macos: change config access to evented, derived config like libghostty

Previously, we would access the `ghostty.config` object from anywhere.
The issue with this is that memory lifetime access to the underlying
`ghostty_config_t` was messy. It was easy when the apprt owned every
reference but since automatic theme changes were implemented, this isn't
always true anymore.

To fix this, we move to the same pattern we use internally in the core
of ghostty: whenever the config changes, we handle an event, derive our
desired values out of the config (copy them), and then let the caller
free the config if they want to. This way, we can be sure that any
information we need from the config is always owned by us.

macos/Sources/Features/QuickTerminal/QuickTerminalController.swift

@@ -18,12 +18,16 @@ class QuickTerminalController: BaseTerminalController {
     /// application to the front.
     private var previousApp: NSRunningApplication? = nil
 
+    /// The configuration derived from the Ghostty config so we don't need to rely on references.
+    private var derivedConfig: DerivedConfig
+
     init(_ ghostty: Ghostty.App,
          position: QuickTerminalPosition = .top,
          baseConfig base: Ghostty.SurfaceConfiguration? = nil,
          surfaceTree tree: Ghostty.SplitNode? = nil
     ) {
         self.position = position
+        self.derivedConfig = DerivedConfig(ghostty.config)
         super.init(ghostty, baseConfig: base, surfaceTree: tree)
 
         // Setup our notifications for behaviors
@@ -35,8 +39,8 @@ class QuickTerminalController: BaseTerminalController {
             object: nil)
         center.addObserver(
             self,
-            selector: #selector(ghosttyDidReloadConfig),
-            name: Ghostty.Notification.ghosttyDidReloadConfig,
+            selector: #selector(ghosttyConfigDidChange(_:)),
+            name: .ghosttyConfigDidChange,
             object: nil)
     }
 
@@ -64,7 +68,7 @@ class QuickTerminalController: BaseTerminalController {
         window.isRestorable = false
 
         // Setup our configured appearance that we support.
-        syncAppearance()
+        syncAppearance(ghostty.config)
 
         // Setup our initial size based on our configured position
         position.setLoaded(window)
@@ -186,7 +190,7 @@ class QuickTerminalController: BaseTerminalController {
     }
 
     private func animateWindowIn(window: NSWindow, from position: QuickTerminalPosition) {
-        guard let screen = ghostty.config.quickTerminalScreen.screen else { return }
+        guard let screen = derivedConfig.quickTerminalScreen.screen else { return }
 
         // Move our window off screen to the top
         position.setInitial(in: window, on: screen)
@@ -197,7 +201,7 @@ class QuickTerminalController: BaseTerminalController {
         // Run the animation that moves our window into the proper place and makes
         // it visible.
         NSAnimationContext.runAnimationGroup({ context in
-            context.duration = ghostty.config.quickTerminalAnimationDuration
+            context.duration = derivedConfig.quickTerminalAnimationDuration
             context.timingFunction = .init(name: .easeIn)
             position.setFinal(in: window.animator(), on: screen)
         }, completionHandler: {
@@ -287,7 +291,7 @@ class QuickTerminalController: BaseTerminalController {
         }
 
         NSAnimationContext.runAnimationGroup({ context in
-            context.duration = ghostty.config.quickTerminalAnimationDuration
+            context.duration = derivedConfig.quickTerminalAnimationDuration
             context.timingFunction = .init(name: .easeIn)
             position.setInitial(in: window.animator(), on: screen)
         }, completionHandler: {
@@ -297,7 +301,7 @@ class QuickTerminalController: BaseTerminalController {
         })
     }
 
-    private func syncAppearance() {
+    private func syncAppearance(_ config: Ghostty.Config) {
         guard let window else { return }
 
         // If our window is not visible, then delay this. This is possible specifically
@@ -306,7 +310,7 @@ class QuickTerminalController: BaseTerminalController {
         // APIs such as window blur have no effect unless the window is visible.
         guard window.isVisible else {
             // Weak window so that if the window changes or is destroyed we aren't holding a ref
-            DispatchQueue.main.async { [weak self] in self?.syncAppearance() }
+            DispatchQueue.main.async { [weak self] in self?.syncAppearance(config) }
             return
         }
 
@@ -314,7 +318,7 @@ class QuickTerminalController: BaseTerminalController {
         // to "native" which is typically P3. There is a lot more resources
         // covered in this GitHub issue: https://github.com/mitchellh/ghostty/pull/376
         // Ghostty defaults to sRGB but this can be overridden.
-        switch (ghostty.config.windowColorspace) {
+        switch (config.windowColorspace) {
         case "display-p3":
             window.colorSpace = .displayP3
         case "srgb":
@@ -324,7 +328,7 @@ class QuickTerminalController: BaseTerminalController {
         }
 
         // If we have window transparency then set it transparent. Otherwise set it opaque.
-        if (ghostty.config.backgroundOpacity < 1) {
+        if (config.backgroundOpacity < 1) {
             window.isOpaque = false
 
             // This is weird, but we don't use ".clear" because this creates a look that
@@ -371,8 +375,35 @@ class QuickTerminalController: BaseTerminalController {
         toggleFullscreen(mode: .nonNative)
     }
 
-    @objc private func ghosttyDidReloadConfig(notification: SwiftUI.Notification) {
-        syncAppearance()
+    @objc private func ghosttyConfigDidChange(_ notification: Notification) {
+        // We only care if the configuration is a global configuration, not a
+        // surface-specific one.
+        guard notification.object == nil else { return }
+
+        // Get our managed configuration object out
+        guard let config = notification.userInfo?[
+            Notification.Name.GhosttyConfigChangeKey
+        ] as? Ghostty.Config else { return }
+
+        // Update our derived config
+        self.derivedConfig = DerivedConfig(config)
+
+        syncAppearance(config)
+    }
+
+    private struct DerivedConfig {
+        let quickTerminalScreen: QuickTerminalScreen
+        let quickTerminalAnimationDuration: Double
+
+        init() {
+            self.quickTerminalScreen = .main
+            self.quickTerminalAnimationDuration = 0.2
+        }
+
+        init(_ config: Ghostty.Config) {
+            self.quickTerminalScreen = config.quickTerminalScreen
+            self.quickTerminalAnimationDuration = config.quickTerminalAnimationDuration
+        }
     }
 }