => {
+                // 0 = Extra small, 1 = Small, 2 = Default, 3 = Large,
+                // 4 = Extra large. Startup-time choice — SLINT_SCALE_FACTOR is
+                // set at the very top of main() before the backend exists, so
+                // it applies on the next launch.
+                let mut prefs = crate::ui_prefs::load();
+                prefs.ui_scale = crate::ui_prefs::ui_scale_for_index(index).to_string();
+                crate::ui_prefs::save(&prefs);
+                crate::toast::info_weak(
+                    &theme_weak,
+                    qbz_i18n::t("Interface size changed — restart QBZ to apply"),
+                );
+            }
             "language" => {
                 // 0 = Auto, 1 = English, 2 = Español, 3 = Français, 4 = Deutsch,
                 // 5 = Português, 6 = Русский, 7 = 日本語. Persist the RAW user

crates/qbz/src/offline_favorites.rs

@@ -141,7 +141,10 @@ pub fn load(weak: slint::Weak<AppWindow>, handle: tokio::runtime::Handle) {
                 id: t.track_id.to_string(),
                 title: t.title.clone(),
                 artist: t.artist.clone(),
-                cover: crate::artwork::decode_local_pixels(&cover, COVER_DECODE_SIZE),
+                cover: crate::artwork::decode_local_pixels(
+                    &cover,
+                    crate::artwork::scaled_decode(COVER_DECODE_SIZE),
+                ),
             });
         }
         for lt in &lib_rows {
@@ -158,7 +161,7 @@ pub fn load(weak: slint::Weak<AppWindow>, handle: tokio::runtime::Handle) {
                 artist: lt.artist.clone(),
                 cover: crate::artwork::decode_local_pixels(
                     lt.artwork_path.as_deref().unwrap_or_default(),
-                    COVER_DECODE_SIZE,
+                    crate::artwork::scaled_decode(COVER_DECODE_SIZE),
                 ),
             });
         }

crates/qbz/src/offline_manager.rs

@@ -230,7 +230,10 @@ pub async fn rebuild(weak: slint::Weak<AppWindow>) {
             ),
             status: album_status,
             progress: 0.0,
-            cover: crate::artwork::decode_local_pixels(&cover_path, COVER_DECODE_SIZE),
+            cover: crate::artwork::decode_local_pixels(
+                &cover_path,
+                crate::artwork::scaled_decode(COVER_DECODE_SIZE),
+            ),
             number: String::new(),
         });
         for (i, t) in group.iter().enumerate() {

crates/qbz/src/ui_prefs.rs

@@ -183,6 +183,41 @@ pub fn renderer_index(key: &str) -> i32 {
     }
 }
 
+/// Interface-size select index (0 = Extra small, 1 = Small, 2 = Default,
+/// 3 = Large, 4 = Extra large) -> persisted key. Unknown indices fall back
+/// to "default".
+pub fn ui_scale_for_index(index: i32) -> &'static str {
+    match index {
+        0 => "xs",
+        1 => "small",
+        3 => "large",
+        4 => "xl",
+        _ => "default",
+    }
+}
+
+/// Inverse: select index for a persisted interface-size key.
+pub fn ui_scale_index(key: &str) -> i32 {
+    match key {
+        "xs" => 0,
+        "small" => 1,
+        "large" => 3,
+        "xl" => 4,
+        _ => 2,
+    }
+}
+
+/// Numeric window-scale multiplier for a persisted interface-size key.
+pub fn ui_scale_factor(key: &str) -> f32 {
+    match key {
+        "xs" => 0.8,
+        "small" => 0.9,
+        "large" => 1.2,
+        "xl" => 1.5,
+        _ => 1.0,
+    }
+}
+
 /// Miniplayer default-view select index -> persisted key (mirrors the
 /// miniplayer's own reader in `miniplayer.rs`). 0 = "remember".
 pub fn mini_default_view_for_index(index: i32) -> &'static str {
@@ -427,6 +462,18 @@ pub struct UiPrefs {
     /// window comes up, the next start reverts this to "auto".
     #[serde(default = "default_renderer")]
     pub renderer: String,
+    /// Interface-size preset: `"default"` | `"small"` | `"large"` | `"xl"`.
+    /// Read at the very top of main() (before ANY thread exists) to set
+    /// SLINT_SCALE_FACTOR, so changes apply on restart.
+    #[serde(default = "default_ui_scale")]
+    pub ui_scale: String,
+    /// Last observed compositor device-pixel-ratio. SLINT_SCALE_FACTOR
+    /// OVERRIDES the compositor DPR (it does not multiply), so a scaled
+    /// launch must bake the real DPR into the env value itself:
+    /// `env = last_dpr × preset`. Refreshed a few seconds after the window
+    /// maps (winit reports the real compositor value there).
+    #[serde(default = "default_last_dpr")]
+    pub last_dpr: f32,
 }
 
 /// Sentinel for "no saved window position" (let the WM place the window).
@@ -438,6 +485,14 @@ fn default_renderer() -> String {
     "auto".to_string()
 }
 
+fn default_ui_scale() -> String {
+    "default".to_string()
+}
+
+fn default_last_dpr() -> f32 {
+    1.0
+}
+
 fn default_mini_surface() -> i32 {
     2
 }
@@ -566,6 +621,8 @@ impl Default for UiPrefs {
             window_x: default_window_pos(),
             window_y: default_window_pos(),
             renderer: default_renderer(),
+            ui_scale: default_ui_scale(),
+            last_dpr: default_last_dpr(),
         }
     }
 }