This PR represents a testing and debugging cycle following v3.0.2. Initial work on sync group volume management uncovered multiple UI bugs that required fixes. The final result addresses:

1. **Fix: Group Player Volume Management** - Two distinct volume control issues for Music Assistant sync groups
2. **Feature: Hardware Volume Button Integration** - Phone volume buttons now control Music Assistant player volume from lockscreen / shade widget / app minimised
3. **UI Bug Fixes** - Five UI issues discovered during sync group testing, which had to be fixed to get the sync groups to work without crashes
4. **Fix: Cold Start Homepage Race Condition** - Intermittent empty homepage on app cold start - surfaced once sync group volume calculations were introduced.
5. **Code Quality: Cleanup and Optimization** - Removes dead code and eliminates duplicate logic - mine, not yours, I tried to not to touch your code as much as possible

All changes have been tested and verified with `dart analyze` showing no new issues.

---

**Issue:** Volume control for Music Assistant sync groups had two distinct problems depending on how the group was created:

1. **Server-side groups**: Volume slider would snap back to 0 immediately after release
2. **In-app created groups**: Adjusting the leader's volume only changed that one player, not all members proportionally

**Root Cause:** The Music Assistant API returns `volume_level: null` for certain group players (pre-configured speaker groups with `provider == 'player_group'` and some server-side sync groups). The app had no logic to handle this case, so the null volume was interpreted as 0.

**Solution:** Implemented `GroupVolumeManager` service with dual-tier volume protection:

- **Tier 1 (GroupVolumeManager):** Computes effective volume from group members (detects groups, resolves nested, averages volumes, caches pending for 30s, confirms with ±3 tolerance).
- **Tier 2 (Provider-level):** Optimistic update protection (caches for 8s/30s, prevents stale overwrites).

**Root Cause:** For in-app groups, leader has non-null volume, so `setVolume()` only affects leader, not members.

**Expected behavior:** Leader adjustment changes all members proportionally; individual adjustments affect only that member.

**Solution:** In `setVolume()`, for group leaders with non-null volume:
1. Calculate proportional: `memberNewVol = (memberCurrentVol * newVol / leaderCurrentVol).round()` (handle zero case with absolute).
2. Cache pending, update optimistically, fire parallel API calls.

**Files Changed:**
- `lib/services/group_volume_manager.dart` (NEW - 162 lines)
- `lib/providers/music_assistant_provider.dart` (added manager, helper, updated events/state/volume methods)

---

**Feature:** Phone hardware volume buttons (including lockscreen) control MA player volume, with system HUD mirroring.

**Implementation:**
- **Android Native:** `MainActivity.kt` (~120 lines) - VolumeContentObserver, MethodChannel commands, lifecycle.
- **Flutter Service:** `hardware_volume_service.dart` (~65 lines) - streams, observer methods, sync.
- **Integration:** `main.dart` (~35 lines) - adjust/set/update methods, subscription.

**Why This Matters:** Seamless remote control from lockscreen/tray/buttons.

---

During sync group testing, fixed these UI bugs:

**File:** `lib/main.dart`

**Issue:** Console warnings during init.

**Root Cause:** Init code outside `runZonedGuarded()`.

**Fix:** Move init inside `runZonedGuarded()`.

---

**Files:** `lib/screens/home_screen.dart`, `lib/widgets/global_player_overlay.dart`

**Issue:** Crash on nav interaction.

**Root Cause:** Nav in Stack without Overlay.

**Fix:** Move nav to Scaffold.bottomNavigationBar, add extendBody: true.

---

**Files:** `lib/widgets/artist_card.dart`, `lib/widgets/album_card.dart`

**Issue:** Warnings causing corruption.

**Root Cause:** Service calls in initState trigger setState during build.

**Fix:** Defer with addPostFrameCallback, add mounted guard.

---

**File:** `lib/screens/new_library_screen.dart`

**Issue:** Crash on library tabs.

**Root Cause:** context.select in sliver context.

**Fix:** Use Consumer wrappers for tabs.

---

**File:** `lib/widgets/player/queue_panel.dart`

**Issue:** Crash on long-press buttons.

**Root Cause:** Tooltips require Overlay, but in Stack.

**Fix:** Remove tooltip properties.

---

**File:** `lib/screens/settings_screen.dart`

**Issue:** Back button crashes to black screen.

**Root Cause:** Navigator.pop pops home screen.

**Fix:** Use showPlayer + setSelectedIndex(0).

---

**Issue:** Intermittent empty homepage on cold start.

**Root Cause:** isConnected true before auth complete, leading to failed fetches.

**Solution:** Delay broadcasting 'connected' state until auth if required (`music_assistant_provider.dart:1058-1101`).

---

The `GroupVolumeManager` is a stateful service that handles **server-side groups with null volume**:

1. **Detects group players:**
   ```dart
   bool isGroupPlayer(Player player) {
     // Pre-configured MA speaker groups
     if (player.provider == 'player_group') return true;
     // Dynamic sync groups: have multiple members but MA returns null volume
     if (player.groupMembers != null &&
         player.groupMembers!.length > 1 &&
         player.volumeLevel == null) {
       return true;
     }
     return false;
   }
   ```

2. **Computes effective volume:**
   - Recursively resolves nested groups (max depth 3)
   - Averages volumes across all leaf members
   - Skips self-references in `groupMembers`
   - Returns `null` if no members have valid volumes

3. **Caches pending volumes:**
   - When user sets volume: stored with timestamp
   - Returns cached value if within 30s timeout
   - Clears cache when member average converges (±3 tolerance)
   - Falls back to computed average after timeout

4. **Integrates with provider:**
   - Called from `_applyVolumeProtection()` in provider
   - Receives fresh `allPlayers` list for accurate member volumes
   - Injects effective volume into `_selectedPlayer` via `copyWith()`

For **in-app created groups with non-null leader volume**, proportional propagation works as follows:

1. **Detection:** `setVolume()` checks if `player.isGroupLeader && !isGroupPlayer(player)`
   - Leader has `groupMembers` with 2+ entries
   - Leader has its own non-null `volumeLevel`
   - NOT detected as a group player (GroupVolumeManager handles those)

2. **Calculation:** For each member in `groupMembers` (excluding leader itself):
   ```dart
   if (leaderCurrentVol > 0) {
     memberNewVol = (memberVol * newVol / leaderCurrentVol).round().clamp(0, 100)
   } else {
     memberNewVol = newVol  // Can't ratio from zero
   }
   ```

3. **Execution:**
   - Cache `_pendingVolumes[memberId]` and `_pendingVolumeTimestamps[memberId]`
   - Update `_availablePlayers[idx]` optimistically
   - Fire `_api?.setVolume(memberId, memberNewVol)` without awaiting
   - Continue to send leader's own `volume_set` command

4. **Result:** All member volumes scale proportionally with the leader, preserving relative balance.

```
WebSocket connects → MAConnectionState.connected
                    ↓
         Auth required?
        ↙              ↘
      YES              NO
       ↓                ↓
  Don't notify    Set state + notify
  Try auth              ↓
       ↓          Initialize
   Success?
  ↙        ↘
YES        NO
 ↓          ↓
auth     error state
event     + notify
 ↓
Set state
+ notify
 ↓
Initialize
```

**Key:** Listeners only see `isConnected = true` after auth completes (or immediately if no auth required).

android/.../MainActivity.kt                      |  120 + (NEW - ContentObserver)
lib/main.dart                                    |  207 ±
lib/providers/music_assistant_provider.dart      |  165 ±
lib/screens/home_screen.dart                     |  172 ± (BottomNav moved here)
lib/screens/new_library_screen.dart              |   70 ± (Consumer wrappers)
lib/screens/settings_screen.dart                 |    9 ± (back button fix)
lib/services/group_volume_manager.dart           |  162 + (NEW)
lib/services/hardware_volume_service.dart        |   65 + (NEW)
lib/widgets/album_card.dart                      |   23 ± (postFrameCallback)
lib/widgets/artist_card.dart                     |   23 ± (postFrameCallback)
lib/widgets/global_player_overlay.dart           |  171 - (BottomNav moved out)
lib/widgets/player/queue_panel.dart              |    2 - (tooltip removed)

**Total:** ~650 added, ~300 removed/refactored.