fix: stabilize native window layout transitions

Sources/App/CompactWindow.swift

@@ -1,5 +1,4 @@
 import AppKit
-import QuartzCore
 
 @MainActor
 final class CompactWindowController: NSObject {
@@ -379,10 +378,10 @@ final class CompactWindowController: NSObject {
         frameAnimationGeneration &+= 1
         let generation = frameAnimationGeneration
         frameAnimating = true
-        NSAnimationContext.runAnimationGroup { context in
-            context.duration = Self.transitionDuration
-            context.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
-            window.animator().setFrame(frame, display: true)
+        // Coordinate the resize through NSWindow. Its animator proxy races SwiftUI's
+        // animated window sizing and can re-enter layout until AppKit aborts.
+        NSAnimationContext.runAnimationGroup { _ in
+            window.setFrame(frame, display: true, animate: true)
         } completionHandler: { [weak self, weak window] in
             MainActor.assumeIsolated {
                 guard let self, let window, self.window === window, self.frameAnimating,
@@ -397,12 +396,7 @@ final class CompactWindowController: NSObject {
         guard frameAnimating else { return }
         frameAnimating = false
         frameAnimationGeneration &+= 1
-        guard let window else { return }
-        // A zero-duration animator update cancels the native in-flight frame animation.
-        NSAnimationContext.runAnimationGroup { context in
-            context.duration = 0
-            window.animator().setFrame(window.frame, display: true)
-        }
+        // Native resize animation has returned; invalidate only its pending completion.
     }
 
     private func setState(compact: Bool, transitioning: Bool) {