diff --git a/lib/jobs-time-filter.ts b/lib/jobs-time-filter.ts
new file mode 100644
index 0000000..405248e
--- /dev/null
+++ b/lib/jobs-time-filter.ts
@@ -0,0 +1,21 @@
+export const JOBS_TIME_FILTER_VALUES = ['1h', '24h', 'all'] as const;
+
+export type JobsTimeFilter = (typeof JOBS_TIME_FILTER_VALUES)[number];
+
+export const DEFAULT_JOBS_TIME_FILTER: JobsTimeFilter = 'all';
+
+const WINDOW_MS: Record<'1h' | '24h', number> = {
+  '1h': 60 * 60 * 1000,
+  '24h': 24 * 60 * 60 * 1000,
+};
+
+export function isWithinTimeWindow(
+  createdAt: Date | string,
+  filter: JobsTimeFilter,
+  now: number = Date.now(),
+): boolean {
+  if (filter === 'all') return true;
+  const ts = new Date(createdAt).getTime();
+  if (Number.isNaN(ts)) return true;
+  return ts >= now - WINDOW_MS[filter];
+}