Migrate message forwarding to backend REST endpoint

Both real mobile clients (iOS, Android) forward messages via POST
/v1/im/messages/forward, never a client-side {pub} packet -- confirmed
by reading their source directly. Switches web's single-message and
bulk forward paths to the same endpoint, which copies message content
verbatim regardless of shape, eliminating the client-side flat-content
detection this used to require. Comment-sending stays on the existing
sendText() path, unchanged, to preserve current ordering.

Removes send.ts's now-unused forwardMessage/flatForwardPayload.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/features/messages/ConversationView.tsx

@@ -17,7 +17,7 @@ import { VoiceRecorder } from '@/features/messages/VoiceRecorder';
 import { GroupAnnouncementModal } from '@/features/groups/GroupAnnouncementModal';
 import { JoinRequestsModal } from '@/features/groups/JoinRequestsModal';
 import { useBootstrap } from '@/lib/api/hooks';
-import { favoriteMessages, getTopicDraft, type MediaType, putTopicDraft, recallMessage } from '@/lib/api/messages';
+import { favoriteMessages, forwardMessages, getTopicDraft, type MediaType, putTopicDraft, recallMessage } from '@/lib/api/messages';
 import { getAllGroupMembers, getAllGroupMutes, getGroup, getGroupGovernance, getGroupSummary } from '@/lib/api/groups';
 import { getConversationContext, getUserProfile } from '@/lib/api/friends';
 import { getMe } from '@/lib/api/profile';
@@ -31,7 +31,7 @@ import { groupSenderLabel } from '@/lib/messages/sender-name';
 import { sendFile, sendImage, sendVoice } from '@/lib/tinode/attachments';
 import { isTopicGone } from '@/lib/tinode/errors';
 import { useChatList, useTinode, useTopicMessages } from '@/lib/tinode/hooks';
-import { forwardMessage, sendPrebuiltContent, sendReply, sendText } from '@/lib/tinode/send';
+import { sendPrebuiltContent, sendReply, sendText } from '@/lib/tinode/send';
 import {
   closeConversation,
   ensureTopicAttached,
@@ -818,25 +818,36 @@ export function ConversationView() {
     // order, landing #10 ahead of #3 in the target conversation and misrepresenting which one was
     // actually said first.
     const orderedSeqs = [...selectedSeqs].sort((a, b) => a - b);
-    for (const targetTopic of targetTopics) {
-      // A target that isn't the conversation currently open (i.e. almost any real forward target)
-      // is not actually subscribed, and publishing on an unsubscribed topic is rejected outright by
-      // the SDK -- see ensureTopicAttached's own comment for why this is the common case, not an
-      // edge case.
-      ensureTopicAttached(targetTopic)
-        .then((target) => {
-          for (const seq of orderedSeqs) {
-            const msg = topic.findMessage(seq);
-            // A message can be recalled by its sender AFTER it was already selected (the checkbox
-            // itself refuses a NEW selection of a recalled message, but can't retroactively un-select
-            // one recalled mid-session) -- forwarding null content would silently send an empty bubble
-            // with a misleading "forwarded from" tag rather than the message the user actually picked.
-            if (msg && !isRecalled(msg)) forwardMessage(topicId, msg, target).catch((err) => showError(err, '转发失败'));
-          }
-          if (comment) sendText(target, comment).catch((err) => showError(err, '附言发送失败'));
+    // A message can be recalled by its sender AFTER it was already selected (the checkbox itself
+    // refuses a NEW selection of a recalled message, but can't retroactively un-select one recalled
+    // mid-session) -- forwarding null content would silently send an empty bubble with a misleading
+    // "forwarded from" tag rather than the message the user actually picked.
+    const sources = orderedSeqs
+      .map((seq) => topic.findMessage(seq))
+      .filter((msg): msg is StoredMessage => !!msg && !isRecalled(msg))
+      .map((msg) => ({ topic: topicId, seq: msg.seq as number }));
+    // One REST call now covers every (source, target) pair -- forwardMessages()'s own comment
+    // explains why this replaced per-target `ensureTopicAttached()` + per-message client-side
+    // `{pub}` publishes (was N sources x M targets separate WS sends, each independently racing
+    // subscription/attachment; the server handles every pair in one request with real per-pair
+    // success/failure reporting instead of each WS publish failing silently on its own).
+    if (sources.length > 0) {
+      forwardMessages(sources, targetTopics)
+        .then((res) => {
+          if (res.failed.length > 0) showError(undefined, `${res.failed.length} 条消息转发失败`);
         })
         .catch((err) => showError(err, '转发失败'));
     }
+    // Comment stays on the OLD client-side path deliberately -- see forwardMessages()'s own comment
+    // on why (preserves this app's existing "comment appears AFTER the forwarded messages" order,
+    // which the endpoint's own built-in comment field does not).
+    if (comment) {
+      for (const targetTopic of targetTopics) {
+        ensureTopicAttached(targetTopic)
+          .then((target) => sendText(target, comment))
+          .catch((err) => showError(err, '附言发送失败'));
+      }
+    }
     setBulkForwardOpen(false);
     exitSelectMode();
   };
@@ -1218,14 +1229,23 @@ export function ConversationView() {
         <ForwardPickerModal
           onClose={() => setForwardMsg(null)}
           onPick={(targetTopics, comment) => {
-            for (const targetTopic of targetTopics) {
-              ensureTopicAttached(targetTopic)
-                .then((target) => {
-                  forwardMessage(topicId, forwardMsg, target).catch((err) => showError(err, '转发失败'));
-                  if (comment) sendText(target, comment).catch((err) => showError(err, '附言发送失败'));
+            if (typeof forwardMsg.seq === 'number') {
+              forwardMessages([{ topic: topicId, seq: forwardMsg.seq }], targetTopics)
+                .then((res) => {
+                  if (res.failed.length > 0) showError(undefined, `${res.failed.length} 个目标转发失败`);
                 })
                 .catch((err) => showError(err, '转发失败'));
             }
+            // Comment stays on the OLD client-side path deliberately -- see forwardMessages()'s own
+            // comment in lib/api/messages.ts on why (preserves the existing "comment appears AFTER
+            // the forwarded message" order).
+            if (comment) {
+              for (const targetTopic of targetTopics) {
+                ensureTopicAttached(targetTopic)
+                  .then((target) => sendText(target, comment))
+                  .catch((err) => showError(err, '附言发送失败'));
+              }
+            }
             setForwardMsg(null);
           }}
         />