feat(downloads): browsable downloaded library with on-disk usage

Replace the flat download list with a Downloaded browse surface that
reuses the online grids/cards/detail pages, filtered to on-device media,
plus a demoted Transfers tab. Add repository browse commands
(getDownloadedLibraries/Items, disk usage) with offline/hybrid
implementations, a downloadedCatalog service, formatBytes helper, and
per-item/device disk-usage labels on cards and grids. Regenerated
bindings.

Also carries the inseparable UR-052 offline-filter hunks in
offline.rs/hybrid.rs.

TRACES: UR-055 | DR-081, DR-082, DR-083, DR-084; UR-056 | DR-085

src/lib/api/bindings.ts

@@ -784,6 +784,19 @@ async deleteAllDownloads(userId: string) : Promise<number> {
 async deleteAlbumDownloads(albumId: string, userId: string) : Promise<number> {
     return await TAURI_INVOKE("delete_album_downloads", { albumId, userId });
 },
+/**
+ * Remove every completed download at or under a container item.
+ * 
+ * Works at any level of the Downloaded browse: a leaf (removes just that
+ * download), an album/season/series (removes all downloaded descendants linked
+ * via album_id/season_id/series_id/parent_id). Deletes the DB rows and the
+ * on-disk files. Returns the number of downloads removed. Idempotent.
+ * 
+ * TRACES: UR-055 | DR-083
+ */
+async deleteDownloadsUnder(itemId: string, userId: string) : Promise<number> {
+    return await TAURI_INVOKE("delete_downloads_under", { itemId, userId });
+},
 /**
  * Clear all stale pending/failed/paused downloads
  */
@@ -915,6 +928,29 @@ async updateSmartCacheConfig(config: CacheConfig) : Promise<null> {
 async getSmartCacheConfig() : Promise<CacheConfig> {
     return await TAURI_INVOKE("get_smart_cache_config");
 },
+/**
+ * Report the device's current network transport (Android → Rust).
+ * 
+ * The frontend calls this on startup and whenever the native network callback
+ * fires. Updating to an acceptable network re-pumps the download queue, so a
+ * queue parked on "waiting for WiFi" drains itself without user action.
+ * 
+ * TRACES: UR-053 | DR-074
+ */
+async setNetworkState(network: NetworkStateWrapperArg) : Promise<null> {
+    return await TAURI_INVOKE("set_network_state", { network });
+},
+/**
+ * Whether downloads are currently permitted by the WiFi-only gate.
+ * 
+ * The downloads UI uses this to render "Waiting for WiFi" on pending rows
+ * rather than leaving them looking silently stuck.
+ * 
+ * TRACES: UR-053 | DR-074
+ */
+async getDownloadsAllowed() : Promise<boolean> {
+    return await TAURI_INVOKE("get_downloads_allowed");
+},
 /**
  * Get album recommendations based on play history
  */
@@ -1166,6 +1202,33 @@ async repositoryGetItems(handle: string, parentId: string, options: GetItemsOpti
 async repositoryGetItem(handle: string, itemId: string) : Promise<MediaItem> {
     return await TAURI_INVOKE("repository_get_item", { handle, itemId });
 },
+/**
+ * Downloaded-only browse: libraries that contain downloaded content.
+ * 
+ * Backs the Downloads "Downloaded" surface. Never merges server results and is
+ * authoritative — an empty list means nothing is downloaded.
+ * 
+ * TRACES: UR-055 | DR-082
+ */
+async repositoryGetDownloadedLibraries(handle: string) : Promise<Library[]> {
+    return await TAURI_INVOKE("repository_get_downloaded_libraries", { handle });
+},
+/**
+ * Downloaded-only browse: items under a container that are on the device.
+ * 
+ * TRACES: UR-055 | DR-082, DR-083
+ */
+async repositoryGetDownloadedItems(handle: string, parentId: string, options: GetItemsOptions | null) : Promise<SearchResult> {
+    return await TAURI_INVOKE("repository_get_downloaded_items", { handle, parentId, options });
+},
+/**
+ * On-disk usage of downloaded content (device total, per-item/container bytes).
+ * 
+ * TRACES: UR-056 | DR-085
+ */
+async repositoryGetDownloadDiskUsage(handle: string) : Promise<DownloadDiskUsage> {
+    return await TAURI_INVOKE("repository_get_download_disk_usage", { handle });
+},
 /**
  * Query the optional JRay plugin for the actors on screen at time `t`
  * (seconds) in an item. Returns an empty list when JRay isn't installed or
@@ -1626,6 +1689,34 @@ connectionError: string | null;
  * Whether we're currently checking connectivity
  */
 isChecking: boolean }
+/**
+ * On-disk usage of downloaded content, for the Downloads surface.
+ * 
+ * `sizes` maps an item id (leaf *or* container) to its bytes on disk: a leaf's
+ * own file size, a container's summed downloaded descendants. `device_total_bytes`
+ * and `item_count` are the headline figures for the Downloaded surface top bar.
+ * 
+ * TRACES: UR-056 | DR-085
+ */
+export type DownloadDiskUsage = { 
+/**
+ * item id → bytes on disk (leaf's own size, or a container's subtotal).
+ */
+sizes: Partial<{ [key in string]: number }>; 
+/**
+ * Container id → true when it is only *partially* downloaded (has cached
+ * children that are not downloaded). Absent/false ⇒ fully downloaded. Lets
+ * the Downloaded surface badge partial vs. full containers.
+ */
+partialContainers: Partial<{ [key in string]: boolean }>; 
+/**
+ * Sum of all downloaded leaf sizes — the device total.
+ */
+deviceTotalBytes: number; 
+/**
+ * Number of downloaded leaf items (not containers).
+ */
+itemCount: number }
 /**
  * Information about a download
  */
@@ -1757,6 +1848,45 @@ export type MediaType = "audio" | "video"
  * Converts from both local MediaItem and remote NowPlayingItem
  */
 export type MergedMediaItem = { id: string; title: string; artist: string | null; album: string | null; albumId: string | null; duration: number | null; primaryImageTag: string | null; mediaType: string }
+/**
+ * Argument struct for [`set_network_state`].
+ * 
+ * TRACES: UR-053 | DR-074
+ */
+export type NetworkStateWrapperArg = { networkType: NetworkType; unmetered: boolean }
+/**
+ * Kind of network transport currently active.
+ * 
+ * Mirrors the string constants in `NetworkTypeMonitor.kt`; the two must stay
+ * in sync (the serde rename below is what the frontend sends).
+ * 
+ * TRACES: UR-053 | DR-074
+ */
+export type NetworkType = 
+/**
+ * No active network.
+ */
+"none" | 
+/**
+ * WiFi (may still be metered — check `unmetered`).
+ */
+"wifi" | 
+/**
+ * Wired ethernet, typical on Android TV and desktop.
+ */
+"ethernet" | 
+/**
+ * Mobile data — never acceptable when wifi-only is enabled.
+ */
+"cellular" | 
+/**
+ * Some other transport (VPN over unknown carrier, Bluetooth tethering, …).
+ */
+"other" | 
+/**
+ * Could not determine the transport.
+ */
+"unknown"
 export type NowPlayingItem = { id: string | null; name: string | null; runTimeTicks: number | null; album: string | null; albumId: string | null; albumArtist: string | null; artists: string[] | null; imageTags: Partial<{ [key in string]: string }> | null; primaryImageTag: string | null; albumPrimaryImageTag: string | null; Type: string | null }
 export type OfflineItem = { id: string; name: string; itemType: string; albumId: string | null; albumName: string | null; artists: string | null; runtimeTicks: number | null; primaryImageTag: string | null }
 /**

src/lib/api/repository-client.test.ts

@@ -337,6 +337,46 @@ describe("RepositoryClient", () => {
         requestId: 0,
       });
     });
+
+    // Downloaded-only browse path (UR-055 | DR-082) — verifies command names and
+    // camelCase params per the Tauri v2 rule (CLAUDE.md).
+    it("should get downloaded libraries from backend", async () => {
+      const mockLibraries = [{ id: "lib1", name: "Music", collectionType: "music" }];
+      (invoke as any).mockResolvedValueOnce(mockLibraries);
+
+      const libraries = await client.getDownloadedLibraries();
+
+      expect(libraries).toEqual(mockLibraries);
+      expect(invoke).toHaveBeenCalledWith("repository_get_downloaded_libraries", {
+        handle: "test-handle-123",
+      });
+    });
+
+    it("should get downloaded items with camelCase params", async () => {
+      const mockResult = { items: [{ id: "t1", name: "Track", type: "Audio" }], totalRecordCount: 1 };
+      (invoke as any).mockResolvedValueOnce(mockResult);
+
+      const result = await client.getDownloadedItems("album1", { limit: 50 });
+
+      expect(result).toEqual(mockResult);
+      expect(invoke).toHaveBeenCalledWith("repository_get_downloaded_items", {
+        handle: "test-handle-123",
+        parentId: "album1",
+        options: { limit: 50 },
+      });
+    });
+
+    it("should get download disk usage from backend", async () => {
+      const mockUsage = { sizes: { t1: 1000 }, partialContainers: {}, deviceTotalBytes: 1000, itemCount: 1 };
+      (invoke as any).mockResolvedValueOnce(mockUsage);
+
+      const usage = await client.getDownloadDiskUsage();
+
+      expect(usage).toEqual(mockUsage);
+      expect(invoke).toHaveBeenCalledWith("repository_get_download_disk_usage", {
+        handle: "test-handle-123",
+      });
+    });
   });
 
   describe("Playback Methods", () => {

src/lib/api/repository-client.ts

@@ -3,7 +3,7 @@
 // NO direct HTTP calls - everything routes through Rust backend
 
 import { commands } from "./bindings";
-import type { JRayActor } from "./bindings";
+import type { JRayActor, DownloadDiskUsage } from "./bindings";
 import type { QualityPreset } from "./quality-presets";
 import type {
   Library,
@@ -91,6 +91,31 @@ export class RepositoryClient {
     return commands.repositoryGetItem(this.ensureHandle(), itemId);
   }
 
+  /**
+   * Downloaded-only browse: libraries that contain downloaded content.
+   * Never merges server results; an empty list is authoritative.
+   * TRACES: UR-055 | DR-082
+   */
+  async getDownloadedLibraries(): Promise<Library[]> {
+    return commands.repositoryGetDownloadedLibraries(this.ensureHandle());
+  }
+
+  /**
+   * Downloaded-only browse: items under a container that are on the device.
+   * TRACES: UR-055 | DR-082, DR-083
+   */
+  async getDownloadedItems(parentId: string, options?: GetItemsOptions): Promise<SearchResult> {
+    return commands.repositoryGetDownloadedItems(this.ensureHandle(), parentId, options ?? null);
+  }
+
+  /**
+   * On-disk usage of downloaded content (device total + per-item/container bytes).
+   * TRACES: UR-056 | DR-085
+   */
+  async getDownloadDiskUsage(): Promise<DownloadDiskUsage> {
+    return commands.repositoryGetDownloadDiskUsage(this.ensureHandle());
+  }
+
   /**
    * Query the optional JRay plugin for the actors on screen at time `t`
    * (seconds) in an item. Resolves to an empty array when JRay isn't installed