feat(library): album-identity mode — header dropdown, Settings row, persistence

Spec 2026-07-19-local-album-grouping-mode (A2-A5 + i18n). The Albums tab
gains a third header dropdown ('Albums by folder' / 'Albums by metadata')
and Settings > Local Library a matching 'Album grouping' row — both write
the same pref: LocalLibraryState.albums-id-mode, persisted in
locallibrary_ui.json (default 'folder': compilations and box sets stay
whole; the metadata split stays opt-in for #411's use case).

The group key changes with the mode, so switching reloads the Albums set
(reload_albums) and invalidates the Artists tab (its album cache groups
the same way — a folder-mode compilation cross-lists under every artist
in all_artists, the owner's 'appears in all artists' ask). Threaded
through spawn_albums_load, seed_counts, the Plex quality-hydration
aggregate lookup, and the artists feed; myqbz_builder pins Metadata
(artist-scoped candidates, not the Albums view).

5 msgids x 8 locales (msgfmt clean); slintcheck green.

km

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

@@ -4750,3 +4750,18 @@ msgstr "Begrenzt durch das Qualitätslimit für {}"
 
 msgid "capped for this device"
 msgstr "für dieses Gerät begrenzt"
+
+msgid "Albums by folder"
+msgstr "Alben nach Ordner"
+
+msgid "Albums by metadata"
+msgstr "Alben nach Metadaten"
+
+msgid "ALBUMS VIEW"
+msgstr "ALBENANSICHT"
+
+msgid "Album grouping"
+msgstr "Album-Gruppierung"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "Ordner: eine Karte pro Album-Ordner — ideal für Compilations und Boxsets. Metadaten: nach Album- + Künstler-Tags aufteilen."

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

@@ -543,3 +543,18 @@ msgstr "Limited by the quality cap for {}"
 
 msgid "capped for this device"
 msgstr "capped for this device"
+
+msgid "Albums by folder"
+msgstr "Albums by folder"
+
+msgid "Albums by metadata"
+msgstr "Albums by metadata"
+
+msgid "ALBUMS VIEW"
+msgstr "ALBUMS VIEW"
+
+msgid "Album grouping"
+msgstr "Album grouping"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."

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

@@ -4780,3 +4780,18 @@ msgstr "Limitado por el límite de calidad para {}"
 
 msgid "capped for this device"
 msgstr "limitado para este dispositivo"
+
+msgid "Albums by folder"
+msgstr "Álbumes por carpeta"
+
+msgid "Albums by metadata"
+msgstr "Álbumes por metadatos"
+
+msgid "ALBUMS VIEW"
+msgstr "VISTA DE ÁLBUMES"
+
+msgid "Album grouping"
+msgstr "Agrupación de álbumes"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "Carpetas: una tarjeta por carpeta de álbum — ideal para compilaciones y box sets. Metadatos: separar por etiquetas de álbum + artista."

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

@@ -4750,3 +4750,18 @@ msgstr "Limité par le plafond de qualité pour {}"
 
 msgid "capped for this device"
 msgstr "plafonné pour cet appareil"
+
+msgid "Albums by folder"
+msgstr "Albums par dossier"
+
+msgid "Albums by metadata"
+msgstr "Albums par métadonnées"
+
+msgid "ALBUMS VIEW"
+msgstr "VUE ALBUMS"
+
+msgid "Album grouping"
+msgstr "Regroupement des albums"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "Dossiers : une carte par dossier d'album — idéal pour les compilations et coffrets. Métadonnées : séparer par tags album + artiste."

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

@@ -4738,3 +4738,18 @@ msgstr "{}の音質上限により制限されています"
 
 msgid "capped for this device"
 msgstr "このデバイス向けに上限適用中"
+
+msgid "Albums by folder"
+msgstr "フォルダー別アルバム"
+
+msgid "Albums by metadata"
+msgstr "メタデータ別アルバム"
+
+msgid "ALBUMS VIEW"
+msgstr "アルバムビュー"
+
+msgid "Album grouping"
+msgstr "アルバムのグループ化"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "フォルダー: アルバムフォルダーごとに1枚のカード — コンピレーションやボックスセットに最適。メタデータ: アルバム+アーティストのタグで分割。"

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

@@ -4762,3 +4762,18 @@ msgstr "Beperkt door de kwaliteitslimiet voor {}"
 
 msgid "capped for this device"
 msgstr "begrensd voor dit apparaat"
+
+msgid "Albums by folder"
+msgstr "Albums per map"
+
+msgid "Albums by metadata"
+msgstr "Albums per metadata"
+
+msgid "ALBUMS VIEW"
+msgstr "ALBUMWEERGAVE"
+
+msgid "Album grouping"
+msgstr "Albumgroepering"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "Mappen: één kaart per albummap — ideaal voor compilaties en boxsets. Metadata: splitsen op album- + artiesttags."

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

@@ -4750,3 +4750,18 @@ msgstr "Limitado pelo limite de qualidade para {}"
 
 msgid "capped for this device"
 msgstr "limitado para este dispositivo"
+
+msgid "Albums by folder"
+msgstr "Álbuns por pasta"
+
+msgid "Albums by metadata"
+msgstr "Álbuns por metadados"
+
+msgid "ALBUMS VIEW"
+msgstr "VISTA DE ÁLBUNS"
+
+msgid "Album grouping"
+msgstr "Agrupamento de álbuns"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "Pastas: um cartão por pasta de álbum — ideal para compilações e box sets. Metadados: dividir por etiquetas de álbum + artista."

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

@@ -4764,3 +4764,18 @@ msgstr "Ограничено пределом качества для {}"
 
 msgid "capped for this device"
 msgstr "ограничено для этого устройства"
+
+msgid "Albums by folder"
+msgstr "Альбомы по папкам"
+
+msgid "Albums by metadata"
+msgstr "Альбомы по метаданным"
+
+msgid "ALBUMS VIEW"
+msgstr "ВИД АЛЬБОМОВ"
+
+msgid "Album grouping"
+msgstr "Группировка альбомов"
+
+msgid "Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags."
+msgstr "Папки: одна карточка на папку альбома — лучше для сборников и бокс-сетов. Метаданные: разделение по тегам альбома + исполнителя."

crates/qbz-ui/ui/locallibrary/LocalLibraryView.slint

@@ -838,6 +838,25 @@ export component LocalLibraryView inherits Rectangle {
                         }
                     }
                 }
+                // Album identity ("Albums by") — what one album IS: a folder
+                // (compilations/box sets stay whole) or metadata tag pairs
+                // (split per album+artist, #411). Persisted; reloads the set.
+                VerticalLayout {
+                    alignment: center;
+                    QbzSelect {
+                        menu-width: 190px;
+                        sm: true;
+                        options: [
+                            @tr("Albums by folder"),
+                            @tr("Albums by metadata"),
+                        ];
+                        current-index: LocalLibraryState.albums-id-mode == "metadata" ? 1 : 0;
+                        selected(i) => {
+                            LocalLibraryActions.albums-set-id-mode(
+                                i == 1 ? "metadata" : "folder");
+                        }
+                    }
+                }
                 // Quality/format/source filter (popup) + active-count badge.
                 VerticalLayout {
                     alignment: center;

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

@@ -9,11 +9,12 @@
 import { Theme } from "../foundation/semantic-colors.slint";
 import { Typography } from "../foundation/typography.slint";
 import { Radius } from "../foundation/radius.slint";
-import { LibraryFoldersState, LibraryManageActions, LibraryScanState, PlexSettingsState, PlexAuthActions , UiFocusState } from "../state.slint";
+import { LibraryFoldersState, LibraryManageActions, LibraryScanState, PlexSettingsState, PlexAuthActions , UiFocusState, LocalLibraryState, LocalLibraryActions } from "../state.slint";
 import { SettingRow } from "SettingRow.slint";
 import { QbzIcon } from "../primitives/QbzIcon.slint";
 import { QbzCheckbox } from "../primitives/QbzCheckbox.slint";
 import { QbzToggle } from "../primitives/QbzToggle.slint";
+import { QbzSelect } from "../primitives/QbzSelect.slint";
 import { ExpandableSearch } from "../primitives/ExpandableSearch.slint";
 import { ScrollView, LineEdit } from "std-widgets.slint";
 
@@ -421,6 +422,32 @@ export component LocalLibrarySettings inherits VerticalLayout {
 
     Rectangle { height: 22px; }
 
+    // --- Albums view -------------------------------------------------------
+    // Same pref as the Albums-tab header dropdown — this is the discoverable
+    // home, the header is the quick switch (both write albums-id-mode).
+    GroupHeader { text: @tr("ALBUMS VIEW"); }
+    SettingRow {
+        label: @tr("Album grouping");
+        description: @tr("Folders: one card per album folder — best for compilations and box sets. Metadata: split by album + artist tags.");
+        VerticalLayout {
+            alignment: center;
+            QbzSelect {
+                menu-width: 190px;
+                sm: true;
+                options: [
+                    @tr("Albums by folder"),
+                    @tr("Albums by metadata"),
+                ];
+                current-index: LocalLibraryState.albums-id-mode == "metadata" ? 1 : 0;
+                selected(i) => {
+                    LocalLibraryActions.albums-set-id-mode(i == 1 ? "metadata" : "folder");
+                }
+            }
+        }
+    }
+
+    Rectangle { height: 22px; }
+
     // --- Maintenance -----------------------------------------------------
     GroupHeader { text: @tr("MAINTENANCE"); }
     SettingRow {

crates/qbz-ui/ui/state.slint

@@ -1194,6 +1194,12 @@ export global LocalLibraryState {
     in property <[AlbumCardItem]> albums-visible: [];
     in property <[DiscoverSection]> albums-grouped: [];
     in-out property <string> albums-group: "off";        // off | alpha | artist
+    // Album IDENTITY mode — what one "album" IS on the Albums tab:
+    // "folder" (one card per album-root folder; default — compilations/box
+    // sets stay whole) | "metadata" (split by album+artist tags, #411).
+    // Persisted in locallibrary_ui.json; switching re-queries the DB (unlike
+    // sort/group, which re-derive client-side).
+    in-out property <string> albums-id-mode: "folder";
     in property <[AlphaJump]> albums-alpha: [];           // A-Z jumps (alpha group)
     in property <int> albums-shown: 0;                    // count after filter
     in-out property <bool> albums-multi-select: false;    // album checkboxes on
@@ -1318,6 +1324,9 @@ export global LocalLibraryActions {
     callback albums-set-sort(string /* sort key */);
     // Set group mode (off|alpha|artist) + re-derive.
     callback albums-set-group(string /* mode */);
+    // Set the album identity mode (folder|metadata) + persist + reload the
+    // albums set (the group key changes — a derive is not enough).
+    callback albums-set-id-mode(string /* mode */);
     // Set grid|list view.
     callback albums-set-view(string /* mode */);
     // A quality/format/source filter toggle changed -> re-derive.