diff --git a/ui/src/hooks/useIssueExternalObjects.test.ts b/ui/src/hooks/useIssueExternalObjects.test.ts
new file mode 100644
index 00000000000..0dc3f0e06ea
--- /dev/null
+++ b/ui/src/hooks/useIssueExternalObjects.test.ts
@@ -0,0 +1,48 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import type { ExternalObjectSummary } from "@paperclipai/shared";
+import { externalObjectsApi } from "../api/externalObjects";
+import {
+  EXTERNAL_OBJECT_SUMMARY_BATCH_SIZE,
+  fetchIssueExternalObjectSummariesInBatches,
+} from "./useIssueExternalObjects";
+
+vi.mock("../api/externalObjects", () => ({
+  externalObjectsApi: {
+    getIssueSummaries: vi.fn(),
+  },
+}));
+
+const emptySummary: ExternalObjectSummary = {
+  total: 0,
+  byStatusCategory: {},
+  byLiveness: {},
+  highestSeverity: "neutral",
+  objects: [],
+};
+
+describe("fetchIssueExternalObjectSummariesInBatches", () => {
+  afterEach(() => {
+    vi.mocked(externalObjectsApi.getIssueSummaries).mockReset();
+  });
+
+  it("chunks bulk summary requests below the server validation cap and merges results", async () => {
+    const issueIds = Array.from(
+      { length: EXTERNAL_OBJECT_SUMMARY_BATCH_SIZE * 2 + 3 },
+      (_entry, index) => `issue-${index}`,
+    );
+    vi.mocked(externalObjectsApi.getIssueSummaries).mockImplementation(async (_companyId, ids) => ({
+      summaries: Object.fromEntries(ids.map((id) => [id, { ...emptySummary, total: id.endsWith("-0") ? 1 : 0 }])),
+    }));
+
+    const result = await fetchIssueExternalObjectSummariesInBatches("company-1", issueIds);
+
+    expect(externalObjectsApi.getIssueSummaries).toHaveBeenCalledTimes(3);
+    expect(vi.mocked(externalObjectsApi.getIssueSummaries).mock.calls.map((call) => call[1].length)).toEqual([
+      EXTERNAL_OBJECT_SUMMARY_BATCH_SIZE,
+      EXTERNAL_OBJECT_SUMMARY_BATCH_SIZE,
+      3,
+    ]);
+    expect(Object.keys(result.summaries)).toHaveLength(issueIds.length);
+    expect(result.summaries["issue-0"]?.total).toBe(1);
+  });
+});
diff --git a/ui/src/hooks/useIssueExternalObjects.ts b/ui/src/hooks/useIssueExternalObjects.ts
index 3e1a9bf4648..8f8052afb0d 100644
--- a/ui/src/hooks/useIssueExternalObjects.ts
+++ b/ui/src/hooks/useIssueExternalObjects.ts
@@ -12,6 +12,21 @@ import type { MarkdownExternalReferenceMap } from "../components/MarkdownBody";
 import type { ExternalObjectPillData } from "../components/ExternalObjectPill";
 import { instanceSettingsApi } from "../api/instanceSettings";
 
+export const EXTERNAL_OBJECT_SUMMARY_BATCH_SIZE = 500;
+
+export async function fetchIssueExternalObjectSummariesInBatches(
+  companyId: string,
+  issueIds: readonly string[],
+) {
+  const summaries: Record<string, ExternalObjectSummary> = {};
+  for (let index = 0; index < issueIds.length; index += EXTERNAL_OBJECT_SUMMARY_BATCH_SIZE) {
+    const batch = issueIds.slice(index, index + EXTERNAL_OBJECT_SUMMARY_BATCH_SIZE);
+    const response = await externalObjectsApi.getIssueSummaries(companyId, batch);
+    Object.assign(summaries, response.summaries);
+  }
+  return { summaries };
+}
+
 /**
  * Browser-side mention-source label. Keep in sync with the shared formatter
  * without coupling this hook to the server-only URL canonicalization helpers.
@@ -201,7 +216,7 @@ export function useIssueExternalObjectSummaries(
   const enabled = externalObjectsFeature.isEnabled && Boolean(companyId) && normalizedIssueIds.length > 0;
   const query = useQuery({
     queryKey: queryKeys.externalObjects.issueSummaries(companyId ?? "__none__", normalizedIssueIds),
-    queryFn: () => externalObjectsApi.getIssueSummaries(companyId!, normalizedIssueIds),
+    queryFn: () => fetchIssueExternalObjectSummariesInBatches(companyId!, normalizedIssueIds),
     enabled,
     staleTime: 60_000,
   });