feat(agent): enhance Codex reasoning summary with Markdown rendering and improve message history merging

web/src/components/agent/agent-chat-message.tsx

@@ -121,7 +121,9 @@ function AgentReasoningSummary({ text, detail, theme }: { text: string; detail?:
                     <ChevronRight className="size-3.5 shrink-0 transition-transform group-open:rotate-90" />
                 </div>
             </summary>
-            <div className="whitespace-pre-wrap break-words pb-1 pl-6 pr-2 text-xs leading-5" style={{ color: theme.node.muted }}>{text}</div>
+            <div className="break-words pb-1 pl-6 pr-2 text-xs leading-5 [&_code]:rounded [&_code]:px-1 [&_p]:my-1 [&_pre]:my-2" style={{ color: theme.node.muted }}>
+                <Streamdown animated isAnimating={running}>{text}</Streamdown>
+            </div>
         </details>
     );
 }

web/src/components/agent/agent-event-formatters.ts

@@ -487,3 +487,15 @@ export function mergeHistoryAttachments(messages: AgentChatItem[], currentMessag
         })
         .reverse();
 }
+
+export function mergeHistoryMessages(historyMessages: AgentChatItem[], currentMessages: AgentChatItem[]) {
+    if (!currentMessages.length) return historyMessages;
+    const remaining = [...historyMessages];
+    const messages = currentMessages.map((current) => {
+        const index = remaining.findIndex((history) => history.id === current.id || ((current.role === "user" || current.role === "assistant") && history.role === current.role && history.text === current.text));
+        if (index < 0) return current;
+        const history = remaining.splice(index, 1)[0];
+        return { ...current, ...history, id: current.id, attachments: current.attachments || history.attachments };
+    });
+    return [...messages, ...remaining];
+}

web/src/components/agent/local-agent-panel.tsx

@@ -38,6 +38,7 @@ import {
     isConnectionErrorMessage,
     isCurrentThreadEvent,
     mergeHistoryAttachments,
+    mergeHistoryMessages,
     mergeAgentText,
     normalizeHistoryMessages,
     normalizeText,
@@ -131,7 +132,8 @@ export function LocalAgentPanel({ embedded, headless, autoConnect }: { embedded?
                 let thread = await currentThreadRequest;
                 thread ||= await fetchAgentJson<AgentThreadResponse>(endpoint, token, `/agent/codex/threads/${encodeURIComponent(currentThreadId)}`);
                 const storedMessages = (await storedMessagesRequest) || [];
-                nextMessages = mergeHistoryAttachments(normalizeHistoryMessages(thread.messages || []), [...storedMessages, ...useAgentStore.getState().messages]);
+                const currentMessages = useAgentStore.getState().messages;
+                nextMessages = mergeHistoryMessages(mergeHistoryAttachments(normalizeHistoryMessages(thread.messages || []), [...storedMessages, ...currentMessages]), currentMessages);
             }
             if (sequence !== loadThreadsSequenceRef.current) return;
             setAgentState({ threads: data.data || [], workspacePath: data.workspace?.workspacePath || "", ...(skipHistory ? {} : { messages: nextMessages }) });