perf: optimize first-launch startup and fix play button shader

Shfl/Domain/ShufflePlayer.swift

@@ -160,6 +160,19 @@ final class ShufflePlayer: ObservableObject {
         rebuildQueueIfPlaying()
     }
 
+    func addSongs(_ newSongs: [Song]) throws {
+        let existingIds = Set(songs.map(\.id))
+        let uniqueNewSongs = newSongs.filter { !existingIds.contains($0.id) }
+
+        let availableCapacity = Self.maxSongs - songs.count
+        guard uniqueNewSongs.count <= availableCapacity else {
+            throw ShufflePlayerError.capacityReached
+        }
+
+        songs.append(contentsOf: uniqueNewSongs)
+        // Don't rebuild queue during initial load - not playing yet
+    }
+
     func removeSong(id: String) {
         songs.removeAll { $0.id == id }
         rebuildQueueIfPlaying()
@@ -203,9 +216,13 @@ final class ShufflePlayer: ObservableObject {
         lastObservedSongId = nil
 
         if !isQueuePrepared {
+            // Emit loading state for immediate UI feedback
+            if let firstSong = songs.first {
+                playbackState = .loading(firstSong)
+            }
             try await prepareQueue()
         }
-        
+
         try await musicService.play()
     }
 

Shfl/ViewModels/AppViewModel.swift

@@ -12,6 +12,7 @@ final class AppViewModel: ObservableObject {
 
     @Published var isAuthorized = false
     @Published var isLoading = true
+    @Published var loadingMessage = "Loading..."
     @Published var showingManage = false
     @Published var showingPicker = false
     @Published var showingPickerDirect = false
@@ -40,21 +41,33 @@ final class AppViewModel: ObservableObject {
     }
 
     func onAppear() async {
-        isAuthorized = await musicService.isAuthorized
+        // Check authorization in parallel with song loading
+        loadingMessage = "Loading your music..."
+        async let authStatus = musicService.isAuthorized
 
+        // Load songs (synchronous SwiftData call, runs on MainActor)
+        var songs: [Song] = []
         do {
-            let songs = try repository.loadSongs()
-            for song in songs {
-                try? player.addSong(song)
-            }
+            songs = try repository.loadSongs()
         } catch {
             print("Failed to load songs: \(error)")
         }
 
-        isLoading = false
+        // Batch-add songs (O(n) instead of O(n²))
+        if !songs.isEmpty {
+            try? player.addSongs(songs)
+        }
+
+        // Wait for auth check
+        isAuthorized = await authStatus
 
-        // Prepare queue in background for instant playback
-        Task { try? await player.prepareQueue() }
+        // Prepare queue before dismissing loading screen
+        if !player.songs.isEmpty {
+            loadingMessage = "Preparing playback..."
+            try? await player.prepareQueue()
+        }
+
+        isLoading = false
     }
 
     func requestAuthorization() async {

Shfl/Views/Components/PlayPauseButton.swift

@@ -23,14 +23,15 @@ struct PlayPauseButton: View {
         ZStack {
             Circle()
                 .fill(buttonBackgroundColor)
+                .frame(width: buttonSize, height: buttonSize)
                 .colorEffect(
                     ShaderLibrary.shfl_brushedMetal(
                         .float2(buttonSize / 2, buttonSize / 2),
                         .float2(highlightOffset),
                         .float(theme.brushedMetalIntensity)
                     )
                 )
-                .frame(width: buttonSize, height: buttonSize)
+                .clipShape(Circle())
                 .shadow(
                     color: .black.opacity(0.1),
                     radius: isPressed ? ClickWheelFeedback.centerPressedShadowRadius : ClickWheelFeedback.centerNormalShadowRadius,

Shfl/Views/MainView.swift

@@ -77,7 +77,7 @@ struct MainView: View {
             ProgressView()
                 .scaleEffect(1.5)
 
-            Text("Loading your music...")
+            Text(viewModel.loadingMessage)
                 .font(.subheadline)
                 .foregroundStyle(.secondary)
         }