frontend phase 15

client/src/services/payouts/hooks/usePreviewPayoutBatch.ts

@@ -0,0 +1,15 @@
+import { useMutation } from '@tanstack/react-query';
+import { payoutsApi } from '../apis';
+import type { PayoutBatchPreview } from '../types';
+
+/**
+ * The eligibility dry-run for a window — a **mutation**, not an auto-fetching query: it runs only when the
+ * admin explicitly asks to preview (never on mount), and its result (the eligible/skipped breakdown + the
+ * server's holiday-shifted processing date) is read from the mutation's `data`. The client renders it; it
+ * never computes eligibility or the shifted date.
+ */
+export function usePreviewPayoutBatch() {
+  return useMutation<PayoutBatchPreview, unknown, { periodStart: string; periodEnd: string }>({
+    mutationFn: ({ periodStart, periodEnd }) => payoutsApi.previewPayoutBatch(periodStart, periodEnd),
+  });
+}