The lockscreen controls drifted out of sync, especially while casting, and
couldn't control remote playback. Two media sessions were competing (a Media3
MediaSession driving transport vs a MediaSessionCompat driving the notification),
position was only pushed on play/pause so the scrubber froze mid-track, and
remote mode showed stale local metadata with dead buttons.
- Make MediaSessionCompat the single source of truth; route all transport
commands (both the Compat callback and the Media3 wrappedPlayer) through Rust
via nativeOnMediaCommand instead of touching ExoPlayer directly.
- Push position on every 250ms tick via a lightweight updatePlaybackPosition,
and report 0.0 playback speed when paused so Android stops extrapolating.
- Mirror the remote session's now-playing onto the lockscreen from the native
session poller (works while the screen is locked, unlike WebView timers) via
a new player::update_lockscreen_metadata JNI bridge.
- Make MediaSessionHandler mode-aware: in remote mode forward play/pause/next/
prev/seek to the remote Jellyfin session; Stop while casting emits
RemoteDisconnectRequested, which the frontend handles by transferring to local.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
