fix(ui): show embedded subagent history while visibility stays inactive

Busy context-panel session chats could render only the working-status row
when the iframe booted inactive or lost its visibility handshake, because
message reads shared the composer/background-work gate. Keep message
subscriptions enabled in the mounted session-chat panel so materialized
history remains visible (#2903, #2892).

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/components/views/ChatView.tsx

@@ -5,17 +5,29 @@ import { useSessionUIStore } from '@/sync/session-ui-store';
 
 type ChatViewProps = {
     active?: boolean;
+    /**
+     * Controls message-history subscription independently of `active`.
+     * Embedded session-chat panels keep this true so history stays visible
+     * while composer focus / background work remain gated by visibility.
+     */
+    messagesEnabled?: boolean;
     readOnly?: boolean;
     initialAllowPromptingSubagentSessions?: boolean;
 };
 
-export const ChatView: React.FC<ChatViewProps> = ({ active = true, readOnly = false, initialAllowPromptingSubagentSessions }) => {
+export const ChatView: React.FC<ChatViewProps> = ({
+    active = true,
+    messagesEnabled,
+    readOnly = false,
+    initialAllowPromptingSubagentSessions,
+}) => {
     const currentSessionId = useSessionUIStore((state) => state.currentSessionId);
 
     return (
         <ChatErrorBoundary sessionId={currentSessionId || undefined}>
             <ChatContainer
                 active={active}
+                messagesEnabled={messagesEnabled}
                 readOnly={readOnly}
                 initialAllowPromptingSubagentSessions={initialAllowPromptingSubagentSessions}
             />