With native video on, coming back from background audio left a black screen: a
play overlay pinned at 0:00, a seek bar at zero, and a play button that did
nothing. Nothing crashed — the process stayed up and the frontend kept logging —
the transition was simply dropped.
The two render paths resume by different means, and exitBackgroundAudioHandoff
only ever performed one of them. The webview <video> reloads off its stream URL:
an $effect watches it, reinitialises HLS or sets element.src, and canplay drives
the seek and play. ExoPlayer owns no element and nothing watches the URL on its
behalf — native playback is only ever started by an explicit player_play_item
plus adapter load, which the component issues once, from onMount. So reassigning
the URL restarted precisely nothing, and since player_exit_background_audio had
already stopped the handoff's audio player, the backend came back holding no item
at all. That is why the play button was inert: there was nothing loaded to play.
The return now re-issues that pair on the native path, in the same order as the
initial load, carrying the position the audio reached. Subtitle configurations are
reused from the ones resolved at mount — ExoPlayer sideloads them as
MediaItem.SubtitleConfigurations and cannot accept one after prepare().
Which path to take is decided by planHandoffReturn, a pure helper in
backgroundAudioHandoff.ts, so the branch is unit-testable without mounting the
player. It also folds in shouldResumeOnForeground, so a pause taken on the
lockscreen during the handoff still wins over the snapshot captured on the way
out.
Verified on device (HONOR ROD2-W09, Android 16): handoff to audio-only at 69:54,
return restored native video playing at 70:18. Previously the same sequence left
the player idle and black.
The requirements count pin in extract-traces.test.ts moves with the new DR-196.
Pausing from the lockscreen did nothing while a video's audio played in
the background. The handoff starts native ExoPlayer audio and only then
tears the WebView <video> down, and that teardown fires a DOM `pause`
the frontend reports like any other — leaving html5_playing = Some(false).
Transport therefore stayed aimed at the element: the lockscreen pause
emitted a ControlCommand into a <video> that no longer existed while the
native player carried on.
The controller now tracks a background-audio handoff explicitly. Entering
one hands transport authority to the native backend and drops the dying
element's state/position/media-loaded reports, which also stop flipping
the UI to paused and dragging the position backwards. Exiting restores
the element as the player.
A lockscreen pause also has to survive the return to the foreground: the
video used to resume from a snapshot taken at handoff time, undoing the
pause on the way back in. shouldResumeOnForeground() lets an explicit
`paused` from the player override that snapshot.
TRACES: UR-040, UR-005 | DR-052, DR-097
Hand video playback off to a native audio-only stream when the app is
backgrounded or locked, with no on-device video decode (UR-040). Adds
player_enter/exit_background_audio commands, an audio-only stream URL
for video items across the repository layer, and the frontend handoff
state machine wired into VideoPlayer. Includes accompanying
repository/offline/player refactoring and regenerates the traceability
matrix.
dtourolle