refactor(examples-chat): onTimelineFork uses ThreadsService.create()

[blove]

Summary

Last remaining raw-fetch call against LangGraph in the example shell. ThreadsService.create() already does the same POST /threads through @langchain/langgraph-sdk's Client (added in Phase 3b) and returns the new thread id.

This closes out the SDK-audit follow-up tracked from Phase 3b — the codebase now uses the SDK Client uniformly for every thread CRUD operation.

 async onTimelineFork(checkpointId: string): Promise<void> {
-  await fetch('http://localhost:2024/threads', {
-    method: 'POST',
-    headers: { 'Content-Type': 'application/json' },
-    body: '{}',
-  })
-    .then((r) => r.json())
-    .then((t: { thread_id: string }) => {
-      this.threadIdSignal.set(t.thread_id);
-      this.persistence.write('threadId', t.thread_id);
-      void this.agent.submit(null as never, { checkpointId } as never);
-    });
+  const id = await this.threadsSvc.create();
+  if (!id) return;
+  this.threadIdSignal.set(id);
+  this.persistence.write('threadId', id);
+  void this.agent.submit(null as never, { checkpointId } as never);
 }

Test plan

• nx run examples-chat-angular:build — clean
• Live timeline-fork behavior: requires exercising the chat-debug timeline replay flow (deeper UI). Functionally equivalent to existing "New chat" path which uses the same ThreadsService.create() and is exercised every session.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
cacheplane	Ready	Preview, Comment	May 12, 2026 10:51pm