refactor(audio): Phase 4 — unify song tracking, remove compat aliases

playerStore: remove currentPlayingSongId/currentPlayingBandId/setCurrentPlayingSong.
Single pair (currentSongId/currentBandId) now set exclusively when play() is
called, not when the page opens. This means MiniPlayer and sidebar links only
appear after audio has been started — correct UX for a "now playing" widget.

audioService: play() calls setCurrentSong instead of setCurrentPlayingSong;
cleanup() clears it. Remove isReadyForPlayback() and canAttemptPlayback()
aliases — all callers now use isWaveformReady() directly.

useWaveform: remove setCurrentSong call from init (store updated by play()
now); restore-playback snapshot reads currentSongId/currentBandId.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/hooks/useWaveform.ts

@@ -41,17 +41,12 @@ export function useWaveform(
       try {
         await audioService.initialize(containerRef.current!, options.url!);
 
-        // Update global song context
-        if (options.songId && options.bandId) {
-          usePlayerStore.getState().setCurrentSong(options.songId, options.bandId);
-        }
-
         // Restore playback if this song was already playing when the page loaded.
         // Read as a one-time snapshot — these values must NOT be reactive deps or
         // the effect would re-run on every time update (re-initializing WaveSurfer).
         const {
-          currentPlayingSongId,
-          currentPlayingBandId,
+          currentSongId,
+          currentBandId,
           isPlaying: wasPlaying,
           currentTime: savedTime,
         } = usePlayerStore.getState();
@@ -59,8 +54,8 @@ export function useWaveform(
         if (
           options.songId &&
           options.bandId &&
-          currentPlayingSongId === options.songId &&
-          currentPlayingBandId === options.bandId &&
+          currentSongId === options.songId &&
+          currentBandId === options.bandId &&
           wasPlaying &&
           audioService.isWaveformReady()
         ) {

web/src/services/audioService.ts

@@ -86,7 +86,7 @@ class AudioService {
     }
     await this.wavesurfer.play();
     if (songId && bandId) {
-      usePlayerStore.getState().setCurrentPlayingSong(songId, bandId);
+      usePlayerStore.getState().setCurrentSong(songId, bandId);
     }
   }
 
@@ -116,19 +116,10 @@ class AudioService {
     return this.isReady && !!this.wavesurfer;
   }
 
-  // Aliases kept for callers until Phase 3 cleans them up
-  public isReadyForPlayback(): boolean {
-    return this.isWaveformReady();
-  }
-
-  public canAttemptPlayback(): boolean {
-    return this.isWaveformReady();
-  }
-
   public cleanup(): void {
     this.destroyWaveSurfer();
     const store = usePlayerStore.getState();
-    store.setCurrentPlayingSong(null, null);
+    store.setCurrentSong(null, null);
     store.batchUpdate({ isPlaying: false, currentTime: 0 });
   }
 

web/src/stores/playerStore.ts

@@ -4,17 +4,16 @@ interface PlayerState {
   isPlaying: boolean;
   currentTime: number;
   duration: number;
+  // Set when audio starts playing; cleared on cleanup.
+  // Drives MiniPlayer visibility and sidebar "go to now playing" links.
   currentSongId: string | null;
   currentBandId: string | null;
-  currentPlayingSongId: string | null; // Track which song is actively playing
-  currentPlayingBandId: string | null;  // Track which band's song is actively playing
   setPlaying: (isPlaying: boolean) => void;
   setCurrentTime: (currentTime: number) => void;
   setDuration: (duration: number) => void;
   setCurrentSong: (songId: string | null, bandId: string | null) => void;
-  setCurrentPlayingSong: (songId: string | null, bandId: string | null) => void;
   reset: () => void;
-  batchUpdate: (updates: Partial<Omit<PlayerState, 'setPlaying' | 'setCurrentTime' | 'setDuration' | 'setCurrentSong' | 'setCurrentPlayingSong' | 'reset' | 'batchUpdate'>>) => void;
+  batchUpdate: (updates: Partial<Omit<PlayerState, 'setPlaying' | 'setCurrentTime' | 'setDuration' | 'setCurrentSong' | 'reset' | 'batchUpdate'>>) => void;
 }
 
 export const usePlayerStore = create<PlayerState>()((set) => ({
@@ -23,21 +22,16 @@ export const usePlayerStore = create<PlayerState>()((set) => ({
   duration: 0,
   currentSongId: null,
   currentBandId: null,
-  currentPlayingSongId: null,
-  currentPlayingBandId: null,
   setPlaying: (isPlaying) => set({ isPlaying }),
   setCurrentTime: (currentTime) => set({ currentTime }),
   setDuration: (duration) => set({ duration }),
   setCurrentSong: (songId, bandId) => set({ currentSongId: songId, currentBandId: bandId }),
-  setCurrentPlayingSong: (songId, bandId) => set({ currentPlayingSongId: songId, currentPlayingBandId: bandId }),
   batchUpdate: (updates) => set(updates),
-  reset: () => set({ 
-    isPlaying: false, 
-    currentTime: 0, 
-    duration: 0, 
-    currentSongId: null, 
+  reset: () => set({
+    isPlaying: false,
+    currentTime: 0,
+    duration: 0,
+    currentSongId: null,
     currentBandId: null,
-    currentPlayingSongId: null,
-    currentPlayingBandId: null
   })
-}));
+}));

web/tests/audioService.test.ts

@@ -164,19 +164,19 @@ describe('AudioService', () => {
       expect(mockWs.play).toHaveBeenCalled();
     });
 
-    it('updates currentPlayingSongId/BandId in the store', async () => {
+    it('updates currentSongId/BandId in the store', async () => {
       await initService(service);
       await service.play('song-1', 'band-1');
       const state = usePlayerStore.getState();
-      expect(state.currentPlayingSongId).toBe('song-1');
-      expect(state.currentPlayingBandId).toBe('band-1');
+      expect(state.currentSongId).toBe('song-1');
+      expect(state.currentBandId).toBe('band-1');
     });
 
     it('does not update store ids when called without ids', async () => {
       await initService(service);
       await service.play();
       const state = usePlayerStore.getState();
-      expect(state.currentPlayingSongId).toBeNull();
+      expect(state.currentSongId).toBeNull();
     });
   });