fix(scrobbler): proxy NowPlaying even when ignoreScrobble is set (#5559)

* fix(scrobbler): proxy NowPlaying even when ignoreScrobble is set

When a client reports playback with ignoreScrobble=true, the reportPlayback
handler suppressed both the scrobble submission and the NowPlaying update sent
to external agents (Last.fm, ListenBrainz, plugins). These are independent
concerns: ignoring the scrobble submission should not stop Navidrome from
telling external services what is currently playing.

The !params.IgnoreScrobble guard now applies only to the scrobble submission
and play-count path; the NowPlaying dispatch is gated solely by the player's
ScrobbleEnabled flag. This mirrors the legacy scrobble endpoint, where
submission=false has always still set NowPlaying.

* test(scrobbler): assert no scrobble dispatch when ignoreScrobble=true

Address PR review feedback: explicitly verify that ignoreScrobble=true
suppresses the scrobble submission (not just the play count) while NowPlaying
is still dispatched, so the flag cannot regress into ignoring nothing. Also
expand the NowPlaying gating comment to spell out the IgnoreScrobble vs
ScrobbleEnabled rules and identify the external agents involved.

core/scrobbler/play_tracker.go

@@ -371,7 +371,14 @@ func (p *playTracker) ReportPlayback(ctx context.Context, params ReportPlaybackP
 		p.broker.SendBroadcastMessage(ctx, &events.NowPlayingCount{Count: p.playMap.Len()})
 	}
 
-	if !params.IgnoreScrobble && player.ScrobbleEnabled &&
+	// NowPlaying gating, by design distinct from scrobble submission:
+	//   - IgnoreScrobble=true   -> still send NowPlaying (suppresses only the
+	//     scrobble submission/play-count above), mirroring the legacy scrobble
+	//     endpoint's submission=false behavior.
+	//   - player.ScrobbleEnabled=false -> never send NowPlaying.
+	// External agents here are the active scrobblers (Last.fm, ListenBrainz, and
+	// scrobbler plugins) returned by getActiveScrobblers; see dispatchNowPlaying.
+	if player.ScrobbleEnabled &&
 		(params.State == StateStarting || params.State == StatePlaying) {
 		if info, err := p.playMap.Get(clientId); err == nil {
 			p.enqueueNowPlaying(ctx, clientId, user.ID, &info.MediaFile, int(params.PositionMs/1000))

core/scrobbler/play_tracker_test.go

@@ -521,6 +521,7 @@ var _ = Describe("PlayTracker", func() {
 			})
 
 			It("does NOT scrobble when ignoreScrobble=true even if threshold met", func() {
+				fake.ScrobbleCalled.Store(false)
 				err := tracker.ReportPlayback(ctx, ReportPlaybackParams{
 					MediaId: "123", PositionMs: 0, State: "starting", PlaybackRate: 1.0, ClientId: defaultClientId,
 				})
@@ -531,6 +532,7 @@ var _ = Describe("PlayTracker", func() {
 				})
 				Expect(err).ToNot(HaveOccurred())
 				Expect(track.PlayCount).To(Equal(int64(0)))
+				Consistently(func() bool { return fake.ScrobbleCalled.Load() }).Should(BeFalse())
 			})
 
 			It("does NOT scrobble when player ScrobbleEnabled=false even if threshold met", func() {
@@ -715,14 +717,14 @@ var _ = Describe("PlayTracker", func() {
 				Consistently(func() bool { return fake.GetNowPlayingCalled() }).Should(BeFalse())
 			})
 
-			It("does NOT dispatch when ignoreScrobble=true", func() {
+			It("still dispatches NowPlaying when ignoreScrobble=true", func() {
 				fake.nowPlayingCalled.Store(false)
 				err := tracker.ReportPlayback(ctx, ReportPlaybackParams{
 					MediaId: "123", PositionMs: 0, State: "starting", PlaybackRate: 1.0, ClientId: defaultClientId,
 					IgnoreScrobble: true,
 				})
 				Expect(err).ToNot(HaveOccurred())
-				Consistently(func() bool { return fake.GetNowPlayingCalled() }).Should(BeFalse())
+				Eventually(func() bool { return fake.GetNowPlayingCalled() }).Should(BeTrue())
 			})
 
 			It("does NOT dispatch when ScrobbleEnabled=false", func() {