feat(desktop): ask once what closing the window should do (cinny-desktop #5)

The first time the window is closed, a dialog asks "Keep Lotus Chat
running?" — Keep running in the tray (default, focused) / Quit when I
close the window — with an opt-in "Start Lotus Chat when I sign in"
checkbox in the same moment (per the approved design: one dialog, no
wizard). The choice is saved natively; Settings → General → "When I
close the window" changes it later (tray / quit / ask me).

The dialog is role="dialog" aria-modal, labelled and described, with
focus on the default button. Web-side flow verified with a stubbed
native side: event → dialog → checkbox + Quit sends autostart enable +
resolve_close_request("quit"); the Settings select saves "tray".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/components/CloseBehaviorPrompt.tsx

@@ -0,0 +1,114 @@
+import React, { useCallback, useEffect, useState } from 'react';
+import FocusTrap from 'focus-trap-react';
+import {
+  Box,
+  Button,
+  Checkbox,
+  Dialog,
+  Header,
+  Overlay,
+  OverlayBackdrop,
+  OverlayCenter,
+  Text,
+  config,
+} from 'folds';
+import { invokeTauri, isTauri, tauriInvoke, useTauriEvent } from '../hooks/useTauri';
+import { useModalStyle } from '../hooks/useModalStyle';
+
+/**
+ * cinny-desktop #5: the first time the window is closed, ask whether Lotus Chat
+ * should keep running in the tray (calls, messages, notifications) or quit —
+ * and, in the same moment, whether it should start when you sign in. Asked
+ * once; changeable in Settings → General. The native side sends
+ * `lotus-close-requested` only while the choice is still "ask", and never
+ * during a call (a call always goes to the tray).
+ */
+export function CloseBehaviorPrompt() {
+  const [open, setOpen] = useState(false);
+  const [launchOnLogin, setLaunchOnLogin] = useState(false);
+  const modalStyle = useModalStyle(420);
+
+  // Tells the native side we're listening (see get_close_behavior).
+  useEffect(() => {
+    if (!isTauri()) return;
+    tauriInvoke()?.('get_close_behavior').catch(() => undefined);
+  }, []);
+
+  useTauriEvent('lotus-close-requested', () => setOpen(true));
+
+  const choose = useCallback(
+    (value: 'tray' | 'quit') => {
+      if (launchOnLogin) invokeTauri('plugin:autostart|enable');
+      setOpen(false);
+      invokeTauri('resolve_close_request', { value });
+    },
+    [launchOnLogin],
+  );
+
+  if (!open) return null;
+  return (
+    <Overlay open backdrop={<OverlayBackdrop />}>
+      <OverlayCenter>
+        <FocusTrap
+          focusTrapOptions={{
+            initialFocus: '#close-behavior-keep',
+            // Dismissing without choosing keeps the window open; the next close
+            // asks again.
+            onDeactivate: () => setOpen(false),
+            clickOutsideDeactivates: true,
+          }}
+        >
+          <Dialog
+            variant="Surface"
+            role="dialog"
+            aria-modal="true"
+            aria-labelledby="close-behavior-title"
+            aria-describedby="close-behavior-body"
+            style={modalStyle}
+          >
+            <Header
+              style={{
+                padding: `0 ${config.space.S400}`,
+                borderBottomWidth: config.borderWidth.B300,
+              }}
+              variant="Surface"
+              size="500"
+            >
+              <Text as="h2" size="H4" id="close-behavior-title">
+                Keep Lotus Chat running?
+              </Text>
+            </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.
+              </Text>
+              <Box as="label" alignItems="Center" gap="200" style={{ cursor: 'pointer' }}>
+                <Checkbox
+                  size="300"
+                  variant="Primary"
+                  checked={launchOnLogin}
+                  onClick={(e: React.MouseEvent<HTMLInputElement>) =>
+                    setLaunchOnLogin(e.currentTarget.checked)
+                  }
+                />
+                <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>
+              </Box>
+              <Text size="T200" priority="300">
+                You can change this in Settings → General.
+              </Text>
+            </Box>
+          </Dialog>
+        </FocusTrap>
+      </OverlayCenter>
+    </Overlay>
+  );
+}

src/app/features/settings/general/General.tsx

@@ -164,11 +164,18 @@ function AutostartSetting() {
   // [cinny-desktop #3] null until the native side answers (older builds don't
   // have the command, so the switch just stays hidden there).
   const [startMinimized, setStartMinimized] = useState<boolean | null>(null);
+  // [cinny-desktop #5] "ask" | "tray" | "quit"; null on builds without it.
+  const [closeBehavior, setCloseBehavior] = useState<string | null>(null);
 
   useEffect(() => {
     tauriInvoke()?.('plugin:autostart|is_enabled')
       .then((value) => setEnabled(value === true))
       .catch(() => undefined);
+    tauriInvoke()?.('get_close_behavior')
+      .then((value) => {
+        if (typeof value === 'string') setCloseBehavior(value);
+      })
+      .catch(() => undefined);
     tauriInvoke()?.('get_start_minimized')
       .then((value) => {
         if (typeof value === 'boolean') setStartMinimized(value);
@@ -181,6 +188,11 @@ function AutostartSetting() {
     setEnabled(value);
   };
 
+  const handleCloseBehavior = (value: string) => {
+    invokeTauri('set_close_behavior', { value });
+    setCloseBehavior(value);
+  };
+
   const handleStartMinimized = (value: boolean) => {
     invokeTauri('set_start_minimized', { value });
     setStartMinimized(value);
@@ -194,6 +206,24 @@ function AutostartSetting() {
         description="Start Lotus Chat automatically when you sign in to your computer."
         after={<Switch variant="Primary" value={enabled} onChange={handleChange} />}
       />
+      {closeBehavior !== null && (
+        <SettingTile
+          title="When I close the window"
+          description="Keep Lotus Chat running in the system tray (messages, notifications and calls keep arriving), or quit it. During a call, closing always keeps it running."
+          after={
+            <SettingsSelect
+              value={closeBehavior}
+              onChange={handleCloseBehavior}
+              aria-label="When I close the window"
+              options={[
+                { value: 'tray', label: 'Keep running in the tray' },
+                { value: 'quit', label: 'Quit Lotus Chat' },
+                { value: 'ask', label: 'Ask me' },
+              ]}
+            />
+          }
+        />
+      )}
       {enabled && startMinimized !== null && (
         <SettingTile
           title="Start minimized"

src/app/pages/client/ClientNonUIFeatures.tsx

@@ -70,6 +70,7 @@ import { getRoomRetentionMs, isExpired } from '../../utils/retention';
 import { useTauriUpdateProgress, useTauriUpdater } from '../../hooks/useTauriUpdater';
 import { isNetworkUpdateError } from '../../utils/updateErrors';
 import { invokeTauri, isTauri as isTauriApp, useTauriEvent } from '../../hooks/useTauri';
+import { CloseBehaviorPrompt } from '../../components/CloseBehaviorPrompt';
 import { TauriDesktopFeatures } from '../../components/TauriDesktopFeatures';
 import { KeyboardShortcutsDialog, useKeyboardShortcutsTrigger } from '../../features/shortcuts';
 import { useRoomsListener } from '../../hooks/useRoomsListener';
@@ -1088,6 +1089,7 @@ export function ClientNonUIFeatures({ children }: ClientNonUIFeaturesProps) {
       <RetentionSweeper />
       <TauriUpdateFeature />
       <TauriDesktopFeatures />
+      <CloseBehaviorPrompt />
       <LotusDenoiseFeature />
       <DeepLinkNavigator />
       <KeyboardShortcutsFeature />