- Add isPaused to WorkoutActivityAttributes.ContentState
- Show PAUSED badge, freeze timer to static text, dim content when paused
- Prevent stale spinner on pause by extending staleDate to 1 hour
- Add 6s timer warning color, progress bar, compact heavy timer
- Pulsing compact indicator during WORK phase
- Lock Screen margins aligned to Apple's 14pt HIG spec
- Add Sendable conformance to MusicActivityAttributes.ContentState
- Remove @preconcurrency on ActivityKit import
- Use nonisolated(unsafe) guards for Activity refs in task closures
- Add observeActivityState() to handle stale/ended/dismissed activity states
- Set staleDate (120s) instead of nil for push notification support
**Architecture (PlayerViewModel):**
- Move ActivityKit lifecycle from SwiftUI View to ViewModel (MVVM correction)
- call syncActivity() at END of enterPhase() — after all state is set,
eliminating the race where phase was Published before timeRemaining
- Always recalculate phaseEndDate = Date() + timeRemaining (no stale cache)
- Dedicated Timer in ViewModel for periodic heart-rate/track sync (5s)
- Start/stop activity sync timer on play/pause/resume/abandon/finish
- stale activity reference discard + recreate-on-failure fallback
- Modern iOS 16.2+ API: ActivityContent, non-throwing update()
**PlayerView:**
- Remove all ActivityKit code (import, @State workoutActivity,
phaseEndDate, dynamicIslandAvailable, 4 methods, .onReceive timer)
- Delegate to ViewModel: onChange(musicVM.currentTrack) sets vm.trackTitle/Artist
and calls vm.syncActivity(); onDisappear calls await vm.endActivity()
- Music/audio onChange handlers no longer contain activity logic
**Info.plist:**
- Add UIBackgroundModes → audio so music continues and app stays alive
in background, allowing Timer-based activity updates
- Widget Info.plist: add NSSupportsLiveActivitiesFrequentUpdates
**WorkoutActivityAttributes.ContentState:**
- Add Sendable conformance for Swift 6 strict concurrency
Fixes: timer stuck at 0 on first work phase, exercise name missing,
music stopping in background, Dynamic Island freezing in background,
widget drift due to cached phaseEndDate
## What changed
### Player Redesign (video-first layout)
- New compact timer ring (110pt) with phase label, replaces 240pt ring
- Auto-hide top bar with block progress dots (3s auto-dismiss)
- Expandable now-playing music pill with skip control
- Bottom control bar with heart rate, play/pause, and skip
- Exercise caption with 'Next' preview during rest phases
- Compact round counter (capsule dots)
### Dynamic Island & Live Activities
- WorkoutLiveActivity widget: expanded, compact, and minimal views
- Phase-colored timers with Text(timerInterval:) countdown
- Shows exercise name, round progress, heart rate, music track
- MusicLiveActivity: standalone music now-playing widget
- LiveActivityMusicBars animated component
- Deep link from Dynamic Island back to app
### Timer Drift Fix (critical)
- Store a stable phaseEndDate once per phase instead of
recalculating Date() + timeRemaining on every update
- Prevents dynamic island countdown from rubber-banding
due to 5-second periodic update recalculation drift
- Reset phaseEndDate on phase change and resume from pause
- Guard Live Activity updates behind vm.isRunning to prevent
premature creation when music track loads before workout start
- Fixes timer showing 0 in Dynamic Island when expanding
from home screen
### New PlayerViewModel timer engine
- Full phase support: prep, warmup, work, rest,
interBlockRest, cooldown, complete
- 1-second countdown with audio cues at 3-2-1
- Phase transitions with spring animation and haptics
- HealthKit live session integration
- Workout session recording with completion
### Music Service
- New MusicPlayerViewModel with vibe-based playlist loading
- Track info exposed for Dynamic Island display
- Skip track support from Dynamic Island notification action
- Automatic play/pause based on phase and running state
### Additional
- ZoneHighlightIcon component for HomeTab zone cards
- Updated watchOS localizations with complication strings
- Info.plist updated for widget extension
