macos: restore focused split on app restore

macos/Sources/Features/Terminal/TerminalRestorable.swift

@@ -6,9 +6,11 @@ class TerminalRestorableState: Codable {
     static let versionKey = "version"
     static let version: Int = 1
     
+    let focusedSurface: String?
     let surfaceTree: Ghostty.SplitNode?
     
     init(from controller: TerminalController) {
+        self.focusedSurface = controller.focusedSurface?.uuid.uuidString
         self.surfaceTree = controller.surfaceTree
     }
     
@@ -25,6 +27,7 @@ class TerminalRestorableState: Codable {
         }
         
         self.surfaceTree = v.value.surfaceTree
+        self.focusedSurface = v.value.focusedSurface
     }
     
     func encode(with coder: NSCoder) {
@@ -86,7 +89,31 @@ class TerminalWindowRestoration: NSObject, NSWindowRestoration {
         
         // Setup our restored state on the controller
         c.surfaceTree = state.surfaceTree
+        if let focusedStr = state.focusedSurface,
+           let focusedUUID = UUID(uuidString: focusedStr),
+           let view = c.surfaceTree?.findUUID(uuid: focusedUUID) {
+            c.focusedSurface = view
+            restoreFocus(to: view, inWindow: window)
+        }
         
         completionHandler(window, nil)
     }
+    
+    /// This restores the focus state of the surfaceview within the given window. When restoring,
+    /// the view isn't immediately attached to the window since we have to wait for SwiftUI to
+    /// catch up. Therefore, we sit in an async loop waiting for the attachment to happen.
+    private static func restoreFocus(to: Ghostty.SurfaceView, inWindow: NSWindow) {
+        DispatchQueue.main.async {
+            // If the view is not attached to a window yet then we repeat.
+            guard let viewWindow = to.window else {
+                restoreFocus(to: to, inWindow: inWindow)
+                return
+            }
+            
+            // If the view is attached to some other window, we give up
+            guard viewWindow == inWindow else { return }
+            
+            inWindow.makeFirstResponder(to)
+        }
+    }
 }

macos/Sources/Ghostty/Ghostty.SplitNode.swift

@@ -101,6 +101,22 @@ extension Ghostty {
             }
         }
         
+        /// Find a surface view by UUID.
+        func findUUID(uuid: UUID) -> SurfaceView? {
+            switch (self) {
+            case .leaf(let leaf):
+                if (leaf.surface.uuid == uuid) {
+                    return leaf.surface
+                }
+                
+                return nil
+
+            case .split(let container):
+                return container.topLeft.findUUID(uuid: uuid) ??
+                    container.bottomRight.findUUID(uuid: uuid)
+            }
+        }
+        
         // MARK: - Equatable
         
         static func == (lhs: SplitNode, rhs: SplitNode) -> Bool {
@@ -121,7 +137,7 @@ extension Ghostty {
             weak var parent: SplitNode.Container?
 
             /// Initialize a new leaf which creates a new terminal surface.
-            init(_ app: ghostty_app_t, baseConfig: SurfaceConfiguration? = nil, uuid: NSUUID? = nil) {
+            init(_ app: ghostty_app_t, baseConfig: SurfaceConfiguration? = nil, uuid: UUID? = nil) {
                 self.app = app
                 self.surface = SurfaceView(app, baseConfig: baseConfig, uuid: uuid)
             }
@@ -155,7 +171,7 @@ extension Ghostty {
                 }
                 
                 let container = try decoder.container(keyedBy: CodingKeys.self)
-                let uuid = NSUUID(uuidString: try container.decode(String.self, forKey: .uuid))
+                let uuid = UUID(uuidString: try container.decode(String.self, forKey: .uuid))
                 var config = SurfaceConfiguration()
                 config.workingDirectory = try container.decode(String?.self, forKey: .pwd)
                 

macos/Sources/Ghostty/SurfaceView.swift

@@ -264,7 +264,7 @@ extension Ghostty {
     /// The NSView implementation for a terminal surface.
     class SurfaceView: NSView, NSTextInputClient, ObservableObject {
         /// Unique ID per surface
-        let uuid: NSUUID
+        let uuid: UUID
         
         // The current title of the surface as defined by the pty. This can be
         // changed with escape codes. This is public because the callbacks go
@@ -347,7 +347,7 @@ extension Ghostty {
             case pendingHidden
         }
 
-        init(_ app: ghostty_app_t, baseConfig: SurfaceConfiguration? = nil, uuid: NSUUID? = nil) {
+        init(_ app: ghostty_app_t, baseConfig: SurfaceConfiguration? = nil, uuid: UUID? = nil) {
             self.markedText = NSMutableAttributedString()
             self.uuid = uuid ?? .init()