fix: deduplicate messages and UI cards when streamSubgraphs is true

With streamSubgraphs:true, subgraph values events push messages that
the parent Supervisor later merges, causing the same message.id to
appear multiple times in thread.messages. Similarly, the same card_id
can appear in both subgraph and parent values snapshots.

- Add deduplicateMessages() at module level: keeps the last (most
  up-to-date) copy per message.id, eliminating duplicate AI messages
  caused by subgraph-then-parent merge events.
- Apply deduplicateUiItems() to the full allUi array before per-message
  card matching, so loading→done card pairs pushed by subgraphs and
  parent are collapsed globally before orphan attribution runs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

langgraph/src/main.tsx

@@ -73,6 +73,16 @@ function deduplicateUiItems(items: UIMsgLocal[]): UIMsgLocal[] {
   });
 }
 
+// ─── Message deduplication by id ────────────────────────────────────────────
+// With streamSubgraphs:true, subgraph values events push messages that the
+// parent graph later merges. The same message.id can appear multiple times in
+// thread.messages. Keep only the last (most up-to-date) copy per id.
+function deduplicateMessages(msgs: Message[]): Message[] {
+  const seen = new Map<string, number>();
+  msgs.forEach((m, i) => { if (m.id) seen.set(m.id, i); });
+  return msgs.filter((m, i) => !m.id || seen.get(m.id) === i);
+}
+
 // ─── Tool groups ────────────────────────────────────────────────────────────
 const TOOL_GROUPS = [
   { key: "knowledge", label: "知识库", icon: BookOpen, tools: ["kb_search"] },
@@ -551,12 +561,13 @@ function App() {
   if (thread.messages.length > 0) {
     lastMessagesRef.current = thread.messages;
   }
-  const activeMessages: Message[] =
+  const activeMessages: Message[] = deduplicateMessages(
     thread.messages.length > 0
       ? thread.messages
       : lastMessagesRef.current.length > 0
         ? lastMessagesRef.current
-        : historicalMessages;
+        : historicalMessages
+  );
 
   // ── Collect completed tool call IDs ─────────────────────────────────────
   const completedToolIds = new Set(
@@ -677,11 +688,16 @@ function App() {
           )}
 
           {activeMessages.map((message, idx) => {
-            // Render UI cards attached to this message
+            // Render UI cards attached to this message.
+            // Apply deduplicateUiItems to the full ui array first so that cards
+            // pushed by both subgraph and parent-graph values events (same card_id)
+            // are collapsed before any per-message matching logic runs.
             // eslint-disable-next-line @typescript-eslint/no-explicit-any
-            const allUi: UIMsgLocal[] = thread.messages.length > 0
+            const allUi: UIMsgLocal[] = deduplicateUiItems(
+              thread.messages.length > 0
                 ? ((thread.values as any)?.ui ?? [])
-              : historicalUi;
+                : historicalUi
+            );
             // Match UI items by message_id; for subgraph messages where IDs
             // may not align, fallback: distribute orphaned cards by tool name.
             let matchedUi = allUi.filter(