diff --git a/test/leaderboard-cache.test.ts b/test/leaderboard-cache.test.ts
new file mode 100644
index 00000000..386f7614
--- /dev/null
+++ b/test/leaderboard-cache.test.ts
@@ -0,0 +1,90 @@
+import { describe, it, expect } from "vitest";
+import { pruneExpiredLeaderboardCache, pruneExpiredRateLimits } from "../src/lib/leaderboard-cache";
+
+describe("pruneExpiredRateLimits", () => {
+  it("removes only expired IP buckets", () => {
+    const buckets = new Map([
+      ["expired", { count: 20, resetAt: 1_000 }],
+      ["active", { count: 2, resetAt: 5_000 }],
+    ]);
+
+    pruneExpiredRateLimits(buckets, 2_000);
+
+    expect(buckets.has("expired")).toBe(false);
+    expect(buckets.get("active")).toEqual({ count: 2, resetAt: 5_000 });
+  });
+});
+
+describe("pruneExpiredLeaderboardCache", () => {
+  it("clears stale leaderboard payloads", () => {
+    const cache = {
+      expiresAt: 1_000,
+      payload: { ok: true },
+    };
+
+    expect(pruneExpiredLeaderboardCache(cache, 1_001)).toBe(null);
+  });
+
+  it("keeps fresh leaderboard payloads", () => {
+    const cache = {
+      expiresAt: 2_000,
+      payload: { ok: true },
+    };
+
+    expect(pruneExpiredLeaderboardCache(cache, 1_999)).toBe(cache);
+  });
+
+  it("expires entry exactly at boundary timestamp", () => {
+    const cache = {
+      expiresAt: 1_000,
+      payload: { data: "test" },
+    };
+
+    expect(pruneExpiredLeaderboardCache(cache, 1_000)).toBe(null);
+  });
+
+  it("handles entry expiring 1ms before current", () => {
+    const cache = {
+      expiresAt: 999,
+      payload: { data: "almost-expired" },
+    };
+
+    expect(pruneExpiredLeaderboardCache(cache, 1_000)).toBe(null);
+  });
+
+  it("handles null entry", () => {
+    expect(pruneExpiredLeaderboardCache(null)).toBe(null);
+    expect(pruneExpiredLeaderboardCache(null, 500)).toBe(null);
+  });
+
+  it("keeps entry with far future expiry", () => {
+    const now = Date.now();
+    const cache = {
+      expiresAt: now + 86400000,
+      payload: { data: "future" },
+    };
+
+    expect(pruneExpiredLeaderboardCache(cache, now)).toEqual(cache);
+  });
+
+  it("works with different generic types", () => {
+    const now = Date.now();
+    const stringCache = {
+      expiresAt: now + 1000,
+      payload: "string data",
+    };
+    expect(pruneExpiredLeaderboardCache(stringCache, now)).toBe(stringCache);
+
+    const numberCache = {
+      expiresAt: now + 1000,
+      payload: 42,
+    };
+    expect(pruneExpiredLeaderboardCache(numberCache, now)).toBe(numberCache);
+
+    const arrayCache = {
+      expiresAt: now + 1000,
+      payload: [1, 2, 3],
+    };
+    expect(pruneExpiredLeaderboardCache(arrayCache, now)).toEqual(arrayCache);
+  });
+});
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