fix(forward): full-width search + deep-audit fixes for message forwarding

Audit of ForwardMessageDialog, fixes:
- Search input was intrinsic-width (sat in a default Row Box with no grow) —
  now a Column Box stretches it full-width, matching every other search input.
- Search field is auto-focused on open (FocusTrap initialFocus; was nothing).
- Edited messages now forward the LATEST edit (m.new_content via
  getEditedEvent) instead of the stale pre-edit body.
- Reply fallbacks stripped (trimReplyFromBody + <mx-reply> block) along with
  m.relates_to, so forwards stand alone instead of quoting the old room.
- Undecryptable events are refused with an inline error (previously forwarded
  m.bad.encrypted junk); send failures now show an error instead of silently
  resetting.
- sendEvent uses the typed threadId-aware overload (explicit null) instead of
  an untyped (mx as any) call relying on the SDK's legacy arg-sniffing.
- Room list + filter memoized (was re-sorting all rooms every keystroke).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/features/room/message/ForwardMessageDialog.tsx

@@ -1,8 +1,9 @@
-import React, { ChangeEvent, useCallback, useState } from 'react';
+import React, { ChangeEvent, useCallback, useMemo, useRef, useState } from 'react';
 import FocusTrap from 'focus-trap-react';
 import {
   Avatar,
   Box,
+  color,
   config,
   Header,
   Icon,
@@ -28,6 +29,7 @@ import { mDirectAtom } from '../../../state/mDirectList';
 import { useMediaAuthentication } from '../../../hooks/useMediaAuthentication';
 import { mxcUrlToHttp } from '../../../utils/matrix';
 import { RoomAvatar, RoomIcon } from '../../../components/room-avatar';
+import { getEditedEvent, trimReplyFromBody, trimReplyFromFormattedBody } from '../../../utils/room';
 
 type RoomRowProps = {
   room: Room;
@@ -86,35 +88,83 @@ export function ForwardMessageDialog({ mEvent, onClose }: Props) {
   const modalStyle = useModalStyle(400);
   const directs = useAtomValue(mDirectAtom);
   const useAuthentication = useMediaAuthentication();
+  const searchInputRef = useRef<HTMLInputElement>(null);
   const [query, setQuery] = useState('');
   const [sending, setSending] = useState(false);
   const [sentTo, setSentTo] = useState<string | null>(null);
+  const [error, setError] = useState<string | null>(null);
 
-  const allRooms = mx
-    .getRooms()
-    .filter((r) => r.getMyMembership() === 'join' && !r.isSpaceRoom())
-    .sort((a, b) => (b.getLastActiveTimestamp() ?? 0) - (a.getLastActiveTimestamp() ?? 0));
+  const allRooms = useMemo(
+    () =>
+      mx
+        .getRooms()
+        .filter((r) => r.getMyMembership() === 'join' && !r.isSpaceRoom())
+        .sort((a, b) => (b.getLastActiveTimestamp() ?? 0) - (a.getLastActiveTimestamp() ?? 0)),
+    [mx],
+  );
 
-  const filtered = query
-    ? allRooms.filter((r) => r.name.toLowerCase().includes(query.toLowerCase()))
-    : allRooms;
+  const filtered = useMemo(() => {
+    if (!query) return allRooms;
+    const q = query.toLowerCase();
+    return allRooms.filter((r) => r.name.toLowerCase().includes(q));
+  }, [allRooms, query]);
+
+  /**
+   * Build the content to forward:
+   * - undecryptable events are refused (would forward `m.bad.encrypted` junk)
+   * - edited messages forward the LATEST edit (`m.new_content`), not the
+   *   original pre-edit body
+   * - reply fallbacks (`> <@user> …` quote + `<mx-reply>` block) are stripped
+   *   along with the `m.relates_to` reply/thread relation, so the forwarded
+   *   message stands alone in the target room
+   */
+  const buildForwardContent = useCallback((): Record<string, unknown> | undefined => {
+    if (mEvent.isDecryptionFailure()) return undefined;
+
+    let content = { ...mEvent.getContent() };
+
+    const eventId = mEvent.getId();
+    const room = mx.getRoom(mEvent.getRoomId());
+    if (eventId && room) {
+      const editedEvent = getEditedEvent(eventId, mEvent, room.getUnfilteredTimelineSet());
+      const newContent = editedEvent?.getContent()['m.new_content'];
+      if (newContent && typeof newContent === 'object') {
+        content = { ...(newContent as Record<string, unknown>) };
+      }
+    }
+
+    delete content['m.relates_to'];
+    if (typeof content.body === 'string') {
+      content.body = trimReplyFromBody(content.body);
+    }
+    if (typeof content.formatted_body === 'string') {
+      content.formatted_body = trimReplyFromFormattedBody(content.formatted_body);
+    }
+    return content;
+  }, [mx, mEvent]);
 
   const forward = useCallback(
     async (room: Room) => {
       if (sending) return;
+      const fwdContent = buildForwardContent();
+      if (!fwdContent) {
+        setError('This message could not be decrypted, so it cannot be forwarded.');
+        return;
+      }
       setSending(true);
-      const fwdContent: Record<string, unknown> = { ...mEvent.getContent() };
-      delete fwdContent['m.relates_to'];
+      setError(null);
       try {
+        // threadId-aware overload (P3-8): explicit null = send to the main timeline.
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        await (mx as any).sendEvent(room.roomId, mEvent.getType(), fwdContent);
+        await mx.sendEvent(room.roomId, null, mEvent.getType() as any, fwdContent);
         setSentTo(room.name);
         setTimeout(onClose, 1400);
       } catch {
         setSending(false);
+        setError(`Failed to forward to ${room.name}. Try again.`);
       }
     },
-    [mx, mEvent, onClose, sending],
+    [mx, mEvent, onClose, sending, buildForwardContent],
   );
 
   return (
@@ -122,7 +172,7 @@ export function ForwardMessageDialog({ mEvent, onClose }: Props) {
       <OverlayCenter>
         <FocusTrap
           focusTrapOptions={{
-            initialFocus: false,
+            initialFocus: () => searchInputRef.current ?? false,
             onDeactivate: onClose,
             clickOutsideDeactivates: true,
             escapeDeactivates: stopPropagation,
@@ -153,8 +203,13 @@ export function ForwardMessageDialog({ mEvent, onClose }: Props) {
               </IconButton>
             </Header>
             {!sentTo && (
-              <Box shrink="No" style={{ padding: `${config.space.S200} ${config.space.S400}` }}>
+              <Box
+                shrink="No"
+                direction="Column"
+                style={{ padding: `${config.space.S200} ${config.space.S400}` }}
+              >
                 <Input
+                  ref={searchInputRef}
                   variant="Background"
                   size="400"
                   radii="400"
@@ -163,6 +218,14 @@ export function ForwardMessageDialog({ mEvent, onClose }: Props) {
                   value={query}
                   onChange={(e: ChangeEvent<HTMLInputElement>) => setQuery(e.target.value)}
                 />
+                {error && (
+                  <Text
+                    size="T200"
+                    style={{ color: color.Critical.Main, paddingTop: config.space.S100 }}
+                  >
+                    {error}
+                  </Text>
+                )}
               </Box>
             )}
             <Line size="300" />