fix(desktop-gpui): retry thumbnail sweeps a capture hang cut short

A sweep sends its target list before capturing, and the receiver commits
that list's signature when the channel closes. A sweep that a hang ended
early was therefore recorded as complete, and with an unchanged window
list windows_stale() stayed false, so window thumbnails never retried
after the pause. Skip the commit while captures are paused so the picker
retries the sweep once the pause lifts.

Also add the pause duration with Duration::saturating_sub in the test,
per the repository's time-subtraction rule.

Author: AatmanAJ

apps/desktop-gpui/src/main_window.rs

@@ -1269,9 +1269,13 @@ impl MainWindow {
                     // `setDisplayThumbnailsSignature` runs
                     // (`new-main/index.tsx:2617-2620`). Committing the
                     // signature at `Listed` time instead would mark a sweep
-                    // that never landed as up to date.
+                    // that never landed as up to date. Likewise a sweep that a
+                    // capture hang cut short: it stays stale so the picker
+                    // retries it once the pause lifts.
                     this.update(cx, |this, cx| {
-                        if let Some(signature) = swept {
+                        if let Some(signature) = swept
+                            && !target_thumbnails::captures_paused()
+                        {
                             this.thumbnails.set_display_signature(signature);
                         }
                         this.thumbnails.set_display_inflight(false);
@@ -1316,7 +1320,9 @@ impl MainWindow {
                         }
                     }
                     this.update(cx, |this, cx| {
-                        if let Some(signature) = swept {
+                        if let Some(signature) = swept
+                            && !target_thumbnails::captures_paused()
+                        {
                             this.thumbnails.set_window_signature(signature);
                         }
                         this.thumbnails.set_window_inflight(false);

apps/desktop-gpui/src/target_thumbnails.rs

@@ -1571,7 +1571,7 @@ mod tests {
         assert!(!pause.active_at(now));
         pause.start_at(now);
         assert!(pause.active_at(now));
-        assert!(pause.active_at(now + CAPTURE_HANG_PAUSE - Duration::from_millis(1)));
+        assert!(pause.active_at(now + CAPTURE_HANG_PAUSE.saturating_sub(Duration::from_millis(1))));
         assert!(!pause.active_at(now + CAPTURE_HANG_PAUSE));
     }
 }