fix(schedule): load scheduled messages from the server; offer to cancel them at logout (#322)

The tray only knew what this browser had scheduled (localStorage), but
Synapse lists every pending one via MSC4140 GET /delayed_events. Load it
when the tray mounts and on window focus (localStorage stays as a first-
paint cache), keeping only non-state m.room.message events. Logout now
says "N scheduled messages still send after you log out" and offers to
cancel them.

Fixes #322

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

src/app/components/LogoutDialog.tsx

@@ -1,4 +1,4 @@
-import React, { forwardRef, useCallback } from 'react';
+import React, { forwardRef, useCallback, useEffect, useState } from 'react';
 import { Dialog, Header, config, Box, Text, Button, Spinner, color } from 'folds';
 import { useAtom } from 'jotai';
 import { AsyncStatus, useAsyncCallback } from '../hooks/useAsyncCallback';
@@ -9,6 +9,8 @@ import { useMatrixClient } from '../hooks/useMatrixClient';
 import { useModalStyle } from '../hooks/useModalStyle';
 import { useCrossSigningActive } from '../hooks/useCrossSigning';
 import { InfoCard } from './info-card';
+import { ScheduledMessage } from '../state/scheduledMessages';
+import { cancelScheduledMessage, fetchScheduledMessages } from '../utils/scheduledMessages';
 import {
   useDeviceVerificationStatus,
   VerificationStatus,
@@ -36,17 +38,36 @@ export const LogoutDialog = forwardRef<HTMLDivElement, LogoutDialogProps>(
 
     const [callEmbed, setCallEmbed] = useAtom(callEmbedAtom);
 
-    const [logoutState, logout] = useAsyncCallback<void, Error, []>(
-      useCallback(async () => {
-        // [Gitea #29] Logging out mid-call must hang up first, or the MatrixRTC
-        // membership (expires: 4 h) stays behind as a ghost participant and
-        // everyone else sees you "in call" until it times out.
-        if (callEmbed && callEmbed.joined && !callEmbed.disposed) {
-          await hangupCallAndWait(mx, callEmbed);
-          setCallEmbed(undefined);
-        }
-        await logoutClient(mx);
-      }, [mx, callEmbed, setCallEmbed]),
+    // [Gitea #322] Scheduled messages live on the server and still send after
+    // logout, where no client would show them. Say so, and offer to cancel.
+    const [scheduled, setScheduled] = useState<ScheduledMessage[]>([]);
+    useEffect(() => {
+      let alive = true;
+      fetchScheduledMessages(mx)
+        .then((list) => alive && setScheduled(list))
+        .catch(() => undefined);
+      return () => {
+        alive = false;
+      };
+    }, [mx]);
+
+    const [logoutState, logout] = useAsyncCallback<void, Error, [boolean?]>(
+      useCallback(
+        async (cancelScheduled?: boolean) => {
+          if (cancelScheduled) {
+            await Promise.all(scheduled.map((m) => cancelScheduledMessage(mx, m.delayId)));
+          }
+          // [Gitea #29] Logging out mid-call must hang up first, or the MatrixRTC
+          // membership (expires: 4 h) stays behind as a ghost participant and
+          // everyone else sees you "in call" until it times out.
+          if (callEmbed && callEmbed.joined && !callEmbed.disposed) {
+            await hangupCallAndWait(mx, callEmbed);
+            setCallEmbed(undefined);
+          }
+          await logoutClient(mx);
+        },
+        [mx, callEmbed, setCallEmbed, scheduled],
+      ),
     );
 
     const ongoingLogout = logoutState.status === AsyncStatus.Loading;
@@ -93,6 +114,13 @@ export const LogoutDialog = forwardRef<HTMLDivElement, LogoutDialogProps>(
                 description="Enable device verification or export your encrypted data from settings to avoid losing access to your messages."
               />
             ))}
+          {scheduled.length > 0 && (
+            <InfoCard
+              variant="Warning"
+              title={`${scheduled.length} scheduled message${scheduled.length === 1 ? '' : 's'}`}
+              description="Scheduled messages still send after you log out. Cancel them now if you don't want them sent."
+            />
+          )}
           <Text priority="400">You’re about to log out. Are you sure?</Text>
           {logoutState.status === AsyncStatus.Error && (
             <Text style={{ color: color.Critical.Main }} size="T300">
@@ -102,12 +130,24 @@ export const LogoutDialog = forwardRef<HTMLDivElement, LogoutDialogProps>(
           <Box direction="Column" gap="200">
             <Button
               variant="Critical"
-              onClick={logout}
+              onClick={() => logout()}
               disabled={ongoingLogout}
               before={ongoingLogout && <Spinner variant="Critical" fill="Solid" size="200" />}
             >
-              <Text size="B400">Logout</Text>
+              <Text size="B400">
+                {scheduled.length > 0 ? 'Logout and keep scheduled messages' : 'Logout'}
+              </Text>
             </Button>
+            {scheduled.length > 0 && (
+              <Button
+                variant="Critical"
+                fill="Soft"
+                onClick={() => logout(true)}
+                disabled={ongoingLogout}
+              >
+                <Text size="B400">Cancel scheduled messages and logout</Text>
+              </Button>
+            )}
             <Button variant="Secondary" fill="Soft" onClick={handleClose} disabled={ongoingLogout}>
               <Text size="B400">Cancel</Text>
             </Button>