fix(showcase): use uuid explicit thread demo id

Author: marthakelly

showcase/integrations/langgraph-python/qa/threadid-frontend-tool-roundtrip.md

@@ -16,8 +16,12 @@ thread active across a frontend tool call and follow-up run.
       `label: X` and `result: handled X`.
 - [ ] Verify the assistant reply `Frontend tool finished for X.` appears.
 - [ ] Verify the chat does not return to the empty state.
-- [ ] Check `Explicit threadId`, send the same prompt again, and verify the
-      same message/tool/reply persistence behavior.
+- [ ] Refresh the page or open a new tab, check `Explicit threadId` before
+      sending any message, send the same prompt again, and verify the same
+      message/tool/reply persistence behavior.
+- [ ] Optionally toggle `Explicit threadId` after a generated-thread
+      conversation and verify the chat switches to the explicit thread's
+      history. An empty explicit thread on first use is expected.
 
 ## Automated Coverage
 

showcase/integrations/langgraph-python/src/app/demos/threadid-frontend-tool-roundtrip/page.tsx

@@ -10,7 +10,7 @@ import {
 import { z } from "zod";
 
 const AGENT_ID = "threadid-frontend-tool-roundtrip";
-const FIXED_THREAD_ID = "ent-658-explicit-thread";
+const FIXED_THREAD_ID = "a9e7e9c4-6c72-4b8a-9d74-c5c0e05f6580";
 
 function ThreadIdRoundTripChat() {
   const [explicitThreadId, setExplicitThreadId] = useState(false);