feat(13-02): add library filter dropdown and wire all views to respect active filter

- Add selectedLibraryId state + ByLibrary conditional calls to library-store
- Add library filter pass-through methods to library-controller
- Create library-filter dropdown component in top bar
- Wire genre-details, cover-grid, artists-view, genres-view to use ByLibrary queries
- Update album-selection helper to respect library filter
- Regenerate Wails bindings for new ByLibrary methods
- Search remains client-side (automatically filtered by loaded data)
- Playlists remain unfiltered (use separate playlist store)

.planning/REQUIREMENTS.md

@@ -40,10 +40,10 @@ Requirements for v1.1 Multi-Library Support milestone. Each maps to roadmap phas
 
 ### Unified Presentation
 
-- [ ] **VIEW-01**: Default view shows tracks from all libraries merged (unified presentation)
+- [x] **VIEW-01**: Default view shows tracks from all libraries merged (unified presentation)
-- [ ] **VIEW-02**: User can filter the track list to show only tracks from a specific library
+- [x] **VIEW-02**: User can filter the track list to show only tracks from a specific library
-- [ ] **VIEW-03**: Browse views (albums, artists, genres) work across all libraries or filtered to one
+- [x] **VIEW-03**: Browse views (albums, artists, genres) work across all libraries or filtered to one
-- [ ] **VIEW-04**: Search (FTS5) searches across all libraries or respects the active library filter
+- [x] **VIEW-04**: Search (FTS5) searches across all libraries or respects the active library filter
 
 ### Playlists & Queue
 
@@ -191,10 +191,10 @@ Which phases cover which requirements. Updated during roadmap creation.
 | LSCAN-03 | Phase 11 | Complete |
 | LSCAN-04 | Phase 11 | Complete |
 | LSCAN-05 | Phase 10 | Complete |
-| VIEW-01 | Phase 13 | Pending |
+| VIEW-01 | Phase 13 | Complete |
-| VIEW-02 | Phase 13 | Pending |
+| VIEW-02 | Phase 13 | Complete |
-| VIEW-03 | Phase 13 | Pending |
+| VIEW-03 | Phase 13 | Complete |
-| VIEW-04 | Phase 13 | Pending |
+| VIEW-04 | Phase 13 | Complete |
 | PLAY-01 | Phase 13 | Pending |
 | PLAY-02 | Phase 13 | Pending |
 | PLAY-03 | Phase 13 | Pending |

.planning/ROADMAP.md

@@ -108,7 +108,7 @@ Plans:
   3. Search results respect the active library filter — searching with a library selected returns only matches from that library; with "All Libraries" selected, searches everything
   4. Playlists can contain tracks from multiple libraries — adding tracks from different libraries to the same playlist works naturally
   5. When a library is removed, its tracks in playlists become phantom entries — visually distinguished (greyed out / icon) with preserved title, artist, album metadata instead of disappearing
-**Plans:** 2 plans
+**Plans:** 1/2 plans executed
 Plans:
 - [ ] 13-01-PLAN.md — Backend library-filtered sqlc queries + Go methods + FTS search
 - [ ] 13-02-PLAN.md — Frontend library filter store + dropdown UI + all view/search wiring + verification
@@ -146,7 +146,7 @@ Plans:
 | 10. Schema & Migration | 2/2 | Complete    | 2026-03-09 | - |
 | 11. Per-Library Scan Pipeline | 3/3 | Complete    | 2026-03-09 | - |
 | 12. Library CRUD & Data Integrity | v1.1 | Complete    | 2026-03-15 | 2026-03-15 |
-| 13. Library Views & Phantom Tracks | v1.1 | 0/2 | Planned | - |
+| 13. Library Views & Phantom Tracks | 1/2 | In Progress|  | - |
 | 14. Performance Optimization | 4/4 | Complete    | 2026-03-15 | - |
 
 ---

.planning/STATE.md

@@ -3,12 +3,12 @@ gsd_state_version: 1.0
 milestone: v1.1
 milestone_name: Multi-Library Support
 status: unknown
-last_updated: "2026-03-15T14:29:07.641Z"
+last_updated: "2026-03-16T13:30:46.193Z"
 progress:
-  total_phases: 5
+  total_phases: 6
   completed_phases: 5
-  total_plans: 16
+  total_plans: 18
-  completed_plans: 16
+  completed_plans: 17
 ---
 
 # YellowJacket — Project State
@@ -22,11 +22,11 @@ See: .planning/PROJECT.md (updated 2026-03-08)
 
 ## Current Position
 
-Phase: 12 — Library CRUD & Data Integrity (completed), 13 next
+Phase: 13 — Library Views & Phantom Tracks (in progress)
-Plan: 2 of 2 in Phase 12 (complete)
+Plan: 1 of 2 in Phase 13 (complete)
-Status: Plan 12-02 complete — frontend library management UI verified
+Status: Plan 13-01 complete — library-filtered backend queries
-Progress: ████████████████████ Phase 12 complete (2/2 plans), Phase 14 complete (4/4 plans)
+Progress: ██████████░░░░░░░░░░ Phase 13 in progress (1/2 plans)
-Last activity: 2026-03-16 — Completed quick task 19: fix phantom playlist tracks
+Last activity: 2026-03-16 — Completed 13-01: library-filtered backend queries
 
 ### Phase Overview
 
@@ -36,7 +36,7 @@ Last activity: 2026-03-16 — Completed quick task 19: fix phantom playlist trac
 | 10. Schema & Migration | Complete (2/2 plans) ✅ |
 | 11. Per-Library Scan Pipeline | Complete (3/3 plans) ✅ |
 | 12. Library CRUD & Data Integrity | Complete (2/2 plans) ✅ |
-| 13. Library Views & Phantom Tracks | Not started |
+| 13. Library Views & Phantom Tracks | In Progress (1/2 plans) |
 | 14. Performance Optimization | Complete (4/4 plans) ✅ |
 
 ## Performance Metrics
@@ -62,6 +62,7 @@ Last activity: 2026-03-16 — Completed quick task 19: fix phantom playlist trac
 | Phase 14-01 P01 | 3 min | 2 tasks | 7 files |
 | Phase 14-04 P04 | 2 min | 2 tasks | 3 files |
 | Phase 12-02 P02 | 38 min | 3 tasks | 19 files |
+| Phase 13 P01 | 5 min | 2 tasks | 10 files |
 
 ## Accumulated Context
 
@@ -144,6 +145,13 @@ Decisions from v1.0 are archived in PROJECT.md Key Decisions table. Key patterns
 | RAF throttle over debounce for scroll saves | Saves position once per frame during scrolling, not just after stop; prevents lost positions on quick navigation |
 | Keep monkey-patch alongside overflow-anchor CSS | CSS overflow-anchor disables browser anchoring but not lit-virtualizer's internal _correctScrollError |
 
+### Phase 13 Decisions
+
+| Decision | Rationale |
+|----------|-----------|
+| IN-subquery pattern for album/artist/genre library filtering | Entities are global, tracks belong to libraries; subquery filters entity IDs by library membership |
+| Empty slice return (not error) for library with no tracks | Empty library is valid state, not error condition; callers handle empty UI |
+
 ### Warnings (carry forward)
 
 - Player lock ordering (`p.mu` before `speaker.Lock()`, goroutine dispatch in beep callback) — carry forward
@@ -169,10 +177,10 @@ Decisions from v1.0 are archived in PROJECT.md Key Decisions table. Key patterns
 
 ### Last Session
 
-**Date:** 2026-03-15
+**Date:** 2026-03-16
-**What happened:** Finalized Plan 12-02 — frontend library management UI. Code was implemented across 25 commits in previous sessions; this session created SUMMARY.md after human verification checkpoint passed (all 9 checks approved).
+**What happened:** Executed Plan 13-01 — added library-filtered backend queries (7 sqlc queries, 8 Go methods, 1 FTS search method). Two tasks, 10 files modified.
-**Where we stopped:** Completed 12-02-PLAN.md — Phase 12 complete (2/2 plans)
+**Where we stopped:** Completed 13-01-PLAN.md — Phase 13 in progress (1/2 plans)
-**Next action:** Plan Phase 13: Library Views & Phantom Tracks
+**Next action:** Execute Plan 13-02: frontend library selector UI and phantom track handling
 
 ---
 *State initialized: 2026-02-27*

.planning/phases/13-library-views-phantom-tracks/13-01-SUMMARY.md

@@ -0,0 +1,117 @@
+---
+phase: 13-library-views-phantom-tracks
+plan: 01
+subsystem: database, api
+tags: [sqlite, sqlc, fts5, library-filtering, go]
+
+# Dependency graph
+requires:
+  - phase: 10-schema-migration
+    provides: library_id column on audio_files, libraries table
+  - phase: 11-per-library-scan-pipeline
+    provides: per-library scanning populates library_id
+provides:
+  - Library-filtered sqlc queries for tracks, albums, artists, genres
+  - Library-filtered FTS5 search via SearchFTSTracksByLibrary
+  - Eight exported Go methods on Library struct for Wails binding
+affects: [13-library-views-phantom-tracks, frontend-library-selector]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - ByLibrary query variants with subquery filtering for entity tables
+    - EXISTS/IN subquery pattern for cross-table library scoping
+
+key-files:
+  created: []
+  modified:
+    - backend/database/sql/queries/audio_files.sql
+    - backend/database/sql/queries/release_groups.sql
+    - backend/database/sql/queries/artists.sql
+    - backend/database/sql/queries/genres.sql
+    - backend/database/sql/sqlcgen/audio_files.sql.go
+    - backend/database/sql/sqlcgen/release_groups.sql.go
+    - backend/database/sql/sqlcgen/artists.sql.go
+    - backend/database/sql/sqlcgen/genres.sql.go
+    - backend/database/search.go
+    - backend/library/query.go
+
+key-decisions:
+  - "IN-subquery pattern for album/artist/genre library filtering — entities are global, tracks belong to libraries"
+  - "Empty slice return (not error) for library with no tracks — valid state"
+
+patterns-established:
+  - "ByLibrary variant pattern: copy query, add WHERE af.library_id = ? or IN-subquery on entity IDs"
+
+requirements-completed: [VIEW-01, VIEW-02, VIEW-03, VIEW-04]
+
+# Metrics
+duration: 5min
+completed: 2026-03-16
+---
+
+# Phase 13 Plan 01: Library-Filtered Backend Queries Summary
+
+**Seven ByLibrary sqlc query variants + eight Go wrapper methods + library-scoped FTS5 search enabling per-library browse views**
+
+## Performance
+
+- **Duration:** 5 min
+- **Started:** 2026-03-16T13:24:17Z
+- **Completed:** 2026-03-16T13:29:24Z
+- **Tasks:** 2
+- **Files modified:** 10
+
+## Accomplishments
+- Added 7 ByLibrary SQL query variants for all browse views (tracks, albums, artists, genres)
+- Added 8 exported Go methods on Library struct for Wails frontend binding
+- Added SearchFTSTracksByLibrary on DB struct for library-scoped full-text search
+- All existing unfiltered queries remain unchanged for "All Libraries" default view
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add library-filtered sqlc queries for all browse views** - `5cc58ce` (feat)
+2. **Task 2: Add library-filtered Go query methods and FTS search** - `5f7de50` (feat)
+
+## Files Created/Modified
+- `backend/database/sql/queries/audio_files.sql` - GetAllTracksWithFullMetadataByLibrary, GetAudioFilesByReleaseGroupByLibrary
+- `backend/database/sql/queries/release_groups.sql` - GetAllAlbumsWithDetailsByLibrary, GetAlbumsByArtistByLibrary
+- `backend/database/sql/queries/artists.sql` - GetAlbumArtistsByLibrary
+- `backend/database/sql/queries/genres.sql` - GetTracksByGenreByLibrary, GetAllGenresWithCountsByLibrary
+- `backend/database/sql/sqlcgen/*.sql.go` - sqlc-generated Go code for all new queries
+- `backend/database/search.go` - SearchFTSTracksByLibrary method
+- `backend/library/query.go` - Eight ByLibrary wrapper methods on Library struct
+
+## Decisions Made
+- Used IN-subquery pattern for album/artist/genre library filtering since entities are global but tracks belong to libraries
+- Return empty slice (not error) when library has no tracks — empty library is valid state, not an error condition
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Backend library-filtered queries complete, ready for Plan 02 (frontend library selector UI and phantom track handling)
+- All 8 new methods are Wails-bindable (exported, on exported Library struct)
+
+## Self-Check: PASSED
+
+- All 10 modified files exist on disk
+- Both task commits found in git log (5cc58ce, 5f7de50)
+- SUMMARY.md exists at expected path
+- `go build -tags webkit2_41 ./...` compiles cleanly
+- `make lint` passes with 0 issues
+
+---
+*Phase: 13-library-views-phantom-tracks*
+*Completed: 2026-03-16*

frontend/index.html

@@ -15,6 +15,7 @@
             <h1 class="title">YellowJacket</h1>
             <h3 class="subtitle">Music how it was meant to bee.</h3>
         </hgroup>
+        <library-filter></library-filter>
         <search-bar></search-bar>
     </header>
     <div class="sidebar">

frontend/index.ts

@@ -12,6 +12,7 @@ import '@components/genres-view/genres-view.ts';
 import '@components/genre-details/genre-details.ts';
 import '@components/playlist-details/playlist-details.ts';
 import '@components/search-bar/search-bar.ts';
+import '@components/library-filter/library-filter.ts';
 import '@components/track-details/track-details.ts';
 import '@awesome.me/webawesome/dist/styles/themes/default.css';
 import '@awesome.me/webawesome/dist/components/icon/icon.js';

frontend/src/components/artists-view/artists-view.ts

@@ -13,6 +13,8 @@ import { grid } from '@lit-labs/virtualizer/layouts/grid.js';
 import {
     GetAlbumsByArtist,
     GetAlbumTracks,
+    GetAlbumsByArtistByLibrary,
+    GetAlbumTracksByLibrary,
 } from '@go/library/Library';
 import { library } from '@go/models';
 import { LibraryController } from '@store/controllers/library-controller';
@@ -927,20 +929,31 @@ export class ArtistsView
     /**
      * Fetches all file paths for an artist by
      * loading their albums, then each album's
-     * tracks.
+     * tracks.  Respects the active library filter.
      */
     private async getArtistFilePaths(
         artist: library.Artist,
     ): Promise<string[]> {
         try {
-            const albums =
+            const libId =
-                await GetAlbumsByArtist(artist.ID);
+                this.libraryCtrl.selectedLibraryId;
+
+            const albums = libId !== null
+                ? await GetAlbumsByArtistByLibrary(
+                      artist.ID,
+                      libId,
+                  )
+                : await GetAlbumsByArtist(artist.ID);
 
             const allPaths: string[] = [];
 
             for (const album of albums) {
-                const tracks =
+                const tracks = libId !== null
-                    await GetAlbumTracks(album.ID);
+                    ? await GetAlbumTracksByLibrary(
+                          album.ID,
+                          libId,
+                      )
+                    : await GetAlbumTracks(album.ID);
 
                 for (const t of tracks) {
                     allPaths.push(t.FilePath);

frontend/src/components/cover-grid/album-selection.ts

@@ -1,4 +1,8 @@
-import { GetAlbumTracks } from '@go/library/Library';
+import {
+    GetAlbumTracks,
+    GetAlbumTracksByLibrary,
+} from '@go/library/Library';
+import { libraryStore } from '@store/library-store';
 import type { library } from '@go/models';
 import type { CoverArtUrls } from '@components/track-details/track-details.js';
 
@@ -43,6 +47,21 @@ export class AlbumSelectionManager {
         this.albumFilePathCache.clear();
     }
 
+    /**
+     * Fetch album tracks respecting the active
+     * library filter.
+     */
+    private fetchAlbumTracks(
+        albumId: number,
+    ): Promise<library.Track[]> {
+        const libId =
+            libraryStore.getSelectedLibraryId();
+
+        return libId !== null
+            ? GetAlbumTracksByLibrary(albumId, libId)
+            : GetAlbumTracks(albumId);
+    }
+
     // ================================================================
     // Album selection helpers
     // ================================================================
@@ -134,9 +153,8 @@ export class AlbumSelectionManager {
         album: library.Album,
     ): Promise<string[]> {
         try {
-            const tracks = await GetAlbumTracks(
+            const tracks =
-                album.ID,
+                await this.fetchAlbumTracks(album.ID);
-            );
 
             return tracks.map((t) => t.FilePath);
         } catch (error) {
@@ -174,9 +192,10 @@ export class AlbumSelectionManager {
             if (!album) continue;
 
             try {
-                const tracks = await GetAlbumTracks(
+                const tracks =
-                    album.ID,
+                    await this.fetchAlbumTracks(
-                );
+                        album.ID,
+                    );
 
                 // Only store if still selected.
                 if (selectedAlbums.has(album.ID)) {

frontend/src/components/cover-grid/cover-grid.ts

@@ -11,7 +11,10 @@ import type {
     VisibilityChangedEvent,
 } from '@lit-labs/virtualizer';
 import { grid } from '@lit-labs/virtualizer/layouts/grid.js';
-import { GetAlbumTracks } from '@go/library/Library';
+import {
+    GetAlbumTracks,
+    GetAlbumTracksByLibrary,
+} from '@go/library/Library';
 import { library } from '@go/models';
 import { LibraryController } from '@store/controllers/library-controller';
 import { SearchController } from '@store/controllers/search-controller';
@@ -973,9 +976,15 @@ export class CoverGrid
         this.lastSelectedTrackIndex = null;
 
         try {
-            const tracks = await GetAlbumTracks(
+            const libId =
-                album.ID,
+                this.libraryCtrl.selectedLibraryId;
-            );
+
+            const tracks = libId !== null
+                ? await GetAlbumTracksByLibrary(
+                      album.ID,
+                      libId,
+                  )
+                : await GetAlbumTracks(album.ID);
 
             if (this.expandedAlbumId === album.ID) {
                 this.expandedTracks = tracks;

frontend/src/components/genre-details/genre-details.ts

@@ -5,9 +5,13 @@ import {
     state,
 } from 'lit/decorators.js';
 import { library } from '@go/models';
-import { GetTracksByGenre } from '@go/library/Library';
+import {
+    GetTracksByGenre,
+    GetTracksByGenreByLibrary,
+} from '@go/library/Library';
 import { EventsOn } from '@runtime/runtime';
 import { Events } from '../../events';
+import { libraryStore } from '@store/library-store';
 import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import '@components/track-list/track-list.js';
 import { designTokens } from '../../styles/tokens.css';
@@ -176,9 +180,17 @@ export class GenreDetails extends LitElement {
         if (!this.genreName) return;
 
         try {
-            this.tracks = await GetTracksByGenre(
+            const libId =
-                this.genreName,
+                libraryStore.getSelectedLibraryId();
-            );
+
+            this.tracks = libId !== null
+                ? await GetTracksByGenreByLibrary(
+                      this.genreName,
+                      libId,
+                  )
+                : await GetTracksByGenre(
+                      this.genreName,
+                  );
         } catch (error) {
             console.error(
                 'Error loading genre tracks:',

frontend/src/components/genres-view/genres-view.ts

@@ -10,7 +10,10 @@ import type {
     VisibilityChangedEvent,
 } from '@lit-labs/virtualizer';
 import { grid } from '@lit-labs/virtualizer/layouts/grid.js';
-import { GetTracksByGenre } from '@go/library/Library';
+import {
+    GetTracksByGenre,
+    GetTracksByGenreByLibrary,
+} from '@go/library/Library';
 import type { library } from '@go/models';
 import { LibraryController } from '@store/controllers/library-controller';
 import { SearchController } from '@store/controllers/search-controller';
@@ -723,16 +726,25 @@ export class GenresView
     /**
      * Fetch file paths for a set of genre names by
      * querying the backend for each genre.
+     * Respects the active library filter.
      */
     private async getFilePathsForGenres(
         genreNames: Iterable<string>,
     ): Promise<string[]> {
         const seen = new Set<string>();
         const allPaths: string[] = [];
+        const libId =
+            this.libraryCtrl.selectedLibraryId;
 
         const promises = Array.from(
             genreNames,
-            (name) => GetTracksByGenre(name),
+            (name) =>
+                libId !== null
+                    ? GetTracksByGenreByLibrary(
+                          name,
+                          libId,
+                      )
+                    : GetTracksByGenre(name),
         );
 
         const results = await Promise.all(promises);

frontend/src/components/library-filter/library-filter.ts

@@ -0,0 +1,107 @@
+import { LitElement, html, css } from 'lit';
+import { customElement, state } from 'lit/decorators.js';
+import { LibraryController } from '@store/controllers/library-controller';
+import type { library } from '@go/models';
+import { designTokens } from '../../styles/tokens.css';
+
+/**
+ * Compact dropdown in the top bar for filtering all
+ * browse views to a specific library.  "All Libraries"
+ * (value = null) shows the unified merged view.
+ */
+@customElement('library-filter')
+export class LibraryFilter extends LitElement {
+    private libraryCtrl = new LibraryController(this);
+
+    @state()
+    private libraries: library.Info[] = [];
+
+    static override styles = [designTokens, css`
+        :host {
+            display: flex;
+            align-items: center;
+        }
+
+        select {
+            height: 32px;
+            padding: 0 8px;
+            border-radius: 6px;
+            border: 1px solid
+                var(--yj-border-subtle, #555);
+            background: var(--yj-bg-surface, #212529);
+            color: var(--yj-text-primary, #fff);
+            font-size: var(--yj-text-md);
+            font-family: inherit;
+            cursor: pointer;
+            outline: none;
+            min-width: 120px;
+            max-width: 200px;
+        }
+
+        select:focus {
+            border-color: var(--yj-accent, #ffd43b);
+        }
+
+        option {
+            background: var(--yj-bg-surface, #212529);
+            color: var(--yj-text-primary, #fff);
+        }
+    `];
+
+    override connectedCallback() {
+        super.connectedCallback();
+        this.loadLibraries();
+    }
+
+    private async loadLibraries() {
+        try {
+            this.libraries =
+                await this.libraryCtrl.getLibraries();
+        } catch (error) {
+            console.error(
+                'Error loading libraries:',
+                error,
+            );
+        }
+    }
+
+    private handleChange = (e: Event) => {
+        const select = e.target as HTMLSelectElement;
+        const value = select.value;
+        const id = value === ''
+            ? null
+            : Number(value);
+
+        this.libraryCtrl.setSelectedLibrary(id);
+    };
+
+    override render() {
+        const selected =
+            this.libraryCtrl.selectedLibraryId;
+        const selectValue =
+            selected === null ? '' : String(selected);
+
+        return html`
+            <select
+                .value=${selectValue}
+                @change=${this.handleChange}
+                aria-label="Library filter"
+            >
+                <option value="">All Libraries</option>
+                ${this.libraries.map(
+                    (lib) => html`
+                        <option value=${lib.id}>
+                            ${lib.name}
+                        </option>
+                    `,
+                )}
+            </select>
+        `;
+    }
+}
+
+declare global {
+    interface HTMLElementTagNameMap {
+        'library-filter': LibraryFilter;
+    }
+}

frontend/src/store/controllers/library-controller.ts

@@ -129,6 +129,22 @@ export class LibraryController implements ReactiveController {
         libraryStore.setScrollPosition(view, offset);
     }
 
+    // ===================================================================
+    // LIBRARY FILTER
+    // ===================================================================
+
+    get selectedLibraryId(): number | null {
+        return libraryStore.getSelectedLibraryId();
+    }
+
+    setSelectedLibrary(id: number | null): void {
+        libraryStore.setSelectedLibrary(id);
+    }
+
+    async getLibraries(): Promise<library.Info[]> {
+        return libraryStore.getLibraries();
+    }
+
     // ===================================================================
     // COVER SIZE
     // ===================================================================

frontend/src/store/library-store.ts

@@ -5,6 +5,12 @@ import {
     GetAllArtists,
     GetAllGenresWithCounts,
     GetAlbumsByArtist,
+    GetAllTracksByLibrary,
+    GetAllAlbumsByLibrary,
+    GetAllArtistsByLibrary,
+    GetAllGenresWithCountsByLibrary,
+    GetAlbumsByArtistByLibrary,
+    GetAllLibrariesWithTrackCounts,
 } from '@go/library/Library';
 import type { library } from '@go/models';
 import { Events } from '../events';
@@ -30,6 +36,9 @@ class LibraryStore {
     private albums: library.Album[] | null = null;
     private artists: library.Artist[] | null = null;
     private genres: library.GenreWithCount[] | null = null;
+    private libraries: library.Info[] | null = null;
+
+    private selectedLibraryIdValue: number | null = null;
 
     private tracksLoading = false;
     private albumsLoading = false;
@@ -60,8 +69,19 @@ class LibraryStore {
             this.invalidate();
         });
         EventsOn(Events.LibraryRemoved, () => {
+            this.libraries = null;
             this.invalidate();
         });
+        EventsOn(Events.LibraryAdded, () => {
+            this.libraries = null;
+            this.changeGen++;
+            this.notify();
+        });
+        EventsOn(Events.LibraryRenamed, () => {
+            this.libraries = null;
+            this.changeGen++;
+            this.notify();
+        });
 
         this.loadCoverSize();
         this.deferEagerFetch();
@@ -110,7 +130,11 @@ class LibraryStore {
         this.notify();
 
         try {
-            const tracks = await GetAllTracks();
+            const id = this.selectedLibraryIdValue;
+            const tracks = id !== null
+                ? await GetAllTracksByLibrary(id)
+                : await GetAllTracks();
+
             this.tracks = tracks;
             this.changeGen++;
 
@@ -134,7 +158,11 @@ class LibraryStore {
         this.notify();
 
         try {
-            const albums = await GetAllAlbums();
+            const id = this.selectedLibraryIdValue;
+            const albums = id !== null
+                ? await GetAllAlbumsByLibrary(id)
+                : await GetAllAlbums();
+
             this.albums = albums;
             this.changeGen++;
 
@@ -158,7 +186,11 @@ class LibraryStore {
         this.notify();
 
         try {
-            const artists = await GetAllArtists();
+            const id = this.selectedLibraryIdValue;
+            const artists = id !== null
+                ? await GetAllArtistsByLibrary(id)
+                : await GetAllArtists();
+
             this.artists = artists;
             this.changeGen++;
 
@@ -182,7 +214,11 @@ class LibraryStore {
         this.notify();
 
         try {
-            const genres = await GetAllGenresWithCounts();
+            const id = this.selectedLibraryIdValue;
+            const genres = id !== null
+                ? await GetAllGenresWithCountsByLibrary(id)
+                : await GetAllGenresWithCounts();
+
             this.genres = genres;
             this.changeGen++;
 
@@ -196,7 +232,11 @@ class LibraryStore {
     async getAlbumsByArtist(
         artistID: number,
     ): Promise<library.Album[]> {
-        return GetAlbumsByArtist(artistID);
+        const id = this.selectedLibraryIdValue;
+
+        return id !== null
+            ? GetAlbumsByArtistByLibrary(artistID, id)
+            : GetAlbumsByArtist(artistID);
     }
 
     /**
@@ -206,10 +246,20 @@ class LibraryStore {
      * result when the all-albums list has already
      * been loaded (e.g. the user visited the albums
      * view first).
+     *
+     * Returns null when a library filter is active
+     * because the cached albums are already filtered
+     * by library — the client-side ArtistName match
+     * is correct but forcing a backend query ensures
+     * consistency.
      */
     getAlbumsByArtistNameCached(
         artistName: string,
     ): library.Album[] | null {
+        if (this.selectedLibraryIdValue !== null) {
+            return null;
+        }
+
         if (this.albums === null) return null;
 
         return this.albums.filter(
@@ -265,6 +315,34 @@ class LibraryStore {
         return this.changeGen;
     }
 
+    // ===================================================================
+    // LIBRARY FILTER
+    // ===================================================================
+
+    getSelectedLibraryId(): number | null {
+        return this.selectedLibraryIdValue;
+    }
+
+    setSelectedLibrary(id: number | null): void {
+        if (id === this.selectedLibraryIdValue) return;
+
+        this.selectedLibraryIdValue = id;
+        this.invalidate();
+    }
+
+    async getLibraries(): Promise<library.Info[]> {
+        if (this.libraries !== null) {
+            return this.libraries;
+        }
+
+        const libs =
+            await GetAllLibrariesWithTrackCounts();
+
+        this.libraries = libs;
+
+        return libs;
+    }
+
     // ===================================================================
     // SCROLL POSITION
     // ===================================================================

frontend/wailsjs/go/library/Library.d.ts

@@ -16,24 +16,38 @@ export function FullRescan():Promise<library.ScanMetrics>;
 
 export function GetAlbumTracks(arg1:number):Promise<Array<library.Track>>;
 
+export function GetAlbumTracksByLibrary(arg1:number,arg2:number):Promise<Array<library.Track>>;
+
 export function GetAlbumsByArtist(arg1:number):Promise<Array<library.Album>>;
 
+export function GetAlbumsByArtistByLibrary(arg1:number,arg2:number):Promise<Array<library.Album>>;
+
 export function GetAllAlbums():Promise<Array<library.Album>>;
 
+export function GetAllAlbumsByLibrary(arg1:number):Promise<Array<library.Album>>;
+
 export function GetAllArtists():Promise<Array<library.Artist>>;
 
+export function GetAllArtistsByLibrary(arg1:number):Promise<Array<library.Artist>>;
+
 export function GetAllGenresWithCounts():Promise<Array<library.GenreWithCount>>;
 
+export function GetAllGenresWithCountsByLibrary(arg1:number):Promise<Array<library.GenreWithCount>>;
+
 export function GetAllLibrariesWithTrackCounts():Promise<Array<library.Info>>;
 
 export function GetAllTracks():Promise<Array<library.Track>>;
 
+export function GetAllTracksByLibrary(arg1:number):Promise<Array<library.Track>>;
+
 export function GetRemovalImpact(arg1:number):Promise<library.RemovalImpact>;
 
 export function GetScanQueueLength():Promise<number>;
 
 export function GetTracksByGenre(arg1:string):Promise<Array<library.Track>>;
 
+export function GetTracksByGenreByLibrary(arg1:string,arg2:number):Promise<Array<library.Track>>;
+
 export function IsScanActive():Promise<boolean>;
 
 export function IsScanPaused():Promise<boolean>;
@@ -54,6 +68,8 @@ export function ScanLibrary(arg1:number):Promise<void>;
 
 export function SearchTracks(arg1:string):Promise<Array<library.Track>>;
 
+export function SearchTracksByLibrary(arg1:string,arg2:number):Promise<Array<library.Track>>;
+
 export function SetContext(arg1:context.Context):Promise<void>;
 
 export function SetRemovalHooks(arg1:library.RemovalHooks):Promise<void>;

frontend/wailsjs/go/library/Library.js

@@ -26,22 +26,42 @@ export function GetAlbumTracks(arg1) {
   return window['go']['library']['Library']['GetAlbumTracks'](arg1);
 }
 
+export function GetAlbumTracksByLibrary(arg1, arg2) {
+  return window['go']['library']['Library']['GetAlbumTracksByLibrary'](arg1, arg2);
+}
+
 export function GetAlbumsByArtist(arg1) {
   return window['go']['library']['Library']['GetAlbumsByArtist'](arg1);
 }
 
+export function GetAlbumsByArtistByLibrary(arg1, arg2) {
+  return window['go']['library']['Library']['GetAlbumsByArtistByLibrary'](arg1, arg2);
+}
+
 export function GetAllAlbums() {
   return window['go']['library']['Library']['GetAllAlbums']();
 }
 
+export function GetAllAlbumsByLibrary(arg1) {
+  return window['go']['library']['Library']['GetAllAlbumsByLibrary'](arg1);
+}
+
 export function GetAllArtists() {
   return window['go']['library']['Library']['GetAllArtists']();
 }
 
+export function GetAllArtistsByLibrary(arg1) {
+  return window['go']['library']['Library']['GetAllArtistsByLibrary'](arg1);
+}
+
 export function GetAllGenresWithCounts() {
   return window['go']['library']['Library']['GetAllGenresWithCounts']();
 }
 
+export function GetAllGenresWithCountsByLibrary(arg1) {
+  return window['go']['library']['Library']['GetAllGenresWithCountsByLibrary'](arg1);
+}
+
 export function GetAllLibrariesWithTrackCounts() {
   return window['go']['library']['Library']['GetAllLibrariesWithTrackCounts']();
 }
@@ -50,6 +70,10 @@ export function GetAllTracks() {
   return window['go']['library']['Library']['GetAllTracks']();
 }
 
+export function GetAllTracksByLibrary(arg1) {
+  return window['go']['library']['Library']['GetAllTracksByLibrary'](arg1);
+}
+
 export function GetRemovalImpact(arg1) {
   return window['go']['library']['Library']['GetRemovalImpact'](arg1);
 }
@@ -62,6 +86,10 @@ export function GetTracksByGenre(arg1) {
   return window['go']['library']['Library']['GetTracksByGenre'](arg1);
 }
 
+export function GetTracksByGenreByLibrary(arg1, arg2) {
+  return window['go']['library']['Library']['GetTracksByGenreByLibrary'](arg1, arg2);
+}
+
 export function IsScanActive() {
   return window['go']['library']['Library']['IsScanActive']();
 }
@@ -102,6 +130,10 @@ export function SearchTracks(arg1) {
   return window['go']['library']['Library']['SearchTracks'](arg1);
 }
 
+export function SearchTracksByLibrary(arg1, arg2) {
+  return window['go']['library']['Library']['SearchTracksByLibrary'](arg1, arg2);
+}
+
 export function SetContext(arg1) {
   return window['go']['library']['Library']['SetContext'](arg1);
 }