fix: respond to macOS system playback controls

Sources/App/TerebiApp.swift

@@ -48,6 +48,7 @@ final class PlayerModel: ObservableObject {
     private var progressURL: URL?
     private var resumePosition: Double?
     private var lastSavedPosition: Double?
+    private var systemPlayback: SystemPlaybackControls?
 
     init(defaults: UserDefaults = .standard) {
         playbackProgress = PlaybackProgress(defaults: defaults)
@@ -65,6 +66,7 @@ final class PlayerModel: ObservableObject {
         timer = Timer.scheduledTimer(withTimeInterval: 0.05, repeats: true) { [weak self] _ in
             MainActor.assumeIsolated { self?.poll() }
         }
+        systemPlayback = SystemPlaybackControls(model: self)
     }
 
     var isBusy: Bool { resolvingYouTube || pendingRevision != nil || state.status == PLAYER_OPENING }
@@ -138,6 +140,7 @@ final class PlayerModel: ObservableObject {
         let request = UUID()
         youtubeRequest = request
         resolvingYouTube = true
+        systemPlayback?.update()
         commandError = nil
         revealControls()
         youtubeTask = Task { [weak self] in
@@ -212,6 +215,7 @@ final class PlayerModel: ObservableObject {
         window?.representedURL = url
         window?.title = title
         revealControls()
+        systemPlayback?.update()
     }
 
     func open(_ url: URL) {
@@ -236,10 +240,16 @@ final class PlayerModel: ObservableObject {
     }
 
     func togglePlayback() {
-        guard let handle, canTogglePlayback else { return }
-        let accepted = state.status == PLAYER_PLAYING ? player_pause(handle) : player_play(handle)
+        setPlayback(playing: state.status != PLAYER_PLAYING)
+    }
+
+    @discardableResult
+    func setPlayback(playing: Bool) -> Bool {
+        guard let handle, canTogglePlayback else { return false }
+        let accepted = playing ? player_play(handle) : player_pause(handle)
         commandError = accepted ? nil : "Could not queue playback. Please try again."
         revealControls()
+        return accepted
     }
 
     func finishSeeking() {
@@ -275,10 +285,12 @@ final class PlayerModel: ObservableObject {
         window?.representedURL = nil
         window?.title = "terebi"
         revealControls()
+        systemPlayback?.update()
     }
 
-    func seekRelative(_ seconds: Double) {
-        guard canSeek, let handle else { return }
+    @discardableResult
+    func seekRelative(_ seconds: Double) -> Bool {
+        guard canSeek, let handle, seconds.isFinite else { return false }
         let target = min(max(0, (seekPending ? seekPosition : state.position) + seconds), duration)
         let accepted = player_seek(handle, target)
         if accepted {
@@ -287,6 +299,7 @@ final class PlayerModel: ObservableObject {
         }
         commandError = accepted ? nil : "Could not queue the seek. Please try again."
         revealControls()
+        return accepted
     }
 
     func stepFrame(_ direction: Int32) {
@@ -458,6 +471,7 @@ final class PlayerModel: ObservableObject {
             guard next.revision != revision, next.status != PLAYER_OPENING else { return }
             pendingRevision = nil
         }
+        defer { systemPlayback?.update() }
         let statusChanged = state.status != next.status
         state = next
         if next.status == PLAYER_EMPTY || next.status == PLAYER_ERROR ||
@@ -496,6 +510,8 @@ final class PlayerModel: ObservableObject {
     func shutdown() {
         saveProgress()
         cancelYouTubeResolution()
+        systemPlayback?.shutdown()
+        systemPlayback = nil
         compactWindow.restore(resumeFullScreen: false)
         timer?.invalidate()
         timer = nil
@@ -1151,7 +1167,9 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
     }
 }
 
+#if !PLAYER_CHECK
 @main
+#endif
 @MainActor
 struct TerebiApp: App {
     @NSApplicationDelegateAdaptor(AppDelegate.self) private var delegate