Improve invite handling

tests/invites.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from "vitest";
+import { inviteExpiresAt, isInviteExpired } from "../src/lib/invites";
+
+const now = Date.UTC(2026, 0, 1);
+const day = 24 * 60 * 60 * 1000;
+
+describe("inviteExpiresAt", () => {
+  it("returns null for invalid or non-expiring values", () => {
+    expect(inviteExpiresAt(null, now)).toBeNull();
+    expect(inviteExpiresAt("0", now)).toBeNull();
+    expect(inviteExpiresAt("-3", now)).toBeNull();
+    expect(inviteExpiresAt("not-a-number", now)).toBeNull();
+  });
+
+  it("creates an expiration date for valid day counts", () => {
+    expect(inviteExpiresAt("7", now)?.getTime()).toBe(now + 7 * day);
+  });
+
+  it("caps expiration at one year", () => {
+    expect(inviteExpiresAt("9999", now)?.getTime()).toBe(now + 365 * day);
+  });
+
+  it("detects expired invite timestamps", () => {
+    expect(isInviteExpired(new Date(now - day), now)).toBe(true);
+    expect(isInviteExpired(new Date(now + day), now)).toBe(false);
+    expect(isInviteExpired(null, now)).toBe(false);
+  });
+});