chore: import upstream snapshot with attribution

showcase/integrations/langgraph-python/tests/e2e/threadid-frontend-tool-roundtrip.spec.ts

@@ -0,0 +1,27 @@
+import { test, expect } from "@playwright/test";
+
+// QA reference: qa/threadid-frontend-tool-roundtrip.md
+// Demo source: src/app/demos/threadid-frontend-tool-roundtrip/page.tsx
+//
+// The source-level regression for ENT-658 lives in react-core. This smoke keeps
+// the showcase demo route and generated-thread toggle covered without depending
+// on fixture-driven tool execution in the standalone showcase package.
+
+test.describe("Thread ID frontend-tool round trip", () => {
+  test.beforeEach(async ({ page }) => {
+    await page.goto("/demos/threadid-frontend-tool-roundtrip");
+  });
+
+  test("page loads with generated-thread mode selected", async ({ page }) => {
+    await expect(page.getByPlaceholder("Type a message")).toBeVisible();
+    await expect(page.getByLabel("Explicit threadId")).not.toBeChecked();
+    await expect(page.getByTestId("ent-658-thread-mode")).toHaveText(
+      /SDK-generated thread/i,
+    );
+
+    await page.getByLabel("Explicit threadId").check();
+    await expect(page.getByTestId("ent-658-thread-mode")).toHaveText(
+      /explicit thread/i,
+    );
+  });
+});