fix: stabilize layout at minimum window height and refine player controls

Wrap breadcrumb + content area in a constrained VStack so search bar,
playlist bar, and player controls stay pinned when toggling Home view.
Refactor PlayerControlsView to use a full-width progress track above
transport buttons. Allow play/pause to start from first track when
nothing is queued.

Music/ContentView.swift

@@ -60,6 +60,7 @@ struct ContentView: View {
                 .padding(.vertical, 4)
             }
 
+            VStack(spacing: 0) {
                 if showHome || playlist.selectedItem != nil {
                     HStack(spacing: 4) {
                         Button(action: {
@@ -144,6 +145,8 @@ struct ContentView: View {
                         scrollToPlayingTrigger: scrollToPlayingTrigger
                     )
                 }
+            }
+            .frame(maxHeight: .infinity)
 
             PlaylistBarView(
                 playlists: playlist.allPlaylists,
@@ -280,7 +283,17 @@ struct ContentView: View {
             duration: audio.duration,
             volume: audio.volume,
             isShuffled: player.isShuffled,
-            onPlayPause: { audio.togglePlayPause() },
+            onPlayPause: {
+                if player.currentTrack == nil {
+                    let trackList = playlist.selectedItem != nil ? playlist.playlistTracks : library.tracks
+                    if let first = trackList.first {
+                        player.setQueue(trackList)
+                        player.play(first)
+                    }
+                } else {
+                    audio.togglePlayPause()
+                }
+            },
             onNext: { player.next() },
             onPrevious: { player.previous() },
             onSeek: { audio.seek(to: $0) },
@@ -294,7 +307,7 @@ struct ContentView: View {
     }
 
     private func installKeyboardMonitor() {
-        keyMonitor = NSEvent.addLocalMonitorForEvents(matching: .keyDown) { [audio, player] event in
+        keyMonitor = NSEvent.addLocalMonitorForEvents(matching: .keyDown) { [audio, player, library, playlist] event in
             guard event.modifierFlags.intersection([.command, .control, .option, .shift]).isEmpty else {
                 return event
             }
@@ -304,7 +317,15 @@ struct ContentView: View {
             }
             switch event.keyCode {
             case 49: // space
+                if player.currentTrack == nil {
+                    let trackList = playlist.selectedItem != nil ? playlist.playlistTracks : library.tracks
+                    if let first = trackList.first {
+                        player.setQueue(trackList)
+                        player.play(first)
+                    }
+                } else {
                     audio.togglePlayPause()
+                }
                 return nil
             case 123: // left arrow
                 player.previous()

Music/Views/PlayerControlsView.swift

@@ -22,6 +22,8 @@ struct PlayerControlsView: View {
     @State private var dragValue: Double = 0
 
     var body: some View {
+        VStack(spacing: 0) {
+            progressTrack
             HStack(spacing: 0) {
                 nowPlayingSection
                     .frame(maxWidth: .infinity, alignment: .leading)
@@ -34,6 +36,7 @@ struct PlayerControlsView: View {
             }
             .padding(.horizontal, 16)
             .padding(.vertical, 8)
+        }
         .background(.bar)
     }
 
@@ -75,8 +78,68 @@ struct PlayerControlsView: View {
         }
     }
 
+    private var progressTrack: some View {
+        let trackHeight: CGFloat = 4
+        let thumbWidth: CGFloat = 4
+        let thumbHeight: CGFloat = 12
+        let displayedTime = isDragging ? dragValue : currentTime
+        let maxDuration = max(duration, 1)
+        let fraction = displayedTime / maxDuration
+
+        return VStack(spacing: 2) {
+            GeometryReader { geo in
+                let trackWidth = geo.size.width
+                ZStack(alignment: .leading) {
+                    Rectangle()
+                        .fill(.quaternary)
+                        .frame(height: trackHeight)
+
+                    Rectangle()
+                        .fill(.blue)
+                        .frame(width: trackWidth * fraction, height: trackHeight)
+
+                    RoundedRectangle(cornerRadius: 1)
+                        .fill(.blue)
+                        .frame(width: thumbWidth, height: thumbHeight)
+                        .offset(x: trackWidth * fraction - thumbWidth / 2)
+                }
+                .frame(maxHeight: .infinity)
+                .contentShape(Rectangle())
+                .gesture(
+                    DragGesture(minimumDistance: 0)
+                        .onChanged { value in
+                            let newValue = min(max(Double(value.location.x / trackWidth) * maxDuration, 0), maxDuration)
+                            if !isDragging {
+                                isDragging = true
+                                dragValue = currentTime
+                                onScrubStart()
+                            }
+                            dragValue = newValue
+                            onScrub(newValue)
+                        }
+                        .onEnded { value in
+                            let newValue = min(max(Double(value.location.x / trackWidth) * maxDuration, 0), maxDuration)
+                            onScrubEnd(newValue)
+                            isDragging = false
+                        }
+                )
+            }
+            .frame(height: thumbHeight)
+
+            HStack {
+                Text(Self.formatTime(displayedTime))
+                    .font(.system(size: 10).monospacedDigit())
+                    .foregroundStyle(.secondary)
+                Spacer()
+                Text(Self.formatTime(duration))
+                    .font(.system(size: 10).monospacedDigit())
+                    .foregroundStyle(.secondary)
+            }
+            .padding(.horizontal, 8)
+        }
+    }
+
     private var transportSection: some View {
-        VStack(spacing: 4) {
         HStack(spacing: 20) {
             Button(action: onShuffleToggle) {
                 Image(systemName: "shuffle")
@@ -103,46 +166,6 @@ struct PlayerControlsView: View {
                     .font(.system(size: 14))
             }
             .buttonStyle(.plain)
-
-                Spacer()
-                    .frame(width: 12)
-            }
-
-            HStack(spacing: 8) {
-                Text(Self.formatTime(isDragging ? dragValue : currentTime))
-                    .font(.system(size: 10).monospacedDigit())
-                    .foregroundStyle(.secondary)
-                    .frame(width: 45, alignment: .trailing)
-
-                Slider(
-                    value: Binding(
-                        get: { isDragging ? dragValue : currentTime },
-                        set: { newValue in
-                            dragValue = newValue
-                            if isDragging {
-                                onScrub(newValue)
-                            }
-                        }
-                    ),
-                    in: 0...max(duration, 1),
-                    onEditingChanged: { editing in
-                        if editing {
-                            isDragging = true
-                            dragValue = currentTime
-                            onScrubStart()
-                        } else {
-                            onScrubEnd(dragValue)
-                            isDragging = false
-                        }
-                    }
-                )
-                .controlSize(.small)
-
-                Text(Self.formatTime(duration))
-                    .font(.system(size: 10).monospacedDigit())
-                    .foregroundStyle(.secondary)
-                    .frame(width: 45, alignment: .leading)
-            }
         }
         .frame(maxWidth: 400)
     }