fix(ui): start new album from track 1 after closing player (#5441)

When a user played an album, advanced a few tracks, closed the player,
then played a different album, playback started mid-album at the
previous track index instead of track 1.

The root cause was in reduceSyncQueue: the hasPendingSwitch check
compared playIndex against savedPlayIndex, but after clearQueue both
reset to 0, making the check falsely conclude no switch was pending.
This caused PLAYER_SYNC_QUEUE to prematurely clear the playIndex and
clear flags before the music player library could act on them.

Fix: also treat clear=true as a signal that a track switch is pending,
since it means a new queue was just loaded.

ui/src/reducers/playerReducer.js

@@ -164,13 +164,15 @@ const reduceSetVolume = (state, { data: { volume } }) => {
 }
 
 const reduceSyncQueue = (state, { data: { audioInfo, audioLists } }) => {
-  // Only keep clear and playIndex alive when there is an actual pending
-  // track switch (playIndex differs from savedPlayIndex). This lets
-  // PLAYER_PLAY_TRACKS selections survive the sync, while allowing
-  // PLAYER_PLAY_NEXT (which sets playIndex to the current track) to
-  // reset immediately and avoid restarting playback.
+  // Keep clear and playIndex alive when there is a pending track switch.
+  // A switch is pending when playIndex is set AND either:
+  //   - playIndex differs from savedPlayIndex, OR
+  //   - clear is true (a new queue was loaded, e.g. after clearQueue + playTracks)
+  // The clear check handles the edge case where both playIndex and
+  // savedPlayIndex are 0 (close player then play a new album from track 1).
   const hasPendingSwitch =
-    state.playIndex != null && state.playIndex !== state.savedPlayIndex
+    state.playIndex != null &&
+    (state.clear || state.playIndex !== state.savedPlayIndex)
   return {
     ...state,
     queue: audioLists,

ui/src/reducers/playerReducer.test.js

@@ -96,6 +96,88 @@ describe('playerReducer', () => {
     })
   })
 
+  describe('play new album after closing player (issue #5440)', () => {
+    it('SYNC_QUEUE preserves pending playIndex=0 after clearQueue', () => {
+      // Scenario: user plays album A, advances to track 3, closes player,
+      // then plays album B. After clearQueue, savedPlayIndex=0.
+      // PLAYER_PLAY_TRACKS sets playIndex=0. SYNC_QUEUE must NOT clear it.
+      const stateAfterClearThenPlay = {
+        queue: [
+          { trackId: 'b1', uuid: 'u1', name: 'B Song 1' },
+          { trackId: 'b2', uuid: 'u2', name: 'B Song 2' },
+          { trackId: 'b3', uuid: 'u3', name: 'B Song 3' },
+        ],
+        current: {},
+        playIndex: 0,
+        savedPlayIndex: 0, // reset by clearQueue
+        clear: true,
+        volume: 1,
+      }
+
+      const action = {
+        type: PLAYER_SYNC_QUEUE,
+        data: {
+          audioInfo: {},
+          audioLists: stateAfterClearThenPlay.queue,
+        },
+      }
+      const result = playerReducer(stateAfterClearThenPlay, action)
+      expect(result.playIndex).toBe(0)
+      expect(result.clear).toBe(true)
+    })
+
+    it('CURRENT for wrong track preserves pending playIndex=0 after clearQueue', () => {
+      // The music player fires onAudioPlay for the old track (at index 3)
+      // before switching to the new track at index 0.
+      const stateAfterClearThenPlay = {
+        queue: [
+          { trackId: 'b1', uuid: 'u1', name: 'B Song 1' },
+          { trackId: 'b2', uuid: 'u2', name: 'B Song 2' },
+          { trackId: 'b3', uuid: 'u3', name: 'B Song 3' },
+          { trackId: 'b4', uuid: 'u4', name: 'B Song 4' },
+        ],
+        current: {},
+        playIndex: 0,
+        savedPlayIndex: 0,
+        clear: true,
+        volume: 1,
+      }
+
+      // Player reports track at index 3 as current (stale callback)
+      const action = {
+        type: PLAYER_CURRENT,
+        data: { uuid: 'u4', name: 'B Song 4', volume: 1 },
+      }
+      const result = playerReducer(stateAfterClearThenPlay, action)
+      expect(result.playIndex).toBe(0)
+      expect(result.clear).toBe(true)
+    })
+
+    it('CURRENT for correct track consumes pending playIndex=0', () => {
+      const stateAfterClearThenPlay = {
+        queue: [
+          { trackId: 'b1', uuid: 'u1', name: 'B Song 1' },
+          { trackId: 'b2', uuid: 'u2', name: 'B Song 2' },
+        ],
+        current: {},
+        playIndex: 0,
+        savedPlayIndex: 0,
+        clear: true,
+        volume: 1,
+      }
+
+      // Player confirms it switched to track at index 0
+      const action = {
+        type: PLAYER_CURRENT,
+        data: { uuid: 'u1', name: 'B Song 1', volume: 1 },
+      }
+      const result = playerReducer(stateAfterClearThenPlay, action)
+      expect(result.playIndex).toBeUndefined()
+      expect(result.clear).toBe(false)
+      expect(result.savedPlayIndex).toBe(0)
+    })
+  })
+
   describe('PLAYER_REFRESH_QUEUE', () => {
     it('clamps negative savedPlayIndex to 0', () => {
       const state = {