наверное работает

shine-UI/js/pages/chat-view.js

@@ -7,6 +7,7 @@ import {
   getChatMessages,
   markChatRead,
   markOutgoingSent,
+  markReadReceiptSentByBaseKey,
   authService,
   state,
 } from '../state.js';
@@ -33,10 +34,10 @@ function renderLog(list, chatId) {
   messages.forEach((msg) => {
     if (!unreadSeparatorInserted && msg?.from === 'in' && msg?.unread) {
       const sep = document.createElement('div');
-      sep.className = 'meta-muted';
-      sep.style.textAlign = 'center';
-      sep.style.margin = '8px 0';
-      sep.textContent = 'Новые сообщения';
+      sep.className = 'chat-unread-separator';
+      const label = document.createElement('span');
+      label.textContent = 'Новые сообщения';
+      sep.append(label);
       list.append(sep);
       unreadSeparatorInserted = true;
     }
@@ -216,7 +217,11 @@ async function sendReadReceiptsForVisible(chatId) {
         refNonce: ref.nonce,
         refType: 1,
       });
-      row.readReceiptSent = true;
+      if (row.baseKey) {
+        markReadReceiptSentByBaseKey(row.baseKey);
+      } else {
+        row.readReceiptSent = true;
+      }
     } catch (e) {
       addAppLogEntry({
         level: 'warn',