Adopt @Observable in SwiftUI code

This moves off of ObservableObject and @Published over to @Observable, which is preferred as it allows views
to observe changes on a per-property basis rather than an entire object at a time.

I went through the app and tried to compare behavior where I could, and I couldn't spot any visual differences,
but I am sure there's good chance I have missed something.

This also requires updating the minimum macOS deployment target to 14.0. If that is unacceptable, I am happy just
closing this PR.

macos/Ghostty.xcodeproj/project.pbxproj

@@ -784,7 +784,7 @@
 					"$(inherited)",
 					"@executable_path/../Frameworks",
 				);
-				MACOSX_DEPLOYMENT_TARGET = 13.0;
+				MACOSX_DEPLOYMENT_TARGET = 14.0;
 				MARKETING_VERSION = 0.1;
 				"OTHER_LDFLAGS[arch=*]" = "-lstdc++";
 				PRODUCT_BUNDLE_IDENTIFIER = com.mitchellh.ghostty;
@@ -953,7 +953,7 @@
 					"$(inherited)",
 					"@executable_path/../Frameworks",
 				);
-				MACOSX_DEPLOYMENT_TARGET = 13.0;
+				MACOSX_DEPLOYMENT_TARGET = 14.0;
 				MARKETING_VERSION = 0.1;
 				"OTHER_LDFLAGS[arch=*]" = "-lstdc++";
 				PRODUCT_BUNDLE_IDENTIFIER = com.mitchellh.ghostty.debug;
@@ -1006,7 +1006,7 @@
 					"$(inherited)",
 					"@executable_path/../Frameworks",
 				);
-				MACOSX_DEPLOYMENT_TARGET = 13.0;
+				MACOSX_DEPLOYMENT_TARGET = 14.0;
 				MARKETING_VERSION = 0.1;
 				"OTHER_LDFLAGS[arch=*]" = "-lstdc++";
 				PRODUCT_BUNDLE_IDENTIFIER = com.mitchellh.ghostty;

macos/Sources/App/iOS/iOSApp.swift

@@ -2,18 +2,18 @@ import SwiftUI
 
 @main
 struct Ghostty_iOSApp: App {
-    @StateObject private var ghostty_app = Ghostty.App()
+    @State private var ghostty_app = Ghostty.App()
 
     var body: some Scene {
         WindowGroup {
             iOS_GhosttyTerminal()
-                .environmentObject(ghostty_app)
+                .environment(ghostty_app)
         }
     }
 }
 
 struct iOS_GhosttyTerminal: View {
-    @EnvironmentObject private var ghostty_app: Ghostty.App
+    @Environment(Ghostty.App.self) private var ghostty_app: Ghostty.App
 
     var body: some View {
         ZStack {
@@ -26,7 +26,7 @@ struct iOS_GhosttyTerminal: View {
 }
 
 struct iOS_GhosttyInitView: View {
-    @EnvironmentObject private var ghostty_app: Ghostty.App
+    @Environment(Ghostty.App.self) private var ghostty_app: Ghostty.App
 
     var body: some View {
         VStack {

macos/Sources/App/macOS/AppDelegate.swift

@@ -4,8 +4,8 @@ import OSLog
 import Sparkle
 import GhosttyKit
 
+@Observable
 class AppDelegate: NSObject,
-                    ObservableObject,
                     NSApplicationDelegate,
                     UNUserNotificationCenterDelegate,
                     GhosttyAppDelegate
@@ -99,7 +99,7 @@ class AppDelegate: NSObject,
     private var appearanceObserver: NSKeyValueObservation? = nil
 
     /// The custom app icon image that is currently in use.
-    @Published private(set) var appIcon: NSImage? = nil {
+    private(set) var appIcon: NSImage? = nil {
         didSet {
             NSApplication.shared.applicationIconImage = appIcon
         }

macos/Sources/Features/Secure Input/SecureInput.swift

@@ -12,7 +12,8 @@ import OSLog
 // it. You have to yield secure input on application deactivation (because
 // it'll affect other apps) and reacquire on reactivation, and every enable
 // needs to be balanced with a disable.
-class SecureInput : ObservableObject {
+@Observable
+class SecureInput {
     static let shared = SecureInput()
 
     private static let logger = Logger(
@@ -28,10 +29,11 @@ class SecureInput : ObservableObject {
     }
 
     // The scoped objects and whether they're currently in focus.
+    @ObservationIgnored
     private var scoped: [ObjectIdentifier: Bool] = [:]
 
     // This is set to true when we've successfully called EnableSecureInput.
-    @Published private(set) var enabled: Bool = false
+    private(set) var enabled: Bool = false
 
     // This is true if we want to enable secure input. We want to enable
     // secure input if its enabled globally or any of the scoped objects are

macos/Sources/Features/Settings/ConfigurationErrorsView.swift

@@ -1,11 +1,11 @@
 import SwiftUI
 
-protocol ConfigurationErrorsViewModel: ObservableObject {
+protocol ConfigurationErrorsViewModel: AnyObject, Observable {
     var errors: [String] { get set }
 }
 
 struct ConfigurationErrorsView<ViewModel: ConfigurationErrorsViewModel>: View {
-    @ObservedObject var model: ViewModel
+    var model: ViewModel
 
     var body: some View {
         VStack {

macos/Sources/Features/Settings/SettingsView.swift

@@ -2,7 +2,7 @@ import SwiftUI
 
 struct SettingsView: View {
     // We need access to our app delegate to know if we're quitting or not.
-    @EnvironmentObject private var appDelegate: AppDelegate
+    @Environment(AppDelegate.self) private var appDelegate: AppDelegate
 
     var body: some View {
         HStack {

macos/Sources/Features/Terminal/BaseTerminalController.swift

@@ -25,6 +25,7 @@ import GhosttyKit
 ///
 /// The primary idea of all the behaviors we don't implement here are that subclasses may not
 /// want these behaviors.
+@Observable
 class BaseTerminalController: NSWindowController,
                               NSWindowDelegate,
                               TerminalViewDelegate,
@@ -36,12 +37,13 @@ class BaseTerminalController: NSWindowController,
     let ghostty: Ghostty.App
 
     /// The currently focused surface.
+    @ObservationIgnored
     var focusedSurface: Ghostty.SurfaceView? = nil {
         didSet { syncFocusToSurfaceTree() }
     }
 
     /// The surface tree for this window.
-    @Published var surfaceTree: Ghostty.SplitNode? = nil {
+    var surfaceTree: Ghostty.SplitNode? = nil {
         didSet { surfaceTreeDidChange(from: oldValue, to: surfaceTree) }
     }
 

macos/Sources/Features/Terminal/TerminalController.swift

@@ -610,21 +610,22 @@ class TerminalController: BaseTerminalController {
         syncAppearance(focusedSurface.derivedConfig)
 
         // We also want to get notified of certain changes to update our appearance.
-        focusedSurface.$derivedConfig
+        observeFocusedSurface(focusedSurface)
-            .sink { [weak self, weak focusedSurface] _ in self?.syncAppearanceOnPropertyChange(focusedSurface) }
-            .store(in: &surfaceAppearanceCancellables)
-        focusedSurface.$backgroundColor
-            .sink { [weak self, weak focusedSurface] _ in self?.syncAppearanceOnPropertyChange(focusedSurface) }
-            .store(in: &surfaceAppearanceCancellables)
     }
-
+    
-    private func syncAppearanceOnPropertyChange(_ surface: Ghostty.SurfaceView?) {
+    func observeFocusedSurface(_ focusedSurface: Ghostty.SurfaceView) {
-        guard let surface else { return }
+        /// Use Observable to observe properties that will invalidate the surface
-        DispatchQueue.main.async { [weak self, weak surface] in
+        /// appearance.
-            guard let surface else { return }
+        withObservationTracking {
+            _ = focusedSurface.derivedConfig
+            _ = focusedSurface.backgroundColor
+        } onChange: { [weak self] in
             guard let self else { return }
-            guard self.focusedSurface == surface else { return }
+            DispatchQueue.main.async {
-            self.syncAppearance(surface.derivedConfig)
+                guard self.focusedSurface == focusedSurface else { return }
+                self.syncAppearance(focusedSurface.derivedConfig)
+                self.observeFocusedSurface(focusedSurface)
+            }
         }
     }
 

macos/Sources/Features/Terminal/TerminalView.swift

@@ -28,18 +28,18 @@ protocol TerminalViewDelegate: AnyObject {
 /// The view model is a required implementation for TerminalView callers. This contains
 /// the main state between the TerminalView caller and SwiftUI. This abstraction is what
 /// allows AppKit to own most of the data in SwiftUI.
-protocol TerminalViewModel: ObservableObject {
+protocol TerminalViewModel: AnyObject, Observable {
     /// The tree of terminal surfaces (splits) within the view. This is mutated by TerminalView
-    /// and children. This should be @Published.
+    /// and children.
     var surfaceTree: Ghostty.SplitNode? { get set }
 }
 
 /// The main terminal view. This terminal view supports splits.
 struct TerminalView<ViewModel: TerminalViewModel>: View {
-    @ObservedObject var ghostty: Ghostty.App
+    var ghostty: Ghostty.App
 
     // The required view model
-    @ObservedObject var viewModel: ViewModel
+    @Bindable var viewModel: ViewModel
 
     // An optional delegate to receive information about terminal changes.
     weak var delegate: (any TerminalViewDelegate)? = nil
@@ -86,9 +86,9 @@ struct TerminalView<ViewModel: TerminalViewModel>: View {
                 if (Ghostty.info.mode == GHOSTTY_BUILD_MODE_DEBUG || Ghostty.info.mode == GHOSTTY_BUILD_MODE_RELEASE_SAFE) {
                     DebugBuildWarningView()
                 }
-
+                
                 Ghostty.TerminalSplit(node: $viewModel.surfaceTree)
-                    .environmentObject(ghostty)
+                    .environment(ghostty)
                     .focused($focused)
                     .onAppear { self.focused = true }
                     .onChange(of: focusedSurface) { newValue in

macos/Sources/Ghostty/Ghostty.App.swift

@@ -13,7 +13,8 @@ protocol GhosttyAppDelegate: AnyObject {
 extension Ghostty {
     // IMPORTANT: THIS IS NOT DONE.
     // This is a refactor/redo of Ghostty.AppState so that it supports both macOS and iOS
-    class App: ObservableObject {
+    @Observable
+    class App {
         enum Readiness: String {
             case loading, error, ready
         }
@@ -22,16 +23,16 @@ extension Ghostty {
         weak var delegate: GhosttyAppDelegate?
 
         /// The readiness value of the state.
-        @Published var readiness: Readiness = .loading
+        var readiness: Readiness = .loading
 
         /// The global app configuration. This defines the app level configuration plus any behavior
         /// for new windows, tabs, etc. Note that when creating a new window, it may inherit some
         /// configuration (i.e. font size) from the previously focused window. This would override this.
-        @Published private(set) var config: Config
+        private(set) var config: Config
 
         /// The ghostty app instance. We only have one of these for the entire app, although I guess
         /// in theory you can have multiple... I don't know why you would...
-        @Published var app: ghostty_app_t? = nil {
+        var app: ghostty_app_t? = nil {
             didSet {
                 guard let old = oldValue else { return }
                 ghostty_app_free(old)

macos/Sources/Ghostty/Ghostty.Config.swift

@@ -3,7 +3,7 @@ import GhosttyKit
 
 extension Ghostty {
     /// Maps to a `ghostty_config_t` and the various operations on that.
-    class Config: ObservableObject {
+    class Config {
         // The underlying C pointer to the Ghostty config structure. This
         // should never be accessed directly. Any operations on this should
         // be called from the functions on this or another class.

macos/Sources/Ghostty/Ghostty.SplitNode.swift

@@ -195,9 +195,10 @@ extension Ghostty {
             }
         }
 
-        class Leaf: ObservableObject, Equatable, Hashable, Codable {
+        @Observable
+        class Leaf: Equatable, Hashable, Codable {
             let app: ghostty_app_t
-            @Published var surface: SurfaceView
+            var surface: SurfaceView
 
             weak var parent: SplitNode.Container?
 
@@ -250,13 +251,14 @@ extension Ghostty {
             }
         }
 
-        class Container: ObservableObject, Equatable, Hashable, Codable {
+        @Observable
+        class Container: Equatable, Hashable, Codable {
             let app: ghostty_app_t
             let direction: SplitViewDirection
 
-            @Published var topLeft: SplitNode
+            var topLeft: SplitNode
-            @Published var bottomRight: SplitNode
+            var bottomRight: SplitNode
-            @Published var split: CGFloat = 0.5
+            var split: CGFloat = 0.5
 
             var resizeEvent: PassthroughSubject<Double, Never> = .init()
 

macos/Sources/Ghostty/Ghostty.TerminalSplit.swift

@@ -294,11 +294,11 @@ extension Ghostty {
 
     /// This represents a split view that is in the horizontal or vertical split state.
     private struct TerminalSplitContainer: View {
-        @EnvironmentObject var ghostty: Ghostty.App
+        @Environment(Ghostty.App.self) var ghostty: Ghostty.App
 
         let neighbors: SplitNode.Neighbors
         @Binding var node: SplitNode?
-        @StateObject var container: SplitNode.Container
+        @Bindable var container: SplitNode.Container
 
         var body: some View {
             SplitView(

macos/Sources/Ghostty/InspectorView.swift

@@ -6,10 +6,10 @@ import GhosttyKit
 extension Ghostty {
     /// InspectableSurface is a type of Surface view that allows an inspector to be attached.
     struct InspectableSurface: View {
-        @EnvironmentObject var ghostty: Ghostty.App
+        @Environment(Ghostty.App.self) var ghostty: Ghostty.App
 
         /// Same as SurfaceWrapper, see the doc comments there.
-        @ObservedObject var surfaceView: SurfaceView
+        var surfaceView: SurfaceView
         var isSplit: Bool = false
 
         // Maintain whether our view has focus or not

macos/Sources/Ghostty/SurfaceView.swift

@@ -5,7 +5,7 @@ import GhosttyKit
 extension Ghostty {
     /// Render a terminal for the active app in the environment.
     struct Terminal: View {
-        @EnvironmentObject private var ghostty: Ghostty.App
+        @Environment(Ghostty.App.self) private var ghostty: Ghostty.App
         @FocusedValue(\.ghosttySurfaceTitle) private var surfaceTitle: String?
 
         var body: some View {
@@ -22,10 +22,10 @@ extension Ghostty {
     struct SurfaceForApp<Content: View>: View {
         let content: ((SurfaceView) -> Content)
 
-        @StateObject private var surfaceView: SurfaceView
+        @State private var surfaceView: SurfaceView
 
         init(_ app: ghostty_app_t, @ViewBuilder content: @escaping ((SurfaceView) -> Content)) {
-            _surfaceView = StateObject(wrappedValue: SurfaceView(app))
+            _surfaceView = State(wrappedValue: SurfaceView(app))
             self.content = content
         }
 
@@ -37,7 +37,7 @@ extension Ghostty {
     struct SurfaceWrapper: View {
         // The surface to create a view for. This must be created upstream. As long as this
         // remains the same, the surface that is being rendered remains the same.
-        @ObservedObject var surfaceView: SurfaceView
+        var surfaceView: SurfaceView
 
         // True if this surface is part of a split view. This is important to know so
         // we know whether to dim the surface out of focus.
@@ -54,10 +54,15 @@ extension Ghostty {
 
         #if canImport(AppKit)
         // Observe SecureInput to detect when its enabled
-        @ObservedObject private var secureInput = SecureInput.shared
+        private var secureInput = SecureInput.shared
         #endif
+        
+        init(surfaceView: SurfaceView, isSplit: Bool = false) {
+            self.surfaceView = surfaceView
+            self.isSplit = isSplit
+        }
 
-        @EnvironmentObject private var ghostty: Ghostty.App
+        @Environment(Ghostty.App.self) private var ghostty: Ghostty.App
 
         var body: some View {
             let center = NotificationCenter.default

macos/Sources/Ghostty/SurfaceView_AppKit.swift

@@ -5,55 +5,56 @@ import GhosttyKit
 
 extension Ghostty {
     /// The NSView implementation for a terminal surface.
-    class SurfaceView: OSView, ObservableObject {
+    @Observable
+    class SurfaceView: OSView {
         /// Unique ID per surface
         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
         // to the app level and it is set from there.
-        @Published private(set) var title: String = "👻"
+        private(set) var title: String = "👻"
 
         // The current pwd of the surface as defined by the pty. This can be
         // changed with escape codes.
-        @Published var pwd: String? = nil
+        var pwd: String? = nil
 
         // The cell size of this surface. This is set by the core when the
         // surface is first created and any time the cell size changes (i.e.
         // when the font size changes). This is used to allow windows to be
         // resized in discrete steps of a single cell.
-        @Published var cellSize: NSSize = .zero
+        var cellSize: NSSize = .zero
 
         // The health state of the surface. This currently only reflects the
         // renderer health. In the future we may want to make this an enum.
-        @Published var healthy: Bool = true
+        var healthy: Bool = true
 
         // Any error while initializing the surface.
-        @Published var error: Error? = nil
+        var error: Error? = nil
 
         // The hovered URL string
-        @Published var hoverUrl: String? = nil
+        var hoverUrl: String? = nil
 
         // The currently active key sequence. The sequence is not active if this is empty.
-        @Published var keySequence: [Ghostty.KeyEquivalent] = []
+        var keySequence: [Ghostty.KeyEquivalent] = []
 
         // The time this surface last became focused. This is a ContinuousClock.Instant
         // on supported platforms.
-        @Published var focusInstant: ContinuousClock.Instant? = nil
+        var focusInstant: ContinuousClock.Instant? = nil
 
         // Returns sizing information for the surface. This is the raw C
         // structure because I'm lazy.
-        @Published var surfaceSize: ghostty_surface_size_s? = nil
+        var surfaceSize: ghostty_surface_size_s? = nil
 
         // Whether the pointer should be visible or not
-        @Published private(set) var pointerStyle: BackportPointerStyle = .default
+        private(set) var pointerStyle: BackportPointerStyle = .default
 
         /// The configuration derived from the Ghostty config so we don't need to rely on references.
-        @Published private(set) var derivedConfig: DerivedConfig
+        private(set) var derivedConfig: DerivedConfig
 
         /// The background color within the color palette of the surface. This is only set if it is
         /// dynamically updated. Otherwise, the background color is the default background color.
-        @Published private(set) var backgroundColor: Color? = nil
+        private(set) var backgroundColor: Color? = nil
 
         // An initial size to request for a window. This will only affect
         // then the view is moved to a new window.
@@ -89,7 +90,7 @@ extension Ghostty {
         }
 
         // True if the inspector should be visible
-        @Published var inspectorVisible: Bool = false {
+        var inspectorVisible: Bool = false {
             didSet {
                 if (oldValue && !inspectorVisible) {
                     guard let surface = self.surface else { return }

macos/Sources/Ghostty/SurfaceView_UIKit.swift

@@ -3,37 +3,38 @@ import GhosttyKit
 
 extension Ghostty {
     /// The UIView implementation for a terminal surface.
-    class SurfaceView: UIView, ObservableObject {
+    @Observable
+    class SurfaceView: UIView {
         /// Unique ID per surface
         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
         // to the app level and it is set from there.
-        @Published var title: String = "👻"
+        var title: String = "👻"
 
         // The current pwd of the surface.
-        @Published var pwd: String? = nil
+        var pwd: String? = nil
 
         // The cell size of this surface. This is set by the core when the
         // surface is first created and any time the cell size changes (i.e.
         // when the font size changes). This is used to allow windows to be
         // resized in discrete steps of a single cell.
-        @Published var cellSize: OSSize = .zero
+        var cellSize: OSSize = .zero
 
         // The health state of the surface. This currently only reflects the
         // renderer health. In the future we may want to make this an enum.
-        @Published var healthy: Bool = true
+        var healthy: Bool = true
 
         // Any error while initializing the surface.
-        @Published var error: Error? = nil
+        var error: Error? = nil
 
         // The hovered URL
-        @Published var hoverUrl: String? = nil
+        var hoverUrl: String? = nil
 
         // The time this surface last became focused. This is a ContinuousClock.Instant
         // on supported platforms.
-        @Published var focusInstant: ContinuousClock.Instant? = nil
+        var focusInstant: ContinuousClock.Instant? = nil
 
         // Returns sizing information for the surface. This is the raw C
         // structure because I'm lazy.