feat(android): music keeps playing with the screen off

While a track plays, the page asks the shell to stay awake
(playback:keep-alive): on Android the cast's foreground service and
visible WebView, with a notification; on desktop a power save blocker.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 20 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/music-player.js b/packages/meshbay-hub/src/meshbay_hub/static/music-player.js
index f0f7c47..500f518 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/music-player.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/music-player.js
@@ -6,6 +6,7 @@ import { t } from './i18n.js';
 import { Icon } from './icon.js';
 import { useStickyBand } from './sticky.js';
 import { CHUNK_SIZE, pipelinedDownload } from './file-utils.js';
+import { playback } from './platform.js';
 
 /**
  * The Music app's persistent player bar (docs/MESHBAY_DESIGN.md §9.8).
@@ -279,6 +280,15 @@ function MusicPlayerBar({ getConnection, queue, onClose, userPrefs, onSaveQueue
     for (const { url } of blobCacheRef.current.values()) URL.revokeObjectURL(url);
   }, []);
 
+  // Held for as long as a track plays, through the advance to the next one:
+  // without it a phone freezes the page a minute after the screen goes off,
+  // and the next track never loads.
+  useEffect(() => {
+    if (!playing) return;
+    playback.keepAlive(true);
+    return () => playback.keepAlive(false);
+  }, [playing]);
+
   // Screen Wake Lock, opt-in only (Settings → music_keep_screen_on) and only
   // while a track is actually playing — off by default because the ordinary
   // expectation, matching Spotify/Deezer, is that the phone locks on its own
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/platform.js b/packages/meshbay-hub/src/meshbay_hub/static/platform.js
index c131495..0174edc 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/platform.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/platform.js
@@ -204,6 +204,16 @@ export const folder = {
   async forget() { return bridge && bridge.folder ? bridge.folder.forget() : false; },
 };
 
+/**
+ * Music is playing: the shell keeps what playback needs awake (on a phone, the
+ * page itself with the screen off). A no-op in a browser.
+ */
+export const playback = {
+  keepAlive(on) {
+    if (bridge && bridge.playback) bridge.playback.keepAlive(on).catch(() => {});
+  },
+};
+
 /** Pick a directory to add as a group root. Returns { path, name } or null. */
 export const rootPicker = {
   available: Boolean(bridge && bridge.rootPicker),