fix: harden macos ax window fallback

crates/macos/src/system/window_inventory.rs

@@ -166,8 +166,12 @@ fn ax_window_for_app(app_info: &AppInfo) -> Option<WindowInfo> {
     let window = focused_window_element(&app)
         .or_else(|| crate::tree::copy_element_attr(&app, "AXMainWindow"))
         .or_else(|| {
-            crate::tree::copy_ax_array(&app, "AXWindows")
-                .and_then(|windows| windows.into_iter().next())
+            let windows = crate::tree::copy_ax_array(&app, "AXWindows")?;
+            child_bearing_window_index(&windows, |window| {
+                crate::tree::element::count_children(window, None)
+            })
+            .map(|index| windows[index].clone())
+            .or_else(|| windows.into_iter().next())
         })?;
     if crate::tree::copy_string_attr(&window, "AXRole").as_deref() != Some("AXWindow") {
         return None;
@@ -195,6 +199,13 @@ fn ax_window_info(
     }
 }
 
+fn child_bearing_window_index<T>(
+    windows: &[T],
+    mut count_children: impl FnMut(&T) -> u32,
+) -> Option<usize> {
+    windows.iter().position(|window| count_children(window) > 0)
+}
+
 type FocusedWindowIdentity = Option<(Option<String>, Option<i64>)>;
 
 fn focused_window_identity(pid: i32) -> FocusedWindowIdentity {

crates/macos/src/system/window_inventory_tests.rs

@@ -213,6 +213,23 @@ fn ax_window_info_uses_resolved_app_identity() {
     assert_eq!(window.id, "w-7");
 }
 
+#[test]
+fn child_bearing_window_index_prefers_first_window_with_children() {
+    let windows = [0, 7, 3];
+
+    assert_eq!(
+        child_bearing_window_index(&windows, |count| *count),
+        Some(1)
+    );
+}
+
+#[test]
+fn child_bearing_window_index_returns_none_when_all_windows_are_empty() {
+    let windows = [0, 0];
+
+    assert_eq!(child_bearing_window_index(&windows, |count| *count), None);
+}
+
 fn app(name: &str, pid: i32) -> AppInfo {
     AppInfo {
         name: name.to_string(),

crates/macos/src/tree/builder.rs

@@ -23,7 +23,10 @@ pub fn window_element_for(pid: i32, win_title: &str) -> AXElement {
     if let Some(windows) = copy_ax_array(&app, kAXWindowsAttribute) {
         for win in &windows {
             let title = copy_string_attr(win, kAXTitleAttribute);
-            if title.as_deref() == Some(win_title) {
+            if title
+                .as_deref()
+                .is_some_and(|title| window_titles_are_exact_match(title, win_title))
+            {
                 return win.clone();
             }
         }
@@ -31,7 +34,7 @@ pub fn window_element_for(pid: i32, win_title: &str) -> AXElement {
             let title = copy_string_attr(win, kAXTitleAttribute);
             if title
                 .as_deref()
-                .is_some_and(|t| !t.is_empty() && (t.contains(win_title) || win_title.contains(t)))
+                .is_some_and(|title| window_titles_are_partial_match(title, win_title))
             {
                 return win.clone();
             }
@@ -49,6 +52,18 @@ pub fn window_element_for(pid: i32, win_title: &str) -> AXElement {
     app
 }
 
+#[cfg(target_os = "macos")]
+fn window_titles_are_exact_match(candidate_title: &str, requested_title: &str) -> bool {
+    !candidate_title.is_empty() && !requested_title.is_empty() && candidate_title == requested_title
+}
+
+#[cfg(target_os = "macos")]
+fn window_titles_are_partial_match(candidate_title: &str, requested_title: &str) -> bool {
+    !candidate_title.is_empty()
+        && !requested_title.is_empty()
+        && (candidate_title.contains(requested_title) || requested_title.contains(candidate_title))
+}
+
 #[cfg(target_os = "macos")]
 pub fn build_subtree(
     el: &AXElement,

crates/macos/src/tree/builder_tests.rs

@@ -1,4 +1,7 @@
-use super::{child_attributes, redact_secure_value};
+use super::{
+    child_attributes, redact_secure_value, window_titles_are_exact_match,
+    window_titles_are_partial_match,
+};
 
 #[test]
 fn test_browser_children_use_columns() {
@@ -27,3 +30,25 @@ fn test_secure_text_value_is_redacted() {
         Some("visible".into())
     );
 }
+
+#[test]
+fn window_title_matching_rejects_empty_titles() {
+    assert!(!window_titles_are_exact_match("", ""));
+    assert!(!window_titles_are_exact_match("Inbox", ""));
+    assert!(!window_titles_are_exact_match("", "Inbox"));
+    assert!(!window_titles_are_partial_match("Inbox", ""));
+    assert!(!window_titles_are_partial_match("", "Inbox"));
+}
+
+#[test]
+fn window_title_matching_accepts_exact_and_truncated_titles() {
+    assert!(window_titles_are_exact_match("Inbox", "Inbox"));
+    assert!(window_titles_are_partial_match(
+        "noy4/agent-desktop: Native desktop automation",
+        "noy4/agent-desktop"
+    ));
+    assert!(window_titles_are_partial_match(
+        "noy4/agent-desktop: Native desk...",
+        "noy4/agent-desktop: Native desk"
+    ));
+}