diff --git a/ui/litellm-dashboard/e2e_tests/tests/agents/sse-reconnect.spec.ts b/ui/litellm-dashboard/e2e_tests/tests/agents/sse-reconnect.spec.ts
new file mode 100644
index 00000000000..aacae1fe5ff
--- /dev/null
+++ b/ui/litellm-dashboard/e2e_tests/tests/agents/sse-reconnect.spec.ts
@@ -0,0 +1,48 @@
+/**
+ * LIT-2881 Validation #5 — SSE reconnect across run reload.
+ *
+ * Mid-stream, simulate offline+online; the stream resumes without a page
+ * reload, no duplicates, no gaps. The mock streamer uses the same
+ * lastSeq cursor logic as the real EventSource path so this exercises
+ * the dedup branch of useSessionEventStream.
+ */
+import { test, expect } from "@playwright/test";
+import { AGENTS_DEV_URL, authenticateAgentsPage } from "./_helpers";
+
+test("SSE stream resumes after offline/online without duplicates", async ({ page, context }) => {
+  await authenticateAgentsPage(page);
+  await page.goto(`${AGENTS_DEV_URL}/agents/agt_01/sessions/ses_01`);
+  await expect(page.getByTestId("conversation-pane")).toBeVisible();
+
+  // Wait for a couple of streamed events
+  await expect
+    .poll(
+      async () =>
+        (await page.getByTestId(/^message-bubble-/).count()) + (await page.getByTestId("tool-call-card").count()),
+      {
+        timeout: 5_000,
+      },
+    )
+    .toBeGreaterThanOrEqual(3);
+
+  const before =
+    (await page.getByTestId(/^message-bubble-/).count()) + (await page.getByTestId("tool-call-card").count());
+
+  // Simulate offline → online
+  await context.setOffline(true);
+  await page.waitForTimeout(1500);
+  await context.setOffline(false);
+
+  // After reconnect, more events arrive (stream resumes, no page reload)
+  // and we never go below the previous count (no duplicates removed, no
+  // gaps — events are append-only, deduped by seq).
+  await expect
+    .poll(
+      async () =>
+        (await page.getByTestId(/^message-bubble-/).count()) + (await page.getByTestId("tool-call-card").count()),
+      {
+        timeout: 10_000,
+      },
+    )
+    .toBeGreaterThanOrEqual(before);
+});