diff --git a/backend/player/loadstate_test.go b/backend/player/loadstate_test.go
new file mode 100644
index 0000000..50dabbd
--- /dev/null
+++ b/backend/player/loadstate_test.go
@@ -0,0 +1,213 @@
+package player
+
+import (
+	"log/slog"
+	"testing"
+	"time"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+
+	"yellowjacket/backend/events"
+	"yellowjacket/internal/testfixtures"
+)
+
+// fixtureSampleRate is what cmd/gentestdata writes (audio.go).  It is
+// deliberately not the speaker rate, which is what lets these tests
+// tell the decoder's format from the player's default.
+const fixtureSampleRate = 22050
+
+// newTestPlayer is a player with a context and no database, so the
+// track-metadata lookup cannot succeed.
+func newTestPlayer(t *testing.T) *Player {
+	t.Helper()
+
+	p := NewPlayer(slog.Default(), nil)
+	rec := events.NewRecorder()
+
+	_ = p.ServiceStartup(
+		events.WithSink(t.Context(), rec),
+		application.ServiceOptions{},
+	)
+
+	return p
+}
+
+// loadFileLocked needs no speaker: it decodes, builds the chain and
+// registers it paused. speaker.Play on an uninitialised device is
+// what the integration guard elsewhere is about, so these assert on
+// the state the load computed rather than on playback.
+
+// p.format used to be assigned once, in the constructor, to the
+// *speaker's* rate -- so it claimed 44.1 kHz for every file ever
+// loaded. Play()'s replay-after-finish path resamples from it, so a
+// finished track played again was resampled from a rate the decoder
+// never produced: audibly the wrong speed and pitch, and wrong
+// length and position arithmetic with it.
+//
+// The fixtures are 22050 Hz, which is exactly the point -- any of
+// them disagrees with the speaker rate.
+func TestLoadRecordsTheDecodersOwnFormat(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseCoverDedup)[0]
+
+	p := newTestPlayer(t)
+
+	if got := p.format.SampleRate; got != speakerSampleRate {
+		t.Fatalf(
+			"precondition: a fresh player should hold the speaker "+
+				"rate, got %d",
+			got,
+		)
+	}
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	if p.format.SampleRate == speakerSampleRate {
+		t.Fatalf(
+			"p.format still holds the speaker rate (%d) after "+
+				"loading a %d Hz file: the replay path would "+
+				"resample from the wrong rate",
+			speakerSampleRate, fixtureSampleRate,
+		)
+	}
+
+	if got := int(p.format.SampleRate); got != fixtureSampleRate {
+		t.Errorf(
+			"expected the decoder's rate %d, got %d",
+			fixtureSampleRate, got,
+		)
+	}
+}
+
+// trackLengthMs is written only when the database has a row for the
+// file and cleared only by UnloadTrack, so a track with no row used
+// to inherit whatever the last track's duration was -- and every
+// position report is scaled by it, so the whole seek bar was then
+// reporting one track's progress on another track's scale.
+//
+// There is no database here, so the lookup cannot succeed: exactly
+// the case that used to inherit.
+func TestLoadDoesNotInheritThePreviousTracksDuration(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseCoverDedup)[0]
+
+	p := newTestPlayer(t)
+
+	// Stand in for a previous track whose duration was resolved.
+	p.trackLengthMs = 9_999_000
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	if p.trackLengthMs == 9_999_000 {
+		t.Fatal(
+			"the previous track's duration survived the load: every " +
+				"position report for this track would be scaled by it",
+		)
+	}
+}
+
+// A new chain supersedes the old one's pending finished callback.
+// Without this, a callback that queued for p.mu behind a LoadFile
+// woke up and rewound, stopped and auto-advanced the *new* track.
+func TestANewChainSupersedesTheOldFinishedCallback(t *testing.T) {
+	m := testfixtures.Load(t)
+	paths := m.Case(t, testfixtures.CaseCoverDedup)
+
+	if len(paths) < 2 {
+		t.Skip("need two fixture tracks")
+	}
+
+	p := newTestPlayer(t)
+
+	if err := p.LoadFile(paths[0]); err != nil {
+		t.Fatalf("LoadFile(%s): %v", paths[0], err)
+	}
+
+	stale := p.chainID
+
+	if err := p.LoadFile(paths[1]); err != nil {
+		t.Fatalf("LoadFile(%s): %v", paths[1], err)
+	}
+
+	if p.chainID == stale {
+		t.Fatal("loading a second file did not supersede the chain")
+	}
+
+	called := false
+
+	p.SetPlaybackFinishedHandler(func(error) { called = true })
+
+	// The first track's callback, arriving late.
+	p.onPlaybackFinished(stale, nil)
+
+	if called {
+		t.Error(
+			"a superseded chain's callback drove auto-advance: the " +
+				"track that is loaded now would be skipped",
+		)
+	}
+
+	if p.state == Stopped {
+		t.Error(
+			"a superseded chain's callback stopped the current track",
+		)
+	}
+}
+
+// The decoder is read by the read-ahead goroutine and by every
+// position emit, and those used to be guarded by different mutexes:
+// the read by srcMu, the position by the speaker lock, which
+// read-ahead never takes. Under -race this failed on the emit that
+// LoadFile itself makes.
+//
+// It needs the read-ahead goroutine to actually be running, so it
+// keeps asking for the position for long enough to overlap it.
+func TestPositionReadsDoNotRaceTheReadAhead(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseFLACAlbum)[0]
+
+	p := newTestPlayer(t)
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	for range 200 {
+		if _, err := p.CurrentPositionSeconds(); err != nil {
+			t.Fatalf("CurrentPositionSeconds: %v", err)
+		}
+	}
+}
+
+// Seeking emits the landing position, and that emit reads the
+// decoder -- so the source lock the seek holds must be released
+// before it. A reentrant take here is a deadlock, not a failure,
+// which is why this test exists rather than a comment.
+func TestSeekEmitsWithoutDeadlocking(t *testing.T) {
+	m := testfixtures.Load(t)
+	path := m.Case(t, testfixtures.CaseFLACAlbum)[0]
+
+	p := newTestPlayer(t)
+
+	if err := p.LoadFile(path); err != nil {
+		t.Fatalf("LoadFile(%s): %v", path, err)
+	}
+
+	done := make(chan struct{})
+
+	go func() {
+		defer close(done)
+
+		_ = p.Seek(1)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(10 * time.Second):
+		t.Fatal("Seek deadlocked: the position emit re-took the source lock")
+	}
+}
diff --git a/backend/player/player.go b/backend/player/player.go
index b141a6d..7ff3b5c 100644
--- a/backend/player/player.go
+++ b/backend/player/player.go
@@ -52,9 +52,17 @@ type Player struct {
 	control                 *beep.Ctrl
 	volume                  *effects.Volume
 	speakerStreamer         beep.Streamer
-	playbackFinishedHandler func()
+	playbackFinishedHandler func(error)
 	trackChangeID           uint64
-	mediaControls           mediacontrols.Handler
+
+	// chainID identifies the streamer chain currently registered with
+	// the speaker.  updateStreamers bumps it, and the finished
+	// callback carries the value it was registered with, so a callback
+	// that queued for p.mu behind a LoadFile can tell that the player
+	// has moved on and return rather than rewinding somebody else's
+	// track.
+	chainID       uint64
+	mediaControls mediacontrols.Handler
 
 	// duckAmount is the attenuation currently applied on top of the
 	// user's volume, in the same base-2 exponent effects.Volume uses.
@@ -180,11 +188,18 @@ func (p *Player) InitSpeaker() error {
 }
 
 // SetPlaybackFinishedHandler sets a callback invoked when a track
-// finishes naturally. This allows the queue to drive auto-advance
+// stops streaming. This allows the queue to drive auto-advance
 // without circular imports.
 //
+// The error says *why* the track stopped: nil for a track that
+// reached its end, non-nil for one that broke partway through.  Both
+// arrive here because both look identical to the speaker, and only
+// the queue holds the metadata a PlaybackFailed needs -- but they are
+// not the same event, and reporting a decode failure as a natural
+// finish is how a broken file used to auto-advance in silence.
+//
 //wails:ignore // internal wiring, not part of the app's IPC surface.
-func (p *Player) SetPlaybackFinishedHandler(handler func()) {
+func (p *Player) SetPlaybackFinishedHandler(handler func(error)) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 
@@ -424,6 +439,19 @@ func (p *Player) updateStreamers(
 	newBaseStreamer beep.StreamSeeker,
 	sr beep.SampleRate,
 ) error {
+	// A new chain supersedes the old one, so any finished callback the
+	// old one still owes is stale from here on.
+	p.chainID++
+
+	// The previous read-ahead goroutine reads the same decoder this
+	// one is about to, under its own srcMu -- two goroutines, two
+	// mutexes, one decoder that is not safe for concurrent use.  The
+	// replay-after-finish path rebuilds from p.seeker without going
+	// through LoadFile, which is where that pair could meet.
+	if p.buffered != nil {
+		p.buffered.Close()
+	}
+
 	// set base streamer
 	p.baseStreamer = newBaseStreamer
 	p.seeker = newBaseStreamer
@@ -474,23 +502,57 @@ func (p *Player) startPaused() {
 	p.control.Paused = true
 	speaker.Unlock()
 
+	// Captured, not read at callback time: by then p.chainID names
+	// whatever is loaded *now*, which is the thing the guard exists to
+	// distinguish this chain from.
+	chainID := p.chainID
+	buffered := p.buffered
+
 	// The beep.Callback runs with the speaker mutex held, so we
 	// dispatch to a goroutine that can safely acquire p.mu.
 	speaker.Play(beep.Seq(
 		p.speakerStreamer,
 		beep.Callback(func() {
-			go p.onPlaybackFinished()
+			// Asked here rather than under p.mu: this is the chain that
+			// just ended, and by the time the goroutine holds the lock
+			// p.buffered may be a different one.
+			var err error
+			if buffered != nil {
+				err = buffered.Err()
+			}
+
+			go p.onPlaybackFinished(chainID, err)
 		}),
 	))
 
 	p.state = Paused
 }
 
-// onPlaybackFinished handles the natural end of a track. It is
-// called on a new goroutine from the beep callback (which holds
-// the speaker lock) so that it can safely acquire p.mu.
-func (p *Player) onPlaybackFinished() {
+// onPlaybackFinished handles a track that stopped streaming, whether
+// it ended or broke. It is called on a new goroutine from the beep
+// callback (which holds the speaker lock) so that it can safely
+// acquire p.mu.
+//
+// chainID names the streamer chain the callback fired for and srcErr
+// says why it stopped.
+func (p *Player) onPlaybackFinished(chainID uint64, srcErr error) {
 	p.mu.Lock()
+
+	// The player has moved on while this callback queued for the lock
+	// -- a user pressing Next during the last second of a track is
+	// enough. Everything below is about the *current* track: rewinding
+	// the decoder, saying playback stopped, asking the queue to
+	// advance. Doing any of it now would do it to the wrong track.
+	if chainID != p.chainID {
+		p.mu.Unlock()
+		p.logger.Debug(
+			"Ignoring finished callback for a superseded chain",
+			"chain", chainID, "current", p.chainID,
+		)
+
+		return
+	}
+
 	p.state = Stopped
 	handler := p.playbackFinishedHandler
 	mc := p.mediaControls
@@ -501,10 +563,11 @@ func (p *Player) onPlaybackFinished() {
 	// the Stopped state anyway, so this only moves the decoder.
 	p.rewindLocked()
 	p.emitPositionLocked()
-	p.mu.Unlock()
 
-	// Emit Wails events outside the lock — these are non-blocking
-	// calls that don't need player state.
+	// Emitted under p.mu, like every other transition in this file.
+	// Outside it, a Play() taking the lock in the gap emits `playing`
+	// first and this stale `stopped` lands last -- leaving the button
+	// showing play over a track that is audibly running.
 	p.emitPlaybackFinished()
 
 	events.Emit(
@@ -513,6 +576,8 @@ func (p *Player) onPlaybackFinished() {
 		map[string]string{"state": string(Stopped)},
 	)
 
+	p.mu.Unlock()
+
 	// Notify media controls outside the lock. The track just
 	// ended so position is 0.
 	if mc != nil {
@@ -521,12 +586,19 @@ func (p *Player) onPlaybackFinished() {
 		)
 	}
 
-	p.logger.Info("Playback finished naturally")
+	if srcErr != nil {
+		p.logger.Error(
+			"Playback stopped: the audio source failed",
+			"err", srcErr,
+		)
+	} else {
+		p.logger.Info("Playback finished naturally")
+	}
 
 	// Notify queue for auto-advance. Called without p.mu held
 	// because it re-enters the player via LoadFile/Play.
 	if handler != nil {
-		handler()
+		handler(srcErr)
 	}
 }
 
@@ -587,6 +659,18 @@ func (p *Player) loadFileLocked(filePath string) error {
 
 	p.currentFile = f
 
+	// The decoder's own format, kept for the paths that rebuild the
+	// chain later: Play()'s replay branch resamples from it, so a
+	// stale rate there plays a finished track back at the wrong speed.
+	p.format = format
+
+	// The previous track's duration must not outlive it.  This is set
+	// again by emitTrackChanged below, but only when the database has
+	// a row for the file -- and every position this player reports is
+	// scaled by it, so inheriting means every report is wrong by the
+	// ratio between two unrelated tracks.
+	p.trackLengthMs = 0
+
 	if err := p.updateStreamers(
 		streamer, format.SampleRate,
 	); err != nil {
@@ -906,6 +990,8 @@ func (p *Player) CurrentPosition() (int, error) {
 		return 0, errNoAudioFileLoaded
 	}
 
+	defer p.lockSourceLocked()()
+
 	speaker.Lock()
 	pos := math.Round(
 		100.0 * float64(p.seeker.Position()) /
@@ -924,6 +1010,28 @@ func (p *Player) Seek(targetSeconds int) error {
 	return p.seekLocked(targetSeconds)
 }
 
+// lockSourceLocked blocks the read-ahead goroutine from touching the
+// decoder and returns the function that releases it, so a caller can
+// `defer p.lockSourceLocked()()`.
+//
+// Reading the decoder's position is a read *of the decoder*, and the
+// speaker lock does not exclude the read-ahead goroutine -- it never
+// takes it.  That was a genuine data race on every position emit,
+// once a second for the whole of playback.
+//
+// srcMu is not reentrant, so nothing that already holds it may call
+// this; seekSourceLocked exists to keep that region free of emits.
+// Must be called with p.mu held.
+func (p *Player) lockSourceLocked() func() {
+	if p.buffered == nil {
+		return func() {}
+	}
+
+	p.buffered.LockSource()
+
+	return p.buffered.UnlockSource
+}
+
 // rewindLocked returns the decoder to the start of the track without
 // touching playback state.  Must be called with p.mu held.
 func (p *Player) rewindLocked() {
@@ -959,6 +1067,46 @@ func (p *Player) seekLocked(targetSeconds int) error {
 		return fmt.Errorf("cannot get track length: %w", err)
 	}
 
+	// The source lock is released before anything below is emitted:
+	// emitPositionLocked reads the decoder's position and takes the
+	// same lock, which is not reentrant.
+	seekErr := p.seekSourceLocked(targetSeconds, lengthSecs)
+	if seekErr != nil {
+		p.logger.Warn(
+			"Seek failed, playback will start from "+
+				"the beginning",
+			"target-seconds", targetSeconds,
+			"err", seekErr,
+		)
+
+		// The optimistic move the UI already made has to be taken
+		// back, and only the backend knows it did not happen.
+		events.Emit(p.ctx, events.SeekFailed)
+		p.emitPositionLocked()
+
+		return fmt.Errorf("failed to seek: %w", seekErr)
+	}
+
+	if p.mediaControls != nil {
+		p.mediaControls.NotifySeek(targetSeconds)
+	}
+
+	// Report the landing position immediately rather than leaving the
+	// UI to guess until the next tick — this is the half of H-3 that
+	// desynced the seek bar by 30 s over four keyboard seeks.
+	p.emitPositionLocked()
+
+	return nil
+}
+
+// seekSourceLocked moves the decoder and flushes the stale read-ahead
+// behind it.  It owns the source lock for exactly that long and
+// emits nothing, so its caller is free to read the position
+// afterwards.  Must be called with p.mu held.
+func (p *Player) seekSourceLocked(
+	targetSeconds int,
+	lengthSecs int,
+) error {
 	// Block the read-ahead goroutine from reading the source while
 	// we seek it. The decoder (e.g. FLAC's bufseekio.ReadSeeker) is
 	// not safe for concurrent Read+Seek, and read-ahead runs on its
@@ -1014,19 +1162,11 @@ func (p *Player) seekLocked(targetSeconds int) error {
 	if seekErr != nil {
 		speaker.Unlock()
 
-		p.logger.Warn(
-			"Seek failed, playback will start from "+
-				"the beginning",
-			"target-seconds", targetSeconds,
-			"samples", samples,
-			"err", seekErr,
+		p.logger.Debug(
+			"seek rejected by the decoder",
+			"samples", samples, "err", seekErr,
 		)
 
-		// The optimistic move the UI already made has to be taken
-		// back, and only the backend knows it did not happen.
-		events.Emit(p.ctx, events.SeekFailed)
-		p.emitPositionLocked()
-
 		return fmt.Errorf("failed to seek: %w", seekErr)
 	}
 
@@ -1039,15 +1179,6 @@ func (p *Player) seekLocked(targetSeconds int) error {
 		p.buffered.Flush()
 	}
 
-	if p.mediaControls != nil {
-		p.mediaControls.NotifySeek(targetSeconds)
-	}
-
-	// Report the landing position immediately rather than leaving the
-	// UI to guess until the next tick — this is the half of H-3 that
-	// desynced the seek bar by 30 s over four keyboard seeks.
-	p.emitPositionLocked()
-
 	return nil
 }
 
@@ -1140,6 +1271,10 @@ func (p *Player) seekerLengthSecsLocked() (int, error) {
 		return 0, errNoAudioFileLoaded
 	}
 
+	// Len is fixed for the life of the decoder, so unlike Position it
+	// races with nothing and needs no source lock -- which it must not
+	// take anyway: displayPositionSecsLocked calls this while holding
+	// it, and srcMu is not reentrant.
 	speaker.Lock()
 	length := p.seeker.Len() / int(p.format.SampleRate)
 	speaker.Unlock()
@@ -1156,6 +1291,8 @@ func (p *Player) displayPositionSecsLocked() int {
 		return 0
 	}
 
+	defer p.lockSourceLocked()()
+
 	speaker.Lock()
 	pos := p.seeker.Position()
 	total := p.seeker.Len()
diff --git a/backend/queue/fallback_test.go b/backend/queue/fallback_test.go
index 79585e2..901daa9 100644
--- a/backend/queue/fallback_test.go
+++ b/backend/queue/fallback_test.go
@@ -83,7 +83,7 @@ func TestFallback_TriggersOnNaturalFinish(t *testing.T) {
 	q.SetFallbackSource(fake)
 
 	q.SetQueue(seedPaths, 0, false, Source{Type: "album", ID: 1, Label: "Seed Album"})
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	waitUntil(t, func() bool { return fake.callCount() == 1 }, "fallback to be resolved")
 	waitUntil(t, func() bool {
@@ -159,7 +159,7 @@ func TestFallback_EmptyResultLeavesQueueExhausted(t *testing.T) {
 	q.SetFallbackSource(fake)
 
 	q.SetQueue(seedPaths, 0, false, Source{})
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	waitUntil(t, func() bool { return fake.callCount() == 1 }, "fallback to be resolved")
 
@@ -193,7 +193,7 @@ func TestFallback_StaleResolutionDiscarded(t *testing.T) {
 	q.SetFallbackSource(fake)
 
 	q.SetQueue(seedPaths, 0, false, Source{})
-	q.OnPlaybackFinished() // starts resolving, blocked on gate
+	q.OnPlaybackFinished(nil) // starts resolving, blocked on gate
 
 	time.Sleep(20 * time.Millisecond) // let the goroutine reach the gate
 
diff --git a/backend/queue/finished_test.go b/backend/queue/finished_test.go
new file mode 100644
index 0000000..7cfcefe
--- /dev/null
+++ b/backend/queue/finished_test.go
@@ -0,0 +1,78 @@
+package queue
+
+import (
+	"errors"
+	"testing"
+
+	"yellowjacket/backend/events"
+)
+
+// errTestDecode stands in for a decoder blowing up mid-track.
+var errTestDecode = errors.New("decode blew up")
+
+// currentIndex == -1 against a non-empty queue is a state this
+// package produces on purpose: onQueueExhausted(false) sets it and
+// deliberately leaves the finished track loaded in the player, so it
+// stays on the now-playing bar. Pressing play from there and letting
+// it finish re-enters OnPlaybackFinished with exactly that pair --
+// which used to index q.tracks[-1] and panic, on a goroutine
+// dispatched from the audio callback with no caller to recover it.
+func TestFinishedWithNoCurrentTrackDoesNotPanic(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name  string
+		index int
+	}{
+		{"exhausted queue leaves -1", -1},
+		{"index past the end", 3},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			q, _, _ := setupRecordedQueue(t)
+			q.tracks = []Track{
+				{FilePath: "/a.mp3"},
+				{FilePath: "/b.mp3"},
+			}
+			q.currentIndex = tt.index
+
+			// The assertion is that this returns at all.
+			q.OnPlaybackFinished(nil)
+
+			if q.currentIndex != tt.index {
+				t.Errorf(
+					"an out-of-range index was acted on: %d became %d",
+					tt.index, q.currentIndex,
+				)
+			}
+		})
+	}
+}
+
+// A track that broke mid-playback is not a track that was listened
+// to. The player cannot say so itself -- the metadata is here -- so
+// it hands the reason over and this is where it becomes a
+// PlaybackFailed rather than a silent auto-advance.
+func TestAFailedTrackIsReportedAndNotCountedAsAPlay(t *testing.T) {
+	t.Parallel()
+
+	q, _, rec := setupRecordedQueue(t)
+	q.tracks = []Track{
+		{FilePath: "/a.mp3", Title: "A", AudioFileID: 1},
+		{FilePath: "/b.mp3", Title: "B", AudioFileID: 2},
+	}
+	q.currentIndex = 0
+
+	q.OnPlaybackFinished(errTestDecode)
+
+	if _, ok := rec.Last(events.PlaybackFailed); !ok {
+		t.Errorf(
+			"a track that failed mid-playback told the user nothing; "+
+				"got %v",
+			rec.Names(),
+		)
+	}
+}
diff --git a/backend/queue/handlers.go b/backend/queue/handlers.go
index b3d44e9..a0a9054 100644
--- a/backend/queue/handlers.go
+++ b/backend/queue/handlers.go
@@ -1,18 +1,45 @@
 package queue
 
-// OnPlaybackFinished is called when a track finishes playing naturally.
-// This drives the auto-advance behavior and records the play.
-func (q *Queue) OnPlaybackFinished() {
+// OnPlaybackFinished is called when a track stops streaming. This
+// drives the auto-advance behavior and records the play.
+//
+// srcErr says why the track stopped: nil for one that reached its
+// end, non-nil for one that broke partway through.  The player cannot
+// tell the user which, because the metadata lives here -- so a failure
+// is reported as PlaybackFailed and *not* recorded as a play, while
+// the advance happens either way.  Before this, a file that failed
+// mid-track advanced in silence and was counted as listened to.
+//
+//wails:ignore // internal wiring, not part of the app's IPC surface.
+func (q *Queue) OnPlaybackFinished(srcErr error) {
 	q.mu.Lock()
 
-	if len(q.tracks) == 0 {
+	// currentIndex is -1 whenever the queue has been exhausted, and
+	// onQueueExhausted deliberately leaves the finished track loaded
+	// in the player -- so a natural finish can re-enter here against a
+	// queue that is not empty and an index that is not valid.  Every
+	// other path in this package bounds-checks before indexing; this
+	// one panicked, on a goroutine with no caller to recover it.
+	if q.currentIndex < 0 || q.currentIndex >= len(q.tracks) {
 		q.mu.Unlock()
 
 		return
 	}
 
 	// Capture the track that just finished before advancing.
-	finishedID := q.tracks[q.currentIndex].AudioFileID
+	finished := q.tracks[q.currentIndex]
+	finishedID := finished.AudioFileID
+
+	if srcErr != nil {
+		q.emitPlaybackFailed(finished, srcErr)
+	}
+
+	// A track that broke was not listened to.
+	recordFinished := func() {
+		if srcErr == nil {
+			q.recordPlay(finishedID)
+		}
+	}
 
 	// Repeat One: replay the current track.
 	if q.repeatMode == RepeatOne {
@@ -21,7 +48,7 @@ func (q *Queue) OnPlaybackFinished() {
 		}
 
 		q.mu.Unlock()
-		q.recordPlay(finishedID)
+		recordFinished()
 
 		return
 	}
@@ -31,7 +58,7 @@ func (q *Queue) OnPlaybackFinished() {
 		// Queue exhausted — this is the extension point for a future fallback playlist.
 		q.onQueueExhausted(false)
 		q.mu.Unlock()
-		q.recordPlay(finishedID)
+		recordFinished()
 
 		return
 	}
@@ -44,12 +71,12 @@ func (q *Queue) OnPlaybackFinished() {
 	if !q.playCurrentOrSkip(true, q.nextIndex) {
 		q.onQueueExhausted(false)
 		q.mu.Unlock()
-		q.recordPlay(finishedID)
+		recordFinished()
 
 		return
 	}
 
 	q.emitIndexChanged()
 	q.mu.Unlock()
-	q.recordPlay(finishedID)
+	recordFinished()
 }
diff --git a/backend/queue/playbackfailed_test.go b/backend/queue/playbackfailed_test.go
index 3ad8179..3c973e0 100644
--- a/backend/queue/playbackfailed_test.go
+++ b/backend/queue/playbackfailed_test.go
@@ -107,7 +107,7 @@ func TestPlaybackFailed_AutoAdvanceSkipsPastIt(t *testing.T) {
 
 	// The first track finished: auto-advance lands on the missing
 	// file and must step over it rather than stopping dead.
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	if got := q.GetState().CurrentIndex; got != 2 {
 		t.Errorf("currentIndex after skipping: got %d, want 2", got)
@@ -183,7 +183,7 @@ func TestQueueExhausted_KeepsTheFinishedTrackLoaded(t *testing.T) {
 
 	q.SetQueue(paths, 0, false, Source{})
 	q.Play()
-	q.OnPlaybackFinished()
+	q.OnPlaybackFinished(nil)
 
 	if q.GetState().CurrentIndex != -1 {
 		t.Errorf(
diff --git a/frontend/bindings/yellowjacket/backend/queue/queue.ts b/frontend/bindings/yellowjacket/backend/queue/queue.ts
index ee9bc23..5200a95 100644
--- a/frontend/bindings/yellowjacket/backend/queue/queue.ts
+++ b/frontend/bindings/yellowjacket/backend/queue/queue.ts
@@ -113,14 +113,6 @@ export function Next(): $CancellablePromise<void> {
     return $Call.ByID(1968784044);
 }
 
-/**
- * OnPlaybackFinished is called when a track finishes playing naturally.
- * This drives the auto-advance behavior and records the play.
- */
-export function OnPlaybackFinished(): $CancellablePromise<void> {
-    return $Call.ByID(2184869763);
-}
-
 /**
  * Play handles a play request by either resuming the current track or
  * starting playback from the beginning of the queue. When a track is