fix(desktop): without a tray, the first-close dialog defaults to Quit (cinny-desktop #37)

On desktops with no tray host (stock GNOME), "Keep running in the tray"
hid the window with no icon to bring it back. Ask the desktop app
(has_tray_host); without a tray, say so, focus "Quit when I close the
window", and offer "Keep running in the background" as the secondary
choice. Older desktop builds keep the current dialog.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/components/CloseBehaviorPrompt.tsx

@@ -26,6 +26,10 @@ import { useModalStyle } from '../hooks/useModalStyle';
 export function CloseBehaviorPrompt() {
   const [open, setOpen] = useState(false);
   const [launchOnLogin, setLaunchOnLogin] = useState(false);
+  // [cinny-desktop #37] Stock GNOME has no tray host: "keep running in the
+  // tray" would hide the window with no icon to bring it back. Older desktop
+  // builds lack the command; assume a tray then (the old behaviour).
+  const [hasTray, setHasTray] = useState(true);
   const modalStyle = useModalStyle(420);
 
   // Tells the native side we're listening (see get_close_behavior).
@@ -34,7 +38,17 @@ export function CloseBehaviorPrompt() {
     tauriInvoke()?.('get_close_behavior').catch(() => undefined);
   }, []);
 
-  useTauriEvent('lotus-close-requested', () => setOpen(true));
+  useTauriEvent('lotus-close-requested', () => {
+    const ask = tauriInvoke()?.('has_tray_host');
+    if (!ask) {
+      setOpen(true);
+      return;
+    }
+    ask
+      .then((v) => setHasTray(v !== false))
+      .catch(() => setHasTray(true))
+      .finally(() => setOpen(true));
+  });
 
   const choose = useCallback(
     (value: 'tray' | 'quit') => {
@@ -51,7 +65,7 @@ export function CloseBehaviorPrompt() {
       <OverlayCenter>
         <FocusTrap
           focusTrapOptions={{
-            initialFocus: '#close-behavior-keep',
+            initialFocus: hasTray ? '#close-behavior-keep' : '#close-behavior-quit',
             // Dismissing without choosing keeps the window open; the next close
             // asks again.
             onDeactivate: () => setOpen(false),
@@ -80,8 +94,9 @@ export function CloseBehaviorPrompt() {
             </Header>
             <Box style={{ padding: config.space.S400 }} direction="Column" gap="400">
               <Text priority="400" id="close-behavior-body">
-                Lotus Chat can keep running in the system tray when you close this window, so
-                messages, notifications and calls still reach you. Open it again from the tray icon.
+                {hasTray
+                  ? 'Lotus Chat can keep running in the system tray when you close this window, so messages, notifications and calls still reach you. Open it again from the tray icon.'
+                  : "Your desktop doesn't show tray icons, so if Lotus Chat keeps running after you close this window, the only way back is to launch it again."}
               </Text>
               <Box as="label" alignItems="Center" gap="200" style={{ cursor: 'pointer' }}>
                 <Checkbox
@@ -95,12 +110,43 @@ export function CloseBehaviorPrompt() {
                 <Text size="T300">Start Lotus Chat when I sign in to my computer</Text>
               </Box>
               <Box direction="Column" gap="200">
-                <Button id="close-behavior-keep" variant="Primary" onClick={() => choose('tray')}>
-                  <Text size="B400">Keep running in the tray</Text>
-                </Button>
-                <Button variant="Secondary" fill="Soft" onClick={() => choose('quit')}>
-                  <Text size="B400">Quit when I close the window</Text>
-                </Button>
+                {hasTray ? (
+                  <>
+                    <Button
+                      id="close-behavior-keep"
+                      variant="Primary"
+                      onClick={() => choose('tray')}
+                    >
+                      <Text size="B400">Keep running in the tray</Text>
+                    </Button>
+                    <Button
+                      id="close-behavior-quit"
+                      variant="Secondary"
+                      fill="Soft"
+                      onClick={() => choose('quit')}
+                    >
+                      <Text size="B400">Quit when I close the window</Text>
+                    </Button>
+                  </>
+                ) : (
+                  <>
+                    <Button
+                      id="close-behavior-quit"
+                      variant="Primary"
+                      onClick={() => choose('quit')}
+                    >
+                      <Text size="B400">Quit when I close the window</Text>
+                    </Button>
+                    <Button
+                      id="close-behavior-keep"
+                      variant="Secondary"
+                      fill="Soft"
+                      onClick={() => choose('tray')}
+                    >
+                      <Text size="B400">Keep running in the background</Text>
+                    </Button>
+                  </>
+                )}
               </Box>
               <Text size="T200" priority="300">
                 You can change this in Settings → General.