feat(library): focused music/TV/movie landing screens + self-draining download queue

Library screens:
- Add dedicated music, TV, and movie landing pages (hero banner +
  horizontal carousels) backed by new music/tv/movies stores.
- Route tvshows libraries to /library/tv; surface rediscover ("haven't
  listened to in a while") albums via a new repository method across
  online/offline/hybrid repos plus the repository_get_rediscover_albums
  command.
- Add an A-Z jump bar for long alphabetically-sorted lists, with grid
  index anchors in LibraryGrid/LibraryListView/TrackList.
- Filter the "Podcasts" folder out of music library queries.

Downloads:
- Add a backend queue pump: enqueue_download / enqueue_video_downloads
  persist the resolved stream URL + target dir on each row (migration
  017), and the pump starts up to max_concurrent and drains the rest
  automatically as slots free, instead of the frontend silently dropping
  items past the concurrency limit. Album/series/season buttons now
  enqueue rather than calling start_download directly.

Other fixes:
- Hybrid search now returns instant cache results and pushes the merged
  cache+server union via a request-id-tagged search-event, so superseded
  queries can't clobber fresher results.
- URL-encode SearchTerm / genres / item types in online repo requests.
- Android: pause on audio-becoming-noisy (headphone/BT disconnect).

src-tauri/src/commands/download/mod.rs

@@ -2,8 +2,9 @@
 
 #[cfg(test)]
 use crate::utils::lock::MutexSafe;
+use std::path::PathBuf;
 use std::sync::{Arc, Mutex};
-use tauri::State;
+use tauri::{Manager, State};
 use log::{debug, error, info, warn};
 
 use crate::download::{DownloadInfo, DownloadManager};
@@ -818,9 +819,7 @@ pub async fn start_download(
     stream_url: String,
     target_dir: String,
 ) -> Result<(), String> {
-    use crate::download::{DownloadTask, DownloadWorker};
     use crate::download::events::DownloadEvent;
-    use std::path::PathBuf;
     use tauri::Emitter;
 
     debug!("start_download called for download_id: {}", download_id);
@@ -906,16 +905,27 @@ pub async fn start_download(
         }
     };
 
-    // Update status to downloading and save file_size if we got it
+    // Update status to downloading and save file_size if we got it.
+    // Also persist the resolved stream URL + target dir so the queue pump can
+    // restart/resume this download by itself if needed.
     let update_query = if let Some(size) = file_size_from_server {
         Query::with_params(
-            "UPDATE downloads SET status = 'downloading', started_at = CURRENT_TIMESTAMP, file_size = ? WHERE id = ?",
-            vec![QueryParam::Int64(size), QueryParam::Int64(download_id)],
+            "UPDATE downloads SET status = 'downloading', started_at = CURRENT_TIMESTAMP, file_size = ?, stream_url = ?, target_dir = ? WHERE id = ?",
+            vec![
+                QueryParam::Int64(size),
+                QueryParam::String(stream_url.clone()),
+                QueryParam::String(target_dir.clone()),
+                QueryParam::Int64(download_id),
+            ],
         )
     } else {
         Query::with_params(
-            "UPDATE downloads SET status = 'downloading', started_at = CURRENT_TIMESTAMP WHERE id = ?",
-            vec![QueryParam::Int64(download_id)],
+            "UPDATE downloads SET status = 'downloading', started_at = CURRENT_TIMESTAMP, stream_url = ?, target_dir = ? WHERE id = ?",
+            vec![
+                QueryParam::String(stream_url.clone()),
+                QueryParam::String(target_dir.clone()),
+                QueryParam::Int64(download_id),
+            ],
         )
     };
 
@@ -936,29 +946,304 @@ pub async fn start_download(
     // Build target path
     let target_path = PathBuf::from(&target_dir).join(&file_path);
 
-    // Create download task
-    let task = DownloadTask {
-        url: stream_url,
-        target_path: target_path.clone(),
-    };
-
-    // Start download in background
-    let app_clone = app.clone();
-    let item_id_clone = item_id.clone();
-
     // Get a clone of the active downloads Arc for unregistering later
     let active_downloads = {
         let manager = download_manager.0.lock().map_err(|e| e.to_string())?;
         manager.get_active_downloads()
     };
 
+    // Run the worker in the background; on completion/failure it frees the slot
+    // and pumps the next pending download.
+    spawn_download_worker(
+        app.clone(),
+        download_id,
+        item_id,
+        stream_url,
+        target_path,
+        active_downloads,
+    );
+
+    Ok(())
+}
+
+/// Enqueue a download with its resolved stream URL, then let the queue pump
+/// start it (or a higher-priority pending item) when a slot is free.
+///
+/// Unlike [`start_download`], this never errors when the concurrency limit is
+/// reached: the URL is persisted on the row and the pump will pick it up once a
+/// slot frees. This is the path bulk operations (album/series/season) use so
+/// every queued item eventually downloads without the frontend re-issuing it.
+#[tauri::command]
+#[specta::specta]
+pub async fn enqueue_download(
+    db: State<'_, DatabaseWrapper>,
+    download_manager: State<'_, DownloadManagerWrapper>,
+    app: tauri::AppHandle,
+    download_id: i64,
+    stream_url: String,
+    target_dir: String,
+) -> Result<(), String> {
+    let db_service = {
+        let database = db.0.lock().map_err(|e| e.to_string())?;
+        Arc::new(database.service())
+    };
+
+    // Persist the resolved URL/dir and mark the row pending so the pump can
+    // start it. We don't flip to 'downloading' here — the pump owns that.
+    let update_query = Query::with_params(
+        "UPDATE downloads SET status = 'pending', stream_url = ?, target_dir = ? WHERE id = ?",
+        vec![
+            QueryParam::String(stream_url),
+            QueryParam::String(target_dir),
+            QueryParam::Int64(download_id),
+        ],
+    );
+    db_service.execute(update_query).await.map_err(|e| e.to_string())?;
+
+    // Kick the pump: it will start as many pending downloads as there are slots.
+    let active_downloads = {
+        let manager = download_manager.0.lock().map_err(|e| e.to_string())?;
+        manager.get_active_downloads()
+    };
+    pump_download_queue(app, db_service, active_downloads).await;
+
+    Ok(())
+}
+
+/// Enqueue a batch of already-queued video downloads, resolving each one's
+/// transcode URL from the repository using the `quality_preset` stored on the
+/// row. Then let the pump start them subject to the concurrency limit.
+///
+/// This is the bulk video path (series/season): `download_series`/
+/// `download_season` insert the rows, then this resolves URLs and enqueues them
+/// so they actually start. Resolving server-side avoids round-tripping every
+/// episode URL through the frontend.
+#[tauri::command]
+#[specta::specta]
+pub async fn enqueue_video_downloads(
+    db: State<'_, DatabaseWrapper>,
+    download_manager: State<'_, DownloadManagerWrapper>,
+    repository: State<'_, crate::commands::repository::RepositoryManagerWrapper>,
+    app: tauri::AppHandle,
+    handle: String,
+    download_ids: Vec<i64>,
+    target_dir: String,
+) -> Result<(), String> {
+    use crate::repository::MediaRepository;
+
+    let repo = repository.0.get(&handle).ok_or("Repository not found")?;
+
+    let db_service = {
+        let database = db.0.lock().map_err(|e| e.to_string())?;
+        Arc::new(database.service())
+    };
+
+    for download_id in download_ids {
+        // Read the item + quality preset for this queued download.
+        let info_query = Query::with_params(
+            "SELECT item_id, COALESCE(quality_preset, 'original') FROM downloads WHERE id = ?",
+            vec![QueryParam::Int64(download_id)],
+        );
+        let (item_id, quality): (String, String) = match db_service
+            .query_one(info_query, |row| Ok((row.get(0)?, row.get(1)?)))
+            .await
+        {
+            Ok(row) => row,
+            Err(e) => {
+                warn!("[enqueue_video] Skipping download {}: {}", download_id, e);
+                continue;
+            }
+        };
+
+        // Build the transcode URL (pure URL builder, no server round-trip).
+        let stream_url = repo.as_ref().get_video_download_url(&item_id, &quality, None);
+
+        let update_query = Query::with_params(
+            "UPDATE downloads SET status = 'pending', stream_url = ?, target_dir = ? WHERE id = ?",
+            vec![
+                QueryParam::String(stream_url),
+                QueryParam::String(target_dir.clone()),
+                QueryParam::Int64(download_id),
+            ],
+        );
+        if let Err(e) = db_service.execute(update_query).await {
+            warn!("[enqueue_video] Failed to persist URL for download {}: {}", download_id, e);
+        }
+    }
+
+    // Pump once: starts up to max_concurrent, the rest drain as slots free.
+    let active_downloads = {
+        let manager = download_manager.0.lock().map_err(|e| e.to_string())?;
+        manager.get_active_downloads()
+    };
+    pump_download_queue(app, db_service, active_downloads).await;
+
+    Ok(())
+}
+
+/// Start as many pending downloads as there are free concurrency slots.
+///
+/// Picks the highest-priority `pending` rows that have a persisted `stream_url`
+/// (FIFO within a priority), registers each, flips it to `downloading`, and
+/// spawns a worker. Each spawned worker calls this again on completion/failure,
+/// so the queue drains itself without any frontend involvement.
+async fn pump_download_queue(
+    app: tauri::AppHandle,
+    db_service: Arc<crate::storage::db_service::RusqliteService>,
+    active_downloads: Arc<Mutex<std::collections::HashSet<i64>>>,
+) {
+    use crate::download::events::DownloadEvent;
+    use tauri::Emitter;
+
+    let max_concurrent = {
+        let manager = app.state::<DownloadManagerWrapper>();
+        let manager = match manager.0.lock() {
+            Ok(m) => m,
+            Err(e) => {
+                error!("[pump] Failed to lock download manager: {}", e);
+                return;
+            }
+        };
+        manager.max_concurrent()
+    };
+
+    loop {
+        // How many slots are free right now?
+        let free_slots = {
+            let active = match active_downloads.lock() {
+                Ok(a) => a,
+                Err(e) => {
+                    error!("[pump] Failed to lock active downloads: {}", e);
+                    return;
+                }
+            };
+            max_concurrent.saturating_sub(active.len())
+        };
+        if free_slots == 0 {
+            return;
+        }
+
+        // Find the next pending, startable download (has a stream URL). Exclude
+        // anything already registered as active to avoid double-starting.
+        let next_query = Query::with_params(
+            "SELECT id, item_id, file_path, stream_url, target_dir
+             FROM downloads
+             WHERE status = 'pending'
+               AND stream_url IS NOT NULL
+               AND target_dir IS NOT NULL
+             ORDER BY priority DESC, queued_at ASC",
+            vec![],
+        );
+
+        let candidates: Vec<(i64, String, String, String, String)> = match db_service
+            .query_many(next_query, |row| {
+                Ok((row.get(0)?, row.get(1)?, row.get(2)?, row.get(3)?, row.get(4)?))
+            })
+            .await
+        {
+            Ok(rows) => rows,
+            Err(e) => {
+                error!("[pump] Failed to query pending downloads: {}", e);
+                return;
+            }
+        };
+
+        // Pick the first candidate not already active.
+        let next = candidates.into_iter().find(|(id, _, _, _, _)| {
+            active_downloads
+                .lock()
+                .map(|active| !active.contains(id))
+                .unwrap_or(false)
+        });
+
+        let (download_id, item_id, file_path, stream_url, target_dir) = match next {
+            Some(n) => n,
+            None => return, // Nothing pending to start
+        };
+
+        // Register the slot. If registration fails (race: another pump filled
+        // the last slot), stop — we'll be re-pumped when a slot frees.
+        {
+            let manager = app.state::<DownloadManagerWrapper>();
+            let manager = match manager.0.lock() {
+                Ok(m) => m,
+                Err(e) => {
+                    error!("[pump] Failed to lock download manager: {}", e);
+                    return;
+                }
+            };
+            if !manager.register_download(download_id) {
+                return;
+            }
+            info!(
+                "[pump] Download {} started. Active downloads: {}/{}",
+                download_id,
+                manager.active_count(),
+                manager.max_concurrent()
+            );
+        }
+
+        // Mark as downloading and stamp started_at.
+        let update_query = Query::with_params(
+            "UPDATE downloads SET status = 'downloading', started_at = CURRENT_TIMESTAMP WHERE id = ?",
+            vec![QueryParam::Int64(download_id)],
+        );
+        if let Err(e) = db_service.execute(update_query).await {
+            error!("[pump] Failed to mark download {} downloading: {}", download_id, e);
+            if let Ok(mut a) = active_downloads.lock() {
+                a.remove(&download_id);
+            }
+            continue;
+        }
+
+        // Emit started event so the UI flips the row.
+        let _ = app.emit(
+            "download-event",
+            DownloadEvent::Started {
+                download_id,
+                item_id: item_id.clone(),
+            },
+        );
+
+        let target_path = PathBuf::from(&target_dir).join(&file_path);
+        spawn_download_worker(
+            app.clone(),
+            download_id,
+            item_id,
+            stream_url,
+            target_path,
+            active_downloads.clone(),
+        );
+    }
+}
+
+/// Spawn the background worker for one download. On completion or failure it
+/// unregisters the slot, emits the terminal event, and pumps the queue so the
+/// next pending download starts automatically.
+fn spawn_download_worker(
+    app: tauri::AppHandle,
+    download_id: i64,
+    item_id: String,
+    stream_url: String,
+    target_path: std::path::PathBuf,
+    active_downloads: Arc<Mutex<std::collections::HashSet<i64>>>,
+) {
+    use crate::download::{DownloadTask, DownloadWorker};
+    use crate::download::events::DownloadEvent;
+    use tauri::Emitter;
+
+    let task = DownloadTask {
+        url: stream_url,
+        target_path: target_path.clone(),
+    };
+
     tauri::async_runtime::spawn(async move {
         debug!("Download task started for download_id: {}", download_id);
         let worker = DownloadWorker::new();
 
         // Progress callback that emits events to the frontend
-        let progress_app = app_clone.clone();
-        let progress_item_id = item_id_clone.clone();
+        let progress_app = app.clone();
+        let progress_item_id = item_id.clone();
         let on_progress = move |bytes_downloaded: u64, total_bytes: Option<u64>| {
             let progress = total_bytes
                 .filter(|&t| t > 0)
@@ -975,54 +1260,55 @@ pub async fn start_download(
             let _ = progress_app.emit("download-event", event);
         };
 
-        match worker.download(&task, on_progress).await {
-            Ok(result) => {
-                info!("Download completed successfully: {} bytes", result.bytes_downloaded);
+        let result = worker.download(&task, on_progress).await;
 
-                // Unregister from download manager
-                if let Ok(mut active) = active_downloads.lock() {
-                    active.remove(&download_id);
-                    debug!("   Unregistered download {}. Active downloads: {}", download_id, active.len());
-                }
+        // Free the slot before pumping so the next download can take it.
+        if let Ok(mut active) = active_downloads.lock() {
+            active.remove(&download_id);
+            debug!("   Unregistered download {}. Active downloads: {}", download_id, active.len());
+        }
 
-                // Emit completed event - the frontend will handle state updates
+        match result {
+            Ok(res) => {
+                info!("Download completed successfully: {} bytes", res.bytes_downloaded);
                 let completed_event = DownloadEvent::Completed {
                     download_id,
-                    item_id: item_id_clone,
+                    item_id,
                     file_path: target_path.to_string_lossy().to_string(),
                 };
-                debug!("Emitting completed event: {:?}", completed_event);
-                debug!("   Serialized: {}", serde_json::to_string(&completed_event).unwrap_or_default());
-                match app_clone.emit("download-event", completed_event) {
+                match app.emit("download-event", completed_event) {
                     Ok(_) => debug!("   Completed event emitted successfully"),
                     Err(e) => error!("   Completed event emit failed: {:?}", e),
                 }
             }
             Err(e) => {
                 error!("Download failed: {:?}", e);
-
-                // Unregister from download manager
-                if let Ok(mut active) = active_downloads.lock() {
-                    active.remove(&download_id);
-                    debug!("   Unregistered failed download {}. Active downloads: {}", download_id, active.len());
-                }
-
-                // Emit failed event - the frontend will handle state updates
                 let failed_event = DownloadEvent::Failed {
                     download_id,
-                    item_id: item_id_clone.clone(),
+                    item_id,
                     error: e.to_string(),
                 };
-                debug!("Emitting failed event: {:?}", failed_event);
-                match app_clone.emit("download-event", failed_event) {
+                match app.emit("download-event", failed_event) {
                     Ok(_) => debug!("   Failed event emitted successfully"),
                     Err(e) => error!("   Failed event emit failed: {:?}", e),
                 }
             }
         }
-    });
 
-    Ok(())
+        // A slot just freed — start the next pending download (if any).
+        let db_service = {
+            let db = app.state::<DatabaseWrapper>();
+            let database = match db.0.lock() {
+                Ok(d) => d,
+                Err(e) => {
+                    error!("[pump] Failed to lock database after download {}: {}", download_id, e);
+                    return;
+                }
+            };
+            Arc::new(database.service())
+        };
+        pump_download_queue(app.clone(), db_service, active_downloads).await;
+    });
 }
 
 /// Delete a completed download