fix(macos): disable TouchBar to prevent KVO crash on shutdown

Fixes a SIGILL crash on macOS during app shutdown caused by AppKit's
TouchBar KVO observers. macOS registers observers on the responder chain
to track Touch Bar availability; during eframe/winit teardown, the
observed objects are deallocated before the observers are cleaned up,
triggering an exception in _NSTouchBarFinderObservation invalidate.

Calling [NSApplication setAutomaticCustomizeTouchBarMenuItemEnabled: NO]
before the app window is created prevents macOS from installing those
observers in the first place. The app does not use the Touch Bar.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: lklimek

src/main.rs

@@ -61,6 +61,8 @@ async fn start(app_data_dir: &std::path::Path) -> Result<(), eframe::Error> {
         ..Default::default()
     };
 
+    crate::platform::disable_touchbar();
+
     eframe::run_native(
         &format!("Dash Evo Tool v{}", VERSION),
         native_options,

src/platform/macos.rs

@@ -2,6 +2,34 @@ use objc2::MainThreadMarker;
 use objc2::msg_send;
 use objc2::runtime::{AnyClass, AnyObject};
 
+/// Disables automatic Touch Bar customization to prevent a KVO crash on
+/// shutdown. macOS registers KVO observers on the responder chain to track
+/// Touch Bar availability; during eframe/winit teardown the observed objects
+/// can be deallocated before the observers are removed, causing a SIGILL in
+/// `_NSTouchBarFinderObservation invalidate`.
+///
+/// Calling `[NSApplication setAutomaticCustomizeTouchBarMenuItemEnabled: NO]`
+/// before the app window is created prevents macOS from installing those
+/// observers in the first place.
+///
+/// # Thread safety
+///
+/// This function calls AppKit APIs that must run on the main thread.
+/// The `MainThreadMarker` parameter enforces this at compile time.
+pub fn disable_touchbar(_mtm: MainThreadMarker) {
+    // SAFETY: `setAutomaticCustomizeTouchBarMenuItemEnabled:` is a class
+    // method on NSApplication, stable since macOS 10.12.1. Passing a BOOL
+    // `false` is ABI-compatible with the Objective-C declaration.
+    unsafe {
+        let Some(cls) = AnyClass::get(c"NSApplication") else {
+            tracing::debug!("NSApplication class not found, skipping TouchBar disable");
+            return;
+        };
+        let _: () = msg_send![cls, setAutomaticCustomizeTouchBarMenuItemEnabled: false];
+    }
+    tracing::debug!("Disabled automatic Touch Bar customization");
+}
+
 /// Queries `accessibilityChildren` on the key window's content view to force
 /// macOS to call the AccessKit adapter's subclassed method, which transitions
 /// the adapter from `Inactive` to `Active`. Without this, tools like Peekaboo

src/platform/mod.rs

@@ -29,3 +29,18 @@ pub fn force_accessibility_activation() -> bool {
         true
     }
 }
+
+/// Disable automatic Touch Bar customization to prevent a KVO crash during
+/// shutdown on macOS. No-op on other platforms.
+///
+/// Must be called before `eframe::run_native()`, from the main thread.
+pub fn disable_touchbar() {
+    #[cfg(target_os = "macos")]
+    {
+        let Some(mtm) = objc2::MainThreadMarker::new() else {
+            tracing::error!("disable_touchbar called from non-main thread");
+            return;
+        };
+        macos::disable_touchbar(mtm);
+    }
+}