fix: drain initial message sync before polling

tauri/src/main.ts

@@ -152,13 +152,37 @@ async function syncLoop(): Promise<void> {
   polling = true;
   while (session.active) {
     try {
-      const response = await fetch(api("/messages/sync"), { method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ channel_id: session.channelID, channel_type: session.channelType, login_uid: session.uid, start_message_seq: session.lastSeq === 0 ? 0 : session.lastSeq + 1, limit: 50 }) });
+      // WuKongIM's legacy sync endpoint can return a single retained message
+      // per request even when `more` is 0.  Drain until it is empty before
+      // switching to the paced live-polling loop; otherwise a reopened chat
+      // with history needs minutes to reach the latest Agent response.
+      while (session.active) {
+        const startMessageSeq = session.lastSeq === 0 ? 0 : session.lastSeq + 1;
+        const response = await fetch(api("/messages/sync"), { method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ channel_id: session.channelID, channel_type: session.channelType, login_uid: session.uid, start_message_seq: startMessageSeq, limit: 50 }) });
         const body = await response.json().catch(() => ({})) as { error?: string; messages?: SyncedMessage[] };
         if (!response.ok) throw new Error(body.error || "同步失败");
-      for (const message of body.messages ?? []) {
+
+        const synced = body.messages ?? [];
+        if (synced.length === 0) {
+          setPresence("已同步，等待消息");
+          break;
+        }
+
+        let advanced = false;
+        for (const message of synced) {
+          const previousSeq = session.lastSeq;
           session.lastSeq = Math.max(session.lastSeq, message.message_seq);
+          advanced ||= session.lastSeq > previousSeq;
           if (message.from_uid !== session.uid) render(decodeConversationItem(decodeBase64(message.payload)));
         }
+
+        // Avoid a hot loop if an upstream response repeats a sequence that
+        // cannot advance the local cursor.
+        if (!advanced) {
+          setPresence("已同步，等待消息");
+          break;
+        }
+      }
     } catch {
       if (session.active) setPresence("同步中断，正在重试…");
     }