feat: report authoritative playback progress from shared backend

Checks/app-startup.swift

@@ -1,4 +1,5 @@
 import AppKit
+import Darwin
 import MediaPlayer
 
 @_cdecl("terebi_app_main")
@@ -92,6 +93,11 @@ private enum CLIInstanceCheck {
     static func run(_ configuration: URL) {
         let settings = try! JSONSerialization.jsonObject(with: Data(contentsOf: configuration)) as! [String: String]
         let directory = URL(fileURLWithPath: settings["directory"]!, isDirectory: true)
+        let stderrURL = directory.appendingPathComponent("stderr-\(ProcessInfo.processInfo.processIdentifier).log")
+        precondition(FileManager.default.createFile(atPath: stderrURL.path, contents: nil))
+        let errorLog = try! FileHandle(forWritingTo: stderrURL)
+        precondition(dup2(errorLog.fileDescriptor, STDERR_FILENO) >= 0)
+        try! errorLog.close()
         setenv("PATH", settings["path"]!, 1)
         _ = NSApplication.shared
         _ = NotificationCenter.default.addObserver(forName: NSApplication.willFinishLaunchingNotification,
@@ -115,17 +121,44 @@ private enum CLIInstanceCheck {
                 let windows = NSApp.windows.filter { $0.canBecomeMain && !($0 is NSPanel) && $0.contentView != nil }
                 for window in windows { window.alphaValue = 0 }
                 let request = directory.appendingPathComponent("keys-\(pid).json")
+                var pendingRequestID = ""
                 if let data = try? Data(contentsOf: request),
                    let command = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
                    let id = command["id"] as? String, id != requestID, let window = windows.first {
+                    pendingRequestID = id
                     if !NSApp.isActive || !window.isKeyWindow || !window.isMainWindow {
-                        NSApp.activate()
+                        // Synthetic native key requests need foreground focus; cooperative activation
+                        // can be refused by the unrelated app currently active on the workstation.
+                        NSApp.activate(ignoringOtherApps: true)
                         window.makeKeyAndOrderFront(nil)
                         window.makeMain()
-                        return
-                    }
+                    } else {
                     requestID = id
                     if let media = command["media"] as? String { model.open(URL(fileURLWithPath: media)) }
+                    if let action = command["action"] as? String {
+                        switch action {
+                        case "youtube":
+                            model.openYouTube(command["url"] as! String)
+                        case "seek":
+                            let position = command["position"] as! Double
+                            precondition(model.seekRelative(position - model.state.position), "Native seek must be accepted")
+                        case "pause":
+                            precondition(model.perform(.pause), "Native pause must be accepted")
+                        case "play":
+                            precondition(model.perform(.play), "Native play must be accepted")
+                        case "quality":
+                            precondition(model.canChangeYouTubeQuality, "Native quality change must be available")
+                            model.setYouTubeQuality((command["height"] as! Int))
+                        case "close":
+                            model.closeFile()
+                        case "quit":
+                            timer?.invalidate()
+                            precondition(model.perform(.quit), "Native quit must be accepted")
+                            return
+                        default:
+                            fatalError("Unknown native check action \(action)")
+                        }
+                    }
                     if let events = command["events"] as? [[String: Any]] {
                         window.makeKey()
                         for input in events {
@@ -159,6 +192,7 @@ private enum CLIInstanceCheck {
                             }
                         }
                     }
+                    }
                 }
                 let applications = NSWorkspace.shared.runningApplications.filter {
                     !$0.isTerminated && $0.bundleURL == Bundle.main.bundleURL
@@ -169,6 +203,13 @@ private enum CLIInstanceCheck {
                     "media": model.fileName ?? "",
                     "status": model.state.status.rawValue,
                     "position": model.state.position,
+                    "duration": model.state.duration,
+                    "seekPending": model.state.seek_pending,
+                    "canSeek": model.canSeek,
+                    "busy": model.isBusy,
+                    "youtubeHeight": model.youtubeHeight ?? 0,
+                    "canChangeQuality": model.canChangeYouTubeQuality,
+                    "qualityHeights": model.youtubeHeights,
                     "windows": windows.count,
                     "hasAudio": model.state.has_audio,
                     "hasVideo": model.state.has_video,
@@ -177,6 +218,10 @@ private enum CLIInstanceCheck {
                     "automaticQuality": model.automaticYouTubeQuality,
                     "snapToEdges": model.compactWindow.snappingEnabled,
                     "requestID": requestID,
+                    "pendingRequestID": pendingRequestID,
+                    "active": NSApp.isActive,
+                    "keyWindow": windows.first?.isKeyWindow ?? false,
+                    "mainWindow": windows.first?.isMainWindow ?? false,
                     "editorText": editorText,
                     "compact": model.isCompact,
                     "onTop": model.isOnTop,