The previous adaptive scheme dropped to 5s when idle and 1s when
paused-with-track. PLAYBACK_STATE_WAKEUP catches synchronous V2
mutations (pause/resume/stop/seek) instantly, but play_data() is
asynchronous: it queues an AudioCommand::Play over a channel and
returns. The audio thread sets is_playing/start_playback_timer only
after decoder + device init (500-2000ms), so the wakeup fires too
early — the loop reads stale state, decides 'idle' or 'paused', and
sleeps for the full long branch before catching the actual transition.
current_position() is wall-clock based (now - playback_start_millis),
so by the time the next idle tick arrives, position is already past
second 1 and the seekbar appears to jump straight to 2+.
Polling uniformly at 250ms catches the async transition within one
cadence and keeps the seekbar showing 0:00 -> 0:01 -> 0:02 from the
start. Cost is negligible (~10 atomic reads x 4 Hz), and should_emit
filters every no-change iteration so the frontend wire is unaffected.
cc
vicrodh
1e16ec52f5